add web server sample

Bumps [golang.org/x/image](https://github.com/golang/image) from 0.12.0 to 0.18.0.
- [Commits](https://github.com/golang/image/compare/v0.12.0...v0.18.0)

---
updated-dependencies:
- dependency-name: golang.org/x/image
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: "Continuous Integration"
+
+on:
+  workflow_dispatch:
+  push:
+    branches: [ main ]
+    paths: [ "*.go" ]
+  pull_request:
+    branches: [ main ]
+    paths: [ "*.go" ]
+
+jobs:
+  ci:
+    name: "Tests"
+    runs-on: ubuntu-latest
+
+    env:
+      GOOS: "linux"
+      GOARCH: "amd64"
+      GO111MODULE: "on"
+      CGO_ENABLED: "0"
+
+    steps:
+    - name: Set up Go
+      uses: actions/setup-go@v3
+      with:
+        go-version: 1.21
+
+    - name: Check out go-incr
+      uses: actions/checkout@v3
+
+    - name: Run all tests
+      run: go test ./...

.gitignore

@@ -1 +1,20 @@
+# Binaries for programs and plugins
+*.exe
+*.dll
+*.so
+*.dylib
+
+# Test binary, build with `go test -c`
+*.test
+
+# Output of the go coverage tool, specifically when used with LiteIDE
+*.out
+
+# Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
+.glide/
+
+# Other
 .vscode
+.DS_Store
+coverage.html
+.idea

.travis.yml

@@ -1,13 +0,0 @@
-language: go
-
-go:
-  - 1.6.2
-
-sudo: false
-
-before_script:
-  - go get -u github.com/blendlabs/go-assert
-  - go get ./...
-
-script:
-  - go test ./...

COVERAGE

@@ -0,0 +1 @@
+29.02

LICENSE

@@ -1,6 +1,7 @@
 MIT License
 
 Copyright (c) 2016 William Charczuk.
+Copyright (c) 2024 Zeni Kim.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -1,9 +1,10 @@
-all: test
+all: new-install test
+
+new-install:
+	@go get -v -u ./...
+
+generate:
+	@go generate ./...
 
 test:
-	@go test ./...
-
-cover:
-	@go test -short -covermode=set -coverprofile=profile.cov
-	@go tool cover -html=profile.cov
-	@rm profile.cov
+	@go test ./...

PROFANITY_RULES.yml

@@ -0,0 +1,4 @@
+go-sdk:
+  excludeFiles: [ "*_test.go" ]
+  importsContain: [ github.com/blend/go-sdk/* ]
+  description: "please don't use go-sdk in this repo"

README.md

@@ -1,55 +1,55 @@
 go-chart
 ========
-[![Build Status](https://travis-ci.org/wcharczuk/go-chart.svg?branch=master)](https://travis-ci.org/wcharczuk/go-chart)[![Go Report Card](https://goreportcard.com/badge/github.com/wcharczuk/go-chart)](https://goreportcard.com/report/github.com/wcharczuk/go-chart)
 
-Package `chart` is a very simple golang native charting library that supports timeseries and continuous
-line charts. 
+This project starts from a full copy from [https://git.smarteching.com/zeni/go-chart](https://git.smarteching.com/zeni/go-chart). 28 Oct 2024.
 
-The v1.0 release has been tagged so things should be more or less stable, if something changes please log an issue.
+-
 
-Master should now be on the v2.x codebase, which brings a couple new features and better handling of basics like axes labeling etc. Per usual, see `_examples` for more information.
+Master should now be on the v3.x codebase, which overhauls the api significantly. Per usual, see `examples` for more information.
 
 # Installation
 
 To install `chart` run the following:
 
 ```bash
-> go get -u github.com/wcharczuk/go-chart
+> go get git.smarteching.com/zeni/go-chart/v2@latest
 ```
 
-Most of the components are interchangeable so feel free to crib whatever you want. 
+Most of the components are interchangeable so feel free to crib whatever you want.
 
-# Output Examples 
+# Output Examples
 
 Spark Lines:
 
-![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/_images/tvix_ltm.png)
+![](https://git.smarteching.com/zeni/go-chart/raw/branch/main/_images/tvix_ltm.png)
 
 Single axis:
 
-![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/_images/goog_ltm.png)
+![](https://git.smarteching.com/zeni/go-chart/raw/branch/main/_images/goog_ltm.png)
 
 Two axis:
 
-![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/_images/two_axis.png)
+![](https://git.smarteching.com/zeni/go-chart/raw/branch/main/_images/two_axis.png)
 
 # Other Chart Types
 
 Pie Chart:
 
-![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/_images/pie_chart.png)
+![](https://git.smarteching.com/zeni/go-chart/raw/branch/main/_images/pie_chart.png)
 
-The code for this chart can be found in `_examples/pie_chart/main.go`.
+The code for this chart can be found in `examples/pie_chart/main.go`.
 
 Stacked Bar:
 
-![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/_images/stacked_bar.png)
+![](https://git.smarteching.com/zeni/go-chart/raw/branch/main/_images/stacked_bar.png)
 
-The code for this chart can be found in `_examples/stacked_bar/main.go`.
+The code for this chart can be found in `examples/stacked_bar/main.go`.
 
 # Code Examples
 
-Actual chart configurations and examples can be found in the `./_examples/` directory. They are web servers, so start them with `go run main.go` then access `http://localhost:8080` to see the output.
+Actual chart configurations and examples can be found in the `./examples/` directory. They are simple CLI programs that write to `output.png` (they are also updated with `go generate`.
+
+If folder ends in "web", has web servers, so start them with `go run main.go` then access `http://localhost:8080` to see the output.
 
 # Usage
 
@@ -61,7 +61,7 @@ import (
     ...
     "bytes"
     ...
-    "github.com/wcharczuk/go-chart" //exposes "chart"
+    "git.smarteching.com/zeni/go-chart/v2" //exposes "chart"
 )
 
 graph := chart.Chart{
@@ -83,8 +83,7 @@ Here, we have a single series with x range values as float64s, rendered to a PNG
 
 # API Overview
 
-Everything on the `chart.Chart` object has defaults that can be overriden. Whenever a developer sets a property on the chart object, it is to be assumed that value will be used instead of the default. One complication here
-is any object's root `chart.Style` object (i.e named `Style`) and the `Show` property specifically, if any other property is set and the `Show` property is unset, it is assumed to be it's default value of `False`.
+Everything on the `chart.Chart` object has defaults that can be overriden. Whenever a developer sets a property on the chart object, it is to be assumed that value will be used instead of the default.
 
 The best way to see the api in action is to look at the examples in the `./_examples/` directory.
 
@@ -96,4 +95,4 @@ The goal with the API itself is to have the "zero value be useful", and to requi
 
 # Contributions
 
-This library is super early but contributions are welcome.
+Contributions are welcome though this library is in a holding pattern for the forseable future.

_colors/colors_extended.txt

@@ -0,0 +1,147 @@
+aliceblue 	#f0f8ff 	240,248,255
+antiquewhite 	#faebd7 	250,235,215
+aqua 	#00ffff 	0,255,255
+aquamarine 	#7fffd4 	127,255,212
+azure 	#f0ffff 	240,255,255
+beige 	#f5f5dc 	245,245,220
+bisque 	#ffe4c4 	255,228,196
+black 	#000000 	0,0,0
+blanchedalmond 	#ffebcd 	255,235,205
+blue 	#0000ff 	0,0,255
+blueviolet 	#8a2be2 	138,43,226
+brown 	#a52a2a 	165,42,42
+burlywood 	#deb887 	222,184,135
+cadetblue 	#5f9ea0 	95,158,160
+chartreuse 	#7fff00 	127,255,0
+chocolate 	#d2691e 	210,105,30
+coral 	#ff7f50 	255,127,80
+cornflowerblue 	#6495ed 	100,149,237
+cornsilk 	#fff8dc 	255,248,220
+crimson 	#dc143c 	220,20,60
+cyan 	#00ffff 	0,255,255
+darkblue 	#00008b 	0,0,139
+darkcyan 	#008b8b 	0,139,139
+darkgoldenrod 	#b8860b 	184,134,11
+darkgray 	#a9a9a9 	169,169,169
+darkgreen 	#006400 	0,100,0
+darkgrey 	#a9a9a9 	169,169,169
+darkkhaki 	#bdb76b 	189,183,107
+darkmagenta 	#8b008b 	139,0,139
+darkolivegreen 	#556b2f 	85,107,47
+darkorange 	#ff8c00 	255,140,0
+darkorchid 	#9932cc 	153,50,204
+darkred 	#8b0000 	139,0,0
+darksalmon 	#e9967a 	233,150,122
+darkseagreen 	#8fbc8f 	143,188,143
+darkslateblue 	#483d8b 	72,61,139
+darkslategray 	#2f4f4f 	47,79,79
+darkslategrey 	#2f4f4f 	47,79,79
+darkturquoise 	#00ced1 	0,206,209
+darkviolet 	#9400d3 	148,0,211
+deeppink 	#ff1493 	255,20,147
+deepskyblue 	#00bfff 	0,191,255
+dimgray 	#696969 	105,105,105
+dimgrey 	#696969 	105,105,105
+dodgerblue 	#1e90ff 	30,144,255
+firebrick 	#b22222 	178,34,34
+floralwhite 	#fffaf0 	255,250,240
+forestgreen 	#228b22 	34,139,34
+fuchsia 	#ff00ff 	255,0,255
+gainsboro 	#dcdcdc 	220,220,220
+ghostwhite 	#f8f8ff 	248,248,255
+gold 	#ffd700 	255,215,0
+goldenrod 	#daa520 	218,165,32
+gray 	#808080 	128,128,128
+green 	#008000 	0,128,0
+greenyellow 	#adff2f 	173,255,47
+grey 	#808080 	128,128,128
+honeydew 	#f0fff0 	240,255,240
+hotpink 	#ff69b4 	255,105,180
+indianred 	#cd5c5c 	205,92,92
+indigo 	#4b0082 	75,0,130
+ivory 	#fffff0 	255,255,240
+khaki 	#f0e68c 	240,230,140
+lavender 	#e6e6fa 	230,230,250
+lavenderblush 	#fff0f5 	255,240,245
+lawngreen 	#7cfc00 	124,252,0
+lemonchiffon 	#fffacd 	255,250,205
+lightblue 	#add8e6 	173,216,230
+lightcoral 	#f08080 	240,128,128
+lightcyan 	#e0ffff 	224,255,255
+lightgoldenrodyellow 	#fafad2 	250,250,210
+lightgray 	#d3d3d3 	211,211,211
+lightgreen 	#90ee90 	144,238,144
+lightgrey 	#d3d3d3 	211,211,211
+lightpink 	#ffb6c1 	255,182,193
+lightsalmon 	#ffa07a 	255,160,122
+lightseagreen 	#20b2aa 	32,178,170
+lightskyblue 	#87cefa 	135,206,250
+lightslategray 	#778899 	119,136,153
+lightslategrey 	#778899 	119,136,153
+lightsteelblue 	#b0c4de 	176,196,222
+lightyellow 	#ffffe0 	255,255,224
+lime 	#00ff00 	0,255,0
+limegreen 	#32cd32 	50,205,50
+linen 	#faf0e6 	250,240,230
+magenta 	#ff00ff 	255,0,255
+maroon 	#800000 	128,0,0
+mediumaquamarine 	#66cdaa 	102,205,170
+mediumblue 	#0000cd 	0,0,205
+mediumorchid 	#ba55d3 	186,85,211
+mediumpurple 	#9370db 	147,112,219
+mediumseagreen 	#3cb371 	60,179,113
+mediumslateblue 	#7b68ee 	123,104,238
+mediumspringgreen 	#00fa9a 	0,250,154
+mediumturquoise 	#48d1cc 	72,209,204
+mediumvioletred 	#c71585 	199,21,133
+midnightblue 	#191970 	25,25,112
+mintcream 	#f5fffa 	245,255,250
+mistyrose 	#ffe4e1 	255,228,225
+moccasin 	#ffe4b5 	255,228,181
+navajowhite 	#ffdead 	255,222,173
+navy 	#000080 	0,0,128
+oldlace 	#fdf5e6 	253,245,230
+olive 	#808000 	128,128,0
+olivedrab 	#6b8e23 	107,142,35
+orange 	#ffa500 	255,165,0
+orangered 	#ff4500 	255,69,0
+orchid 	#da70d6 	218,112,214
+palegoldenrod 	#eee8aa 	238,232,170
+palegreen 	#98fb98 	152,251,152
+paleturquoise 	#afeeee 	175,238,238
+palevioletred 	#db7093 	219,112,147
+papayawhip 	#ffefd5 	255,239,213
+peachpuff 	#ffdab9 	255,218,185
+peru 	#cd853f 	205,133,63
+pink 	#ffc0cb 	255,192,203
+plum 	#dda0dd 	221,160,221
+powderblue 	#b0e0e6 	176,224,230
+purple 	#800080 	128,0,128
+red 	#ff0000 	255,0,0
+rosybrown 	#bc8f8f 	188,143,143
+royalblue 	#4169e1 	65,105,225
+saddlebrown 	#8b4513 	139,69,19
+salmon 	#fa8072 	250,128,114
+sandybrown 	#f4a460 	244,164,96
+seagreen 	#2e8b57 	46,139,87
+seashell 	#fff5ee 	255,245,238
+sienna 	#a0522d 	160,82,45
+silver 	#c0c0c0 	192,192,192
+skyblue 	#87ceeb 	135,206,235
+slateblue 	#6a5acd 	106,90,205
+slategray 	#708090 	112,128,144
+slategrey 	#708090 	112,128,144
+snow 	#fffafa 	255,250,250
+springgreen 	#00ff7f 	0,255,127
+steelblue 	#4682b4 	70,130,180
+tan 	#d2b48c 	210,180,140
+teal 	#008080 	0,128,128
+thistle 	#d8bfd8 	216,191,216
+tomato 	#ff6347 	255,99,71
+turquoise 	#40e0d0 	64,224,208
+violet 	#ee82ee 	238,130,238
+wheat 	#f5deb3 	245,222,179
+white 	#ffffff 	255,255,255
+whitesmoke 	#f5f5f5 	245,245,245
+yellow 	#ffff00 	255,255,0
+yellowgreen 	#9acd32 	154,205,50

_examples/basic/main.go

@@ -1,43 +0,0 @@
-package main
-
-import (
-	"log"
-	"net/http"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-	graph := chart.Chart{
-		Series: []chart.Series{
-			chart.ContinuousSeries{
-				XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
-				YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
-			},
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func drawChartWide(res http.ResponseWriter, req *http.Request) {
-	graph := chart.Chart{
-		Width: 1920, //this overrides the default.
-		Series: []chart.Series{
-			chart.ContinuousSeries{
-				XValues: []float64{1.0, 2.0, 3.0, 4.0},
-				YValues: []float64{1.0, 2.0, 3.0, 4.0},
-			},
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.HandleFunc("/wide", drawChartWide)
-	log.Fatal(http.ListenAndServe(":8080", nil))
-}

_examples/benchmark_line_charts/main.go

@@ -1,73 +0,0 @@
-// Usage: http://localhost:8080?series=100&values=1000
-package main
-
-import (
-	"fmt"
-	"math/rand"
-	"net/http"
-	"strconv"
-	"time"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func random(min, max float64) float64 {
-	return rand.Float64()*(max-min) + min
-}
-
-func drawLargeChart(res http.ResponseWriter, r *http.Request) {
-	numSeriesInt64, err := strconv.ParseInt(r.FormValue("series"), 10, 64)
-	if err != nil {
-		numSeriesInt64 = int64(1)
-	}
-	numSeries := int(numSeriesInt64)
-
-	numValuesInt64, err := strconv.ParseInt(r.FormValue("values"), 10, 64)
-	if err != nil {
-		numValuesInt64 = int64(100)
-	}
-	numValues := int(numValuesInt64)
-
-	series := make([]chart.Series, numSeries)
-
-	for i := 0; i < numSeries; i++ {
-		xValues := make([]time.Time, numValues)
-		yValues := make([]float64, numValues)
-
-		for j := 0; j < numValues; j++ {
-			xValues[j] = time.Now().AddDate(0, 0, (numValues-j)*-1)
-			yValues[j] = random(float64(-500), float64(500))
-		}
-
-		series[i] = chart.TimeSeries{
-			Name:    fmt.Sprintf("aaa.bbb.hostname-%v.ccc.ddd.eee.fff.ggg.hhh.iii.jjj.kkk.lll.mmm.nnn.value", i),
-			XValues: xValues,
-			YValues: yValues,
-		}
-	}
-
-	graph := chart.Chart{
-		XAxis: chart.XAxis{
-			Name:      "Time",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
-		},
-		YAxis: chart.YAxis{
-			Name:      "Value",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
-		},
-		Series: series,
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawLargeChart)
-	http.HandleFunc("/favico.ico", func(res http.ResponseWriter, req *http.Request) {
-		res.Write([]byte{})
-	})
-	http.ListenAndServe(":8080", nil)
-}

_examples/custom_padding/main.go

@@ -1,74 +0,0 @@
-package main
-
-import (
-	"net/http"
-
-	"github.com/wcharczuk/go-chart"
-	"github.com/wcharczuk/go-chart/drawing"
-)
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-	graph := chart.Chart{
-		Background: chart.Style{
-			Padding: chart.Box{
-				Top:    50,
-				Left:   25,
-				Right:  25,
-				Bottom: 10,
-			},
-			FillColor: drawing.ColorFromHex("efefef"),
-		},
-		XAxis: chart.XAxis{
-			Style: chart.Style{
-				Show: true,
-			},
-		},
-		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
-		},
-		Series: []chart.Series{
-			chart.ContinuousSeries{
-				XValues: chart.Sequence.Float64(1.0, 100.0),
-				YValues: chart.Sequence.Random(100.0, 256.0),
-			},
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func drawChartDefault(res http.ResponseWriter, req *http.Request) {
-	graph := chart.Chart{
-		Background: chart.Style{
-			FillColor: drawing.ColorFromHex("efefef"),
-		},
-		XAxis: chart.XAxis{
-			Style: chart.Style{
-				Show: true,
-			},
-		},
-		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
-		},
-		Series: []chart.Series{
-			chart.ContinuousSeries{
-				XValues: chart.Sequence.Float64(1.0, 100.0),
-				YValues: chart.Sequence.Random(100.0, 256.0),
-			},
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.HandleFunc("/default", drawChartDefault)
-	http.ListenAndServe(":8080", nil)
-}

_examples/market_hours/main.go

@@ -1,44 +0,0 @@
-package main
-
-import (
-	"net/http"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-	start := chart.Date.Date(2016, 7, 01, chart.Date.Eastern())
-	end := chart.Date.Date(2016, 07, 21, chart.Date.Eastern())
-	xv := chart.Sequence.MarketHours(start, end, chart.NYSEOpen, chart.NYSEClose, chart.Date.IsNYSEHoliday)
-	yv := chart.Sequence.RandomWithAverage(len(xv), 200, 10)
-
-	graph := chart.Chart{
-		XAxis: chart.XAxis{
-			Style:          chart.StyleShow(),
-			TickPosition:   chart.TickPositionBetweenTicks,
-			ValueFormatter: chart.TimeHourValueFormatter,
-			Range: &chart.MarketHoursRange{
-				MarketOpen:      chart.NYSEOpen,
-				MarketClose:     chart.NYSEClose,
-				HolidayProvider: chart.Date.IsNYSEHoliday,
-			},
-		},
-		YAxis: chart.YAxis{
-			Style: chart.StyleShow(),
-		},
-		Series: []chart.Series{
-			chart.TimeSeries{
-				XValues: xv,
-				YValues: yv,
-			},
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
-}

_examples/poly_regression/main.go

@@ -1,41 +0,0 @@
-package main
-
-import (
-	"net/http"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-
-	/*
-		In this example we add a new type of series, a `PolynomialRegressionSeries` that takes another series as a required argument.
-		InnerSeries only needs to implement `ValueProvider`, so really you could chain `PolynomialRegressionSeries` together if you wanted.
-	*/
-
-	mainSeries := chart.ContinuousSeries{
-		Name:    "A test series",
-		XValues: chart.Sequence.Float64(1.0, 100.0), //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
-		YValues: chart.Sequence.Random(100, 100),    //generates a []float64 randomly from 0 to 100 with 100 elements.
-	}
-
-	polyRegSeries := &chart.PolynomialRegressionSeries{
-		Degree:      3,
-		InnerSeries: mainSeries,
-	}
-
-	graph := chart.Chart{
-		Series: []chart.Series{
-			mainSeries,
-			polyRegSeries,
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
-}

_examples/request_timings/main.go

@@ -1,135 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"net/http"
-	"strconv"
-	"strings"
-	"time"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func parseInt(str string) int {
-	v, _ := strconv.Atoi(str)
-	return v
-}
-
-func parseFloat64(str string) float64 {
-	v, _ := strconv.ParseFloat(str, 64)
-	return v
-}
-
-func readData() ([]time.Time, []float64) {
-	var xvalues []time.Time
-	var yvalues []float64
-	err := chart.File.ReadByLines("requests.csv", func(line string) {
-		parts := strings.Split(line, ",")
-		year := parseInt(parts[0])
-		month := parseInt(parts[1])
-		day := parseInt(parts[2])
-		hour := parseInt(parts[3])
-		elapsedMillis := parseFloat64(parts[4])
-		xvalues = append(xvalues, time.Date(year, time.Month(month), day, hour, 0, 0, 0, time.UTC))
-		yvalues = append(yvalues, elapsedMillis)
-	})
-	if err != nil {
-		fmt.Println(err.Error())
-	}
-	return xvalues, yvalues
-}
-
-func releases() []chart.GridLine {
-	return []chart.GridLine{
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 1, 9, 30, 0, 0, time.UTC))},
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 2, 9, 30, 0, 0, time.UTC))},
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 2, 15, 30, 0, 0, time.UTC))},
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 4, 9, 30, 0, 0, time.UTC))},
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 5, 9, 30, 0, 0, time.UTC))},
-		{Value: chart.Time.ToFloat64(time.Date(2016, 8, 6, 9, 30, 0, 0, time.UTC))},
-	}
-}
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-	xvalues, yvalues := readData()
-	mainSeries := chart.TimeSeries{
-		Name: "Prod Request Timings",
-		Style: chart.Style{
-			Show:        true,
-			StrokeColor: chart.ColorBlue,
-			FillColor:   chart.ColorBlue.WithAlpha(100),
-		},
-		XValues: xvalues,
-		YValues: yvalues,
-	}
-
-	linreg := &chart.LinearRegressionSeries{
-		Name: "Linear Regression",
-		Style: chart.Style{
-			Show:            true,
-			StrokeColor:     chart.ColorAlternateBlue,
-			StrokeDashArray: []float64{5.0, 5.0},
-		},
-		InnerSeries: mainSeries,
-	}
-
-	sma := &chart.SMASeries{
-		Name: "SMA",
-		Style: chart.Style{
-			Show:            true,
-			StrokeColor:     chart.ColorRed,
-			StrokeDashArray: []float64{5.0, 5.0},
-		},
-		InnerSeries: mainSeries,
-	}
-
-	graph := chart.Chart{
-		Width:  1280,
-		Height: 720,
-		Background: chart.Style{
-			Padding: chart.Box{
-				Top: 50,
-			},
-		},
-		YAxis: chart.YAxis{
-			Name:      "Elapsed Millis",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
-			TickStyle: chart.Style{
-				TextRotationDegrees: 45.0,
-			},
-			ValueFormatter: func(v interface{}) string {
-				return fmt.Sprintf("%d ms", int(v.(float64)))
-			},
-		},
-		XAxis: chart.XAxis{
-			Style: chart.Style{
-				Show: true,
-			},
-			ValueFormatter: chart.TimeHourValueFormatter,
-			GridMajorStyle: chart.Style{
-				Show:        true,
-				StrokeColor: chart.ColorAlternateGray,
-				StrokeWidth: 1.0,
-			},
-			GridLines: releases(),
-		},
-		Series: []chart.Series{
-			mainSeries,
-			linreg,
-			chart.LastValueAnnotation(linreg),
-			sma,
-			chart.LastValueAnnotation(sma),
-		},
-	}
-
-	graph.Elements = []chart.Renderable{chart.LegendThin(&graph)}
-
-	res.Header().Set("Content-Type", chart.ContentTypeSVG)
-	graph.Render(chart.SVG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
-}

_examples/simple_moving_average/main.go

@@ -1,42 +0,0 @@
-package main
-
-import (
-	"net/http"
-
-	"github.com/wcharczuk/go-chart"
-)
-
-func drawChart(res http.ResponseWriter, req *http.Request) {
-
-	/*
-		In this example we add a new type of series, a `SimpleMovingAverageSeries` that takes another series as a required argument.
-		InnerSeries only needs to implement `ValueProvider`, so really you could chain `SimpleMovingAverageSeries` together if you wanted.
-	*/
-
-	mainSeries := chart.ContinuousSeries{
-		Name:    "A test series",
-		XValues: chart.Sequence.Float64(1.0, 100.0), //generates a []float64 from 1.0 to 100.0 in 1.0 step increments, or 100 elements.
-		YValues: chart.Sequence.Random(100, 100),    //generates a []float64 randomly from 0 to 100 with 100 elements.
-	}
-
-	// note we create a SimpleMovingAverage series by assignin the inner series.
-	// we need to use a reference because `.Render()` needs to modify state within the series.
-	smaSeries := &chart.SMASeries{
-		InnerSeries: mainSeries,
-	} // we can optionally set the `WindowSize` property which alters how the moving average is calculated.
-
-	graph := chart.Chart{
-		Series: []chart.Series{
-			mainSeries,
-			smaSeries,
-		},
-	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
-}

annotation_series.go

@@ -5,6 +5,11 @@ import (
 	"math"
 )
 
