a color type that actually works.

chart.go

@@ -350,7 +350,7 @@ func (c Chart) drawSeries(r Renderer, canvasBox Box, index int, s Series, xrange
 	var x, y int
 
 	fill := s.GetStyle().GetFillColor()
-	if !ColorIsZero(fill) {
+	if !fill.IsZero() {
 		r.SetFillColor(fill)
 		r.MoveTo(x0+cx, y0+cy)
 		for i := 1; i < s.Len(); i++ {

defaults.go

@@ -1,10 +1,10 @@
 package chart
 
 import (
-	"image/color"
 	"sync"
 
 	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/drawing"
 )
 
 const (
@@ -47,44 +47,44 @@ const (
 var (
 	// DefaultBackgroundColor is the default chart background color.
 	// It is equivalent to css color:white.
-	DefaultBackgroundColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultBackgroundColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
 	// DefaultBackgroundStrokeColor is the default chart border color.
 	// It is equivalent to color:white.
-	DefaultBackgroundStrokeColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultBackgroundStrokeColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
 	// DefaultCanvasColor is the default chart canvas color.
 	// It is equivalent to css color:white.
-	DefaultCanvasColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultCanvasColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
 	// DefaultCanvasStrokColor is the default chart canvas stroke color.
 	// It is equivalent to css color:white.
-	DefaultCanvasStrokColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultCanvasStrokColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
 	// DefaultTextColor is the default chart text color.
 	// It is equivalent to #333333.
-	DefaultTextColor = color.RGBA{R: 51, G: 51, B: 51, A: 255}
+	DefaultTextColor = drawing.Color{R: 51, G: 51, B: 51, A: 255}
 	// DefaultAxisColor is the default chart axis line color.
 	// It is equivalent to #333333.
-	DefaultAxisColor = color.RGBA{R: 51, G: 51, B: 51, A: 255}
+	DefaultAxisColor = drawing.Color{R: 51, G: 51, B: 51, A: 255}
 	// DefaultStrokeColor is the default chart border color.
 	// It is equivalent to #efefef.
-	DefaultStrokeColor = color.RGBA{R: 239, G: 239, B: 239, A: 255}
+	DefaultStrokeColor = drawing.Color{R: 239, G: 239, B: 239, A: 255}
 	// DefaultFillColor is the default fill color.
 	// It is equivalent to #0074d9.
-	DefaultFillColor = color.RGBA{R: 0, G: 217, B: 116, A: 255}
+	DefaultFillColor = drawing.Color{R: 0, G: 217, B: 116, A: 255}
 	// DefaultFinalLabelBackgroundColor is the default final label background color.
-	DefaultFinalLabelBackgroundColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultFinalLabelBackgroundColor = drawing.Color{R: 255, G: 255, B: 255, A: 255}
 )
 
 var (
 	// DefaultSeriesStrokeColors are a couple default series colors.
-	DefaultSeriesStrokeColors = []color.RGBA{
+	DefaultSeriesStrokeColors = []drawing.Color{
-		color.RGBA{R: 0, G: 116, B: 217, A: 255},
+		drawing.Color{R: 0, G: 116, B: 217, A: 255},
-		color.RGBA{R: 0, G: 217, B: 116, A: 255},
+		drawing.Color{R: 0, G: 217, B: 116, A: 255},
-		color.RGBA{R: 217, G: 0, B: 116, A: 255},
+		drawing.Color{R: 217, G: 0, B: 116, A: 255},
 	}
 )
 
 // GetDefaultSeriesStrokeColor returns a color from the default list by index.
 // NOTE: the index will wrap around (using a modulo).g
-func GetDefaultSeriesStrokeColor(index int) color.RGBA {
+func GetDefaultSeriesStrokeColor(index int) drawing.Color {
 	finalIndex := index % len(DefaultSeriesStrokeColors)
 	return DefaultSeriesStrokeColors[finalIndex]
 }

