things work more or less, added a testing service.

chart.go

@@ -2,6 +2,7 @@ package chart
 
 import (
 	"io"
+	"math"
 
 	"github.com/golang/freetype/truetype"
 )
@@ -13,7 +14,6 @@ type Chart struct {
 
 	Width  int
 	Height int
-	Padding Box
 
 	Background      Style
 	Canvas          Style
@@ -29,32 +29,32 @@ type Chart struct {
 
 // GetCanvasTop gets the top corner pixel.
 func (c Chart) GetCanvasTop() int {
-	return c.Padding.GetTop(DefaultCanvasPadding.Top)
+	return c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
 }
 
 // GetCanvasLeft gets the left corner pixel.
 func (c Chart) GetCanvasLeft() int {
-	return c.Padding.GetLeft(DefaultCanvasPadding.Left)
+	return c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left)
 }
 
 // GetCanvasBottom gets the bottom corner pixel.
 func (c Chart) GetCanvasBottom() int {
-	return c.Height - c.Padding.GetBottom(DefaultCanvasPadding.Bottom)
+	return c.Height - c.Canvas.Padding.GetBottom(DefaultCanvasPadding.Bottom)
 }
 
 // GetCanvasRight gets the right corner pixel.
 func (c Chart) GetCanvasRight() int {
-	return c.Width - c.Padding.GetRight(DefaultCanvasPadding.Right)
+	return c.Width - c.Canvas.Padding.GetRight(DefaultCanvasPadding.Right)
 }
 
 // GetCanvasWidth returns the width of the canvas.
 func (c Chart) GetCanvasWidth() int {
-	return c.Width - (c.Padding.GetLeft(DefaultCanvasPadding.Left) + c.Padding.GetRight(DefaultCanvasPadding.Right))
+	return c.Width - (c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left) + c.Canvas.Padding.GetRight(DefaultCanvasPadding.Right))
 }
 
 // GetCanvasHeight returns the height of the canvas.
 func (c Chart) GetCanvasHeight() int {
-	return c.Height - (c.Padding.GetTop(DefaultCanvasPadding.Top) + c.Padding.GetBottom(DefaultCanvasPadding.Bottom))
+	return c.Height - (c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top) + c.Canvas.Padding.GetBottom(DefaultCanvasPadding.Bottom))
 }
 
 // GetFont returns the text font.
@@ -68,21 +68,21 @@ func (c Chart) GetFont() (*truetype.Font, error) {
 // Render renders the chart with the given renderer to the given io.Writer.
 func (c *Chart) Render(provider RendererProvider, w io.Writer) error {
 	xrange, yrange := c.initRanges()
-	println("xrange", xrange.String())
-	println("yrange", yrange.String())
 
-	r := provider(c.Width, c.Height)
+	font, err := c.GetFont()
-	c.drawBackground(r)
-	c.drawCanvas(r)
-	c.drawAxes(r)
-
-	for _, series := range c.Series {
-		c.drawSeries(r, series, xrange, yrange)
-	}
-	err := c.drawTitle(r)
 	if err != nil {
 		return err
 	}
+
+	r := provider(c.Width, c.Height)
+	r.SetFont(font)
+	c.drawBackground(r)
+	c.drawCanvas(r)
+	c.drawAxes(r, xrange, yrange)
+	for _, series := range c.Series {
+		c.drawSeries(r, series, xrange, yrange)
+	}
+	c.drawTitle(r)
 	return r.Save(w)
 }
 
@@ -159,7 +159,7 @@ func (c Chart) drawCanvas(r Renderer) {
 	r.Close()
 }
 
-func (c Chart) drawAxes(r Renderer) {
+func (c Chart) drawAxes(r Renderer, xrange, yrange Range) {
 	if c.Axes.Show {
 		r.SetStrokeColor(c.Axes.GetStrokeColor(DefaultAxisColor))
 		r.SetLineWidth(c.Axes.GetStrokeWidth(DefaultLineWidth))
@@ -167,9 +167,15 @@ func (c Chart) drawAxes(r Renderer) {
 		r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
 		r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
 		r.Stroke()
+
+		c.drawAxesLabels(r, xrange, yrange)
 	}
 }
 
+func (c Chart) drawAxesLabels(r Renderer, xrange, yrange Range) {
+
+}
+
 func (c Chart) drawSeries(r Renderer, s Series, xrange, yrange Range) {
 	r.SetStrokeColor(s.GetStyle().GetStrokeColor(DefaultLineColor))
 	r.SetLineWidth(s.GetStyle().GetStrokeWidth(DefaultLineWidth))
@@ -178,8 +184,8 @@ func (c Chart) drawSeries(r Renderer, s Series, xrange, yrange Range) {
 		return
 	}
 
-	px := c.Padding.GetLeft(DefaultCanvasPadding.Left)
+	px := c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left)
-	py := c.Padding.GetTop(DefaultCanvasPadding.Top)
+	py := c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
 
 	cw := c.GetCanvasWidth()
 