+// Interface Assertions.
+var (
+	_ Series = (*AnnotationSeries)(nil)
+)
+
 // AnnotationSeries is a series of labels on the chart.
 type AnnotationSeries struct {
 	Name        string
@@ -48,17 +53,17 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 		Right:  0,
 		Bottom: 0,
 	}
-	if as.Style.IsZero() || as.Style.Show {
+	if !as.Style.Hidden {
 		seriesStyle := as.Style.InheritFrom(as.annotationStyleDefaults(defaults))
 		for _, a := range as.Annotations {
 			style := a.Style.InheritFrom(seriesStyle)
 			lx := canvasBox.Left + xrange.Translate(a.XValue)
 			ly := canvasBox.Bottom - yrange.Translate(a.YValue)
 			ab := Draw.MeasureAnnotation(r, canvasBox, style, lx, ly, a.Label)
-			box.Top = Math.MinInt(box.Top, ab.Top)
-			box.Left = Math.MinInt(box.Left, ab.Left)
-			box.Right = Math.MaxInt(box.Right, ab.Right)
-			box.Bottom = Math.MaxInt(box.Bottom, ab.Bottom)
+			box.Top = MinInt(box.Top, ab.Top)
+			box.Left = MinInt(box.Left, ab.Left)
+			box.Right = MaxInt(box.Right, ab.Right)
+			box.Bottom = MaxInt(box.Bottom, ab.Bottom)
 		}
 	}
 	return box
@@ -66,7 +71,7 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 
 // Render draws the series.
 func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	if as.Style.IsZero() || as.Style.Show {
+	if !as.Style.Hidden {
 		seriesStyle := as.Style.InheritFrom(as.annotationStyleDefaults(defaults))
 		for _, a := range as.Annotations {
 			style := a.Style.InheritFrom(seriesStyle)

annotation_series_test.go

@@ -4,17 +4,14 @@ import (
 	"image/color"
 	"testing"
 
-	"github.com/blendlabs/go-assert"
-	"github.com/wcharczuk/go-chart/drawing"
+	"git.smarteching.com/zeni/go-chart/v2/drawing"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestAnnotationSeriesMeasure(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	as := AnnotationSeries{
-		Style: Style{
-			Show: true,
-		},
 		Annotations: []Value2{
 			{XValue: 1.0, YValue: 1.0, Label: "1.0"},
 			{XValue: 2.0, YValue: 2.0, Label: "2.0"},
@@ -24,10 +21,10 @@ func TestAnnotationSeriesMeasure(t *testing.T) {
 	}
 
 	r, err := PNG(110, 110)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	f, err := GetDefaultFont()
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	xrange := &ContinuousRange{
 		Min:    1.0,
@@ -52,19 +49,18 @@ func TestAnnotationSeriesMeasure(t *testing.T) {
 	}
 
 	box := as.Measure(r, cb, xrange, yrange, sd)
-	assert.False(box.IsZero())
-	assert.Equal(-5.0, box.Top)
-	assert.Equal(5.0, box.Left)
-	assert.Equal(146.0, box.Right) //the top,left annotation sticks up 5px and out ~44px.
-	assert.Equal(115.0, box.Bottom)
+	testutil.AssertFalse(t, box.IsZero())
+	testutil.AssertEqual(t, -5.0, box.Top)
+	testutil.AssertEqual(t, 5.0, box.Left)
+	testutil.AssertEqual(t, 146.0, box.Right) //the top,left annotation sticks up 5px and out ~44px.
+	testutil.AssertEqual(t, 115.0, box.Bottom)
 }
 
 func TestAnnotationSeriesRender(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	as := AnnotationSeries{
 		Style: Style{
-			Show:        true,
 			FillColor:   drawing.ColorWhite,
 			StrokeColor: drawing.ColorBlack,
 		},
@@ -77,10 +73,10 @@ func TestAnnotationSeriesRender(t *testing.T) {
 	}
 
 	r, err := PNG(110, 110)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	f, err := GetDefaultFont()
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	xrange := &ContinuousRange{
 		Min:    1.0,
@@ -107,13 +103,13 @@ func TestAnnotationSeriesRender(t *testing.T) {
 	as.Render(r, cb, xrange, yrange, sd)
 
 	rr, isRaster := r.(*rasterRenderer)
-	assert.True(isRaster)
-	assert.NotNil(rr)
+	testutil.AssertTrue(t, isRaster)
+	testutil.AssertNotNil(t, rr)
 
 	c := rr.i.At(38, 70)
 	converted, isRGBA := color.RGBAModel.Convert(c).(color.RGBA)
-	assert.True(isRGBA)
-	assert.Equal(0, converted.R)
-	assert.Equal(0, converted.G)
-	assert.Equal(0, converted.B)
+	testutil.AssertTrue(t, isRGBA)
+	testutil.AssertEqual(t, 0, converted.R)
+	testutil.AssertEqual(t, 0, converted.G)
+	testutil.AssertEqual(t, 0, converted.B)
 }

array.go

@@ -0,0 +1,24 @@
+package chart
+
+var (
+	_ Sequence = (*Array)(nil)
+)
+
+// NewArray returns a new array from a given set of values.
+// Array implements Sequence, which allows it to be used with the sequence helpers.
+func NewArray(values ...float64) Array {
+	return Array(values)
+}
+
+// Array is a wrapper for an array of floats that implements `ValuesProvider`.
+type Array []float64
+
+// Len returns the value provider length.
+func (a Array) Len() int {
+	return len(a)
+}
+
+// GetValue returns the value at a given index.
+func (a Array) GetValue(index int) float64 {
+	return a[index]
+}

bar_chart.go

@@ -30,6 +30,9 @@ type BarChart struct {
 
 	BarSpacing int
 
+	UseBaseValue bool
+	BaseValue    float64
+
 	Font        *truetype.Font
 	defaultFont *truetype.Font
 
@@ -125,7 +128,7 @@ func (bc BarChart) Render(rp RendererProvider, w io.Writer) error {
 		canvasBox = bc.getAdjustedCanvasBox(r, canvasBox, yr, yt)
 		yr = bc.setRangeDomains(canvasBox, yr)
 	}
-
+	bc.drawCanvas(r, canvasBox)
 	bc.drawBars(r, canvasBox, yr)
 	bc.drawXAxis(r, canvasBox)
 	bc.drawYAxis(r, canvasBox, yr, yt)
@@ -138,6 +141,10 @@ func (bc BarChart) Render(rp RendererProvider, w io.Writer) error {
 	return r.Save(w)
 }
 
+func (bc BarChart) drawCanvas(r Renderer, canvasBox Box) {
+	Draw.Box(r, canvasBox, bc.getCanvasStyle())
+}
+
 func (bc BarChart) getRanges() Range {
 	var yrange Range
 	if bc.YAxis.Range != nil && !bc.YAxis.Range.IsZero() {
@@ -194,11 +201,20 @@ func (bc BarChart) drawBars(r Renderer, canvasBox Box, yr Range) {
 
 		by = canvasBox.Bottom - yr.Translate(bar.Value)
 
-		barBox = Box{
-			Top:    by,
-			Left:   bxl,
-			Right:  bxr,
-			Bottom: canvasBox.Bottom,
+		if bc.UseBaseValue {
+			barBox = Box{
+				Top:    by,
+				Left:   bxl,
+				Right:  bxr,
+				Bottom: canvasBox.Bottom - yr.Translate(bc.BaseValue),
+			}
+		} else {
+			barBox = Box{
+				Top:    by,
+				Left:   bxl,
+				Right:  bxr,
+				Bottom: canvasBox.Bottom,
+			}
 		}
 
 		Draw.Box(r, barBox, bar.Style.InheritFrom(bc.styleDefaultsBar(index)))
@@ -208,7 +224,7 @@ func (bc BarChart) drawBars(r Renderer, canvasBox Box, yr Range) {
 }
 
 func (bc BarChart) drawXAxis(r Renderer, canvasBox Box) {
-	if bc.XAxis.Show {
+	if !bc.XAxis.Hidden {
 		axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes())
 		axisStyle.WriteToRenderer(r)
 
@@ -247,44 +263,44 @@ func (bc BarChart) drawXAxis(r Renderer, canvasBox Box) {
 }
 
 func (bc BarChart) drawYAxis(r Renderer, canvasBox Box, yr Range, ticks []Tick) {
-	if bc.YAxis.Style.Show {
-		axisStyle := bc.YAxis.Style.InheritFrom(bc.styleDefaultsAxes())
-		axisStyle.WriteToRenderer(r)
-
-		r.MoveTo(canvasBox.Right, canvasBox.Top)
-		r.LineTo(canvasBox.Right, canvasBox.Bottom)
-		r.Stroke()
-
-		r.MoveTo(canvasBox.Right, canvasBox.Bottom)
-		r.LineTo(canvasBox.Right+DefaultHorizontalTickWidth, canvasBox.Bottom)
-		r.Stroke()
-
-		var ty int
-		var tb Box
-		for _, t := range ticks {
-			ty = canvasBox.Bottom - yr.Translate(t.Value)
-
-			axisStyle.GetStrokeOptions().WriteToRenderer(r)
-			r.MoveTo(canvasBox.Right, ty)
-			r.LineTo(canvasBox.Right+DefaultHorizontalTickWidth, ty)
-			r.Stroke()
-
-			axisStyle.GetTextOptions().WriteToRenderer(r)
-			tb = r.MeasureText(t.Label)
-			Draw.Text(r, t.Label, canvasBox.Right+DefaultYAxisMargin+5, ty+(tb.Height()>>1), axisStyle)
-		}
-
+	if !bc.YAxis.Style.Hidden {
+		bc.YAxis.Render(r, canvasBox, yr, bc.styleDefaultsAxes(), ticks)
 	}
 }
 
 func (bc BarChart) drawTitle(r Renderer) {
-	if len(bc.Title) > 0 && bc.TitleStyle.Show {
-		Draw.TextWithin(r, bc.Title, bc.box(), bc.styleDefaultsTitle())
+	if len(bc.Title) > 0 && !bc.TitleStyle.Hidden {
+		r.SetFont(bc.TitleStyle.GetFont(bc.GetFont()))
+		r.SetFontColor(bc.TitleStyle.GetFontColor(bc.GetColorPalette().TextColor()))
+		titleFontSize := bc.TitleStyle.GetFontSize(bc.getTitleFontSize())
+		r.SetFontSize(titleFontSize)
+
+		textBox := r.MeasureText(bc.Title)
+
+		textWidth := textBox.Width()
+		textHeight := textBox.Height()
+
+		titleX := (bc.GetWidth() >> 1) - (textWidth >> 1)
+		titleY := bc.TitleStyle.Padding.GetTop(DefaultTitleTop) + textHeight
+
+		r.Text(bc.Title, titleX, titleY)
+	}
+}
+
+func (bc BarChart) getCanvasStyle() Style {
+	return bc.Canvas.InheritFrom(bc.styleDefaultsCanvas())
+}
+
+func (bc BarChart) styleDefaultsCanvas() Style {
+	return Style{
+		FillColor:   bc.GetColorPalette().CanvasColor(),
+		StrokeColor: bc.GetColorPalette().CanvasStrokeColor(),
+		StrokeWidth: DefaultCanvasStrokeWidth,
 	}
 }
 
 func (bc BarChart) hasAxes() bool {
-	return bc.YAxis.Style.Show
+	return !bc.YAxis.Style.Hidden
 }
 
 func (bc BarChart) setRangeDomains(canvasBox Box, yr Range) Range {
@@ -304,7 +320,7 @@ func (bc BarChart) getValueFormatters() ValueFormatter {
 }
 
 func (bc BarChart) getAxesTicks(r Renderer, yr Range, yf ValueFormatter) (yticks []Tick) {
-	if bc.YAxis.Style.Show {
+	if !bc.YAxis.Style.Hidden {
 		yticks = bc.YAxis.GetTicks(r, yr, bc.styleDefaultsAxes(), yf)
 	}
 	return
@@ -350,7 +366,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 
 	_, _, totalWidth := bc.calculateScaledTotalWidth(canvasBox)
 
-	if bc.XAxis.Show {
+	if !bc.XAxis.Hidden {
 		xaxisHeight := DefaultVerticalTickHeight
 
 		axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes())
@@ -368,7 +384,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 				lines := Text.WrapFit(r, bar.Label, barLabelBox.Width(), axisStyle)
 				linesBox := Text.MeasureLines(r, lines, axisStyle)
 
-				xaxisHeight = Math.MinInt(linesBox.Height()+(2*DefaultXAxisMargin), xaxisHeight)
+				xaxisHeight = MinInt(linesBox.Height()+(2*DefaultXAxisMargin), xaxisHeight)
 			}
 		}
 
@@ -382,7 +398,7 @@ func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range,
 		axesOuterBox = axesOuterBox.Grow(xbox)
 	}
 
-	if bc.YAxis.Style.Show {
+	if !bc.YAxis.Style.Hidden {
 		axesBounds := bc.YAxis.Measure(r, canvasBox, yrange, bc.styleDefaultsAxes(), yticks)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
@@ -396,8 +412,8 @@ func (bc BarChart) box() Box {
 	dpb := bc.Background.Padding.GetBottom(50)
 
 	return Box{
-		Top:    20,
-		Left:   20,
+		Top:    bc.Background.Padding.GetTop(20),
+		Left:   bc.Background.Padding.GetLeft(20),
 		Right:  bc.GetWidth() - dpr,
 		Bottom: bc.GetHeight() - dpb,
 	}
@@ -435,7 +451,7 @@ func (bc BarChart) styleDefaultsTitle() Style {
 }
 
 func (bc BarChart) getTitleFontSize() float64 {
-	effectiveDimension := Math.MinInt(bc.GetWidth(), bc.GetHeight())
+	effectiveDimension := MinInt(bc.GetWidth(), bc.GetHeight())
 	if effectiveDimension >= 2048 {
 		return 48
 	} else if effectiveDimension >= 1024 {

bar_chart_test.go

@@ -5,20 +5,15 @@ import (
 	"math"
 	"testing"
 
-	assert "github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestBarChartRender(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
-		Width:      1024,
-		Title:      "Test Title",
-		TitleStyle: StyleShow(),
-		XAxis:      StyleShow(),
-		YAxis: YAxis{
-			Style: StyleShow(),
-		},
+		Width: 1024,
+		Title: "Test Title",
 		Bars: []Value{
 			{Value: 1.0, Label: "One"},
 			{Value: 2.0, Label: "Two"},
@@ -30,21 +25,16 @@ func TestBarChartRender(t *testing.T) {
 
 	buf := bytes.NewBuffer([]byte{})
 	err := bc.Render(PNG, buf)
-	assert.Nil(err)
-	assert.NotZero(buf.Len())
+	testutil.AssertNil(t, err)
+	testutil.AssertNotZero(t, buf.Len())
 }
 
 func TestBarChartRenderZero(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
-		Width:      1024,
-		Title:      "Test Title",
-		TitleStyle: StyleShow(),
-		XAxis:      StyleShow(),
-		YAxis: YAxis{
-			Style: StyleShow(),
-		},
+		Width: 1024,
+		Title: "Test Title",
 		Bars: []Value{
 			{Value: 0.0, Label: "One"},
 			{Value: 0.0, Label: "Two"},
@@ -53,64 +43,64 @@ func TestBarChartRenderZero(t *testing.T) {
 
 	buf := bytes.NewBuffer([]byte{})
 	err := bc.Render(PNG, buf)
-	assert.NotNil(err)
+	testutil.AssertNotNil(t, err)
 }
 
 func TestBarChartProps(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 
-	assert.Equal(DefaultDPI, bc.GetDPI())
+	testutil.AssertEqual(t, DefaultDPI, bc.GetDPI())
 	bc.DPI = 100
-	assert.Equal(100, bc.GetDPI())
+	testutil.AssertEqual(t, 100, bc.GetDPI())
 
-	assert.Nil(bc.GetFont())
+	testutil.AssertNil(t, bc.GetFont())
 	f, err := GetDefaultFont()
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 	bc.Font = f
-	assert.NotNil(bc.GetFont())
+	testutil.AssertNotNil(t, bc.GetFont())
 
-	assert.Equal(DefaultChartWidth, bc.GetWidth())
+	testutil.AssertEqual(t, DefaultChartWidth, bc.GetWidth())
 	bc.Width = DefaultChartWidth - 1
-	assert.Equal(DefaultChartWidth-1, bc.GetWidth())
+	testutil.AssertEqual(t, DefaultChartWidth-1, bc.GetWidth())
 
-	assert.Equal(DefaultChartHeight, bc.GetHeight())
+	testutil.AssertEqual(t, DefaultChartHeight, bc.GetHeight())
 	bc.Height = DefaultChartHeight - 1
-	assert.Equal(DefaultChartHeight-1, bc.GetHeight())
+	testutil.AssertEqual(t, DefaultChartHeight-1, bc.GetHeight())
 
-	assert.Equal(DefaultBarSpacing, bc.GetBarSpacing())
+	testutil.AssertEqual(t, DefaultBarSpacing, bc.GetBarSpacing())
 	bc.BarSpacing = 150
-	assert.Equal(150, bc.GetBarSpacing())
+	testutil.AssertEqual(t, 150, bc.GetBarSpacing())
 
-	assert.Equal(DefaultBarWidth, bc.GetBarWidth())
+	testutil.AssertEqual(t, DefaultBarWidth, bc.GetBarWidth())
 	bc.BarWidth = 75
-	assert.Equal(75, bc.GetBarWidth())
+	testutil.AssertEqual(t, 75, bc.GetBarWidth())
 }
 
 func TestBarChartRenderNoBars(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 	err := bc.Render(PNG, bytes.NewBuffer([]byte{}))
-	assert.NotNil(err)
+	testutil.AssertNotNil(t, err)
 }
 
 func TestBarChartGetRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 
 	yr := bc.getRanges()
-	assert.NotNil(yr)
-	assert.False(yr.IsZero())
+	testutil.AssertNotNil(t, yr)
+	testutil.AssertFalse(t, yr.IsZero())
 
-	assert.Equal(-math.MaxFloat64, yr.GetMax())
-	assert.Equal(math.MaxFloat64, yr.GetMin())
+	testutil.AssertEqual(t, -math.MaxFloat64, yr.GetMax())
+	testutil.AssertEqual(t, math.MaxFloat64, yr.GetMin())
 }
 
 func TestBarChartGetRangesBarsMinMax(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		Bars: []Value{
@@ -120,15 +110,15 @@ func TestBarChartGetRangesBarsMinMax(t *testing.T) {
 	}
 
 	yr := bc.getRanges()
-	assert.NotNil(yr)
-	assert.False(yr.IsZero())
+	testutil.AssertNotNil(t, yr)
+	testutil.AssertFalse(t, yr.IsZero())
 
-	assert.Equal(10, yr.GetMax())
-	assert.Equal(1, yr.GetMin())
+	testutil.AssertEqual(t, 10, yr.GetMax())
+	testutil.AssertEqual(t, 1, yr.GetMin())
 }
 
 func TestBarChartGetRangesMinMax(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		YAxis: YAxis{
@@ -148,15 +138,15 @@ func TestBarChartGetRangesMinMax(t *testing.T) {
 	}
 
 	yr := bc.getRanges()
-	assert.NotNil(yr)
-	assert.False(yr.IsZero())
+	testutil.AssertNotNil(t, yr)
+	testutil.AssertFalse(t, yr.IsZero())
 
-	assert.Equal(15, yr.GetMax())
-	assert.Equal(5, yr.GetMin())
+	testutil.AssertEqual(t, 15, yr.GetMax())
+	testutil.AssertEqual(t, 5, yr.GetMin())
 }
 
 func TestBarChartGetRangesTicksMinMax(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		YAxis: YAxis{
@@ -172,57 +162,56 @@ func TestBarChartGetRangesTicksMinMax(t *testing.T) {
 	}
 
 	yr := bc.getRanges()
-	assert.NotNil(yr)
-	assert.False(yr.IsZero())
+	testutil.AssertNotNil(t, yr)
+	testutil.AssertFalse(t, yr.IsZero())
 
-	assert.Equal(11, yr.GetMax())
-	assert.Equal(7, yr.GetMin())
+	testutil.AssertEqual(t, 11, yr.GetMax())
+	testutil.AssertEqual(t, 7, yr.GetMin())
 }
 
 func TestBarChartHasAxes(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
-	assert.False(bc.hasAxes())
+	testutil.AssertTrue(t, bc.hasAxes())
 	bc.YAxis = YAxis{
-		Style: StyleShow(),
+		Style: Hidden(),
 	}
-
-	assert.True(bc.hasAxes())
+	testutil.AssertFalse(t, bc.hasAxes())
 }
 
 func TestBarChartGetDefaultCanvasBox(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 	b := bc.getDefaultCanvasBox()
-	assert.False(b.IsZero())
+	testutil.AssertFalse(t, b.IsZero())
 }
 
 func TestBarChartSetRangeDomains(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 	cb := bc.box()
 	yr := bc.getRanges()
 	yr2 := bc.setRangeDomains(cb, yr)
-	assert.NotZero(yr2.GetDomain())
+	testutil.AssertNotZero(t, yr2.GetDomain())
 }
 
 func TestBarChartGetValueFormatters(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{}
 	vf := bc.getValueFormatters()
-	assert.NotNil(vf)
-	assert.Equal("1234.00", vf(1234.0))
+	testutil.AssertNotNil(t, vf)
+	testutil.AssertEqual(t, "1234.00", vf(1234.0))
 
 	bc.YAxis.ValueFormatter = func(_ interface{}) string { return "test" }
-	assert.Equal("test", bc.getValueFormatters()(1234))
+	testutil.AssertEqual(t, "test", bc.getValueFormatters()(1234))
 }
 
 func TestBarChartGetAxesTicks(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		Bars: []Value{
@@ -233,20 +222,21 @@ func TestBarChartGetAxesTicks(t *testing.T) {
 	}
 
 	r, err := PNG(128, 128)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 	yr := bc.getRanges()
 	yf := bc.getValueFormatters()
 
+	bc.YAxis.Style.Hidden = true
 	ticks := bc.getAxesTicks(r, yr, yf)
-	assert.Empty(ticks)
+	testutil.AssertEmpty(t, ticks)
 
-	bc.YAxis.Style.Show = true
+	bc.YAxis.Style.Hidden = false
 	ticks = bc.getAxesTicks(r, yr, yf)
-	assert.Len(ticks, 2)
+	testutil.AssertLen(t, ticks, 2)
 }
 
 func TestBarChartCalculateEffectiveBarSpacing(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		Width:    1024,
@@ -261,15 +251,15 @@ func TestBarChartCalculateEffectiveBarSpacing(t *testing.T) {
 	}
 
 	spacing := bc.calculateEffectiveBarSpacing(bc.box())
-	assert.NotZero(spacing)
+	testutil.AssertNotZero(t, spacing)
 
 	bc.BarWidth = 250
 	spacing = bc.calculateEffectiveBarSpacing(bc.box())
-	assert.Zero(spacing)
+	testutil.AssertZero(t, spacing)
 }
 
 func TestBarChartCalculateEffectiveBarWidth(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BarChart{
 		Width:    1024,
@@ -286,35 +276,35 @@ func TestBarChartCalculateEffectiveBarWidth(t *testing.T) {
 	cb := bc.box()
 
 	spacing := bc.calculateEffectiveBarSpacing(bc.box())
-	assert.NotZero(spacing)
+	testutil.AssertNotZero(t, spacing)
 
 	barWidth := bc.calculateEffectiveBarWidth(bc.box(), spacing)
-	assert.Equal(10, barWidth)
+	testutil.AssertEqual(t, 10, barWidth)
 
 	bc.BarWidth = 250
 	spacing = bc.calculateEffectiveBarSpacing(bc.box())
-	assert.Zero(spacing)
+	testutil.AssertZero(t, spacing)
 	barWidth = bc.calculateEffectiveBarWidth(bc.box(), spacing)
-	assert.Equal(199, barWidth)
+	testutil.AssertEqual(t, 199, barWidth)
 
-	assert.Equal(cb.Width()+1, bc.calculateTotalBarWidth(barWidth, spacing))
+	testutil.AssertEqual(t, cb.Width()+1, bc.calculateTotalBarWidth(barWidth, spacing))
 
 	bw, bs, total := bc.calculateScaledTotalWidth(cb)
-	assert.Equal(spacing, bs)
-	assert.Equal(barWidth, bw)
-	assert.Equal(cb.Width()+1, total)
+	testutil.AssertEqual(t, spacing, bs)
+	testutil.AssertEqual(t, barWidth, bw)
+	testutil.AssertEqual(t, cb.Width()+1, total)
 }
 
 func TestBarChatGetTitleFontSize(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 	size := BarChart{Width: 2049, Height: 2049}.getTitleFontSize()
-	assert.Equal(48, size)
+	testutil.AssertEqual(t, 48, size)
 	size = BarChart{Width: 1025, Height: 1025}.getTitleFontSize()
-	assert.Equal(24, size)
+	testutil.AssertEqual(t, 24, size)
 	size = BarChart{Width: 513, Height: 513}.getTitleFontSize()
-	assert.Equal(18, size)
+	testutil.AssertEqual(t, 18, size)
 	size = BarChart{Width: 257, Height: 257}.getTitleFontSize()
-	assert.Equal(12, size)
+	testutil.AssertEqual(t, 12, size)
 	size = BarChart{Width: 128, Height: 128}.getTitleFontSize()
-	assert.Equal(10, size)
+	testutil.AssertEqual(t, 10, size)
 }

bollinger_band_series.go

@@ -2,7 +2,11 @@ package chart
 
 import (
 	"fmt"
-	"math"
+)
+
+// Interface Assertions.
+var (
+	_ Series = (*BollingerBandsSeries)(nil)
 )
 
 // BollingerBandsSeries draws bollinger bands for an inner series.
@@ -14,9 +18,9 @@ type BollingerBandsSeries struct {
 
 	Period      int
 	K           float64
-	InnerSeries ValueProvider
+	InnerSeries ValuesProvider
 
-	valueBuffer *RingBuffer
+	valueBuffer *ValueBuffer
 }
 
 // GetName returns the name of the time series.
@@ -42,7 +46,9 @@ func (bbs BollingerBandsSeries) GetPeriod() int {
 	return bbs.Period
 }
 