drawing/color.go

@@ -0,0 +1,85 @@
+package drawing
+
+import (
+	"fmt"
+	"strconv"
+)
+
+var (
+	// ColorTransparent is a fully transparent color.
+	ColorTransparent = Color{}
+
+	// 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}
+
+	// ColorBlue is blue.
+	ColorBlue = Color{R: 0, G: 0, B: 255, A: 255}
+)
+
+func parseHex(hex string) uint8 {
+	v, _ := strconv.ParseInt(hex, 16, 16)
+	return uint8(v)
+}
+
+// ColorFromHex returns a color from a css hex code.
+func ColorFromHex(hex string) Color {
+	var c Color
+	if len(hex) == 3 {
+		c.R = parseHex(string(hex[0])) * 0x11
+		c.G = parseHex(string(hex[1])) * 0x11
+		c.B = parseHex(string(hex[2])) * 0x11
+	} else {
+		c.R = parseHex(string(hex[0:2]))
+		c.G = parseHex(string(hex[2:4]))
+		c.B = parseHex(string(hex[4:6]))
+	}
+	c.A = 255
+	return c
+}
+
+// Color is our internal color type because color.Color is bullshit.
+type Color struct {
+	R uint8
+	G uint8
+	B uint8
+	A uint8
+}
+
+// RGBA returns the color as a pre-alpha mixed color set.
+func (c Color) RGBA() (r, g, b, a uint32) {
+	fa := float64(c.A) / 255.0
+	r = uint32(float64(uint32(c.R)) * fa)
+	r |= r << 8
+	g = uint32(float64(uint32(c.G)) * fa)
+	g |= g << 8
+	b = uint32(float64(uint32(c.B)) * fa)
+	b |= b << 8
+	a = uint32(c.A)
+	a |= a << 8
+	return
+}
+
+// IsZero returns if the color has been set or not.
+func (c Color) IsZero() bool {
+	return c.R == 0 && c.G == 0 && c.B == 0 && c.A == 0
+}
+
+// IsTransparent returns if the colors alpha channel is zero.
+func (c Color) IsTransparent() bool {
+	return c.A == 0
+}
+
+// String returns a css string representation of the color.
+func (c Color) String() string {
+	fa := float64(c.A) / float64(255)
+	return fmt.Sprintf("rgba(%v,%v,%v,%.1f)", c.R, c.G, c.B, fa)
+}

drawing/color_test.go

@@ -0,0 +1,41 @@
+package drawing
+
+import (
+	"testing"
+
+	"github.com/blendlabs/go-assert"
+)
+
+func TestColorFromHex(t *testing.T) {
+	assert := assert.New(t)
+
+	white := ColorFromHex("FFFFFF")
+	assert.Equal(ColorWhite, white)
+
+	shortWhite := ColorFromHex("FFF")
+	assert.Equal(ColorWhite, shortWhite)
+
+	black := ColorFromHex("000000")
+	assert.Equal(ColorBlack, black)
+
+	shortBlack := ColorFromHex("000")
+	assert.Equal(ColorBlack, shortBlack)
+
+	red := ColorFromHex("FF0000")
+	assert.Equal(ColorRed, red)
+
+	shortRed := ColorFromHex("F00")
+	assert.Equal(ColorRed, shortRed)
+
+	green := ColorFromHex("00FF00")
+	assert.Equal(ColorGreen, green)
+
+	shortGreen := ColorFromHex("0F0")
+	assert.Equal(ColorGreen, shortGreen)
+
+	blue := ColorFromHex("0000FF")
+	assert.Equal(ColorBlue, blue)
+
+	shortBlue := ColorFromHex("00F")
+	assert.Equal(ColorBlue, shortBlue)
+}

raster_renderer.go

@@ -29,7 +29,7 @@ type rasterRenderer struct {
 	gc *drawing.RasterGraphicContext
 
 	fontSize  float64
-	fontColor color.RGBA
+	fontColor color.Color
 	f         *truetype.Font
 }
 
@@ -39,12 +39,12 @@ func (rr *rasterRenderer) SetDPI(dpi float64) {
 }
 
 // SetStrokeColor implements the interface method.
-func (rr *rasterRenderer) SetStrokeColor(c color.RGBA) {
+func (rr *rasterRenderer) SetStrokeColor(c drawing.Color) {
 	rr.gc.SetStrokeColor(c)
 }
 
 // SetFillColor implements the interface method.
-func (rr *rasterRenderer) SetFillColor(c color.RGBA) {
+func (rr *rasterRenderer) SetFillColor(c drawing.Color) {
 	rr.gc.SetFillColor(c)
 }
 
@@ -109,7 +109,7 @@ func (rr *rasterRenderer) SetFontSize(size float64) {
 }
 
 // SetFontColor implements the interface method.
-func (rr *rasterRenderer) SetFontColor(c color.RGBA) {
+func (rr *rasterRenderer) SetFontColor(c drawing.Color) {
 	rr.fontColor = c
 	rr.gc.SetFillColor(c)
 	rr.gc.SetStrokeColor(c)

renderer.go

@@ -1,10 +1,10 @@
 package chart
 
 import (
-	"image/color"
 	"io"
 
 	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/drawing"
 )
 