@@ -197,16 +203,67 @@ func (c Chart) drawSeries(r Renderer, s Series, xrange, yrange Range) {
 		r.LineTo(x+px, y+py)
 	}
 	r.Stroke()
+
+	c.drawFinalValueLabel(r, s, yrange)
+}
+
+func (c Chart) drawFinalValueLabel(r Renderer, s Series, yrange Range) {
+	if c.FinalValueLabel.Show {
+		_, lv := s.GetValue(s.Len() - 1)
+		_, ll := s.GetLabel(s.Len() - 1)
+
+		py := c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
+		ly := yrange.Translate(lv) + py
+
+		r.SetFontSize(c.FinalValueLabel.GetFontSize(DefaultFinalLabelFontSize))
+
+		textWidth := r.MeasureText(ll)
+		textHeight := int(math.Floor(DefaultFinalLabelFontSize))
+		halfTextHeight := textHeight >> 1
+
+		cx := c.GetCanvasRight() + int(c.Axes.GetStrokeWidth(DefaultAxisLineWidth))
+
+		pt := c.FinalValueLabel.Padding.GetTop(DefaultFinalLabelPadding.Top)
+		pl := c.FinalValueLabel.Padding.GetLeft(DefaultFinalLabelPadding.Left)
+		pr := c.FinalValueLabel.Padding.GetRight(DefaultFinalLabelPadding.Right)
+		pb := c.FinalValueLabel.Padding.GetBottom(DefaultFinalLabelPadding.Bottom)
+
+		textX := cx + pl + DefaultFinalLabelDeltaWidth
+		textY := ly + halfTextHeight
+
+		ltlx := cx + pl + DefaultFinalLabelDeltaWidth
+		ltly := ly - (pt + halfTextHeight)
+
+		ltrx := cx + pl + pr + textWidth
+		ltry := ly - (pt + halfTextHeight)
+
+		lbrx := cx + pl + pr + textWidth
+		lbry := ly + (pb + halfTextHeight)
+
+		lblx := cx + DefaultFinalLabelDeltaWidth
+		lbly := ly + (pb + halfTextHeight)
+
+		//draw the shape...
+		r.SetFillColor(c.FinalValueLabel.GetFillColor(DefaultFinalLabelBackgroundColor))
+		r.SetStrokeColor(c.FinalValueLabel.GetStrokeColor(s.GetStyle().GetStrokeColor(DefaultLineColor)))
+		r.SetLineWidth(c.FinalValueLabel.GetStrokeWidth(DefaultAxisLineWidth))
+		r.MoveTo(cx, ly)
+		r.LineTo(ltlx, ltly)
+		r.LineTo(ltrx, ltry)
+		r.LineTo(lbrx, lbry)
+		r.LineTo(lblx, lbly)
+		r.LineTo(cx, ly)
+		r.Close()
+		r.FillStroke()
+
+		r.SetFontColor(c.FinalValueLabel.GetFontColor(DefaultTextColor))
+		r.Text(ll, textX, textY)
+	}
 }
 
 func (c Chart) drawTitle(r Renderer) error {
 	if len(c.Title) > 0 && c.TitleStyle.Show {
-		font, err := c.GetFont()
-		if err != nil {
-			return err
-		}
 		r.SetFontColor(c.Canvas.GetFontColor(DefaultTextColor))
-		r.SetFont(font)
 		titleFontSize := c.Canvas.GetFontSize(DefaultTitleFontSize)
 		r.SetFontSize(titleFontSize)
 		textWidth := r.MeasureText(c.Title)

defaults.go

@@ -28,6 +28,18 @@ const (
 	DefaultDateFormat = "2006-01-02"
 )
 
+const (
+	// DefaultFinalLabelDeltaWidth is the width of the left triangle out of the final label.
+	DefaultFinalLabelDeltaWidth = 10
+	// DefaultFinalLabelFontSize is the font size of the final label.
+	DefaultFinalLabelFontSize = 10.0
+)
+
+var (
+	// DefaultFinalLabelPadding is the padding around the final label.
+	DefaultFinalLabelPadding = Box{Top: 5, Left: 0, Right: 5, Bottom: 5}
+)
+
 var (
 	// DefaultBackgroundColor is the default chart background color.
 	// It is equivalent to css color:white.
@@ -41,15 +53,17 @@ var (
 	// DefaultAxisColor is the default chart axis line color.
 	// It is equivalent to #333333.
 	DefaultAxisColor = color.RGBA{R: 51, G: 51, B: 51, A: 255}
-	// DefaultBorderColor is the default chart border color.
+	// DefaultStrokeColor is the default chart border color.
 	// It is equivalent to #efefef.
-	DefaultBorderColor = color.RGBA{R: 239, G: 239, B: 239, A: 255}
+	DefaultStrokeColor = color.RGBA{R: 239, G: 239, B: 239, A: 255}
 	// DefaultLineColor is the default (1st) series line color.
 	// It is equivalent to #0074d9.
 	DefaultLineColor = color.RGBA{R: 0, G: 116, B: 217, A: 255}
 	// DefaultFillColor is the default fill color.
 	// It is equivalent to #0074d9.
 	DefaultFillColor = color.RGBA{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}
 )
 
 var (

raster_renderer.go

@@ -1,7 +1,6 @@
 package chart
 
 import (
-	"fmt"
 	"image"
 	"image/color"
 	"image/png"
@@ -35,55 +34,46 @@ type rasterRenderer struct {
 