-// GetK returns the K value.
+// GetK returns the K value, or the number of standard deviations above and below
+// to band the simple moving average with.
+// Typical K value is 2.0.
 func (bbs BollingerBandsSeries) GetK(defaults ...float64) float64 {
 	if bbs.K == 0 {
 		if len(defaults) > 0 {
@@ -54,35 +60,35 @@ func (bbs BollingerBandsSeries) GetK(defaults ...float64) float64 {
 }
 
 // Len returns the number of elements in the series.
-func (bbs *BollingerBandsSeries) Len() int {
+func (bbs BollingerBandsSeries) Len() int {
 	return bbs.InnerSeries.Len()
 }
 
-// GetBoundedValue gets the bounded value for the series.
-func (bbs *BollingerBandsSeries) GetBoundedValue(index int) (x, y1, y2 float64) {
+// GetBoundedValues gets the bounded value for the series.
+func (bbs *BollingerBandsSeries) GetBoundedValues(index int) (x, y1, y2 float64) {
 	if bbs.InnerSeries == nil {
 		return
 	}
 	if bbs.valueBuffer == nil || index == 0 {
-		bbs.valueBuffer = NewRingBufferWithCapacity(bbs.GetPeriod())
+		bbs.valueBuffer = NewValueBufferWithCapacity(bbs.GetPeriod())
 	}
 	if bbs.valueBuffer.Len() >= bbs.GetPeriod() {
 		bbs.valueBuffer.Dequeue()
 	}
-	px, py := bbs.InnerSeries.GetValue(index)
+	px, py := bbs.InnerSeries.GetValues(index)
 	bbs.valueBuffer.Enqueue(py)
 	x = px
 
-	ay := bbs.getAverage(bbs.valueBuffer)
-	std := bbs.getStdDev(bbs.valueBuffer)
+	ay := Seq{bbs.valueBuffer}.Average()
+	std := Seq{bbs.valueBuffer}.StdDev()
 
 	y1 = ay + (bbs.GetK() * std)
 	y2 = ay - (bbs.GetK() * std)
 	return
 }
 
-// GetBoundedLastValue returns the last bounded value for the series.
-func (bbs *BollingerBandsSeries) GetBoundedLastValue() (x, y1, y2 float64) {
+// GetBoundedLastValues returns the last bounded value for the series.
+func (bbs *BollingerBandsSeries) GetBoundedLastValues() (x, y1, y2 float64) {
 	if bbs.InnerSeries == nil {
 		return
 	}
@@ -93,15 +99,15 @@ func (bbs *BollingerBandsSeries) GetBoundedLastValue() (x, y1, y2 float64) {
 		startAt = 0
 	}
 
-	vb := NewRingBufferWithCapacity(period)
+	vb := NewValueBufferWithCapacity(period)
 	for index := startAt; index < seriesLength; index++ {
-		xn, yn := bbs.InnerSeries.GetValue(index)
+		xn, yn := bbs.InnerSeries.GetValues(index)
 		vb.Enqueue(yn)
 		x = xn
 	}
 
-	ay := bbs.getAverage(vb)
-	std := bbs.getStdDev(vb)
+	ay := Seq{vb}.Average()
+	std := Seq{vb}.StdDev()
 
 	y1 = ay + (bbs.GetK() * std)
 	y2 = ay - (bbs.GetK() * std)
@@ -120,37 +126,6 @@ func (bbs *BollingerBandsSeries) Render(r Renderer, canvasBox Box, xrange, yrang
 	Draw.BoundedSeries(r, canvasBox, xrange, yrange, s, bbs, bbs.GetPeriod())
 }
 
-func (bbs BollingerBandsSeries) getAverage(valueBuffer *RingBuffer) float64 {
-	var accum float64
-	valueBuffer.Each(func(v interface{}) {
-		if typed, isTyped := v.(float64); isTyped {
-			accum += typed
-		}
-	})
-	return accum / float64(valueBuffer.Len())
-}
-
-func (bbs BollingerBandsSeries) getVariance(valueBuffer *RingBuffer) float64 {
-	if valueBuffer.Len() == 0 {
-		return 0
-	}
-
-	var variance float64
-	m := bbs.getAverage(valueBuffer)
-
-	valueBuffer.Each(func(v interface{}) {
-		if n, isTyped := v.(float64); isTyped {
-			variance += (float64(n) - m) * (float64(n) - m)
-		}
-	})
-
-	return variance / float64(valueBuffer.Len())
-}
-
-func (bbs BollingerBandsSeries) getStdDev(valueBuffer *RingBuffer) float64 {
-	return math.Pow(bbs.getVariance(valueBuffer), 0.5)
-}
-
 // Validate validates the series.
 func (bbs BollingerBandsSeries) Validate() error {
 	if bbs.InnerSeries == nil {

bollinger_band_series_test.go

@@ -1,18 +1,19 @@
 package chart
 
 import (
+	"fmt"
 	"math"
 	"testing"
 
-	"github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestBollingerBandSeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
-	s1 := mockValueProvider{
-		X: Sequence.Float64(1.0, 100.0),
-		Y: Sequence.Random(100, 1024),
+	s1 := mockValuesProvider{
+		X: LinearRange(1.0, 100.0),
+		Y: RandomValuesWithMax(100, 1024),
 	}
 
 	bbs := &BollingerBandsSeries{
@@ -24,28 +25,28 @@ func TestBollingerBandSeries(t *testing.T) {
 	y2values := make([]float64, 100)
 
 	for x := 0; x < 100; x++ {
-		xvalues[x], y1values[x], y2values[x] = bbs.GetBoundedValue(x)
+		xvalues[x], y1values[x], y2values[x] = bbs.GetBoundedValues(x)
 	}
 
 	for x := bbs.GetPeriod(); x < 100; x++ {
-		assert.True(y1values[x] > y2values[x])
+		testutil.AssertTrue(t, y1values[x] > y2values[x], fmt.Sprintf("%v vs. %v", y1values[x], y2values[x]))
 	}
 }
 
 func TestBollingerBandLastValue(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
-	s1 := mockValueProvider{
-		X: Sequence.Float64(1.0, 100.0),
-		Y: Sequence.Float64(1.0, 100.0),
+	s1 := mockValuesProvider{
+		X: LinearRange(1.0, 100.0),
+		Y: LinearRange(1.0, 100.0),
 	}
 
 	bbs := &BollingerBandsSeries{
 		InnerSeries: s1,
 	}
 
-	x, y1, y2 := bbs.GetBoundedLastValue()
-	assert.Equal(100.0, x)
-	assert.Equal(101, math.Floor(y1))
-	assert.Equal(83, math.Floor(y2))
+	x, y1, y2 := bbs.GetBoundedLastValues()
+	testutil.AssertEqual(t, 100.0, x)
+	testutil.AssertEqual(t, 101, math.Floor(y1))
+	testutil.AssertEqual(t, 83, math.Floor(y2))
 }

bounded_last_values_annotation_series.go

@@ -0,0 +1,36 @@
+package chart
+
+import "fmt"
+
+// BoundedLastValuesAnnotationSeries returns a last value annotation series for a bounded values provider.
+func BoundedLastValuesAnnotationSeries(innerSeries FullBoundedValuesProvider, vfs ...ValueFormatter) AnnotationSeries {
+	lvx, lvy1, lvy2 := innerSeries.GetBoundedLastValues()
+
+	var vf ValueFormatter
+	if len(vfs) > 0 {
+		vf = vfs[0]
+	} else if typed, isTyped := innerSeries.(ValueFormatterProvider); isTyped {
+		_, vf = typed.GetValueFormatters()
+	} else {
+		vf = FloatValueFormatter
+	}
+
+	label1 := vf(lvy1)
+	label2 := vf(lvy2)
+
+	var seriesName string
+	var seriesStyle Style
+	if typed, isTyped := innerSeries.(Series); isTyped {
+		seriesName = fmt.Sprintf("%s - Last Values", typed.GetName())
+		seriesStyle = typed.GetStyle()
+	}
+
+	return AnnotationSeries{
+		Name:  seriesName,
+		Style: seriesStyle,
+		Annotations: []Value2{
+			{XValue: lvx, YValue: lvy1, Label: label1},
+			{XValue: lvx, YValue: lvy2, Label: label2},
+		},
+	}
+}

box.go

@@ -89,12 +89,12 @@ func (b Box) GetBottom(defaults ...int) int {
 
 // Width returns the width
 func (b Box) Width() int {
-	return Math.AbsInt(b.Right - b.Left)
+	return AbsInt(b.Right - b.Left)
 }
 
 // Height returns the height
 func (b Box) Height() int {
-	return Math.AbsInt(b.Bottom - b.Top)
+	return AbsInt(b.Bottom - b.Top)
 }
 
 // Center returns the center of the box
@@ -146,10 +146,10 @@ func (b Box) Equals(other Box) bool {
 // Grow grows a box based on another box.
 func (b Box) Grow(other Box) Box {
 	return Box{
-		Top:    Math.MinInt(b.Top, other.Top),
-		Left:   Math.MinInt(b.Left, other.Left),
-		Right:  Math.MaxInt(b.Right, other.Right),
-		Bottom: Math.MaxInt(b.Bottom, other.Bottom),
+		Top:    MinInt(b.Top, other.Top),
+		Left:   MinInt(b.Left, other.Left),
+		Right:  MaxInt(b.Right, other.Right),
+		Bottom: MaxInt(b.Bottom, other.Bottom),
 	}
 }
 
@@ -220,10 +220,10 @@ func (b Box) Fit(other Box) Box {
 func (b Box) Constrain(other Box) Box {
 	newBox := b.Clone()
 
-	newBox.Top = Math.MaxInt(newBox.Top, other.Top)
-	newBox.Left = Math.MaxInt(newBox.Left, other.Left)
-	newBox.Right = Math.MinInt(newBox.Right, other.Right)
-	newBox.Bottom = Math.MinInt(newBox.Bottom, other.Bottom)
+	newBox.Top = MaxInt(newBox.Top, other.Top)
+	newBox.Left = MaxInt(newBox.Left, other.Left)
+	newBox.Right = MinInt(newBox.Right, other.Right)
+	newBox.Bottom = MinInt(newBox.Bottom, other.Bottom)
 
 	return newBox
 }
@@ -254,6 +254,22 @@ func (b Box) OuterConstrain(bounds, other Box) Box {
 	return newBox
 }
 
+func (b Box) Validate() error {
+	if b.Left < 0 {
+		return fmt.Errorf("invalid left; must be >= 0")
+	}
+	if b.Right < 0 {
+		return fmt.Errorf("invalid right; must be > 0")
+	}
+	if b.Top < 0 {
+		return fmt.Errorf("invalid top; must be > 0")
+	}
+	if b.Bottom < 0 {
+		return fmt.Errorf("invalid bottom; must be > 0")
+	}
+	return nil
+}
+
 // BoxCorners is a box with independent corners.
 type BoxCorners struct {
 	TopLeft, TopRight, BottomRight, BottomLeft Point
@@ -262,36 +278,36 @@ type BoxCorners struct {
 // Box return the BoxCorners as a regular box.
 func (bc BoxCorners) Box() Box {
 	return Box{
-		Top:    Math.MinInt(bc.TopLeft.Y, bc.TopRight.Y),
-		Left:   Math.MinInt(bc.TopLeft.X, bc.BottomLeft.X),
-		Right:  Math.MaxInt(bc.TopRight.X, bc.BottomRight.X),
-		Bottom: Math.MaxInt(bc.BottomLeft.Y, bc.BottomRight.Y),
+		Top:    MinInt(bc.TopLeft.Y, bc.TopRight.Y),
+		Left:   MinInt(bc.TopLeft.X, bc.BottomLeft.X),
+		Right:  MaxInt(bc.TopRight.X, bc.BottomRight.X),
+		Bottom: MaxInt(bc.BottomLeft.Y, bc.BottomRight.Y),
 	}
 }
 
 // Width returns the width
 func (bc BoxCorners) Width() int {
-	minLeft := Math.MinInt(bc.TopLeft.X, bc.BottomLeft.X)
-	maxRight := Math.MaxInt(bc.TopRight.X, bc.BottomRight.X)
+	minLeft := MinInt(bc.TopLeft.X, bc.BottomLeft.X)
+	maxRight := MaxInt(bc.TopRight.X, bc.BottomRight.X)
 	return maxRight - minLeft
 }
 
 // Height returns the height
 func (bc BoxCorners) Height() int {
-	minTop := Math.MinInt(bc.TopLeft.Y, bc.TopRight.Y)
-	maxBottom := Math.MaxInt(bc.BottomLeft.Y, bc.BottomRight.Y)
+	minTop := MinInt(bc.TopLeft.Y, bc.TopRight.Y)
+	maxBottom := MaxInt(bc.BottomLeft.Y, bc.BottomRight.Y)
 	return maxBottom - minTop
 }
 
 // Center returns the center of the box
 func (bc BoxCorners) Center() (x, y int) {
 
-	left := Math.MeanInt(bc.TopLeft.X, bc.BottomLeft.X)
-	right := Math.MeanInt(bc.TopRight.X, bc.BottomRight.X)
+	left := MeanInt(bc.TopLeft.X, bc.BottomLeft.X)
+	right := MeanInt(bc.TopRight.X, bc.BottomRight.X)
 	x = ((right - left) >> 1) + left
 
-	top := Math.MeanInt(bc.TopLeft.Y, bc.TopRight.Y)
-	bottom := Math.MeanInt(bc.BottomLeft.Y, bc.BottomRight.Y)
+	top := MeanInt(bc.TopLeft.Y, bc.TopRight.Y)
+	bottom := MeanInt(bc.BottomLeft.Y, bc.BottomRight.Y)
 	y = ((bottom - top) >> 1) + top
 
 	return
@@ -301,12 +317,12 @@ func (bc BoxCorners) Center() (x, y int) {
 func (bc BoxCorners) Rotate(thetaDegrees float64) BoxCorners {
 	cx, cy := bc.Center()
 
-	thetaRadians := Math.DegreesToRadians(thetaDegrees)
+	thetaRadians := DegreesToRadians(thetaDegrees)
 
-	tlx, tly := Math.RotateCoordinate(cx, cy, bc.TopLeft.X, bc.TopLeft.Y, thetaRadians)
-	trx, try := Math.RotateCoordinate(cx, cy, bc.TopRight.X, bc.TopRight.Y, thetaRadians)
-	brx, bry := Math.RotateCoordinate(cx, cy, bc.BottomRight.X, bc.BottomRight.Y, thetaRadians)
-	blx, bly := Math.RotateCoordinate(cx, cy, bc.BottomLeft.X, bc.BottomLeft.Y, thetaRadians)
+	tlx, tly := RotateCoordinate(cx, cy, bc.TopLeft.X, bc.TopLeft.Y, thetaRadians)
+	trx, try := RotateCoordinate(cx, cy, bc.TopRight.X, bc.TopRight.Y, thetaRadians)
+	brx, bry := RotateCoordinate(cx, cy, bc.BottomRight.X, bc.BottomRight.Y, thetaRadians)
+	blx, bly := RotateCoordinate(cx, cy, bc.BottomLeft.X, bc.BottomLeft.Y, thetaRadians)
 
 	return BoxCorners{
 		TopLeft:     Point{tlx, tly},

box_test.go

@@ -4,131 +4,131 @@ import (
 	"math"
 	"testing"
 
-	"github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestBoxClone(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 	a := Box{Top: 5, Left: 5, Right: 15, Bottom: 15}
 	b := a.Clone()
-	assert.True(a.Equals(b))
-	assert.True(b.Equals(a))
+	testutil.AssertTrue(t, a.Equals(b))
+	testutil.AssertTrue(t, b.Equals(a))
 }
 
 func TestBoxEquals(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 5, Left: 5, Right: 15, Bottom: 15}
 	b := Box{Top: 10, Left: 10, Right: 30, Bottom: 30}
 	c := Box{Top: 5, Left: 5, Right: 15, Bottom: 15}
-	assert.True(a.Equals(a))
-	assert.True(a.Equals(c))
-	assert.True(c.Equals(a))
-	assert.False(a.Equals(b))
-	assert.False(c.Equals(b))
-	assert.False(b.Equals(a))
-	assert.False(b.Equals(c))
+	testutil.AssertTrue(t, a.Equals(a))
+	testutil.AssertTrue(t, a.Equals(c))
+	testutil.AssertTrue(t, c.Equals(a))
+	testutil.AssertFalse(t, a.Equals(b))
+	testutil.AssertFalse(t, c.Equals(b))
+	testutil.AssertFalse(t, b.Equals(a))
+	testutil.AssertFalse(t, b.Equals(c))
 }
 
 func TestBoxIsBiggerThan(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 5, Left: 5, Right: 25, Bottom: 25}
 	b := Box{Top: 10, Left: 10, Right: 20, Bottom: 20} // only half bigger
 	c := Box{Top: 1, Left: 1, Right: 30, Bottom: 30}   //bigger
-	assert.True(a.IsBiggerThan(b))
-	assert.False(a.IsBiggerThan(c))
-	assert.True(c.IsBiggerThan(a))
+	testutil.AssertTrue(t, a.IsBiggerThan(b))
+	testutil.AssertFalse(t, a.IsBiggerThan(c))
+	testutil.AssertTrue(t, c.IsBiggerThan(a))
 }
 
 func TestBoxIsSmallerThan(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 5, Left: 5, Right: 25, Bottom: 25}
 	b := Box{Top: 10, Left: 10, Right: 20, Bottom: 20} // only half bigger
 	c := Box{Top: 1, Left: 1, Right: 30, Bottom: 30}   //bigger
-	assert.False(a.IsSmallerThan(b))
-	assert.True(a.IsSmallerThan(c))
-	assert.False(c.IsSmallerThan(a))
+	testutil.AssertFalse(t, a.IsSmallerThan(b))
+	testutil.AssertTrue(t, a.IsSmallerThan(c))
+	testutil.AssertFalse(t, c.IsSmallerThan(a))
 }
 
 func TestBoxGrow(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 1, Left: 2, Right: 15, Bottom: 15}
 	b := Box{Top: 4, Left: 5, Right: 30, Bottom: 35}
 	c := a.Grow(b)
-	assert.False(c.Equals(b))
-	assert.False(c.Equals(a))
-	assert.Equal(1, c.Top)
-	assert.Equal(2, c.Left)
-	assert.Equal(30, c.Right)
-	assert.Equal(35, c.Bottom)
+	testutil.AssertFalse(t, c.Equals(b))
+	testutil.AssertFalse(t, c.Equals(a))
+	testutil.AssertEqual(t, 1, c.Top)
+	testutil.AssertEqual(t, 2, c.Left)
+	testutil.AssertEqual(t, 30, c.Right)
+	testutil.AssertEqual(t, 35, c.Bottom)
 }
 
 func TestBoxFit(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 64, Left: 64, Right: 192, Bottom: 192}
 	b := Box{Top: 16, Left: 16, Right: 256, Bottom: 170}
 	c := Box{Top: 16, Left: 16, Right: 170, Bottom: 256}
 
 	fab := a.Fit(b)
-	assert.Equal(a.Left, fab.Left)
-	assert.Equal(a.Right, fab.Right)
-	assert.True(fab.Top < fab.Bottom)
-	assert.True(fab.Left < fab.Right)
-	assert.True(math.Abs(b.Aspect()-fab.Aspect()) < 0.02)
+	testutil.AssertEqual(t, a.Left, fab.Left)
+	testutil.AssertEqual(t, a.Right, fab.Right)
+	testutil.AssertTrue(t, fab.Top < fab.Bottom)
+	testutil.AssertTrue(t, fab.Left < fab.Right)
+	testutil.AssertTrue(t, math.Abs(b.Aspect()-fab.Aspect()) < 0.02)
 
 	fac := a.Fit(c)
-	assert.Equal(a.Top, fac.Top)
-	assert.Equal(a.Bottom, fac.Bottom)
-	assert.True(math.Abs(c.Aspect()-fac.Aspect()) < 0.02)
+	testutil.AssertEqual(t, a.Top, fac.Top)
+	testutil.AssertEqual(t, a.Bottom, fac.Bottom)
+	testutil.AssertTrue(t, math.Abs(c.Aspect()-fac.Aspect()) < 0.02)
 }
 
 func TestBoxConstrain(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	a := Box{Top: 64, Left: 64, Right: 192, Bottom: 192}
 	b := Box{Top: 16, Left: 16, Right: 256, Bottom: 170}
 	c := Box{Top: 16, Left: 16, Right: 170, Bottom: 256}
 
 	cab := a.Constrain(b)
-	assert.Equal(64, cab.Top)
-	assert.Equal(64, cab.Left)
-	assert.Equal(192, cab.Right)
-	assert.Equal(170, cab.Bottom)
+	testutil.AssertEqual(t, 64, cab.Top)
+	testutil.AssertEqual(t, 64, cab.Left)
+	testutil.AssertEqual(t, 192, cab.Right)
+	testutil.AssertEqual(t, 170, cab.Bottom)
 
 	cac := a.Constrain(c)
-	assert.Equal(64, cac.Top)
-	assert.Equal(64, cac.Left)
-	assert.Equal(170, cac.Right)
-	assert.Equal(192, cac.Bottom)
+	testutil.AssertEqual(t, 64, cac.Top)
+	testutil.AssertEqual(t, 64, cac.Left)
+	testutil.AssertEqual(t, 170, cac.Right)
+	testutil.AssertEqual(t, 192, cac.Bottom)
 }
 
 func TestBoxOuterConstrain(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	box := NewBox(0, 0, 100, 100)
 	canvas := NewBox(5, 5, 95, 95)
 	taller := NewBox(-10, 5, 50, 50)
 
 	c := canvas.OuterConstrain(box, taller)
-	assert.Equal(15, c.Top, c.String())
-	assert.Equal(5, c.Left, c.String())
-	assert.Equal(95, c.Right, c.String())
-	assert.Equal(95, c.Bottom, c.String())
+	testutil.AssertEqual(t, 15, c.Top, c.String())
+	testutil.AssertEqual(t, 5, c.Left, c.String())
+	testutil.AssertEqual(t, 95, c.Right, c.String())
+	testutil.AssertEqual(t, 95, c.Bottom, c.String())
 
 	wider := NewBox(5, 5, 110, 50)
 	d := canvas.OuterConstrain(box, wider)
-	assert.Equal(5, d.Top, d.String())
-	assert.Equal(5, d.Left, d.String())
-	assert.Equal(85, d.Right, d.String())
-	assert.Equal(95, d.Bottom, d.String())
+	testutil.AssertEqual(t, 5, d.Top, d.String())
+	testutil.AssertEqual(t, 5, d.Left, d.String())
+	testutil.AssertEqual(t, 85, d.Right, d.String())
+	testutil.AssertEqual(t, 95, d.Bottom, d.String())
 }
 
 func TestBoxShift(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	b := Box{
 		Top:    5,
@@ -138,14 +138,14 @@ func TestBoxShift(t *testing.T) {
 	}
 
 	shifted := b.Shift(1, 2)
-	assert.Equal(7, shifted.Top)
-	assert.Equal(6, shifted.Left)
-	assert.Equal(11, shifted.Right)
-	assert.Equal(12, shifted.Bottom)
+	testutil.AssertEqual(t, 7, shifted.Top)
+	testutil.AssertEqual(t, 6, shifted.Left)
+	testutil.AssertEqual(t, 11, shifted.Right)
+	testutil.AssertEqual(t, 12, shifted.Bottom)
 }
 
 func TestBoxCenter(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	b := Box{
 		Top:    10,
@@ -154,12 +154,12 @@ func TestBoxCenter(t *testing.T) {
 		Bottom: 30,
 	}
 	cx, cy := b.Center()
-	assert.Equal(15, cx)
-	assert.Equal(20, cy)
+	testutil.AssertEqual(t, 15, cx)
+	testutil.AssertEqual(t, 20, cy)
 }
 
 func TestBoxCornersCenter(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BoxCorners{
 		TopLeft:     Point{5, 5},
@@ -169,12 +169,12 @@ func TestBoxCornersCenter(t *testing.T) {
 	}
 
 	cx, cy := bc.Center()
-	assert.Equal(10, cx)
-	assert.Equal(10, cy)
+	testutil.AssertEqual(t, 10, cx)
+	testutil.AssertEqual(t, 10, cy)
 }
 
 func TestBoxCornersRotate(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	bc := BoxCorners{
 		TopLeft:     Point{5, 5},
@@ -184,5 +184,5 @@ func TestBoxCornersRotate(t *testing.T) {
 	}
 
 	rotated := bc.Rotate(45)
-	assert.True(rotated.TopLeft.Equals(Point{10, 3}), rotated.String())
+	testutil.AssertTrue(t, rotated.TopLeft.Equals(Point{10, 3}), rotated.String())
 }

chart.go

@@ -32,6 +32,8 @@ type Chart struct {
 
 	Series   []Series
 	Elements []Renderable
+
+	Log Logger
 }
 
 // GetDPI returns the dpi for the chart.
@@ -74,8 +76,8 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 	if len(c.Series) == 0 {
 		return errors.New("please provide at least one series")
 	}
-	if visibleSeriesErr := c.checkHasVisibleSeries(); visibleSeriesErr != nil {
-		return visibleSeriesErr
+	if err := c.checkHasVisibleSeries(); err != nil {
+		return err
 	}
 
 	c.YAxisSecondary.AxisType = YAxisSecondary
@@ -101,6 +103,8 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 	canvasBox := c.getDefaultCanvasBox()
 	xf, yf, yfa := c.getValueFormatters()
 
+	Debugf(c.Log, "chart; canvas box: %v", canvasBox)
+
 	xr, yr, yra = c.setRangeDomains(canvasBox, xr, yr, yra)
 
 	err = c.checkRanges(xr, yr, yra)
@@ -114,6 +118,8 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 		canvasBox = c.getAxesAdjustedCanvasBox(r, canvasBox, xr, yr, yra, xt, yt, yta)
 		xr, yr, yra = c.setRangeDomains(canvasBox, xr, yr, yra)
 