 // RendererProvider is a function that returns a renderer.
@@ -16,10 +16,10 @@ type Renderer interface {
 	SetDPI(dpi float64)
 
 	// SetStrokeColor sets the current stroke color.
-	SetStrokeColor(color.RGBA)
+	SetStrokeColor(drawing.Color)
 
 	// SetFillColor sets the current fill color.
-	SetFillColor(color.RGBA)
+	SetFillColor(drawing.Color)
 
 	// SetStrokeWidth sets the stroke width.
 	SetStrokeWidth(width float64)
@@ -50,7 +50,7 @@ type Renderer interface {
 	SetFont(*truetype.Font)
 
 	// SetFontColor sets a font's color
-	SetFontColor(color.RGBA)
+	SetFontColor(drawing.Color)
 
 	// SetFontSize sets the font size for a text field.
 	SetFontSize(size float64)

style.go

@@ -2,7 +2,6 @@ package chart
 
 import (
 	"fmt"
-	"image/color"
 	"strings"
 
 	"github.com/wcharczuk/go-chart/drawing"
@@ -11,37 +10,37 @@ import (
 // Style is a simple style set.
 type Style struct {
 	Show        bool
-	StrokeColor color.RGBA
+	StrokeColor drawing.Color
-	FillColor   color.RGBA
+	FillColor   drawing.Color
 	StrokeWidth float64
 	FontSize    float64
-	FontColor   color.RGBA
+	FontColor   drawing.Color
 	Padding     Box
 }
 
 // IsZero returns if the object is set or not.
 func (s Style) IsZero() bool {
-	return ColorIsZero(s.StrokeColor) && ColorIsZero(s.FillColor) && s.StrokeWidth == 0 && s.FontSize == 0
+	return s.StrokeColor.IsZero() && s.FillColor.IsZero() && s.StrokeWidth == 0 && s.FontSize == 0
 }
 
 // GetStrokeColor returns the stroke color.
-func (s Style) GetStrokeColor(defaults ...color.RGBA) color.RGBA {
+func (s Style) GetStrokeColor(defaults ...drawing.Color) drawing.Color {
-	if ColorIsZero(s.StrokeColor) {
+	if s.StrokeColor.IsZero() {
 		if len(defaults) > 0 {
 			return defaults[0]
 		}
-		return color.RGBA{}
+		return drawing.ColorTransparent
 	}
 	return s.StrokeColor
 }
 
 // GetFillColor returns the fill color.
-func (s Style) GetFillColor(defaults ...color.RGBA) color.RGBA {
+func (s Style) GetFillColor(defaults ...drawing.Color) drawing.Color {
-	if ColorIsZero(s.FillColor) {
+	if s.FillColor.IsZero() {
 		if len(defaults) > 0 {
 			return defaults[0]
 		}
-		return color.RGBA{}
+		return drawing.ColorTransparent
 	}
 	return s.FillColor
 }
@@ -69,12 +68,12 @@ func (s Style) GetFontSize(defaults ...float64) float64 {
 }
 
 // GetFontColor gets the font size.
-func (s Style) GetFontColor(defaults ...color.RGBA) color.RGBA {
+func (s Style) GetFontColor(defaults ...drawing.Color) drawing.Color {
-	if ColorIsZero(s.FontColor) {
+	if s.FontColor.IsZero() {
 		if len(defaults) > 0 {
 			return defaults[0]
 		}
-		return color.RGBA{}
+		return drawing.ColorTransparent
 	}
 	return s.FontColor
 }
@@ -93,13 +92,13 @@ func (s Style) SVG(dpi float64) string {
 	}
 
 	strokeText := "stroke:none"
-	if !ColorIsZero(sc) {
+	if !sc.IsZero() {
-		strokeText = "stroke:" + ColorAsString(sc)
+		strokeText = "stroke:" + sc.String()
 	}
 
 	fillText := "fill:none"
-	if !ColorIsZero(fc) {
+	if !fc.IsZero() {
-		fillText = "fill:" + ColorAsString(fc)
+		fillText = "fill:" + fc.String()
 	}
 
 	fontSizeText := ""
@@ -107,8 +106,8 @@ func (s Style) SVG(dpi float64) string {
 		fontSizeText = "font-size:" + fmt.Sprintf("%.1fpx", drawing.PointsToPixels(dpi, fs))
 	}
 
-	if !ColorIsZero(fnc) {
+	if !fnc.IsZero() {
-		fillText = "fill:" + ColorAsString(fnc)
+		fillText = "fill:" + fnc.String()
 	}
 	return strings.Join([]string{strokeWidthText, strokeText, fillText, fontSizeText}, ";")
 }

testserver/main.go

@@ -1,11 +1,11 @@
 package main
 
 import (
-	"image/color"
 	"log"
 	"net/http"
 