+		Debugf(c.Log, "chart; axes adjusted canvas box: %v", canvasBox)
+
 		// do a second pass in case things haven't settled yet.
 		xt, yt, yta = c.getAxesTicks(r, xr, yr, yra, xf, yf, yfa)
 		canvasBox = c.getAxesAdjustedCanvasBox(r, canvasBox, xr, yr, yra, xt, yt, yta)
@@ -124,6 +130,8 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 		canvasBox = c.getAnnotationAdjustedCanvasBox(r, canvasBox, xr, yr, yra, xf, yf, yfa)
 		xr, yr, yra = c.setRangeDomains(canvasBox, xr, yr, yra)
 		xt, yt, yta = c.getAxesTicks(r, xr, yr, yra, xf, yf, yfa)
+
+		Debugf(c.Log, "chart; annotation adjusted canvas box: %v", canvasBox)
 	}
 
 	c.drawCanvas(r, canvasBox)
@@ -142,16 +150,14 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 }
 
 func (c Chart) checkHasVisibleSeries() error {
-	hasVisibleSeries := false
 	var style Style
 	for _, s := range c.Series {
 		style = s.GetStyle()
-		hasVisibleSeries = hasVisibleSeries || (style.IsZero() || style.Show)
+		if !style.Hidden {
+			return nil
+		}
 	}
-	if !hasVisibleSeries {
-		return fmt.Errorf("must have (1) visible series; make sure if you set a style, you set .Show = true")
-	}
-	return nil
+	return fmt.Errorf("chart render; must have (1) visible series")
 }
 
 func (c Chart) validateSeries() error {
@@ -175,12 +181,12 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 	// note: a possible future optimization is to not scan the series values if
 	// all axis are represented by either custom ticks or custom ranges.
 	for _, s := range c.Series {
-		if s.GetStyle().IsZero() || s.GetStyle().Show {
+		if !s.GetStyle().Hidden {
 			seriesAxis := s.GetYAxis()
-			if bvp, isBoundedValueProvider := s.(BoundedValueProvider); isBoundedValueProvider {
+			if bvp, isBoundedValuesProvider := s.(BoundedValuesProvider); isBoundedValuesProvider {
 				seriesLength := bvp.Len()
 				for index := 0; index < seriesLength; index++ {
-					vx, vy1, vy2 := bvp.GetBoundedValue(index)
+					vx, vy1, vy2 := bvp.GetBoundedValues(index)
 
 					minx = math.Min(minx, vx)
 					maxx = math.Max(maxx, vx)
@@ -198,10 +204,10 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 						seriesMappedToSecondaryAxis = true
 					}
 				}
-			} else if vp, isValueProvider := s.(ValueProvider); isValueProvider {
+			} else if vp, isValuesProvider := s.(ValuesProvider); isValuesProvider {
 				seriesLength := vp.Len()
 				for index := 0; index < seriesLength; index++ {
-					vx, vy := vp.GetValue(index)
+					vx, vy := vp.GetValues(index)
 
 					minx = math.Min(minx, vx)
 					maxx = math.Max(maxx, vx)
@@ -262,11 +268,10 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 		yrange.SetMin(miny)
 		yrange.SetMax(maxy)
 
-		// only round if we're showing the axis
-		if c.YAxis.Style.Show {
+		if !c.YAxis.Style.Hidden {
 			delta := yrange.GetDelta()
-			roundTo := Math.GetRoundToForDelta(delta)
-			rmin, rmax := Math.RoundDown(yrange.GetMin(), roundTo), Math.RoundUp(yrange.GetMax(), roundTo)
+			roundTo := GetRoundToForDelta(delta)
+			rmin, rmax := RoundDown(yrange.GetMin(), roundTo), RoundUp(yrange.GetMax(), roundTo)
 
 			yrange.SetMin(rmin)
 			yrange.SetMax(rmax)
@@ -285,10 +290,10 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 		yrangeAlt.SetMin(minya)
 		yrangeAlt.SetMax(maxya)
 
-		if c.YAxisSecondary.Style.Show {
+		if !c.YAxisSecondary.Style.Hidden {
 			delta := yrangeAlt.GetDelta()
-			roundTo := Math.GetRoundToForDelta(delta)
-			rmin, rmax := Math.RoundDown(yrangeAlt.GetMin(), roundTo), Math.RoundUp(yrangeAlt.GetMax(), roundTo)
+			roundTo := GetRoundToForDelta(delta)
+			rmin, rmax := RoundDown(yrangeAlt.GetMin(), roundTo), RoundUp(yrangeAlt.GetMax(), roundTo)
 			yrangeAlt.SetMin(rmin)
 			yrangeAlt.SetMax(rmax)
 		}
@@ -298,6 +303,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 }
 
 func (c Chart) checkRanges(xr, yr, yra Range) error {
+	Debugf(c.Log, "checking xrange: %v", xr)
 	xDelta := xr.GetDelta()
 	if math.IsInf(xDelta, 0) {
 		return errors.New("infinite x-range delta")
@@ -309,6 +315,7 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 		return errors.New("zero x-range delta; there needs to be at least (2) values")
 	}
 
+	Debugf(c.Log, "checking yrange: %v", yr)
 	yDelta := yr.GetDelta()
 	if math.IsInf(yDelta, 0) {
 		return errors.New("infinite y-range delta")
@@ -316,11 +323,9 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 	if math.IsNaN(yDelta) {
 		return errors.New("nan y-range delta")
 	}
-	if yDelta == 0 {
-		return errors.New("zero y-range delta")
-	}
 
 	if c.hasSecondarySeries() {
+		Debugf(c.Log, "checking secondary yrange: %v", yra)
 		yraDelta := yra.GetDelta()
 		if math.IsInf(yraDelta, 0) {
 			return errors.New("infinite secondary y-range delta")
@@ -328,9 +333,6 @@ func (c Chart) checkRanges(xr, yr, yra Range) error {
 		if math.IsNaN(yraDelta) {
 			return errors.New("nan secondary y-range delta")
 		}
-		if yraDelta == 0 {
-			return errors.New("zero secondary y-range delta")
-		}
 	}
 
 	return nil
@@ -366,17 +368,17 @@ func (c Chart) getValueFormatters() (x, y, ya ValueFormatter) {
 }
 
 func (c Chart) hasAxes() bool {
-	return c.XAxis.Style.Show || c.YAxis.Style.Show || c.YAxisSecondary.Style.Show
+	return !c.XAxis.Style.Hidden || !c.YAxis.Style.Hidden || !c.YAxisSecondary.Style.Hidden
 }
 
 func (c Chart) getAxesTicks(r Renderer, xr, yr, yar Range, xf, yf, yfa ValueFormatter) (xticks, yticks, yticksAlt []Tick) {
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		xticks = c.XAxis.GetTicks(r, xr, c.styleDefaultsAxes(), xf)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		yticks = c.YAxis.GetTicks(r, yr, c.styleDefaultsAxes(), yf)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden {
 		yticksAlt = c.YAxisSecondary.GetTicks(r, yar, c.styleDefaultsAxes(), yfa)
 	}
 	return
@@ -384,16 +386,19 @@ func (c Chart) getAxesTicks(r Renderer, xr, yr, yar Range, xf, yf, yfa ValueForm
 
 func (c Chart) getAxesAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr, yra Range, xticks, yticks, yticksAlt []Tick) Box {
 	axesOuterBox := canvasBox.Clone()
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		axesBounds := c.XAxis.Measure(r, canvasBox, xr, c.styleDefaultsAxes(), xticks)
+		Debugf(c.Log, "chart; x-axis measured %v", axesBounds)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		axesBounds := c.YAxis.Measure(r, canvasBox, yr, c.styleDefaultsAxes(), yticks)
+		Debugf(c.Log, "chart; y-axis measured %v", axesBounds)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden && c.hasSecondarySeries() {
 		axesBounds := c.YAxisSecondary.Measure(r, canvasBox, yra, c.styleDefaultsAxes(), yticksAlt)
+		Debugf(c.Log, "chart; y-axis secondary measured %v", axesBounds)
 		axesOuterBox = axesOuterBox.Grow(axesBounds)
 	}
 
@@ -410,7 +415,7 @@ func (c Chart) setRangeDomains(canvasBox Box, xr, yr, yra Range) (Range, Range,
 func (c Chart) hasAnnotationSeries() bool {
 	for _, s := range c.Series {
 		if as, isAnnotationSeries := s.(AnnotationSeries); isAnnotationSeries {
-			if as.Style.IsZero() || as.Style.Show {
+			if !as.GetStyle().Hidden {
 				return true
 			}
 		}
@@ -431,7 +436,7 @@ func (c Chart) getAnnotationAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr,
 	annotationSeriesBox := canvasBox.Clone()
 	for seriesIndex, s := range c.Series {
 		if as, isAnnotationSeries := s.(AnnotationSeries); isAnnotationSeries {
-			if as.Style.IsZero() || as.Style.Show {
+			if !as.GetStyle().Hidden {
 				style := c.styleDefaultsSeries(seriesIndex)
 				var annotationBounds Box
 				if as.YAxis == YAxisPrimary {
@@ -468,19 +473,19 @@ func (c Chart) drawCanvas(r Renderer, canvasBox Box) {
 }
 
 func (c Chart) drawAxes(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt Range, xticks, yticks, yticksAlt []Tick) {
-	if c.XAxis.Style.Show {
+	if !c.XAxis.Style.Hidden {
 		c.XAxis.Render(r, canvasBox, xrange, c.styleDefaultsAxes(), xticks)
 	}
-	if c.YAxis.Style.Show {
+	if !c.YAxis.Style.Hidden {
 		c.YAxis.Render(r, canvasBox, yrange, c.styleDefaultsAxes(), yticks)
 	}
-	if c.YAxisSecondary.Style.Show {
+	if !c.YAxisSecondary.Style.Hidden {
 		c.YAxisSecondary.Render(r, canvasBox, yrangeAlt, c.styleDefaultsAxes(), yticksAlt)
 	}
 }
 
 func (c Chart) drawSeries(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt Range, s Series, seriesIndex int) {
-	if s.GetStyle().IsZero() || s.GetStyle().Show {
+	if !s.GetStyle().Hidden {
 		if s.GetYAxis() == YAxisPrimary {
 			s.Render(r, canvasBox, xrange, yrange, c.styleDefaultsSeries(seriesIndex))
 		} else if s.GetYAxis() == YAxisSecondary {
@@ -490,7 +495,7 @@ func (c Chart) drawSeries(r Renderer, canvasBox Box, xrange, yrange, yrangeAlt R
 }
 
 func (c Chart) drawTitle(r Renderer) {
-	if len(c.Title) > 0 && c.TitleStyle.Show {
+	if len(c.Title) > 0 && !c.TitleStyle.Hidden {
 		r.SetFont(c.TitleStyle.GetFont(c.GetFont()))
 		r.SetFontColor(c.TitleStyle.GetFontColor(c.GetColorPalette().TextColor()))
 		titleFontSize := c.TitleStyle.GetFontSize(DefaultTitleFontSize)

chart_test.go

@@ -8,57 +8,57 @@ import (
 	"testing"
 	"time"
 
-	"github.com/blendlabs/go-assert"
-	"github.com/wcharczuk/go-chart/drawing"
+	"git.smarteching.com/zeni/go-chart/v2/drawing"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestChartGetDPI(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	unset := Chart{}
-	assert.Equal(DefaultDPI, unset.GetDPI())
-	assert.Equal(192, unset.GetDPI(192))
+	testutil.AssertEqual(t, DefaultDPI, unset.GetDPI())
+	testutil.AssertEqual(t, 192, unset.GetDPI(192))
 
 	set := Chart{DPI: 128}
-	assert.Equal(128, set.GetDPI())
-	assert.Equal(128, set.GetDPI(192))
+	testutil.AssertEqual(t, 128, set.GetDPI())
+	testutil.AssertEqual(t, 128, set.GetDPI(192))
 }
 
 func TestChartGetFont(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	f, err := GetDefaultFont()
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	unset := Chart{}
-	assert.Nil(unset.GetFont())
+	testutil.AssertNil(t, unset.GetFont())
 
 	set := Chart{Font: f}
-	assert.NotNil(set.GetFont())
+	testutil.AssertNotNil(t, set.GetFont())
 }
 
 func TestChartGetWidth(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	unset := Chart{}
-	assert.Equal(DefaultChartWidth, unset.GetWidth())
+	testutil.AssertEqual(t, DefaultChartWidth, unset.GetWidth())
 
 	set := Chart{Width: DefaultChartWidth + 10}
-	assert.Equal(DefaultChartWidth+10, set.GetWidth())
+	testutil.AssertEqual(t, DefaultChartWidth+10, set.GetWidth())
 }
 
 func TestChartGetHeight(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	unset := Chart{}
-	assert.Equal(DefaultChartHeight, unset.GetHeight())
+	testutil.AssertEqual(t, DefaultChartHeight, unset.GetHeight())
 
 	set := Chart{Height: DefaultChartHeight + 10}
-	assert.Equal(DefaultChartHeight+10, set.GetHeight())
+	testutil.AssertEqual(t, DefaultChartHeight+10, set.GetHeight())
 }
 
 func TestChartGetRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Series: []Series{
@@ -79,14 +79,14 @@ func TestChartGetRanges(t *testing.T) {
 	}
 
 	xrange, yrange, yrangeAlt := c.getRanges()
-	assert.Equal(-2.0, xrange.GetMin())
-	assert.Equal(5.0, xrange.GetMax())
+	testutil.AssertEqual(t, -2.0, xrange.GetMin())
+	testutil.AssertEqual(t, 5.0, xrange.GetMax())
 
-	assert.Equal(-2.1, yrange.GetMin())
-	assert.Equal(4.5, yrange.GetMax())
+	testutil.AssertEqual(t, -2.1, yrange.GetMin())
+	testutil.AssertEqual(t, 4.5, yrange.GetMax())
 
-	assert.Equal(10.0, yrangeAlt.GetMin())
-	assert.Equal(14.0, yrangeAlt.GetMax())
+	testutil.AssertEqual(t, 10.0, yrangeAlt.GetMin())
+	testutil.AssertEqual(t, 14.0, yrangeAlt.GetMax())
 
 	cSet := Chart{
 		XAxis: XAxis{
@@ -116,18 +116,18 @@ func TestChartGetRanges(t *testing.T) {
 	}
 
 	xr2, yr2, yra2 := cSet.getRanges()
-	assert.Equal(9.8, xr2.GetMin())
-	assert.Equal(19.8, xr2.GetMax())
+	testutil.AssertEqual(t, 9.8, xr2.GetMin())
+	testutil.AssertEqual(t, 19.8, xr2.GetMax())
 
-	assert.Equal(9.9, yr2.GetMin())
-	assert.Equal(19.9, yr2.GetMax())
+	testutil.AssertEqual(t, 9.9, yr2.GetMin())
+	testutil.AssertEqual(t, 19.9, yr2.GetMax())
 
-	assert.Equal(9.7, yra2.GetMin())
-	assert.Equal(19.7, yra2.GetMax())
+	testutil.AssertEqual(t, 9.7, yra2.GetMin())
+	testutil.AssertEqual(t, 19.7, yra2.GetMax())
 }
 
 func TestChartGetRangesUseTicks(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	// this test asserts that ticks should supercede manual ranges when generating the overall ranges.
 
@@ -155,15 +155,15 @@ func TestChartGetRangesUseTicks(t *testing.T) {
 	}
 
 	xr, yr, yar := c.getRanges()
-	assert.Equal(-2.0, xr.GetMin())
-	assert.Equal(2.0, xr.GetMax())
-	assert.Equal(0.0, yr.GetMin())
-	assert.Equal(5.0, yr.GetMax())
-	assert.True(yar.IsZero(), yar.String())
+	testutil.AssertEqual(t, -2.0, xr.GetMin())
+	testutil.AssertEqual(t, 2.0, xr.GetMax())
+	testutil.AssertEqual(t, 0.0, yr.GetMin())
+	testutil.AssertEqual(t, 5.0, yr.GetMax())
+	testutil.AssertTrue(t, yar.IsZero(), yar.String())
 }
 
 func TestChartGetRangesUseUserRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		YAxis: YAxis{
@@ -181,15 +181,15 @@ func TestChartGetRangesUseUserRanges(t *testing.T) {
 	}
 
 	xr, yr, yar := c.getRanges()
-	assert.Equal(-2.0, xr.GetMin())
-	assert.Equal(2.0, xr.GetMax())
-	assert.Equal(-5.0, yr.GetMin())
-	assert.Equal(5.0, yr.GetMax())
-	assert.True(yar.IsZero(), yar.String())
+	testutil.AssertEqual(t, -2.0, xr.GetMin())
+	testutil.AssertEqual(t, 2.0, xr.GetMax())
+	testutil.AssertEqual(t, -5.0, yr.GetMin())
+	testutil.AssertEqual(t, 5.0, yr.GetMax())
+	testutil.AssertTrue(t, yar.IsZero(), yar.String())
 }
 
 func TestChartGetBackgroundStyle(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Background: Style{
@@ -198,11 +198,11 @@ func TestChartGetBackgroundStyle(t *testing.T) {
 	}
 
 	bs := c.getBackgroundStyle()
-	assert.Equal(bs.FillColor.String(), drawing.ColorBlack.String())
+	testutil.AssertEqual(t, bs.FillColor.String(), drawing.ColorBlack.String())
 }
 
 func TestChartGetCanvasStyle(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Canvas: Style{
@@ -211,19 +211,19 @@ func TestChartGetCanvasStyle(t *testing.T) {
 	}
 
 	bs := c.getCanvasStyle()
-	assert.Equal(bs.FillColor.String(), drawing.ColorBlack.String())
+	testutil.AssertEqual(t, bs.FillColor.String(), drawing.ColorBlack.String())
 }
 
 func TestChartGetDefaultCanvasBox(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{}
 	canvasBoxDefault := c.getDefaultCanvasBox()
-	assert.False(canvasBoxDefault.IsZero())
-	assert.Equal(DefaultBackgroundPadding.Top, canvasBoxDefault.Top)
-	assert.Equal(DefaultBackgroundPadding.Left, canvasBoxDefault.Left)
-	assert.Equal(c.GetWidth()-DefaultBackgroundPadding.Right, canvasBoxDefault.Right)
-	assert.Equal(c.GetHeight()-DefaultBackgroundPadding.Bottom, canvasBoxDefault.Bottom)
+	testutil.AssertFalse(t, canvasBoxDefault.IsZero())
+	testutil.AssertEqual(t, DefaultBackgroundPadding.Top, canvasBoxDefault.Top)
+	testutil.AssertEqual(t, DefaultBackgroundPadding.Left, canvasBoxDefault.Left)
+	testutil.AssertEqual(t, c.GetWidth()-DefaultBackgroundPadding.Right, canvasBoxDefault.Right)
+	testutil.AssertEqual(t, c.GetHeight()-DefaultBackgroundPadding.Bottom, canvasBoxDefault.Bottom)
 
 	custom := Chart{
 		Background: Style{
@@ -236,15 +236,15 @@ func TestChartGetDefaultCanvasBox(t *testing.T) {
 		},
 	}
 	canvasBoxCustom := custom.getDefaultCanvasBox()
-	assert.False(canvasBoxCustom.IsZero())
-	assert.Equal(DefaultBackgroundPadding.Top+1, canvasBoxCustom.Top)
-	assert.Equal(DefaultBackgroundPadding.Left+1, canvasBoxCustom.Left)
-	assert.Equal(c.GetWidth()-(DefaultBackgroundPadding.Right+1), canvasBoxCustom.Right)
-	assert.Equal(c.GetHeight()-(DefaultBackgroundPadding.Bottom+1), canvasBoxCustom.Bottom)
+	testutil.AssertFalse(t, canvasBoxCustom.IsZero())
+	testutil.AssertEqual(t, DefaultBackgroundPadding.Top+1, canvasBoxCustom.Top)
+	testutil.AssertEqual(t, DefaultBackgroundPadding.Left+1, canvasBoxCustom.Left)
+	testutil.AssertEqual(t, c.GetWidth()-(DefaultBackgroundPadding.Right+1), canvasBoxCustom.Right)
+	testutil.AssertEqual(t, c.GetHeight()-(DefaultBackgroundPadding.Bottom+1), canvasBoxCustom.Bottom)
 }
 
 func TestChartGetValueFormatters(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Series: []Series{
@@ -265,90 +265,95 @@ func TestChartGetValueFormatters(t *testing.T) {
 	}
 
 	dxf, dyf, dyaf := c.getValueFormatters()
-	assert.NotNil(dxf)
-	assert.NotNil(dyf)
-	assert.NotNil(dyaf)
+	testutil.AssertNotNil(t, dxf)
+	testutil.AssertNotNil(t, dyf)
+	testutil.AssertNotNil(t, dyaf)
 }
 
 func TestChartHasAxes(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
-	assert.False(Chart{}.hasAxes())
+	testutil.AssertTrue(t, Chart{}.hasAxes())
+	testutil.AssertFalse(t, Chart{XAxis: XAxis{Style: Hidden()}, YAxis: YAxis{Style: Hidden()}, YAxisSecondary: YAxis{Style: Hidden()}}.hasAxes())
 
 	x := Chart{
 		XAxis: XAxis{
-			Style: Style{
-				Show: true,
-			},
+			Style: Hidden(),
+		},
+		YAxis: YAxis{
+			Style: Shown(),
+		},
+		YAxisSecondary: YAxis{
+			Style: Hidden(),
 		},
 	}
-	assert.True(x.hasAxes())
+	testutil.AssertTrue(t, x.hasAxes())
 
 	y := Chart{
+		XAxis: XAxis{
+			Style: Shown(),
+		},
 		YAxis: YAxis{
-			Style: Style{
-				Show: true,
-			},
+			Style: Hidden(),
+		},
+		YAxisSecondary: YAxis{
+			Style: Hidden(),
 		},
 	}
-	assert.True(y.hasAxes())
+	testutil.AssertTrue(t, y.hasAxes())
 
 	ya := Chart{
+		XAxis: XAxis{
+			Style: Hidden(),
+		},
+		YAxis: YAxis{
+			Style: Hidden(),
+		},
 		YAxisSecondary: YAxis{
-			Style: Style{
-				Show: true,
-			},
+			Style: Shown(),
 		},
 	}
-	assert.True(ya.hasAxes())
+	testutil.AssertTrue(t, ya.hasAxes())
 }
 
 func TestChartGetAxesTicks(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	r, err := PNG(1024, 1024)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	c := Chart{
 		XAxis: XAxis{
-			Style: Style{Show: true},
 			Range: &ContinuousRange{Min: 9.8, Max: 19.8},
 		},
 		YAxis: YAxis{
-			Style: Style{Show: true},
 			Range: &ContinuousRange{Min: 9.9, Max: 19.9},
 		},
 		YAxisSecondary: YAxis{
-			Style: Style{Show: true},
 			Range: &ContinuousRange{Min: 9.7, Max: 19.7},
 		},
 	}
 	xr, yr, yar := c.getRanges()
 
 	xt, yt, yat := c.getAxesTicks(r, xr, yr, yar, FloatValueFormatter, FloatValueFormatter, FloatValueFormatter)
-	assert.NotEmpty(xt)
-	assert.NotEmpty(yt)
-	assert.NotEmpty(yat)
+	testutil.AssertNotEmpty(t, xt)
+	testutil.AssertNotEmpty(t, yt)
+	testutil.AssertNotEmpty(t, yat)
 }
 
 func TestChartSingleSeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 	now := time.Now()
 	c := Chart{
-		Title:      "Hello!",
-		TitleStyle: StyleShow(),
-		Width:      1024,
-		Height:     400,
+		Title:  "Hello!",
+		Width:  1024,
+		Height: 400,
 		YAxis: YAxis{
-			Style: StyleShow(),
 			Range: &ContinuousRange{
 				Min: 0.0,
 				Max: 4.0,
 			},
 		},
-		XAxis: XAxis{
-			Style: StyleShow(),
-		},
 		Series: []Series{
 			TimeSeries{
 				Name:    "goog",
@@ -360,11 +365,11 @@ func TestChartSingleSeries(t *testing.T) {
 
 	buffer := bytes.NewBuffer([]byte{})
 	c.Render(PNG, buffer)
-	assert.NotEmpty(buffer.Bytes())
+	testutil.AssertNotEmpty(t, buffer.Bytes())
 }
 
 func TestChartRegressionBadRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Series: []Series{
@@ -376,11 +381,11 @@ func TestChartRegressionBadRanges(t *testing.T) {
 	}
 	buffer := bytes.NewBuffer([]byte{})
 	c.Render(PNG, buffer)
-	assert.True(true, "Render needs to finish.")
+	testutil.AssertTrue(t, true, "Render needs to finish.")
 }
 
 func TestChartRegressionBadRangesByUser(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		YAxis: YAxis{
@@ -391,43 +396,43 @@ func TestChartRegressionBadRangesByUser(t *testing.T) {
 		},
 		Series: []Series{
 			ContinuousSeries{
-				XValues: Sequence.Float64(1.0, 10.0),
-				YValues: Sequence.Float64(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
+				YValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
 	buffer := bytes.NewBuffer([]byte{})
 	c.Render(PNG, buffer)
-	assert.True(true, "Render needs to finish.")
+	testutil.AssertTrue(t, true, "Render needs to finish.")
 }
 
 func TestChartValidatesSeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Series: []Series{
 			ContinuousSeries{
-				XValues: Sequence.Float64(1.0, 10.0),
-				YValues: Sequence.Float64(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
+				YValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
 
-	assert.Nil(c.validateSeries())
+	testutil.AssertNil(t, c.validateSeries())
 
 	c = Chart{
 		Series: []Series{
 			ContinuousSeries{
-				XValues: Sequence.Float64(1.0, 10.0),
+				XValues: LinearRange(1.0, 10.0),
 			},
 		},
 	}
 