 	"github.com/wcharczuk/go-chart"
+	"github.com/wcharczuk/go-chart/drawing"
 	"github.com/wcharczuk/go-web"
 )
 
@@ -46,7 +46,7 @@ func chartHandler(rc *web.RequestContext) web.ControllerResult {
 				XValues: []float64{1.0, 2.0, 3.0, 4.0},
 				YValues: []float64{2.5, 5.0, 2.0, 3.3},
 				Style: chart.Style{
-					FillColor: color.RGBA{R: 0, G: 116, B: 217, A: 255},
+					FillColor: drawing.Color{R: 0, G: 116, B: 217, A: 128},
 				},
 			},
 			chart.ContinuousSeries{

util.go

@@ -2,21 +2,9 @@ package chart
 
 import (
 	"fmt"
-	"image/color"
 	"time"
 )
 
-// ColorIsZero returns if a color.RGBA is unset or not.
-func ColorIsZero(c color.RGBA) bool {
-	return c.R == 0 && c.G == 0 && c.B == 0 && c.A == 0
-}
-
-// ColorAsString returns if a color.RGBA is unset or not.
-func ColorAsString(c color.RGBA) string {
-	a := float64(c.A) / float64(255)
-	return fmt.Sprintf("rgba(%v,%v,%v,%.1f)", c.R, c.G, c.B, a)
-}
-
 // MinAndMax returns both the min and max in one pass.
 func MinAndMax(values ...float64) (min float64, max float64) {
 	if len(values) == 0 {

vector_renderer.go

@@ -3,7 +3,6 @@ package chart
 import (
 	"bytes"
 	"fmt"
-	"image/color"
 	"io"
 	"strings"
 
@@ -43,12 +42,12 @@ func (vr *vectorRenderer) SetDPI(dpi float64) {
 }
 
 // SetStrokeColor implements the interface method.
-func (vr *vectorRenderer) SetStrokeColor(c color.RGBA) {
+func (vr *vectorRenderer) SetStrokeColor(c drawing.Color) {
 	vr.s.StrokeColor = c
 }
 
 // SetFillColor implements the interface method.
-func (vr *vectorRenderer) SetFillColor(c color.RGBA) {
+func (vr *vectorRenderer) SetFillColor(c drawing.Color) {
 	vr.s.FillColor = c
 }
 
@@ -73,22 +72,22 @@ func (vr *vectorRenderer) Close() {
 
 // Stroke draws the path with no fill.
 func (vr *vectorRenderer) Stroke() {
-	vr.s.FillColor = color.RGBA{}
+	vr.s.FillColor = drawing.ColorTransparent
-	vr.s.FontColor = color.RGBA{}
+	vr.s.FontColor = drawing.ColorTransparent
 	vr.drawPath()
 }
 
 // Fill draws the path with no stroke.
 func (vr *vectorRenderer) Fill() {
-	vr.s.StrokeColor = color.RGBA{}
+	vr.s.StrokeColor = drawing.ColorTransparent
 	vr.s.StrokeWidth = 0
-	vr.s.FontColor = color.RGBA{}
+	vr.s.FontColor = drawing.ColorTransparent
 	vr.drawPath()
 }
 
 // FillStroke draws the path with both fill and stroke.
 func (vr *vectorRenderer) FillStroke() {
-	vr.s.FontColor = color.RGBA{}
+	vr.s.FontColor = drawing.ColorTransparent
 	vr.drawPath()
 }
 
@@ -108,7 +107,7 @@ func (vr *vectorRenderer) SetFont(f *truetype.Font) {
 }
 
 // SetFontColor implements the interface method.
-func (vr *vectorRenderer) SetFontColor(c color.RGBA) {
+func (vr *vectorRenderer) SetFontColor(c drawing.Color) {
 	vr.s.FontColor = c
 }
 
@@ -130,8 +129,8 @@ func (vr *vectorRenderer) svgFontFace() string {
 
 // Text draws a text blob.
 func (vr *vectorRenderer) Text(body string, x, y int) {
-	vr.s.FillColor = color.RGBA{}
+	vr.s.FillColor = drawing.ColorTransparent
-	vr.s.StrokeColor = color.RGBA{}
+	vr.s.StrokeColor = drawing.ColorTransparent
 	vr.s.StrokeWidth = 0
 	vr.c.Text(x, y, body, vr.s.SVG(vr.dpi)+";"+vr.svgFontFace())
 }