-	assert.NotNil(c.validateSeries())
+	testutil.AssertNotNil(t, c.validateSeries())
 }
 
 func TestChartCheckRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		Series: []Series{
@@ -439,27 +444,11 @@ func TestChartCheckRanges(t *testing.T) {
 	}
 
 	xr, yr, yra := c.getRanges()
-	assert.Nil(c.checkRanges(xr, yr, yra))
-}
-
-func TestChartCheckRangesFailure(t *testing.T) {
-	assert := assert.New(t)
-
-	c := Chart{
-		Series: []Series{
-			ContinuousSeries{
-				XValues: []float64{1.0, 2.0},
-				YValues: []float64{3.14, 3.14},
-			},
-		},
-	}
-
-	xr, yr, yra := c.getRanges()
-	assert.NotNil(c.checkRanges(xr, yr, yra))
+	testutil.AssertNil(t, c.checkRanges(xr, yr, yra))
 }
 
 func TestChartCheckRangesWithRanges(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
 		XAxis: XAxis{
@@ -483,7 +472,7 @@ func TestChartCheckRangesWithRanges(t *testing.T) {
 	}
 
 	xr, yr, yra := c.getRanges()
-	assert.Nil(c.checkRanges(xr, yr, yra))
+	testutil.AssertNil(t, c.checkRanges(xr, yr, yra))
 }
 
 func at(i image.Image, x, y int) drawing.Color {
@@ -491,85 +480,115 @@ func at(i image.Image, x, y int) drawing.Color {
 }
 
 func TestChartE2ELine(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	c := Chart{
-		Height: 50,
-		Width:  50,
+		Height:         50,
+		Width:          50,
+		TitleStyle:     Hidden(),
+		XAxis:          HideXAxis(),
+		YAxis:          HideYAxis(),
+		YAxisSecondary: HideYAxis(),
 		Canvas: Style{
-			Padding: Box{IsSet: true},
+			Padding: BoxZero,
 		},
 		Background: Style{
-			Padding: Box{IsSet: true},
+			Padding: BoxZero,
 		},
 		Series: []Series{
 			ContinuousSeries{
-				XValues: Sequence.Float64(0, 4, 1),
-				YValues: Sequence.Float64(0, 4, 1),
+				XValues: LinearRangeWithStep(0, 4, 1),
+				YValues: LinearRangeWithStep(0, 4, 1),
 			},
 		},
 	}
 
 	var buffer = &bytes.Buffer{}
 	err := c.Render(PNG, buffer)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	// do color tests ...
 
 	i, err := png.Decode(buffer)
-	assert.Nil(err)
+	testutil.AssertNil(t, err)
 
 	// test the bottom and top of the line
-	assert.Equal(drawing.ColorWhite, at(i, 0, 0))
-	assert.Equal(drawing.ColorWhite, at(i, 49, 49))
+	testutil.AssertEqual(t, drawing.ColorWhite, at(i, 0, 0))
+	testutil.AssertEqual(t, drawing.ColorWhite, at(i, 49, 49))
 
 	// test a line mid point
 	defaultSeriesColor := GetDefaultColor(0)
-	assert.Equal(defaultSeriesColor, at(i, 0, 49))
-	assert.Equal(defaultSeriesColor, at(i, 49, 0))
-	assert.Equal(drawing.ColorFromHex("bddbf6"), at(i, 24, 24))
+	testutil.AssertEqual(t, defaultSeriesColor, at(i, 0, 49))
+	testutil.AssertEqual(t, defaultSeriesColor, at(i, 49, 0))
+	testutil.AssertEqual(t, drawing.ColorFromHex("bddbf6"), at(i, 24, 24))
 }
 
 func TestChartE2ELineWithFill(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
+
+	logBuffer := new(bytes.Buffer)
 
 	c := Chart{
 		Height: 50,
 		Width:  50,
 		Canvas: Style{
-			Padding: Box{IsSet: true},
+			Padding: BoxZero,
 		},
 		Background: Style{
-			Padding: Box{IsSet: true},
+			Padding: BoxZero,
 		},
+		TitleStyle:     Hidden(),
+		XAxis:          HideXAxis(),
+		YAxis:          HideYAxis(),
+		YAxisSecondary: HideYAxis(),
 		Series: []Series{
 			ContinuousSeries{
 				Style: Style{
-					Show:        true,
 					StrokeColor: drawing.ColorBlue,
 					FillColor:   drawing.ColorRed,
 				},
-				XValues: Sequence.Float64(0, 4, 1),
-				YValues: Sequence.Float64(0, 4, 1),
+				XValues: LinearRangeWithStep(0, 4, 1),
+				YValues: LinearRangeWithStep(0, 4, 1),
+			},
+		},
+		Log: NewLogger(OptLoggerStdout(logBuffer), OptLoggerStderr(logBuffer)),
+	}
+
+	testutil.AssertEqual(t, 5, len(c.Series[0].(ContinuousSeries).XValues))
+	testutil.AssertEqual(t, 5, len(c.Series[0].(ContinuousSeries).YValues))
+
+	var buffer = &bytes.Buffer{}
+	err := c.Render(PNG, buffer)
+	testutil.AssertNil(t, err)
+
+	i, err := png.Decode(buffer)
+	testutil.AssertNil(t, err)
+
+	// test the bottom and top of the line
+	testutil.AssertEqual(t, drawing.ColorWhite, at(i, 0, 0))
+	testutil.AssertEqual(t, drawing.ColorRed, at(i, 49, 49))
+
+	// test a line mid point
+	defaultSeriesColor := drawing.ColorBlue
+	testutil.AssertEqual(t, defaultSeriesColor, at(i, 0, 49))
+	testutil.AssertEqual(t, defaultSeriesColor, at(i, 49, 0))
+}
+
+func Test_Chart_cve(t *testing.T) {
+	poc := StackedBarChart{
+		Title: "poc",
+		Bars: []StackedBar{
+			{
+				Name: "11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111",
+				Values: []Value{
+					{Value: 1, Label: "infinite"},
+					{Value: 1, Label: "loop"},
+				},
 			},
 		},
 	}
 
-	var buffer = &bytes.Buffer{}
-	err := c.Render(PNG, buffer)
-	assert.Nil(err)
-
-	// do color tests ...
-
-	i, err := png.Decode(buffer)
-	assert.Nil(err)
-
-	// test the bottom and top of the line
-	assert.Equal(drawing.ColorWhite, at(i, 0, 0))
-	assert.Equal(drawing.ColorRed, at(i, 49, 49))
-
-	// test a line mid point
-	defaultSeriesColor := drawing.ColorBlue
-	assert.Equal(defaultSeriesColor, at(i, 0, 49))
-	assert.Equal(defaultSeriesColor, at(i, 49, 0))
+	var imgContent bytes.Buffer
+	err := poc.Render(PNG, &imgContent)
+	testutil.AssertNotNil(t, err)
 }

cmd/chart/main.go

@@ -0,0 +1,148 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+var (
+	outputPath = flag.String("output", "", "The output file")
+
+	inputFormat = flag.String("format", "csv", "The input format, either 'csv' or 'tsv' (defaults to 'csv')")
+	inputPath   = flag.String("f", "", "The input file")
+	reverse     = flag.Bool("reverse", false, "If we should reverse the inputs")
+
+	hideLegend     = flag.Bool("hide-legend", false, "If we should omit the chart legend")
+	hideSMA        = flag.Bool("hide-sma", false, "If we should omit simple moving average")
+	hideLinreg     = flag.Bool("hide-linreg", false, "If we should omit linear regressions")
+	hideLastValues = flag.Bool("hide-last-values", false, "If we should omit last values")
+)
+
+func main() {
+	flag.Parse()
+	log := chart.NewLogger()
+
+	var rawData []byte
+	var err error
+	if *inputPath != "" {
+		if *inputPath == "-" {
+			rawData, err = ioutil.ReadAll(os.Stdin)
+			if err != nil {
+				log.FatalErr(err)
+			}
+		} else {
+			rawData, err = ioutil.ReadFile(*inputPath)
+			if err != nil {
+				log.FatalErr(err)
+			}
+		}
+	} else if len(flag.Args()) > 0 {
+		rawData = []byte(flag.Args()[0])
+	} else {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	var parts []string
+	switch *inputFormat {
+	case "csv":
+		parts = chart.SplitCSV(string(rawData))
+	case "tsv":
+		parts = strings.Split(string(rawData), "\t")
+	default:
+		log.FatalErr(fmt.Errorf("invalid format; must be 'csv' or 'tsv'"))
+	}
+
+	yvalues, err := chart.ParseFloats(parts...)
+	if err != nil {
+		log.FatalErr(err)
+	}
+
+	if *reverse {
+		yvalues = chart.ValueSequence(yvalues...).Reverse().Values()
+	}
+
+	var series []chart.Series
+	mainSeries := chart.ContinuousSeries{
+		Name:    "Values",
+		XValues: chart.LinearRange(1, float64(len(yvalues))),
+		YValues: yvalues,
+	}
+	series = append(series, mainSeries)
+
+	smaSeries := &chart.SMASeries{
+		Name: "SMA",
+		Style: chart.Style{
+			Hidden:          *hideSMA,
+			StrokeColor:     chart.ColorRed,
+			StrokeDashArray: []float64{5.0, 5.0},
+		},
+		InnerSeries: mainSeries,
+	}
+	series = append(series, smaSeries)
+
+	linRegSeries := &chart.LinearRegressionSeries{
+		Name: "Values - Lin. Reg.",
+		Style: chart.Style{
+			Hidden: *hideLinreg,
+		},
+		InnerSeries: mainSeries,
+	}
+	series = append(series, linRegSeries)
+
+	mainLastValue := chart.LastValueAnnotationSeries(mainSeries)
+	mainLastValue.Style = chart.Style{
+		Hidden: *hideLastValues,
+	}
+	series = append(series, mainLastValue)
+
+	linregLastValue := chart.LastValueAnnotationSeries(linRegSeries)
+	linregLastValue.Style = chart.Style{
+		Hidden: (*hideLastValues || *hideLinreg),
+	}
+	series = append(series, linregLastValue)
+
+	smaLastValue := chart.LastValueAnnotationSeries(smaSeries)
+	smaLastValue.Style = chart.Style{
+		Hidden: (*hideLastValues || *hideSMA),
+	}
+	series = append(series, smaLastValue)
+
+	graph := chart.Chart{
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 50,
+			},
+		},
+		Series: series,
+	}
+
+	if !*hideLegend {
+		graph.Elements = []chart.Renderable{chart.LegendThin(&graph)}
+	}
+
+	var output *os.File
+	if *outputPath != "" {
+		output, err = os.Create(*outputPath)
+		if err != nil {
+			log.FatalErr(err)
+		}
+	} else {
+		output, err = ioutil.TempFile("", "*.png")
+		if err != nil {
+			log.FatalErr(err)
+		}
+	}
+
+	if err := graph.Render(chart.PNG, output); err != nil {
+		log.FatalErr(err)
+	}
+
+	fmt.Fprintln(os.Stdout, output.Name())
+	os.Exit(0)
+}

colors.go

@@ -1,6 +1,6 @@
 package chart
 
-import "github.com/wcharczuk/go-chart/drawing"
+import "git.smarteching.com/zeni/go-chart/v2/drawing"
 
 var (
 	// ColorWhite is white.

concat_series.go

@@ -7,7 +7,7 @@ type ConcatSeries []Series
 func (cs ConcatSeries) Len() int {
 	total := 0
 	for _, s := range cs {
-		if typed, isValueProvider := s.(ValueProvider); isValueProvider {
+		if typed, isValuesProvider := s.(ValuesProvider); isValuesProvider {
 			total += typed.Len()
 		}
 	}
@@ -19,10 +19,10 @@ func (cs ConcatSeries) Len() int {
 func (cs ConcatSeries) GetValue(index int) (x, y float64) {
 	cursor := 0
 	for _, s := range cs {
-		if typed, isValueProvider := s.(ValueProvider); isValueProvider {
+		if typed, isValuesProvider := s.(ValuesProvider); isValuesProvider {
 			len := typed.Len()
 			if index < cursor+len {
-				x, y = typed.GetValue(index - cursor) //FENCEPOSTS.
+				x, y = typed.GetValues(index - cursor) //FENCEPOSTS.
 				return
 			}
 			cursor += typed.Len()

concat_series_test.go

@@ -3,39 +3,39 @@ package chart
 import (
 	"testing"
 
-	assert "github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestConcatSeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	s1 := ContinuousSeries{
-		XValues: Sequence.Float64(1.0, 10.0),
-		YValues: Sequence.Float64(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
 	s2 := ContinuousSeries{
-		XValues: Sequence.Float64(11, 20.0),
-		YValues: Sequence.Float64(10.0, 1.0),
+		XValues: LinearRange(11, 20.0),
+		YValues: LinearRange(10.0, 1.0),
 	}
 
 	s3 := ContinuousSeries{
-		XValues: Sequence.Float64(21, 30.0),
-		YValues: Sequence.Float64(1.0, 10.0),
+		XValues: LinearRange(21, 30.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
 	cs := ConcatSeries([]Series{s1, s2, s3})
-	assert.Equal(30, cs.Len())
+	testutil.AssertEqual(t, 30, cs.Len())
 
 	x0, y0 := cs.GetValue(0)
-	assert.Equal(1.0, x0)
-	assert.Equal(1.0, y0)
+	testutil.AssertEqual(t, 1.0, x0)
+	testutil.AssertEqual(t, 1.0, y0)
 
 	xm, ym := cs.GetValue(19)
-	assert.Equal(20.0, xm)
-	assert.Equal(1.0, ym)
+	testutil.AssertEqual(t, 20.0, xm)
+	testutil.AssertEqual(t, 1.0, ym)
 
 	xn, yn := cs.GetValue(29)
-	assert.Equal(30.0, xn)
-	assert.Equal(10.0, yn)
+	testutil.AssertEqual(t, 30.0, xn)
+	testutil.AssertEqual(t, 10.0, yn)
 }

continuous_range.go

@@ -62,6 +62,9 @@ func (r *ContinuousRange) SetDomain(domain int) {
 
 // String returns a simple string for the ContinuousRange.
 func (r ContinuousRange) String() string {
+	if r.GetDelta() == 0 {
+		return "ContinuousRange [empty]"
+	}
 	return fmt.Sprintf("ContinuousRange [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
 }
 

continuous_range_test.go

@@ -3,20 +3,20 @@ package chart
 import (
 	"testing"
 
-	"github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestRangeTranslate(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 	values := []float64{1.0, 2.0, 2.5, 2.7, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0}
 	r := ContinuousRange{Domain: 1000}
-	r.Min, r.Max = Math.MinAndMax(values...)
+	r.Min, r.Max = MinMax(values...)
 
 	// delta = ~7.0
 	// value = ~5.0
 	// domain = ~1000
 	// 5/8 * 1000 ~=
-	assert.Equal(0, r.Translate(1.0))
-	assert.Equal(1000, r.Translate(8.0))
-	assert.Equal(572, r.Translate(5.0))
+	testutil.AssertEqual(t, 0, r.Translate(1.0))
+	testutil.AssertEqual(t, 1000, r.Translate(8.0))
+	testutil.AssertEqual(t, 572, r.Translate(5.0))
 }

continuous_series.go

@@ -2,6 +2,13 @@ package chart
 
 import "fmt"
 
+// Interface Assertions.
+var (
+	_ Series              = (*ContinuousSeries)(nil)
+	_ FirstValuesProvider = (*ContinuousSeries)(nil)
+	_ LastValuesProvider  = (*ContinuousSeries)(nil)
+)
+
 // ContinuousSeries represents a line on a chart.
 type ContinuousSeries struct {
 	Name  string
@@ -31,13 +38,18 @@ func (cs ContinuousSeries) Len() int {
 	return len(cs.XValues)
 }
 
-// GetValue gets a value at a given index.
-func (cs ContinuousSeries) GetValue(index int) (float64, float64) {
+// GetValues gets the x,y values at a given index.
+func (cs ContinuousSeries) GetValues(index int) (float64, float64) {
 	return cs.XValues[index], cs.YValues[index]
 }
 
-// GetLastValue gets the last value.
-func (cs ContinuousSeries) GetLastValue() (float64, float64) {
+// GetFirstValues gets the first x,y values.
+func (cs ContinuousSeries) GetFirstValues() (float64, float64) {
+	return cs.XValues[0], cs.YValues[0]
+}
+
+// GetLastValues gets the last x,y values.
+func (cs ContinuousSeries) GetLastValues() (float64, float64) {
 	return cs.XValues[len(cs.XValues)-1], cs.YValues[len(cs.YValues)-1]
 }
 
@@ -70,11 +82,15 @@ func (cs ContinuousSeries) Render(r Renderer, canvasBox Box, xrange, yrange Rang
 // Validate validates the series.
 func (cs ContinuousSeries) Validate() error {
 	if len(cs.XValues) == 0 {
-		return fmt.Errorf("continuous series must have xvalues set")
+		return fmt.Errorf("continuous series; must have xvalues set")
 	}
 
 	if len(cs.YValues) == 0 {
-		return fmt.Errorf("continuous series must have yvalues set")
+		return fmt.Errorf("continuous series; must have yvalues set")
+	}
+
+	if len(cs.XValues) != len(cs.YValues) {
+		return fmt.Errorf("continuous series; must have same length xvalues as yvalues")
 	}
 	return nil
 }

continuous_series_test.go

@@ -4,35 +4,35 @@ import (
 	"fmt"
 	"testing"
 
-	assert "github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestContinuousSeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	cs := ContinuousSeries{
 		Name:    "Test Series",
-		XValues: Sequence.Float64(1.0, 10.0),
-		YValues: Sequence.Float64(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
 
-	assert.Equal("Test Series", cs.GetName())
-	assert.Equal(10, cs.Len())
-	x0, y0 := cs.GetValue(0)
-	assert.Equal(1.0, x0)
-	assert.Equal(1.0, y0)
+	testutil.AssertEqual(t, "Test Series", cs.GetName())
+	testutil.AssertEqual(t, 10, cs.Len())
+	x0, y0 := cs.GetValues(0)
+	testutil.AssertEqual(t, 1.0, x0)
+	testutil.AssertEqual(t, 1.0, y0)
 
-	xn, yn := cs.GetValue(9)
-	assert.Equal(10.0, xn)
-	assert.Equal(10.0, yn)
+	xn, yn := cs.GetValues(9)
+	testutil.AssertEqual(t, 10.0, xn)
+	testutil.AssertEqual(t, 10.0, yn)
 
-	xn, yn = cs.GetLastValue()
-	assert.Equal(10.0, xn)
-	assert.Equal(10.0, yn)
+	xn, yn = cs.GetLastValues()
+	testutil.AssertEqual(t, 10.0, xn)
+	testutil.AssertEqual(t, 10.0, yn)
 }
 
 func TestContinuousSeriesValueFormatter(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	cs := ContinuousSeries{
 		XValueFormatter: func(v interface{}) string {
@@ -44,29 +44,29 @@ func TestContinuousSeriesValueFormatter(t *testing.T) {
 	}
 
 	xf, yf := cs.GetValueFormatters()
-	assert.Equal("0.100000 foo", xf(0.1))
-	assert.Equal("0.100000 bar", yf(0.1))
+	testutil.AssertEqual(t, "0.100000 foo", xf(0.1))
+	testutil.AssertEqual(t, "0.100000 bar", yf(0.1))
 }
 
 func TestContinuousSeriesValidate(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	cs := ContinuousSeries{
 		Name:    "Test Series",
-		XValues: Sequence.Float64(1.0, 10.0),
-		YValues: Sequence.Float64(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
-	assert.Nil(cs.Validate())
+	testutil.AssertNil(t, cs.Validate())
 
 	cs = ContinuousSeries{
 		Name:    "Test Series",
-		XValues: Sequence.Float64(1.0, 10.0),
+		XValues: LinearRange(1.0, 10.0),
 	}
-	assert.NotNil(cs.Validate())
+	testutil.AssertNotNil(t, cs.Validate())
 
 	cs = ContinuousSeries{
 		Name:    "Test Series",
-		YValues: Sequence.Float64(1.0, 10.0),
+		YValues: LinearRange(1.0, 10.0),
 	}
-	assert.NotNil(cs.Validate())
+	testutil.AssertNotNil(t, cs.Validate())
 }

date.go

@@ -1,426 +0,0 @@
-package chart
-
-import (
-	"sync"
-	"time"
-)
-
-const (
-	// AllDaysMask is a bitmask of all the days of the week.
-	AllDaysMask = 1<<uint(time.Sunday) | 1<<uint(time.Monday) | 1<<uint(time.Tuesday) | 1<<uint(time.Wednesday) | 1<<uint(time.Thursday) | 1<<uint(time.Friday) | 1<<uint(time.Saturday)
-	// WeekDaysMask is a bitmask of all the weekdays of the week.
-	WeekDaysMask = 1<<uint(time.Monday) | 1<<uint(time.Tuesday) | 1<<uint(time.Wednesday) | 1<<uint(time.Thursday) | 1<<uint(time.Friday)
-	//WeekendDaysMask is a bitmask of the weekend days of the week.
-	WeekendDaysMask = 1<<uint(time.Sunday) | 1<<uint(time.Saturday)
-)
-
-var (
-	// DaysOfWeek are all the time.Weekday in an array for utility purposes.
-	DaysOfWeek = []time.Weekday{
-		time.Sunday,
-		time.Monday,
-		time.Tuesday,
-		time.Wednesday,
-		time.Thursday,
-		time.Friday,
-		time.Saturday,
-	}
-
-	// WeekDays are the business time.Weekday in an array.
-	WeekDays = []time.Weekday{
-		time.Monday,
-		time.Tuesday,
-		time.Wednesday,
-		time.Thursday,
-		time.Friday,
-	}
-
-	// WeekendDays are the weekend time.Weekday in an array.
-	WeekendDays = []time.Weekday{
-		time.Sunday,
-		time.Saturday,
-	}
-
-	//Epoch is unix epoc saved for utility purposes.
-	Epoch = time.Unix(0, 0)
-)
-
-var (
-	_easternLock sync.Mutex
-	_eastern     *time.Location
-)
-
-// NYSEOpen is when the NYSE opens.
-func NYSEOpen() time.Time { return Date.Time(9, 30, 0, 0, Date.Eastern()) }
-
-// NYSEClose is when the NYSE closes.
-func NYSEClose() time.Time { return Date.Time(16, 0, 0, 0, Date.Eastern()) }
-
-// NASDAQOpen is when NASDAQ opens.
-func NASDAQOpen() time.Time { return Date.Time(9, 30, 0, 0, Date.Eastern()) }
-
-// NASDAQClose is when NASDAQ closes.
-func NASDAQClose() time.Time { return Date.Time(16, 0, 0, 0, Date.Eastern()) }
-
-// NYSEArcaOpen is when NYSEARCA opens.
-func NYSEArcaOpen() time.Time { return Date.Time(4, 0, 0, 0, Date.Eastern()) }
-
-// NYSEArcaClose is when NYSEARCA closes.
-func NYSEArcaClose() time.Time { return Date.Time(20, 0, 0, 0, Date.Eastern()) }
-
-// HolidayProvider is a function that returns if a given time falls on a holiday.
-type HolidayProvider func(time.Time) bool
-
-// defaultHolidayProvider implements `HolidayProvider` and just returns false.
-func defaultHolidayProvider(_ time.Time) bool { return false }
-
-var (
-	// Date contains utility functions that operate on dates.
-	Date = &date{}
-)
-
-type date struct{}
-
-// IsNYSEHoliday returns if a date was/is on a nyse holiday day.
-func (d date) IsNYSEHoliday(t time.Time) bool {
-	te := t.In(d.Eastern())
-	if te.Year() == 2013 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 21
-		} else if te.Month() == 2 {
-			return te.Day() == 18
-		} else if te.Month() == 3 {
-			return te.Day() == 29
-		} else if te.Month() == 5 {
-			return te.Day() == 27
-		} else if te.Month() == 7 {
-			return te.Day() == 4
-		} else if te.Month() == 9 {
-			return te.Day() == 2
-		} else if te.Month() == 11 {
-			return te.Day() == 28
-		} else if te.Month() == 12 {
-			return te.Day() == 25
-		}
-	} else if te.Year() == 2014 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 20
-		} else if te.Month() == 2 {
-			return te.Day() == 17
-		} else if te.Month() == 4 {
-			return te.Day() == 18
-		} else if te.Month() == 5 {
-			return te.Day() == 26
-		} else if te.Month() == 7 {
-			return te.Day() == 4
-		} else if te.Month() == 9 {
-			return te.Day() == 1
-		} else if te.Month() == 11 {
-			return te.Day() == 27
-		} else if te.Month() == 12 {
-			return te.Day() == 25
-		}
-	} else if te.Year() == 2015 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 19
-		} else if te.Month() == 2 {
-			return te.Day() == 16
-		} else if te.Month() == 4 {
-			return te.Day() == 3
-		} else if te.Month() == 5 {
-			return te.Day() == 25
-		} else if te.Month() == 7 {
-			return te.Day() == 3
-		} else if te.Month() == 9 {
-			return te.Day() == 7
-		} else if te.Month() == 11 {
-			return te.Day() == 26
-		} else if te.Month() == 12 {
-			return te.Day() == 25
-		}
-	} else if te.Year() == 2016 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 18
-		} else if te.Month() == 2 {
-			return te.Day() == 15
-		} else if te.Month() == 3 {
-			return te.Day() == 25
-		} else if te.Month() == 5 {
-			return te.Day() == 30
-		} else if te.Month() == 7 {
-			return te.Day() == 4
-		} else if te.Month() == 9 {
-			return te.Day() == 5
-		} else if te.Month() == 11 {
-			return te.Day() == 24 || te.Day() == 25
-		} else if te.Month() == 12 {
-			return te.Day() == 26
-		}
-	} else if te.Year() == 2017 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 16
-		} else if te.Month() == 2 {
-			return te.Day() == 20
-		} else if te.Month() == 4 {
-			return te.Day() == 15
-		} else if te.Month() == 5 {
-			return te.Day() == 29
-		} else if te.Month() == 7 {
-			return te.Day() == 4
-		} else if te.Month() == 9 {
-			return te.Day() == 4
-		} else if te.Month() == 11 {
-			return te.Day() == 23
-		} else if te.Month() == 12 {
-			return te.Day() == 25
-		}
-	} else if te.Year() == 2018 {
-		if te.Month() == 1 {
-			return te.Day() == 1 || te.Day() == 15
-		} else if te.Month() == 2 {
-			return te.Day() == 19
-		} else if te.Month() == 3 {
-			return te.Day() == 30
-		} else if te.Month() == 5 {
-			return te.Day() == 28
-		} else if te.Month() == 7 {
-			return te.Day() == 4
-		} else if te.Month() == 9 {
-			return te.Day() == 3
-		} else if te.Month() == 11 {
-			return te.Day() == 22
-		} else if te.Month() == 12 {
-			return te.Day() == 25
-		}
-	}
-	return false
-}
-
-// IsNYSEArcaHoliday returns that returns if a given time falls on a holiday.
-func (d date) IsNYSEArcaHoliday(t time.Time) bool {
-	return d.IsNYSEHoliday(t)
-}
-
-// IsNASDAQHoliday returns if a date was a NASDAQ holiday day.
-func (d date) IsNASDAQHoliday(t time.Time) bool {
-	return d.IsNYSEHoliday(t)
-}
-
-// Time returns a new time.Time for the given clock components.
-func (d date) Time(hour, min, sec, nsec int, loc *time.Location) time.Time {
-	return time.Date(0, 0, 0, hour, min, sec, nsec, loc)
-}
-
-func (d date) Date(year, month, day int, loc *time.Location) time.Time {
-	return time.Date(year, time.Month(month), day, 12, 0, 0, 0, loc)
-}
-
-// On returns the clock components of clock (hour,minute,second) on the date components of d.
-func (d date) On(clock, cd time.Time) time.Time {
-	tzAdjusted := cd.In(clock.Location())
-	return time.Date(tzAdjusted.Year(), tzAdjusted.Month(), tzAdjusted.Day(), clock.Hour(), clock.Minute(), clock.Second(), clock.Nanosecond(), clock.Location())
-}
-
-// NoonOn is a shortcut for On(Time(12,0,0), cd) a.k.a. noon on a given date.
-func (d date) NoonOn(cd time.Time) time.Time {
-	return time.Date(cd.Year(), cd.Month(), cd.Day(), 12, 0, 0, 0, cd.Location())
-}
-
-// Optional returns a pointer reference to a given time.
-func (d date) Optional(t time.Time) *time.Time {
-	return &t
-}
-
-// IsWeekDay returns if the day is a monday->friday.
-func (d date) IsWeekDay(day time.Weekday) bool {
-	return !d.IsWeekendDay(day)
-}
-
-// IsWeekendDay returns if the day is a monday->friday.
-func (d date) IsWeekendDay(day time.Weekday) bool {
-	return day == time.Saturday || day == time.Sunday
-}
-
-// Before returns if a timestamp is strictly before another date (ignoring hours, minutes etc.)
-func (d date) Before(before, reference time.Time) bool {
-	tzAdjustedBefore := before.In(reference.Location())
-	if tzAdjustedBefore.Year() < reference.Year() {
-		return true
-	}
-	if tzAdjustedBefore.Month() < reference.Month() {
-		return true
-	}
-	return tzAdjustedBefore.Year() == reference.Year() && tzAdjustedBefore.Month() == reference.Month() && tzAdjustedBefore.Day() < reference.Day()
-}
-
-// NextMarketOpen returns the next market open after a given time.
-func (d date) NextMarketOpen(after, openTime time.Time, isHoliday HolidayProvider) time.Time {
-	afterLocalized := after.In(openTime.Location())
-	todaysOpen := d.On(openTime, afterLocalized)
-
-	if isHoliday == nil {
-		isHoliday = defaultHolidayProvider
-	}
-
-	todayIsValidTradingDay := d.IsWeekDay(todaysOpen.Weekday()) && !isHoliday(todaysOpen)
-
-	if (afterLocalized.Equal(todaysOpen) || afterLocalized.Before(todaysOpen)) && todayIsValidTradingDay {
-		return todaysOpen
-	}
-
-	for cursorDay := 1; cursorDay < 7; cursorDay++ {
-		newDay := todaysOpen.AddDate(0, 0, cursorDay)
-		isValidTradingDay := d.IsWeekDay(newDay.Weekday()) && !isHoliday(newDay)
-		if isValidTradingDay {
-			return d.On(openTime, newDay)
-		}
-	}
-	panic("Have exhausted day window looking for next market open.")
-}
-
-// NextMarketClose returns the next market close after a given time.
-func (d date) NextMarketClose(after, closeTime time.Time, isHoliday HolidayProvider) time.Time {
-	afterLocalized := after.In(closeTime.Location())
-
-	if isHoliday == nil {
-		isHoliday = defaultHolidayProvider
-	}
-
-	todaysClose := d.On(closeTime, afterLocalized)
-	if afterLocalized.Before(todaysClose) && d.IsWeekDay(todaysClose.Weekday()) && !isHoliday(todaysClose) {
-		return todaysClose
-	}
-
-	if afterLocalized.Equal(todaysClose) { //rare but it might happen.
-		return todaysClose
-	}
-
-	for cursorDay := 1; cursorDay < 6; cursorDay++ {
-		newDay := todaysClose.AddDate(0, 0, cursorDay)
-		if d.IsWeekDay(newDay.Weekday()) && !isHoliday(newDay) {
-			return d.On(closeTime, newDay)
-		}
-	}
-	panic("Have exhausted day window looking for next market close.")
-}
-
-// CalculateMarketSecondsBetween calculates the number of seconds the market was open between two dates.
-func (d date) CalculateMarketSecondsBetween(start, end, marketOpen, marketClose time.Time, isHoliday HolidayProvider) (seconds int64) {
-	startEastern := start.In(d.Eastern())
-	endEastern := end.In(d.Eastern())
-
-	startMarketOpen := d.On(marketOpen, startEastern)
-	startMarketClose := d.On(marketClose, startEastern)
-
-	if !d.IsWeekendDay(startMarketOpen.Weekday()) && !isHoliday(startMarketOpen) {
-		if (startEastern.Equal(startMarketOpen) || startEastern.After(startMarketOpen)) && startEastern.Before(startMarketClose) {
-			if endEastern.Before(startMarketClose) {
-				seconds += int64(endEastern.Sub(startEastern) / time.Second)
-			} else {
-				seconds += int64(startMarketClose.Sub(startEastern) / time.Second)
-			}
-		}
-	}
-
-	cursor := d.NextMarketOpen(startMarketClose, marketOpen, isHoliday)
-	for d.Before(cursor, endEastern) {
-		if d.IsWeekDay(cursor.Weekday()) && !isHoliday(cursor) {
-			close := d.NextMarketClose(cursor, marketClose, isHoliday)
-			seconds += int64(close.Sub(cursor) / time.Second)
-		}
-		cursor = cursor.AddDate(0, 0, 1)
-	}
-
-	finalMarketOpen := d.NextMarketOpen(cursor, marketOpen, isHoliday)
-	finalMarketClose := d.NextMarketClose(cursor, marketClose, isHoliday)
-	if endEastern.After(finalMarketOpen) {
-		if endEastern.Before(finalMarketClose) {
-			seconds += int64(endEastern.Sub(finalMarketOpen) / time.Second)
-		} else {
-			seconds += int64(finalMarketClose.Sub(finalMarketOpen) / time.Second)
-		}
-	}
-
-	return
-}
-
-const (
-	_secondsPerHour = 60 * 60
-	_secondsPerDay  = 60 * 60 * 24
-)
-
-func (d date) DiffDays(t1, t2 time.Time) (days int) {
-	t1n := t1.Unix()
-	t2n := t2.Unix()
-	diff := t2n - t1n //yields seconds
-	return int(diff / (_secondsPerDay))
-}
-
-func (d date) DiffHours(t1, t2 time.Time) (hours int) {
-	t1n := t1.Unix()
-	t2n := t2.Unix()
-	diff := t2n - t1n //yields seconds
-	return int(diff / (_secondsPerHour))
-}
-
-// NextDay returns the timestamp advanced a day.
-func (d date) NextDay(ts time.Time) time.Time {
-	return ts.AddDate(0, 0, 1)
-}
-
-// NextHour returns the next timestamp on the hour.
-func (d date) NextHour(ts time.Time) time.Time {
-	//advance a full hour ...
-	advanced := ts.Add(time.Hour)
-	minutes := time.Duration(advanced.Minute()) * time.Minute
-	final := advanced.Add(-minutes)
-	return time.Date(final.Year(), final.Month(), final.Day(), final.Hour(), 0, 0, 0, final.Location())
-}
-
-// NextDayOfWeek returns the next instance of a given weekday after a given timestamp.
-func (d date) NextDayOfWeek(after time.Time, dayOfWeek time.Weekday) time.Time {
-	afterWeekday := after.Weekday()
-	if afterWeekday == dayOfWeek {
-		return after.AddDate(0, 0, 7)
-	}
-
-	// 1 vs 5 ~ add 4 days
-	if afterWeekday < dayOfWeek {
-		dayDelta := int(dayOfWeek - afterWeekday)
-		return after.AddDate(0, 0, dayDelta)
-	}
-
-	// 5 vs 1, add 7-(5-1) ~ 3 days
-	dayDelta := 7 - int(afterWeekday-dayOfWeek)
-	return after.AddDate(0, 0, dayDelta)
-}
-
-// Start returns the earliest (min) time in a list of times.
-func (d date) Start(times []time.Time) time.Time {
-	if len(times) == 0 {
-		return time.Time{}
-	}
-
-	start := times[0]
-	for _, t := range times[1:] {
-		if t.Before(start) {
-			start = t
-		}
-	}
-	return start
-}
-
-// Start returns the earliest (min) time in a list of times.
-func (d date) End(times []time.Time) time.Time {
-	if len(times) == 0 {
-		return time.Time{}
-	}
-
-	end := times[0]
-	for _, t := range times[1:] {
-		if t.After(end) {
-			end = t
-		}
-	}
-	return end
-}

date_posix.go

@@ -1,17 +0,0 @@
-// +build !windows
-
-package chart
-
-import "time"
-
-// Eastern returns the eastern timezone.
-func (d date) Eastern() *time.Location {
-	if _eastern == nil {
-		_easternLock.Lock()
-		defer _easternLock.Unlock()
-		if _eastern == nil {
-			_eastern, _ = time.LoadLocation("America/New_York")
-		}
-	}
-	return _eastern
-}

date_test.go

@@ -1,288 +0,0 @@
-package chart
-
-import (
-	"testing"
-	"time"
-
-	assert "github.com/blendlabs/go-assert"
-)
-
-func parse(v string) time.Time {
-	ts, _ := time.Parse("2006-01-02", v)
-	return ts
-}
-
-func TestDateTime(t *testing.T) {
-	assert := assert.New(t)
-
-	ts := Date.Time(5, 6, 7, 8, time.UTC)
-	assert.Equal(05, ts.Hour())
-	assert.Equal(06, ts.Minute())
-	assert.Equal(07, ts.Second())
-	assert.Equal(8, ts.Nanosecond())
-	assert.Equal(time.UTC, ts.Location())
-}
-
-func TestDateDate(t *testing.T) {
-	assert := assert.New(t)
-
-	ts := Date.Date(2015, 5, 6, time.UTC)
-	assert.Equal(2015, ts.Year())
-	assert.Equal(5, ts.Month())
-	assert.Equal(6, ts.Day())
-	assert.Equal(time.UTC, ts.Location())
-}
-
-func TestDateOn(t *testing.T) {
-	assert := assert.New(t)
-
-	ts := Date.On(Date.Time(5, 4, 3, 2, time.UTC), Date.Date(2016, 6, 7, Date.Eastern()))
-	assert.Equal(2016, ts.Year())
-	assert.Equal(6, ts.Month())
-	assert.Equal(7, ts.Day())
-	assert.Equal(5, ts.Hour())
-	assert.Equal(4, ts.Minute())
-	assert.Equal(3, ts.Second())
-	assert.Equal(2, ts.Nanosecond())
-	assert.Equal(time.UTC, ts.Location())
-}
-
-func TestDateNoonOn(t *testing.T) {
-	assert := assert.New(t)
-	noon := Date.NoonOn(time.Date(2016, 04, 03, 02, 01, 0, 0, time.UTC))
-
-	assert.Equal(2016, noon.Year())
-	assert.Equal(4, noon.Month())
-	assert.Equal(3, noon.Day())
-	assert.Equal(12, noon.Hour())
-	assert.Equal(0, noon.Minute())
-	assert.Equal(time.UTC, noon.Location())
-}
-
-func TestDateBefore(t *testing.T) {
-	assert := assert.New(t)
-
-	assert.True(Date.Before(parse("2015-07-02"), parse("2016-07-01")))
-	assert.True(Date.Before(parse("2016-06-01"), parse("2016-07-01")))
-	assert.True(Date.Before(parse("2016-07-01"), parse("2016-07-02")))
-
-	assert.False(Date.Before(parse("2016-07-01"), parse("2016-07-01")))
-	assert.False(Date.Before(parse("2016-07-03"), parse("2016-07-01")))
-	assert.False(Date.Before(parse("2016-08-03"), parse("2016-07-01")))
-	assert.False(Date.Before(parse("2017-08-03"), parse("2016-07-01")))
-}
-
-func TestDateBeforeHandlesTimezones(t *testing.T) {
-	assert := assert.New(t)
-
-	tuesdayUTC := time.Date(2016, 8, 02, 22, 00, 0, 0, time.UTC)
-	mondayUTC := time.Date(2016, 8, 01, 1, 00, 0, 0, time.UTC)
-	sundayEST := time.Date(2016, 7, 31, 22, 00, 0, 0, Date.Eastern())
-
-	assert.True(Date.Before(sundayEST, tuesdayUTC))
-	assert.False(Date.Before(sundayEST, mondayUTC))
-}
-
-func TestNextMarketOpen(t *testing.T) {
-	assert := assert.New(t)
-
-	beforeOpen := time.Date(2016, 07, 18, 9, 0, 0, 0, Date.Eastern())
-	todayOpen := time.Date(2016, 07, 18, 9, 30, 0, 0, Date.Eastern())
-
-	afterOpen := time.Date(2016, 07, 18, 9, 31, 0, 0, Date.Eastern())
-	tomorrowOpen := time.Date(2016, 07, 19, 9, 30, 0, 0, Date.Eastern())
-
-	afterFriday := time.Date(2016, 07, 22, 9, 31, 0, 0, Date.Eastern())
-	mondayOpen := time.Date(2016, 07, 25, 9, 30, 0, 0, Date.Eastern())
-
-	weekend := time.Date(2016, 07, 23, 9, 31, 0, 0, Date.Eastern())
-
-	assert.True(todayOpen.Equal(Date.NextMarketOpen(beforeOpen, NYSEOpen(), Date.IsNYSEHoliday)))
-	assert.True(tomorrowOpen.Equal(Date.NextMarketOpen(afterOpen, NYSEOpen(), Date.IsNYSEHoliday)))
-	assert.True(mondayOpen.Equal(Date.NextMarketOpen(afterFriday, NYSEOpen(), Date.IsNYSEHoliday)))
-	assert.True(mondayOpen.Equal(Date.NextMarketOpen(weekend, NYSEOpen(), Date.IsNYSEHoliday)))
-
-	assert.Equal(Date.Eastern(), todayOpen.Location())
-	assert.Equal(Date.Eastern(), tomorrowOpen.Location())
-	assert.Equal(Date.Eastern(), mondayOpen.Location())
-
-	testRegression := time.Date(2016, 07, 18, 16, 0, 0, 0, Date.Eastern())
-	shouldbe := time.Date(2016, 07, 19, 9, 30, 0, 0, Date.Eastern())
-
-	assert.True(shouldbe.Equal(Date.NextMarketOpen(testRegression, NYSEOpen(), Date.IsNYSEHoliday)))
-}
-
-func TestNextMarketClose(t *testing.T) {
-	assert := assert.New(t)
-
-	beforeClose := time.Date(2016, 07, 18, 15, 0, 0, 0, Date.Eastern())
-	todayClose := time.Date(2016, 07, 18, 16, 00, 0, 0, Date.Eastern())
-
-	afterClose := time.Date(2016, 07, 18, 16, 1, 0, 0, Date.Eastern())
-	tomorrowClose := time.Date(2016, 07, 19, 16, 00, 0, 0, Date.Eastern())
-
-	afterFriday := time.Date(2016, 07, 22, 16, 1, 0, 0, Date.Eastern())
-	mondayClose := time.Date(2016, 07, 25, 16, 0, 0, 0, Date.Eastern())
-
-	weekend := time.Date(2016, 07, 23, 9, 31, 0, 0, Date.Eastern())
-
-	assert.True(todayClose.Equal(Date.NextMarketClose(beforeClose, NYSEClose(), Date.IsNYSEHoliday)))
-	assert.True(tomorrowClose.Equal(Date.NextMarketClose(afterClose, NYSEClose(), Date.IsNYSEHoliday)))
-	assert.True(mondayClose.Equal(Date.NextMarketClose(afterFriday, NYSEClose(), Date.IsNYSEHoliday)))
-	assert.True(mondayClose.Equal(Date.NextMarketClose(weekend, NYSEClose(), Date.IsNYSEHoliday)))
-
-	assert.Equal(Date.Eastern(), todayClose.Location())
-	assert.Equal(Date.Eastern(), tomorrowClose.Location())
-	assert.Equal(Date.Eastern(), mondayClose.Location())
-}
-
-func TestCalculateMarketSecondsBetween(t *testing.T) {
-	assert := assert.New(t)
-
-	start := time.Date(2016, 07, 18, 9, 30, 0, 0, Date.Eastern())
-	end := time.Date(2016, 07, 22, 16, 00, 0, 0, Date.Eastern())
-
-	shouldbe := 5 * 6.5 * 60 * 60
-
-	assert.Equal(shouldbe, Date.CalculateMarketSecondsBetween(start, end, NYSEOpen(), NYSEClose(), Date.IsNYSEHoliday))
-}
-
-func TestCalculateMarketSecondsBetween1D(t *testing.T) {
-	assert := assert.New(t)
-
-	start := time.Date(2016, 07, 22, 9, 45, 0, 0, Date.Eastern())
-	end := time.Date(2016, 07, 22, 15, 45, 0, 0, Date.Eastern())
-
-	shouldbe := 6 * 60 * 60
-
-	assert.Equal(shouldbe, Date.CalculateMarketSecondsBetween(start, end, NYSEOpen(), NYSEClose(), Date.IsNYSEHoliday))
-}
-
-func TestCalculateMarketSecondsBetweenLTM(t *testing.T) {
-	assert := assert.New(t)
-
-	start := time.Date(2015, 07, 01, 9, 30, 0, 0, Date.Eastern())
-	end := time.Date(2016, 07, 01, 9, 30, 0, 0, Date.Eastern())
-
-	shouldbe := 253 * 6.5 * 60 * 60 //253 full market days since this date last year.
-	assert.Equal(shouldbe, Date.CalculateMarketSecondsBetween(start, end, NYSEOpen(), NYSEClose(), Date.IsNYSEHoliday))
-}
-
-func TestDateNextHour(t *testing.T) {
-	assert := assert.New(t)
-
-	start := time.Date(2015, 07, 01, 9, 30, 0, 0, Date.Eastern())
-	next := Date.NextHour(start)
-	assert.Equal(2015, next.Year())
-	assert.Equal(07, next.Month())
-	assert.Equal(01, next.Day())
-	assert.Equal(10, next.Hour())
-	assert.Equal(00, next.Minute())
-
-	next = Date.NextHour(next)
-	assert.Equal(11, next.Hour())
-
-	next = Date.NextHour(next)
-	assert.Equal(12, next.Hour())
-
-}
-
-func TestDateNextDayOfWeek(t *testing.T) {
-	assert := assert.New(t)
-
-	weds := Date.Date(2016, 8, 10, time.UTC)
-	fri := Date.Date(2016, 8, 12, time.UTC)
-	sun := Date.Date(2016, 8, 14, time.UTC)
-	mon := Date.Date(2016, 8, 15, time.UTC)
-	weds2 := Date.Date(2016, 8, 17, time.UTC)
-
-	nextFri := Date.NextDayOfWeek(weds, time.Friday)
-	nextSunday := Date.NextDayOfWeek(weds, time.Sunday)
-	nextMonday := Date.NextDayOfWeek(weds, time.Monday)
-	nextWeds := Date.NextDayOfWeek(weds, time.Wednesday)
-
-	assert.Equal(fri.Year(), nextFri.Year())
-	assert.Equal(fri.Month(), nextFri.Month())
-	assert.Equal(fri.Day(), nextFri.Day())
-
-	assert.Equal(sun.Year(), nextSunday.Year())
-	assert.Equal(sun.Month(), nextSunday.Month())
-	assert.Equal(sun.Day(), nextSunday.Day())
-
-	assert.Equal(mon.Year(), nextMonday.Year())
-	assert.Equal(mon.Month(), nextMonday.Month())
-	assert.Equal(mon.Day(), nextMonday.Day())
-
-	assert.Equal(weds2.Year(), nextWeds.Year())
-	assert.Equal(weds2.Month(), nextWeds.Month())
-	assert.Equal(weds2.Day(), nextWeds.Day())
-
-	assert.Equal(time.UTC, nextFri.Location())
-	assert.Equal(time.UTC, nextSunday.Location())
-	assert.Equal(time.UTC, nextMonday.Location())
-}
-
-func TestDateIsNYSEHoliday(t *testing.T) {
-	assert := assert.New(t)
-
-	cursor := time.Date(2013, 01, 01, 0, 0, 0, 0, time.UTC)
-	end := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
-	var holidays int
-	for Date.Before(cursor, end) {
-		if Date.IsNYSEHoliday(cursor) {
-			holidays++
-		}
-		cursor = cursor.AddDate(0, 0, 1)
-	}
-	assert.Equal(holidays, 55)
-}
-
-func TestTimeStart(t *testing.T) {
-	assert := assert.New(t)
-
-	times := []time.Time{
-		time.Now().AddDate(0, 0, -4),
-		time.Now().AddDate(0, 0, -2),
-		time.Now().AddDate(0, 0, -1),
-		time.Now().AddDate(0, 0, -3),
-		time.Now().AddDate(0, 0, -5),
-	}
-
-	assert.InTimeDelta(Date.Start(times), times[4], time.Millisecond)
-}
-
-func TestTimeEnd(t *testing.T) {
-	assert := assert.New(t)
-
-	times := []time.Time{
-		time.Now().AddDate(0, 0, -4),
-		time.Now().AddDate(0, 0, -2),
-		time.Now().AddDate(0, 0, -1),
-		time.Now().AddDate(0, 0, -3),
-		time.Now().AddDate(0, 0, -5),
-	}
-
-	assert.InTimeDelta(Date.End(times), times[2], time.Millisecond)
-}
-
-func TestDateDiffDays(t *testing.T) {
-	assert := assert.New(t)
-
-	t1 := time.Date(2017, 02, 27, 12, 0, 0, 0, time.UTC)
-	t2 := time.Date(2017, 01, 10, 3, 0, 0, 0, time.UTC)
-	t3 := time.Date(2017, 02, 24, 16, 0, 0, 0, time.UTC)
-
-	assert.Equal(48, Date.DiffDays(t2, t1))
-	assert.Equal(2, Date.DiffDays(t3, t1)) // technically we should round down.
-}
-
-func TestDateDiffHours(t *testing.T) {
-	assert := assert.New(t)
-
-	t1 := time.Date(2017, 02, 27, 12, 0, 0, 0, time.UTC)
-	t2 := time.Date(2017, 02, 24, 16, 0, 0, 0, time.UTC)
-	t3 := time.Date(2017, 02, 28, 12, 0, 0, 0, time.UTC)
-
-	assert.Equal(68, Date.DiffHours(t2, t1))
-	assert.Equal(24, Date.DiffHours(t1, t3))
-}

date_windows.go

@@ -1,17 +0,0 @@
-// +build windows
-
-package chart
-
-import "time"
-
-// Eastern returns the eastern timezone.
-func (d date) Eastern() *time.Location {
-	if _eastern == nil {
-		_easternLock.Lock()
-		defer _easternLock.Unlock()
-		if _eastern == nil {
-			_eastern, _ = time.LoadLocation("EST")
-		}
-	}
-	return _eastern
-}

donut_chart.go

@@ -0,0 +1,315 @@
+package chart
+
+import (
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/golang/freetype/truetype"
+)
+
+// DonutChart is a chart that draws sections of a circle based on percentages with an hole.
+type DonutChart struct {
+	Title      string
+	TitleStyle Style
+
+	ColorPalette ColorPalette
+
+	Width  int
+	Height int
+	DPI    float64
+
+	Background Style
+	Canvas     Style
+	SliceStyle Style
+
+	Font        *truetype.Font
+	defaultFont *truetype.Font
+
+	Values   []Value
+	Elements []Renderable
+}
+
+// GetDPI returns the dpi for the chart.
+func (pc DonutChart) GetDPI(defaults ...float64) float64 {
+	if pc.DPI == 0 {
+		if len(defaults) > 0 {
+			return defaults[0]
+		}
+		return DefaultDPI
+	}
+	return pc.DPI
+}
+
+// GetFont returns the text font.
+func (pc DonutChart) GetFont() *truetype.Font {
+	if pc.Font == nil {
+		return pc.defaultFont
+	}
+	return pc.Font
+}
+
+// GetWidth returns the chart width or the default value.
+func (pc DonutChart) GetWidth() int {
+	if pc.Width == 0 {
+		return DefaultChartWidth
+	}
+	return pc.Width
+}
+
+// GetHeight returns the chart height or the default value.
+func (pc DonutChart) GetHeight() int {
+	if pc.Height == 0 {
+		return DefaultChartWidth
+	}
+	return pc.Height
+}
+
+// Render renders the chart with the given renderer to the given io.Writer.
+func (pc DonutChart) Render(rp RendererProvider, w io.Writer) error {
+	if len(pc.Values) == 0 {
+		return errors.New("please provide at least one value")
+	}
+
+	r, err := rp(pc.GetWidth(), pc.GetHeight())
+	if err != nil {
+		return err
+	}
+
+	if pc.Font == nil {
+		defaultFont, err := GetDefaultFont()
+		if err != nil {
+			return err
+		}
+		pc.defaultFont = defaultFont
+	}
+	r.SetDPI(pc.GetDPI(DefaultDPI))
+
+	canvasBox := pc.getDefaultCanvasBox()
+	canvasBox = pc.getCircleAdjustedCanvasBox(canvasBox)
+
+	pc.drawBackground(r)
+	pc.drawCanvas(r, canvasBox)
+
+	finalValues, err := pc.finalizeValues(pc.Values)
+	if err != nil {
+		return err
+	}
+	pc.drawSlices(r, canvasBox, finalValues)
+	pc.drawTitle(r)
+	for _, a := range pc.Elements {
+		a(r, canvasBox, pc.styleDefaultsElements())
+	}
+
+	return r.Save(w)
+}
+
+func (pc DonutChart) drawBackground(r Renderer) {
+	Draw.Box(r, Box{
+		Right:  pc.GetWidth(),
+		Bottom: pc.GetHeight(),
+	}, pc.getBackgroundStyle())
+}
+
+func (pc DonutChart) drawCanvas(r Renderer, canvasBox Box) {
+	Draw.Box(r, canvasBox, pc.getCanvasStyle())
+}
+
+func (pc DonutChart) drawTitle(r Renderer) {
+	if len(pc.Title) > 0 && !pc.TitleStyle.Hidden {
+		Draw.TextWithin(r, pc.Title, pc.Box(), pc.styleDefaultsTitle())
+	}
+}
+
+func (pc DonutChart) drawSlices(r Renderer, canvasBox Box, values []Value) {
+	cx, cy := canvasBox.Center()
+	diameter := MinInt(canvasBox.Width(), canvasBox.Height())
+	radius := float64(diameter>>1) / 1.1
+	labelRadius := (radius * 2.83) / 3.0
+
+	// draw the donut slices
+	var rads, delta, delta2, total float64
+	var lx, ly int
+
+	if len(values) == 1 {
+		pc.styleDonutChartValue(0).WriteToRenderer(r)
+		r.MoveTo(cx, cy)
+		r.Circle(radius, cx, cy)
+	} else {
+		for index, v := range values {
+			v.Style.InheritFrom(pc.styleDonutChartValue(index)).WriteToRenderer(r)
+			r.MoveTo(cx, cy)
+			rads = PercentToRadians(total)
+			delta = PercentToRadians(v.Value)
+
+			r.ArcTo(cx, cy, (radius / 1.25), (radius / 1.25), rads, delta)
+
+			r.LineTo(cx, cy)
+			r.Close()
+			r.FillStroke()
+			total = total + v.Value
+		}
+	}
+
+	//making the donut hole
+	v := Value{Value: 100, Label: "center"}
+	styletemp := pc.SliceStyle.InheritFrom(Style{
+		StrokeColor: ColorWhite, StrokeWidth: 4.0, FillColor: ColorWhite, FontColor: ColorWhite, //Font:        pc.GetFont(),//FontSize:    pc.getScaledFontSize(),
+	})
+	v.Style.InheritFrom(styletemp).WriteToRenderer(r)
+	r.MoveTo(cx, cy)
+	r.ArcTo(cx, cy, (radius / 3.5), (radius / 3.5), DegreesToRadians(0), DegreesToRadians(359))
+	r.LineTo(cx, cy)
+	r.Close()
+	r.FillStroke()
+
+	// draw the labels
+	total = 0
+	for index, v := range values {
+		v.Style.InheritFrom(pc.styleDonutChartValue(index)).WriteToRenderer(r)
+		if len(v.Label) > 0 {
+			delta2 = PercentToRadians(total + (v.Value / 2.0))
+			delta2 = RadianAdd(delta2, _pi2)
+			lx, ly = CirclePoint(cx, cy, labelRadius, delta2)
+
+			tb := r.MeasureText(v.Label)
+			lx = lx - (tb.Width() >> 1)
+			ly = ly + (tb.Height() >> 1)
+
+			r.Text(v.Label, lx, ly)
+		}
+		total = total + v.Value
+	}
+}
+
+func (pc DonutChart) finalizeValues(values []Value) ([]Value, error) {
+	finalValues := Values(values).Normalize()
+	if len(finalValues) == 0 {
+		return nil, fmt.Errorf("donut chart must contain at least (1) non-zero value")
+	}
+	return finalValues, nil
+}
+
+func (pc DonutChart) getDefaultCanvasBox() Box {
+	return pc.Box()
+}
+
+func (pc DonutChart) getCircleAdjustedCanvasBox(canvasBox Box) Box {
+	circleDiameter := MinInt(canvasBox.Width(), canvasBox.Height())
+
+	square := Box{
+		Right:  circleDiameter,
+		Bottom: circleDiameter,
+	}
+
+	return canvasBox.Fit(square)
+}
+
+func (pc DonutChart) getBackgroundStyle() Style {
+	return pc.Background.InheritFrom(pc.styleDefaultsBackground())
+}
+
+func (pc DonutChart) getCanvasStyle() Style {
+	return pc.Canvas.InheritFrom(pc.styleDefaultsCanvas())
+}
+
+func (pc DonutChart) styleDefaultsCanvas() Style {
+	return Style{
+		FillColor:   pc.GetColorPalette().CanvasColor(),
+		StrokeColor: pc.GetColorPalette().CanvasStrokeColor(),
+		StrokeWidth: DefaultStrokeWidth,
+	}
+}
+
+func (pc DonutChart) styleDefaultsDonutChartValue() Style {
+	return Style{
+		StrokeColor: pc.GetColorPalette().TextColor(),
+		StrokeWidth: 4.0,
+		FillColor:   pc.GetColorPalette().TextColor(),
+	}
+}
+
+func (pc DonutChart) styleDonutChartValue(index int) Style {
+	return pc.SliceStyle.InheritFrom(Style{
+		StrokeColor: ColorWhite,
+		StrokeWidth: 4.0,
+		FillColor:   pc.GetColorPalette().GetSeriesColor(index),
+		FontSize:    pc.getScaledFontSize(),
+		FontColor:   pc.GetColorPalette().TextColor(),
+		Font:        pc.GetFont(),
+	})
+}
+
+func (pc DonutChart) getScaledFontSize() float64 {
+	effectiveDimension := MinInt(pc.GetWidth(), pc.GetHeight())
+	if effectiveDimension >= 2048 {
+		return 48.0
+	} else if effectiveDimension >= 1024 {
+		return 24.0
+	} else if effectiveDimension > 512 {
+		return 18.0
+	} else if effectiveDimension > 256 {
+		return 12.0
+	}
+	return 10.0
+}
+
+func (pc DonutChart) styleDefaultsBackground() Style {
+	return Style{
+		FillColor:   pc.GetColorPalette().BackgroundColor(),
+		StrokeColor: pc.GetColorPalette().BackgroundStrokeColor(),
+		StrokeWidth: DefaultStrokeWidth,
+	}
+}
+
+func (pc DonutChart) styleDefaultsElements() Style {
+	return Style{
+		Font: pc.GetFont(),
+	}
+}
+
+func (pc DonutChart) styleDefaultsTitle() Style {
+	return pc.TitleStyle.InheritFrom(Style{
+		FontColor:           pc.GetColorPalette().TextColor(),
+		Font:                pc.GetFont(),
+		FontSize:            pc.getTitleFontSize(),
+		TextHorizontalAlign: TextHorizontalAlignCenter,
+		TextVerticalAlign:   TextVerticalAlignTop,
+		TextWrap:            TextWrapWord,
+	})
+}
+
+func (pc DonutChart) getTitleFontSize() float64 {
+	effectiveDimension := MinInt(pc.GetWidth(), pc.GetHeight())
+	if effectiveDimension >= 2048 {
+		return 48
+	} else if effectiveDimension >= 1024 {
+		return 24
+	} else if effectiveDimension >= 512 {
+		return 18
+	} else if effectiveDimension >= 256 {
+		return 12
+	}
+	return 10
+}
+
+// GetColorPalette returns the color palette for the chart.
+func (pc DonutChart) GetColorPalette() ColorPalette {
+	if pc.ColorPalette != nil {
+		return pc.ColorPalette
+	}
+	return AlternateColorPalette
+}
+
+// Box returns the chart bounds as a box.
+func (pc DonutChart) Box() Box {
+	dpr := pc.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
+	dpb := pc.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
+
+	return Box{
+		Top:    pc.Background.Padding.GetTop(DefaultBackgroundPadding.Top),
+		Left:   pc.Background.Padding.GetLeft(DefaultBackgroundPadding.Left),
+		Right:  pc.GetWidth() - dpr,
+		Bottom: pc.GetHeight() - dpb,
+	}
+}

donut_chart_test.go

@@ -0,0 +1,69 @@
+package chart
+
+import (
+	"bytes"
+	"testing"
+
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
+)
+
+func TestDonutChart(t *testing.T) {
+	// replaced new assertions helper
+
+	pie := DonutChart{
+		Canvas: Style{
+			FillColor: ColorLightGray,
+		},
+		Values: []Value{
+			{Value: 10, Label: "Blue"},
+			{Value: 9, Label: "Green"},
+			{Value: 8, Label: "Gray"},
+			{Value: 7, Label: "Orange"},
+			{Value: 6, Label: "HEANG"},
+			{Value: 5, Label: "??"},
+			{Value: 2, Label: "!!"},
+		},
+	}
+
+	b := bytes.NewBuffer([]byte{})
+	pie.Render(PNG, b)
+	testutil.AssertNotZero(t, b.Len())
+}
+
+func TestDonutChartDropsZeroValues(t *testing.T) {
+	// replaced new assertions helper
+
+	pie := DonutChart{
+		Canvas: Style{
+			FillColor: ColorLightGray,
+		},
+		Values: []Value{
+			{Value: 5, Label: "Blue"},
+			{Value: 5, Label: "Green"},
+			{Value: 0, Label: "Gray"},
+		},
+	}
+
+	b := bytes.NewBuffer([]byte{})
+	err := pie.Render(PNG, b)
+	testutil.AssertNil(t, err)
+}
+
+func TestDonutChartAllZeroValues(t *testing.T) {
+	// replaced new assertions helper
+
+	pie := DonutChart{
+		Canvas: Style{
+			FillColor: ColorLightGray,
+		},
+		Values: []Value{
+			{Value: 0, Label: "Blue"},
+			{Value: 0, Label: "Green"},
+			{Value: 0, Label: "Gray"},
+		},
+	}
+
+	b := bytes.NewBuffer([]byte{})
+	err := pie.Render(PNG, b)
+	testutil.AssertNotNil(t, err)
+}

draw.go

@@ -1,6 +1,8 @@
 package chart
 
-import "math"
+import (
+	"math"
+)
 
 var (
 	// Draw contains helpers for drawing common objects.
@@ -10,7 +12,7 @@ var (
 type draw struct{}
 
 // LineSeries draws a line series with a renderer.
-func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, vs ValueProvider) {
+func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, vs ValuesProvider) {
 	if vs.Len() == 0 {
 		return
 	}
@@ -18,7 +20,7 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 	cb := canvasBox.Bottom
 	cl := canvasBox.Left
 
-	v0x, v0y := vs.GetValue(0)
+	v0x, v0y := vs.GetValues(0)
 	x0 := cl + xrange.Translate(v0x)
 	y0 := cb - yrange.Translate(v0y)
 
@@ -31,13 +33,13 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 		style.GetFillOptions().WriteDrawingOptionsToRenderer(r)
 		r.MoveTo(x0, y0)
 		for i := 1; i < vs.Len(); i++ {
-			vx, vy = vs.GetValue(i)
+			vx, vy = vs.GetValues(i)
 			x = cl + xrange.Translate(vx)
 			y = cb - yrange.Translate(vy)
 			r.LineTo(x, y)
 		}
-		r.LineTo(x, Math.MinInt(cb, cb-yv0))
-		r.LineTo(x0, Math.MinInt(cb, cb-yv0))
+		r.LineTo(x, MinInt(cb, cb-yv0))
+		r.LineTo(x0, MinInt(cb, cb-yv0))
 		r.LineTo(x0, y0)
 		r.Fill()
 	}
@@ -47,7 +49,7 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 
 		r.MoveTo(x0, y0)
 		for i := 1; i < vs.Len(); i++ {
-			vx, vy = vs.GetValue(i)
+			vx, vy = vs.GetValues(i)
 			x = cl + xrange.Translate(vx)
 			y = cb - yrange.Translate(vy)
 			r.LineTo(x, y)
@@ -60,7 +62,7 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 
 		style.GetDotOptions().WriteDrawingOptionsToRenderer(r)
 		for i := 0; i < vs.Len(); i++ {
-			vx, vy = vs.GetValue(i)
+			vx, vy = vs.GetValues(i)
 			x = cl + xrange.Translate(vx)
 			y = cb - yrange.Translate(vy)
 
@@ -82,8 +84,8 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 	}
 }
 
-// BoundedSeries draws a series that implements BoundedValueProvider.
-func (d draw) BoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, bbs BoundedValueProvider, drawOffsetIndexes ...int) {
+// BoundedSeries draws a series that implements BoundedValuesProvider.
+func (d draw) BoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, bbs BoundedValuesProvider, drawOffsetIndexes ...int) {
 	drawOffsetIndex := 0
 	if len(drawOffsetIndexes) > 0 {
 		drawOffsetIndex = drawOffsetIndexes[0]
@@ -92,7 +94,7 @@ func (d draw) BoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, sty
 	cb := canvasBox.Bottom
 	cl := canvasBox.Left
 
-	v0x, v0y1, v0y2 := bbs.GetBoundedValue(0)
+	v0x, v0y1, v0y2 := bbs.GetBoundedValues(0)
 	x0 := cl + xrange.Translate(v0x)
 	y0 := cb - yrange.Translate(v0y1)
 
@@ -107,7 +109,7 @@ func (d draw) BoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, sty
 	style.GetFillAndStrokeOptions().WriteToRenderer(r)
 	r.MoveTo(x0, y0)
 	for i := 1; i < bbs.Len(); i++ {
-		vx, vy1, vy2 = bbs.GetBoundedValue(i)
+		vx, vy1, vy2 = bbs.GetBoundedValues(i)
 
 		xvalues[i] = vx
 		y2values[i] = vy2
@@ -133,7 +135,7 @@ func (d draw) BoundedSeries(r Renderer, canvasBox Box, xrange, yrange Range, sty
 }
 
 // HistogramSeries draws a value provider as boxes from 0.
-func (d draw) HistogramSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, vs ValueProvider, barWidths ...int) {
+func (d draw) HistogramSeries(r Renderer, canvasBox Box, xrange, yrange Range, style Style, vs ValuesProvider, barWidths ...int) {
 	if vs.Len() == 0 {
 		return
 	}
@@ -150,7 +152,7 @@ func (d draw) HistogramSeries(r Renderer, canvasBox Box, xrange, yrange Range, s
 
 	//foreach datapoint, draw a box.
 	for index := 0; index < seriesLength; index++ {
-		vx, vy := vs.GetValue(index)
+		vx, vy := vs.GetValues(index)
 		y0 := yrange.Translate(0)
 		x := cl + xrange.Translate(vx)
 		y := yrange.Translate(vy)
@@ -294,8 +296,10 @@ func (d draw) TextWithin(r Renderer, text string, box Box, style Style) {
 	switch style.GetTextVerticalAlign() {
 	case TextVerticalAlignBottom, TextVerticalAlignBaseline: // i have to build better baseline handling into measure text
 		y = y - linesBox.Height()
-	case TextVerticalAlignMiddle, TextVerticalAlignMiddleBaseline:
-		y = (y - linesBox.Height()) >> 1
+	case TextVerticalAlignMiddle:
+		y = y + (box.Height() >> 1) - (linesBox.Height() >> 1)
+	case TextVerticalAlignMiddleBaseline:
+		y = y + (box.Height() >> 1) - linesBox.Height()
 	}
 
 	var tx, ty int

drawing/color.go

@@ -2,27 +2,46 @@ package drawing
 
 import (
 	"fmt"
+	"regexp"
 	"strconv"
+	"strings"
 )
 
+// Basic Colors from:
+// https://www.w3.org/wiki/CSS/Properties/color/keywords
 var (
 	// ColorTransparent is a fully transparent color.
-	ColorTransparent = Color{}
-
+	ColorTransparent = Color{R: 255, G: 255, B: 255, A: 0}
 	// ColorWhite is white.
 	ColorWhite = Color{R: 255, G: 255, B: 255, A: 255}
-
 	// ColorBlack is black.
 	ColorBlack = Color{R: 0, G: 0, B: 0, A: 255}
-
 	// ColorRed is red.
 	ColorRed = Color{R: 255, G: 0, B: 0, A: 255}
-
 	// ColorGreen is green.
-	ColorGreen = Color{R: 0, G: 255, B: 0, A: 255}
-
+	ColorGreen = Color{R: 0, G: 128, B: 0, A: 255}
 	// ColorBlue is blue.
 	ColorBlue = Color{R: 0, G: 0, B: 255, A: 255}
+	// ColorSilver is a known color.
+	ColorSilver = Color{R: 192, G: 192, B: 192, A: 255}
+	// ColorMaroon is a known color.
+	ColorMaroon = Color{R: 128, G: 0, B: 0, A: 255}
+	// ColorPurple is a known color.
+	ColorPurple = Color{R: 128, G: 0, B: 128, A: 255}
+	// ColorFuchsia is a known color.
+	ColorFuchsia = Color{R: 255, G: 0, B: 255, A: 255}
+	// ColorLime is a known color.
+	ColorLime = Color{R: 0, G: 255, B: 0, A: 255}
+	// ColorOlive is a known color.
+	ColorOlive = Color{R: 128, G: 128, B: 0, A: 255}
+	// ColorYellow is a known color.
+	ColorYellow = Color{R: 255, G: 255, B: 0, A: 255}
+	// ColorNavy is a known color.
+	ColorNavy = Color{R: 0, G: 0, B: 128, A: 255}
+	// ColorTeal is a known color.
+	ColorTeal = Color{R: 0, G: 128, B: 128, A: 255}
+	// ColorAqua is a known color.
+	ColorAqua = Color{R: 0, G: 255, B: 255, A: 255}
 )
 
 func parseHex(hex string) uint8 {
@@ -30,8 +49,97 @@ func parseHex(hex string) uint8 {
 	return uint8(v)
 }
 
+// ParseColor parses a color from a string.
+func ParseColor(rawColor string) Color {
+	if strings.HasPrefix(rawColor, "rgba") {
+		return ColorFromRGBA(rawColor)
+	}
+	if strings.HasPrefix(rawColor, "rgb") {
+		return ColorFromRGB(rawColor)
+	}
+	if strings.HasPrefix(rawColor, "#") {
+		return ColorFromHex(rawColor)
+	}
+	return ColorFromKnown(rawColor)
+}
+
+var rgbaexpr = regexp.MustCompile(`rgba\((?P<R>.+),(?P<G>.+),(?P<B>.+),(?P<A>.+)\)`)
+
+// ColorFromRGBA returns a color from an `rgba()` css function.
+func ColorFromRGBA(rgba string) (output Color) {
+	values := rgbaexpr.FindStringSubmatch(rgba)
+	for i, name := range rgbaexpr.SubexpNames() {
+		if i == 0 {
+			continue
+		}
+		if i >= len(values) {
+			break
+		}
+		switch name {
+		case "R":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.R = uint8(parsed)
+		case "G":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.G = uint8(parsed)
+		case "B":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.B = uint8(parsed)
+		case "A":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseFloat(value, 32)
+			if parsed > 1 {
+				parsed = 1
+			} else if parsed < 0 {
+				parsed = 0
+			}
+			output.A = uint8(parsed * 255)
+		}
+	}
+	return
+}
+
+var rgbexpr = regexp.MustCompile(`rgb\((?P<R>.+),(?P<G>.+),(?P<B>.+)\)`)
+
+// ColorFromRGB returns a color from an `rgb()` css function.
+func ColorFromRGB(rgb string) (output Color) {
+	output.A = 255
+	values := rgbexpr.FindStringSubmatch(rgb)
+	for i, name := range rgbaexpr.SubexpNames() {
+		if i == 0 {
+			continue
+		}
+		if i >= len(values) {
+			break
+		}
+		switch name {
+		case "R":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.R = uint8(parsed)
+		case "G":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.G = uint8(parsed)
+		case "B":
+			value := strings.TrimSpace(values[i])
+			parsed, _ := strconv.ParseInt(value, 10, 16)
+			output.B = uint8(parsed)
+		}
+	}
+	return
+}
+
 // ColorFromHex returns a color from a css hex code.
+//
+// NOTE: it will trim a leading '#' character if present.
 func ColorFromHex(hex string) Color {
+	if strings.HasPrefix(hex, "#") {
+		hex = strings.TrimPrefix(hex, "#")
+	}
 	var c Color
 	if len(hex) == 3 {
 		c.R = parseHex(string(hex[0])) * 0x11
@@ -46,6 +154,46 @@ func ColorFromHex(hex string) Color {
 	return c
 }
 
+// ColorFromKnown returns an internal color from a known (basic) color name.
+func ColorFromKnown(known string) Color {
+	switch strings.ToLower(known) {
+	case "transparent":
+		return ColorTransparent
+	case "white":
+		return ColorWhite
+	case "black":
+		return ColorBlack
+	case "red":
+		return ColorRed
+	case "blue":
+		return ColorBlue
+	case "green":
+		return ColorGreen
+	case "silver":
+		return ColorSilver
+	case "maroon":
+		return ColorMaroon
+	case "purple":
+		return ColorPurple
+	case "fuchsia":
+		return ColorFuchsia
+	case "lime":
+		return ColorLime
+	case "olive":
+		return ColorOlive
+	case "yellow":
+		return ColorYellow
+	case "navy":
+		return ColorNavy
+	case "teal":
+		return ColorTeal
+	case "aqua":
+		return ColorAqua
+	default:
+		return Color{}
+	}
+}
+
 // ColorFromAlphaMixedRGBA returns the system alpha mixed rgba values.
 func ColorFromAlphaMixedRGBA(r, g, b, a uint32) Color {
 	fa := float64(a) / 255.0

drawing/color_test.go

@@ -1,53 +1,114 @@
 package drawing
 
 import (
+	"fmt"
 	"testing"
 
 	"image/color"
 
-	"github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 func TestColorFromHex(t *testing.T) {
-	assert := assert.New(t)
-
 	white := ColorFromHex("FFFFFF")
-	assert.Equal(ColorWhite, white)
+	testutil.AssertEqual(t, ColorWhite, white)
 
 	shortWhite := ColorFromHex("FFF")
-	assert.Equal(ColorWhite, shortWhite)
+	testutil.AssertEqual(t, ColorWhite, shortWhite)
 
 	black := ColorFromHex("000000")
-	assert.Equal(ColorBlack, black)
+	testutil.AssertEqual(t, ColorBlack, black)
 
 	shortBlack := ColorFromHex("000")
-	assert.Equal(ColorBlack, shortBlack)
+	testutil.AssertEqual(t, ColorBlack, shortBlack)
 
 	red := ColorFromHex("FF0000")
-	assert.Equal(ColorRed, red)
+	testutil.AssertEqual(t, ColorRed, red)
 
 	shortRed := ColorFromHex("F00")
-	assert.Equal(ColorRed, shortRed)
+	testutil.AssertEqual(t, ColorRed, shortRed)
 
-	green := ColorFromHex("00FF00")
-	assert.Equal(ColorGreen, green)
+	green := ColorFromHex("008000")
+	testutil.AssertEqual(t, ColorGreen, green)
 
-	shortGreen := ColorFromHex("0F0")
-	assert.Equal(ColorGreen, shortGreen)
+	// shortGreen := ColorFromHex("0F0")
+	// testutil.AssertEqual(t, ColorGreen, shortGreen)
 
 	blue := ColorFromHex("0000FF")
-	assert.Equal(ColorBlue, blue)
+	testutil.AssertEqual(t, ColorBlue, blue)
 
 	shortBlue := ColorFromHex("00F")
-	assert.Equal(ColorBlue, shortBlue)
+	testutil.AssertEqual(t, ColorBlue, shortBlue)
+}
+
+func TestColorFromHex_handlesHash(t *testing.T) {
+	withHash := ColorFromHex("#FF0000")
+	testutil.AssertEqual(t, ColorRed, withHash)
+
+	withoutHash := ColorFromHex("#FF0000")
+	testutil.AssertEqual(t, ColorRed, withoutHash)
 }
 
 func TestColorFromAlphaMixedRGBA(t *testing.T) {
-	assert := assert.New(t)
-
 	black := ColorFromAlphaMixedRGBA(color.Black.RGBA())
-	assert.True(black.Equals(ColorBlack), black.String())
+	testutil.AssertTrue(t, black.Equals(ColorBlack), black.String())
 
 	white := ColorFromAlphaMixedRGBA(color.White.RGBA())
-	assert.True(white.Equals(ColorWhite), white.String())
+	testutil.AssertTrue(t, white.Equals(ColorWhite), white.String())
+}
+
+func Test_ColorFromRGBA(t *testing.T) {
+	value := "rgba(192, 192, 192, 1.0)"
+	parsed := ColorFromRGBA(value)
+	testutil.AssertEqual(t, ColorSilver, parsed)
+
+	value = "rgba(192,192,192,1.0)"
+	parsed = ColorFromRGBA(value)
+	testutil.AssertEqual(t, ColorSilver, parsed)
+
+	value = "rgba(192,192,192,1.5)"
+	parsed = ColorFromRGBA(value)
+	testutil.AssertEqual(t, ColorSilver, parsed)
+}
+
+func TestParseColor(t *testing.T) {
+	testCases := [...]struct {
+		Input    string
+		Expected Color
+	}{
+		{"", Color{}},
+		{"white", ColorWhite},
+		{"WHITE", ColorWhite}, // caps!
+		{"black", ColorBlack},
+		{"red", ColorRed},
+		{"green", ColorGreen},
+		{"blue", ColorBlue},
+		{"silver", ColorSilver},
+		{"maroon", ColorMaroon},
+		{"purple", ColorPurple},
+		{"fuchsia", ColorFuchsia},
+		{"lime", ColorLime},
+		{"olive", ColorOlive},
+		{"yellow", ColorYellow},
+		{"navy", ColorNavy},
+		{"teal", ColorTeal},
+		{"aqua", ColorAqua},
+
+		{"rgba(192, 192, 192, 1.0)", ColorSilver},
+		{"rgba(192,192,192,1.0)", ColorSilver},
+		{"rgb(192, 192, 192)", ColorSilver},
+		{"rgb(192,192,192)", ColorSilver},
+
+		{"#FF0000", ColorRed},
+		{"#008000", ColorGreen},
+		{"#0000FF", ColorBlue},
+		{"#F00", ColorRed},
+		{"#080", Color{0, 136, 0, 255}},
+		{"#00F", ColorBlue},
+	}
+
+	for index, tc := range testCases {
+		actual := ParseColor(tc.Input)
+		testutil.AssertEqual(t, tc.Expected, actual, fmt.Sprintf("test case: %d -> %s", index, tc.Input))
+	}
 }

drawing/curve_test.go

@@ -3,7 +3,7 @@ package drawing
 import (
 	"testing"
 
-	assert "github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 type point struct {
@@ -23,7 +23,7 @@ func (ml mockLine) Len() int {
 }
 
 func TestTraceQuad(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
 	// Quad
 	// x1, y1, cpx1, cpy2, x2, y2 float64
@@ -31,5 +31,5 @@ func TestTraceQuad(t *testing.T) {
 	quad := []float64{10, 20, 20, 20, 20, 10}
 	liner := &mockLine{}
 	TraceQuad(liner, quad, 0.5)
-	assert.NotZero(liner.Len())
+	testutil.AssertNotZero(t, liner.Len())
 }

ema_series.go

@@ -7,6 +7,13 @@ const (
 	DefaultEMAPeriod = 12
 )
 
+// Interface Assertions.
+var (
+	_ Series              = (*EMASeries)(nil)
+	_ FirstValuesProvider = (*EMASeries)(nil)
+	_ LastValuesProvider  = (*EMASeries)(nil)
+)
+
 // EMASeries is a computed series.
 type EMASeries struct {
 	Name  string
@@ -14,7 +21,7 @@ type EMASeries struct {
 	YAxis YAxisType
 
 	Period      int
-	InnerSeries ValueProvider
+	InnerSeries ValuesProvider
 
 	cache []float64
 }
@@ -52,23 +59,36 @@ func (ema EMASeries) GetSigma() float64 {
 	return 2.0 / (float64(ema.GetPeriod()) + 1)
 }
 
-// GetValue gets a value at a given index.
-func (ema *EMASeries) GetValue(index int) (x, y float64) {
+// GetValues gets a value at a given index.
+func (ema *EMASeries) GetValues(index int) (x, y float64) {
 	if ema.InnerSeries == nil {
 		return
 	}
 	if len(ema.cache) == 0 {
 		ema.ensureCachedValues()
 	}
-	vx, _ := ema.InnerSeries.GetValue(index)
+	vx, _ := ema.InnerSeries.GetValues(index)
 	x = vx
 	y = ema.cache[index]
 	return
 }
 
-// GetLastValue computes the last moving average value but walking back window size samples,
+// GetFirstValues computes the first moving average value.
+func (ema *EMASeries) GetFirstValues() (x, y float64) {
+	if ema.InnerSeries == nil {
+		return
+	}
+	if len(ema.cache) == 0 {
+		ema.ensureCachedValues()
+	}
+	x, _ = ema.InnerSeries.GetValues(0)
+	y = ema.cache[0]
+	return
+}
+
+// GetLastValues computes the last moving average value but walking back window size samples,
 // and recomputing the last moving average chunk.
-func (ema *EMASeries) GetLastValue() (x, y float64) {
+func (ema *EMASeries) GetLastValues() (x, y float64) {
 	if ema.InnerSeries == nil {
 		return
 	}
@@ -76,7 +96,7 @@ func (ema *EMASeries) GetLastValue() (x, y float64) {
 		ema.ensureCachedValues()
 	}
 	lastIndex := ema.InnerSeries.Len() - 1
-	x, _ = ema.InnerSeries.GetValue(lastIndex)
+	x, _ = ema.InnerSeries.GetValues(lastIndex)
 	y = ema.cache[lastIndex]
 	return
 }
@@ -86,7 +106,7 @@ func (ema *EMASeries) ensureCachedValues() {
 	ema.cache = make([]float64, seriesLength)
 	sigma := ema.GetSigma()
 	for x := 0; x < seriesLength; x++ {
-		_, y := ema.InnerSeries.GetValue(x)
+		_, y := ema.InnerSeries.GetValues(x)
 		if x == 0 {
 			ema.cache[x] = y
 			continue

ema_series_test.go

@@ -3,11 +3,11 @@ package chart
 import (
 	"testing"
 
-	"github.com/blendlabs/go-assert"
+	"git.smarteching.com/zeni/go-chart/v2/testutil"
 )
 
 var (
-	emaXValues = Sequence.Float64(1.0, 50.0)
+	emaXValues = LinearRange(1.0, 50.0)
 	emaYValues = []float64{
 		1, 2, 3, 4, 5, 4, 3, 2,
 		1, 2, 3, 4, 5, 4, 3, 2,
@@ -73,13 +73,13 @@ var (
 )
 
 func TestEMASeries(t *testing.T) {
-	assert := assert.New(t)
+	// replaced new assertions helper
 
-	mockSeries := mockValueProvider{
+	mockSeries := mockValuesProvider{
 		emaXValues,
 		emaYValues,
 	}
-	assert.Equal(50, mockSeries.Len())
+	testutil.AssertEqual(t, 50, mockSeries.Len())
 
 	ema := &EMASeries{
 		InnerSeries: mockSeries,
@@ -87,19 +87,19 @@ func TestEMASeries(t *testing.T) {
 	}
 
 	sig := ema.GetSigma()
-	assert.Equal(2.0/(26.0+1), sig)
+	testutil.AssertEqual(t, 2.0/(26.0+1), sig)
 
 	var yvalues []float64
 	for x := 0; x < ema.Len(); x++ {
-		_, y := ema.GetValue(x)
+		_, y := ema.GetValues(x)
 		yvalues = append(yvalues, y)
 	}
 
 	for index, yv := range yvalues {
-		assert.InDelta(yv, emaExpected[index], emaDelta)
+		testutil.AssertInDelta(t, yv, emaExpected[index], emaDelta)
 	}
 
-	lvx, lvy := ema.GetLastValue()
-	assert.Equal(50.0, lvx)
-	assert.InDelta(lvy, emaExpected[49], emaDelta)
+	lvx, lvy := ema.GetLastValues()
+	testutil.AssertEqual(t, 50.0, lvx)
+	testutil.AssertInDelta(t, lvy, emaExpected[49], emaDelta)
 }

examples/annotations/main.go

@@ -1,13 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
-
+func main() {
 	/*
 	   In this example we add an `Annotation` series, which is a special type of series that
 	   draws annotation labels at given X and Y values (as translated by their respective ranges).
@@ -37,11 +38,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 	}
 
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/axes/main.go

@@ -1,12 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	chart "git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 
 	/*
 	   The below will draw the same chart as the `basic` example, except with both the x and y axes turned on.
@@ -14,20 +16,9 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 	*/
 
 	graph := chart.Chart{
-		XAxis: chart.XAxis{
-			Name:      "The XAxis",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
-		},
-		YAxis: chart.YAxis{
-			Name:      "The YAxis",
-			NameStyle: chart.StyleShow(),
-			Style:     chart.StyleShow(),
-		},
 		Series: []chart.Series{
 			chart.ContinuousSeries{
 				Style: chart.Style{
-					Show:        true,
 					StrokeColor: chart.GetDefaultColor(0).WithAlpha(64),
 					FillColor:   chart.GetDefaultColor(0).WithAlpha(64),
 				},
@@ -37,11 +28,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 	}
 
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/axes_labels/main.go

@@ -1,12 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	chart "git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 
 	/*
 	   The below will draw the same chart as the `basic` example, except with both the x and y axes turned on.
@@ -15,19 +17,14 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	graph := chart.Chart{
 		XAxis: chart.XAxis{
-			Style: chart.Style{
-				Show: true, //enables / displays the x-axis
-			},
+			Name: "The XAxis",
 		},
 		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true, //enables / displays the y-axis
-			},
+			Name: "The YAxis",
 		},
 		Series: []chart.Series{
 			chart.ContinuousSeries{
 				Style: chart.Style{
-					Show:        true,
 					StrokeColor: chart.GetDefaultColor(0).WithAlpha(64),
 					FillColor:   chart.GetDefaultColor(0).WithAlpha(64),
 				},
@@ -37,11 +34,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 	}
 
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/bar_chart/main.go

@@ -0,0 +1,35 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+func main() {
+	graph := chart.BarChart{
+		Title: "Test Bar Chart",
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 40,
+			},
+		},
+		Height:   512,
+		BarWidth: 60,
+		Bars: []chart.Value{
+			{Value: 5.25, Label: "Blue"},
+			{Value: 4.88, Label: "Green"},
+			{Value: 4.74, Label: "Gray"},
+			{Value: 3.22, Label: "Orange"},
+			{Value: 3, Label: "Test"},
+			{Value: 2.27, Label: "??"},
+			{Value: 1, Label: "!!"},
+		},
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}

examples/bar_chart_base_value/main.go

@@ -0,0 +1,62 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+	"git.smarteching.com/zeni/go-chart/v2/drawing"
+)
+
+func main() {
+	profitStyle := chart.Style{
+		FillColor:   drawing.ColorFromHex("13c158"),
+		StrokeColor: drawing.ColorFromHex("13c158"),
+		StrokeWidth: 0,
+	}
+
+	lossStyle := chart.Style{
+		FillColor:   drawing.ColorFromHex("c11313"),
+		StrokeColor: drawing.ColorFromHex("c11313"),
+		StrokeWidth: 0,
+	}
+
+	sbc := chart.BarChart{
+		Title: "Bar Chart Using BaseValue",
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 40,
+			},
+		},
+		Height:   512,
+		BarWidth: 60,
+		YAxis: chart.YAxis{
+			Ticks: []chart.Tick{
+				{Value: -4.0, Label: "-4"},
+				{Value: -2.0, Label: "-2"},
+				{Value: 0, Label: "0"},
+				{Value: 2.0, Label: "2"},
+				{Value: 4.0, Label: "4"},
+				{Value: 6.0, Label: "6"},
+				{Value: 8.0, Label: "8"},
+				{Value: 10.0, Label: "10"},
+				{Value: 12.0, Label: "12"},
+			},
+		},
+		UseBaseValue: true,
+		BaseValue:    0.0,
+		Bars: []chart.Value{
+			{Value: 10.0, Style: profitStyle, Label: "Profit"},
+			{Value: 12.0, Style: profitStyle, Label: "More Profit"},
+			{Value: 8.0, Style: profitStyle, Label: "Still Profit"},
+			{Value: -4.0, Style: lossStyle, Label: "Loss!"},
+			{Value: 3.0, Style: profitStyle, Label: "Phew Ok"},
+			{Value: -2.0, Style: lossStyle, Label: "Oh No!"},
+		},
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	sbc.Render(chart.PNG, f)
+}

examples/bar_chart_web/main.go

@@ -1,26 +1,26 @@
 package main
 
+//go:generate go run main.go
+
 import (
 	"fmt"
 	"log"
 	"net/http"
 	"os"
 
-	"github.com/wcharczuk/go-chart"
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
 func drawChart(res http.ResponseWriter, req *http.Request) {
-	sbc := chart.BarChart{
-		Height:   512,
-		BarWidth: 60,
-		XAxis: chart.Style{
-			Show: true,
-		},
-		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
+	graph := chart.BarChart{
+		Title: "Test Bar Chart",
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top: 40,
 			},
 		},
+		Height:   512,
+		BarWidth: 60,
 		Bars: []chart.Value{
 			{Value: 5.25, Label: "Blue"},
 			{Value: 4.88, Label: "Green"},
@@ -33,10 +33,11 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 	}
 
 	res.Header().Set("Content-Type", "image/png")
-	err := sbc.Render(chart.PNG, res)
+	err := graph.Render(chart.PNG, res)
 	if err != nil {
 		fmt.Printf("Error rendering chart: %v\n", err)
 	}
+
 }
 
 func port() string {

examples/basic/main.go

@@ -0,0 +1,23 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+func main() {
+	graph := chart.Chart{
+		Series: []chart.Series{
+			chart.ContinuousSeries{
+				XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
+				YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
+			},
+		},
+	}
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}

examples/benchmark_line_charts/main.go

@@ -0,0 +1,52 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+	"time"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+func random(min, max float64) float64 {
+	return rand.Float64()*(max-min) + min
+}
+
+func main() {
+	numValues := 1024
+	numSeries := 100
+	series := make([]chart.Series, numSeries)
+
+	for i := 0; i < numSeries; i++ {
+		xValues := make([]time.Time, numValues)
+		yValues := make([]float64, numValues)
+
+		for j := 0; j < numValues; j++ {
+			xValues[j] = time.Now().AddDate(0, 0, (numValues-j)*-1)
+			yValues[j] = random(float64(-500), float64(500))
+		}
+
+		series[i] = chart.TimeSeries{
+			Name:    fmt.Sprintf("aaa.bbb.hostname-%v.ccc.ddd.eee.fff.ggg.hhh.iii.jjj.kkk.lll.mmm.nnn.value", i),
+			XValues: xValues,
+			YValues: yValues,
+		}
+	}
+
+	graph := chart.Chart{
+		XAxis: chart.XAxis{
+			Name: "Time",
+		},
+		YAxis: chart.YAxis{
+			Name: "Value",
+		},
+		Series: series,
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}

examples/css_classes/main.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+// Note: Additional examples on how to add Stylesheets are in the custom_stylesheets example
+
+func inlineSVGWithClasses(res http.ResponseWriter, req *http.Request) {
+	res.Write([]byte(
+		"<!DOCTYPE html><html><head>" +
+			"<link rel=\"stylesheet\" type=\"text/css\" href=\"/main.css\">" +
+			"</head>" +
+			"<body>"))
+
+	pie := chart.PieChart{
+		// Notes: * Setting ClassName will cause all other inline styles to be dropped!
+		//        * The following type classes may be added additionally: stroke, fill, text
+		Background: chart.Style{ClassName: "background"},
+		Canvas: chart.Style{
+			ClassName: "canvas",
+		},
+		Width:  512,
+		Height: 512,
+		Values: []chart.Value{
+			{Value: 5, Label: "Blue", Style: chart.Style{ClassName: "blue"}},
+			{Value: 5, Label: "Green", Style: chart.Style{ClassName: "green"}},
+			{Value: 4, Label: "Gray", Style: chart.Style{ClassName: "gray"}},
+		},
+	}
+
+	err := pie.Render(chart.SVG, res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+	res.Write([]byte("</body>"))
+}
+
+func css(res http.ResponseWriter, req *http.Request) {
+	res.Header().Set("Content-Type", "text/css")
+	res.Write([]byte("svg .background { fill: white; }" +
+		"svg .canvas { fill: white; }" +
+		"svg .blue.fill.stroke { fill: blue; stroke: lightblue; }" +
+		"svg .green.fill.stroke { fill: green; stroke: lightgreen; }" +
+		"svg .gray.fill.stroke { fill: gray; stroke: lightgray; }" +
+		"svg .blue.text { fill: white; }" +
+		"svg .green.text { fill: white; }" +
+		"svg .gray.text { fill: white; }"))
+}
+
+func main() {
+	http.HandleFunc("/", inlineSVGWithClasses)
+	http.HandleFunc("/main.css", css)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

examples/custom_formatters/main.go

@@ -1,13 +1,15 @@
 package main
 
+//go:generate go run main.go
+
 import (
 	"fmt"
-	"net/http"
+	"os"
 
-	"github.com/wcharczuk/go-chart"
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 	/*
 	   In this example we use a custom `ValueFormatter` for the y axis, letting us specify how to format text of the y-axis ticks.
 	   You can also do this for the x-axis, or the secondary y-axis.
@@ -16,9 +18,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	graph := chart.Chart{
 		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
 			ValueFormatter: func(v interface{}) string {
 				if vf, isFloat := v.(float64); isFloat {
 					return fmt.Sprintf("%0.6f", vf)
@@ -33,12 +32,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			},
 		},
 	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/custom_padding/main.go

@@ -0,0 +1,34 @@
+package main
+
+//go:generate go run main.go
+
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+	"git.smarteching.com/zeni/go-chart/v2/drawing"
+)
+
+func main() {
+	graph := chart.Chart{
+		Background: chart.Style{
+			Padding: chart.Box{
+				Top:    50,
+				Left:   25,
+				Right:  25,
+				Bottom: 10,
+			},
+			FillColor: drawing.ColorFromHex("efefef"),
+		},
+		Series: []chart.Series{
+			chart.ContinuousSeries{
+				XValues: chart.Seq{Sequence: chart.NewLinearSequence().WithStart(1.0).WithEnd(100.0)}.Values(),
+				YValues: chart.Seq{Sequence: chart.NewRandomSequence().WithLen(100).WithMin(100).WithMax(512)}.Values(),
+			},
+		},
+	}
+
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
+}

examples/custom_ranges/main.go

@@ -1,12 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 	/*
 	   In this example we set a custom range for the y-axis, overriding the automatic range generation.
 	   Note: the chart will still generate the ticks automatically based on the custom range, so the intervals may be a bit weird.
@@ -14,9 +16,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	graph := chart.Chart{
 		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
 			Range: &chart.ContinuousRange{
 				Min: 0.0,
 				Max: 10.0,
@@ -29,12 +28,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			},
 		},
 	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/custom_styles/main.go

@@ -1,13 +1,15 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
-	"github.com/wcharczuk/go-chart/drawing"
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+	"git.smarteching.com/zeni/go-chart/v2/drawing"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 	/*
 	   In this example we set some custom colors for the series and the chart background and canvas.
 	*/
@@ -21,7 +23,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		Series: []chart.Series{
 			chart.ContinuousSeries{
 				Style: chart.Style{
-					Show:        true,                           //note; if we set ANY other properties, we must set this to true.
 					StrokeColor: drawing.ColorRed,               // will supercede defaults
 					FillColor:   drawing.ColorRed.WithAlpha(64), // will supercede defaults
 				},
@@ -31,11 +32,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 	}
 
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/custom_stylesheets/inlineOutput.svg

@@ -0,0 +1,21 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="512" height="512">\n<style type="text/css"><![CDATA[svg .background { fill: white; }svg .canvas { fill: white; }svg path.blue { fill: blue; stroke: lightblue; }svg path.green { fill: green; stroke: lightgreen; }svg path.gray { fill: gray; stroke: lightgray; }svg text.blue { fill: white; }svg text.green { fill: white; }svg text.gray { fill: white; }]]></style><path  d="M 0 0
+L 512 0
+L 512 512
+L 0 512
+L 0 0" class="background"/><path  d="M 5 5
+L 507 5
+L 507 507
+L 5 507
+L 5 5" class="canvas"/><path  d="M 256 256
+L 507 256
+A 251 251 128.56 0 1 100 452
+L 256 256
+Z" class="blue"/><path  d="M 256 256
+L 100 452
+A 251 251 128.56 0 1 201 12
+L 256 256
+Z" class="green"/><path  d="M 256 256
+L 201 12
+A 251 251 102.85 0 1 506 256
+L 256 256
+Z" class="gray"/><text x="313" y="413" class="blue">Blue</text><text x="73" y="226" class="green">Green</text><text x="344" y="133" class="gray">Gray</text></svg>

examples/custom_stylesheets/main.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"git.smarteching.com/zeni/go-chart/v2"
+)
+
+const style = "svg .background { fill: white; }" +
+	"svg .canvas { fill: white; }" +
+	"svg .blue.fill.stroke { fill: blue; stroke: lightblue; }" +
+	"svg .green.fill.stroke { fill: green; stroke: lightgreen; }" +
+	"svg .gray.fill.stroke { fill: gray; stroke: lightgray; }" +
+	"svg .blue.text { fill: white; }" +
+	"svg .green.text { fill: white; }" +
+	"svg .gray.text { fill: white; }"
+
+func svgWithCustomInlineCSS(res http.ResponseWriter, _ *http.Request) {
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+
+	// Render the CSS with custom css
+	err := pieChart().Render(chart.SVGWithCSS(style, ""), res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func svgWithCustomInlineCSSNonce(res http.ResponseWriter, _ *http.Request) {
+	// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/style-src
+	// This should be randomly generated on every request!
+	const nonce = "RAND0MBASE64"
+
+	res.Header().Set("Content-Security-Policy", fmt.Sprintf("style-src 'nonce-%s'", nonce))
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+
+	// Render the CSS with custom css and a nonce.
+	// Try changing the nonce to a different string - your browser should block the CSS.
+	err := pieChart().Render(chart.SVGWithCSS(style, nonce), res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func svgWithCustomExternalCSS(res http.ResponseWriter, _ *http.Request) {
+	// Add external CSS
+	res.Write([]byte(
+		`<?xml version="1.0" standalone="no"?>` +
+			`<?xml-stylesheet href="/main.css" type="text/css"?>` +
+			`<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">`))
+
+	res.Header().Set("Content-Type", chart.ContentTypeSVG)
+	err := pieChart().Render(chart.SVG, res)
+	if err != nil {
+		fmt.Printf("Error rendering pie chart: %v\n", err)
+	}
+}
+
+func pieChart() chart.PieChart {
+	return chart.PieChart{
+		// Note that setting ClassName will cause all other inline styles to be dropped!
+		Background: chart.Style{ClassName: "background"},
+		Canvas: chart.Style{
+			ClassName: "canvas",
+		},
+		Width:  512,
+		Height: 512,
+		Values: []chart.Value{
+			{Value: 5, Label: "Blue", Style: chart.Style{ClassName: "blue"}},
+			{Value: 5, Label: "Green", Style: chart.Style{ClassName: "green"}},
+			{Value: 4, Label: "Gray", Style: chart.Style{ClassName: "gray"}},
+		},
+	}
+}
+
+func css(res http.ResponseWriter, req *http.Request) {
+	res.Header().Set("Content-Type", "text/css")
+	res.Write([]byte(style))
+}
+
+func main() {
+	http.HandleFunc("/", svgWithCustomInlineCSS)
+	http.HandleFunc("/nonce", svgWithCustomInlineCSSNonce)
+	http.HandleFunc("/external", svgWithCustomExternalCSS)
+	http.HandleFunc("/main.css", css)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

examples/custom_ticks/main.go

@@ -1,12 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 	/*
 	   In this example we set a custom set of ticks to use for the y-axis. It can be (almost) whatever you want, including some custom labels for ticks.
 	   Custom ticks will supercede a custom range, which will supercede automatic generation based on series values.
@@ -14,20 +16,17 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 
 	graph := chart.Chart{
 		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
 			Range: &chart.ContinuousRange{
 				Min: 0.0,
 				Max: 4.0,
 			},
 			Ticks: []chart.Tick{
-				{0.0, "0.00"},
-				{2.0, "2.00"},
-				{4.0, "4.00"},
-				{6.0, "6.00"},
-				{8.0, "Eight"},
-				{10.0, "Ten"},
+				{Value: 0.0, Label: "0.00"},
+				{Value: 2.0, Label: "2.00"},
+				{Value: 4.0, Label: "4.00"},
+				{Value: 6.0, Label: "6.00"},
+				{Value: 8.0, Label: "Eight"},
+				{Value: 10.0, Label: "Ten"},
 			},
 		},
 		Series: []chart.Series{
@@ -37,12 +36,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			},
 		},
 	}
-
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }

examples/descending/main.go

@@ -1,12 +1,14 @@
 package main
 
-import (
-	"net/http"
+//go:generate go run main.go
 
-	"github.com/wcharczuk/go-chart"
+import (
+	"os"
+
+	"git.smarteching.com/zeni/go-chart/v2"
 )
 
-func drawChart(res http.ResponseWriter, req *http.Request) {
+func main() {
 
 	/*
 	   The below will draw the same chart as the `basic` example, except with both the x and y axes turned on.
@@ -19,18 +21,12 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 	graph := chart.Chart{
 		Height: 500,
 		Width:  500,
-		XAxis: chart.XAxis{
-			Style: chart.Style{
-				Show: true,
-			},
+		XAxis:  chart.XAxis{
 			/*Range: &chart.ContinuousRange{
 				Descending: true,
 			},*/
 		},
 		YAxis: chart.YAxis{
-			Style: chart.Style{
-				Show: true,
-			},
 			Range: &chart.ContinuousRange{
 				Descending: true,
 			},
@@ -38,7 +34,6 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		Series: []chart.Series{
 			chart.ContinuousSeries{
 				Style: chart.Style{
-					Show:        true,
 					StrokeColor: chart.GetDefaultColor(0).WithAlpha(64),
 					FillColor:   chart.GetDefaultColor(0).WithAlpha(64),
 				},
@@ -48,11 +43,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 		},
 	}
 
-	res.Header().Set("Content-Type", "image/png")
-	graph.Render(chart.PNG, res)
-}
-
-func main() {
-	http.HandleFunc("/", drawChart)
-	http.ListenAndServe(":8080", nil)
+	f, _ := os.Create("output.png")
+	defer f.Close()
+	graph.Render(chart.PNG, f)
 }