 // SetStrokeColor implements the interface method.
 func (rr *rasterRenderer) SetStrokeColor(c color.RGBA) {
-	println("RasterRenderer :: SetStrokeColor", ColorAsString(c))
 	rr.gc.SetStrokeColor(c)
 }
 
 // SetFillColor implements the interface method.
 func (rr *rasterRenderer) SetFillColor(c color.RGBA) {
-	println("RasterRenderer :: SetFillColor", ColorAsString(c))
 	rr.gc.SetFillColor(c)
 }
 
 // SetLineWidth implements the interface method.
 func (rr *rasterRenderer) SetLineWidth(width float64) {
-	println("RasterRenderer :: SetLineWidth", width)
 	rr.gc.SetLineWidth(width)
 }
 
 // MoveTo implements the interface method.
 func (rr *rasterRenderer) MoveTo(x, y int) {
-	println("RasterRenderer :: MoveTo", x, y)
 	rr.gc.MoveTo(float64(x), float64(y))
 }
 
 // LineTo implements the interface method.
 func (rr *rasterRenderer) LineTo(x, y int) {
-	println("RasterRenderer :: LineTo", x, y)
 	rr.gc.LineTo(float64(x), float64(y))
 }
 
 // Close implements the interface method.
 func (rr *rasterRenderer) Close() {
-	println("RasterRenderer :: Close")
 	rr.gc.Close()
 }
 
 // Stroke implements the interface method.
 func (rr *rasterRenderer) Stroke() {
-	println("RasterRenderer :: Stroke")
 	rr.gc.Stroke()
 }
 
 // Fill implements the interface method.
 func (rr *rasterRenderer) Fill() {
-	println("RasterRenderer :: Fill")
 	rr.gc.Fill()
 }
 
 // FillStroke implements the interface method.
 func (rr *rasterRenderer) FillStroke() {
-	println("RasterRenderer :: FillStroke")
 	rr.gc.FillStroke()
 }
 
@@ -108,14 +98,12 @@ func (rr *rasterRenderer) SetFont(f *truetype.Font) {
 
 // SetFontSize implements the interface method.
 func (rr *rasterRenderer) SetFontSize(size float64) {
-	println("RasterRenderer :: SetFontSize", fmt.Sprintf("%.2f", size))
 	rr.fontSize = size
 	rr.gc.SetFontSize(size)
 }
 
 // SetFontColor implements the interface method.
 func (rr *rasterRenderer) SetFontColor(c color.RGBA) {
-	println("RasterRenderer :: SetFontColor", ColorAsString(c))
 	rr.fontColor = c
 	rr.gc.SetFillColor(c)
 	rr.gc.SetStrokeColor(c)
@@ -123,7 +111,6 @@ func (rr *rasterRenderer) SetFontColor(c color.RGBA) {
 
 // Text implements the interface method.
 func (rr *rasterRenderer) Text(body string, x, y int) {
-	println("RasterRenderer :: Text", body, x, y)
 	rr.gc.CreateStringPath(body, float64(x), float64(y))
 	rr.gc.Fill()
 }
@@ -147,6 +134,6 @@ func (rr *rasterRenderer) MeasureText(body string) int {
 
 // Save implements the interface method.
 func (rr *rasterRenderer) Save(w io.Writer) error {
-	println("RasterRenderer :: Save")
+
 	return png.Encode(w, rr.i)
 }

style.go

@@ -10,6 +10,7 @@ type Style struct {
 	StrokeWidth float64
 	FontSize    float64
 	FontColor   color.RGBA
+	Padding     Box
 }
 
 // IsZero returns if the object is set or not.

testserver/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"image/color"
 	"log"
 	"time"
 
@@ -17,16 +18,18 @@ func main() {
 		rc.Response.Header().Set("Content-Type", "image/png")
 		now := time.Now()
 		c := chart.Chart{
-			Title: "Hello!",
+			Title: "Stocks Bruh.",
 			TitleStyle: chart.Style{
 				Show: true,
 			},
 			Width:  1024,
 			Height: 400,
+			Canvas: chart.Style{
 				Padding: chart.Box{
 					Right:  40,
 					Bottom: 40,
 				},
+			},
 			Axes: chart.Style{
 				Show:        true,
 				StrokeWidth: 1.0,
@@ -35,6 +38,9 @@ func main() {
 				Min: 0.0,
 				Max: 7.0,
 			},
+			FinalValueLabel: chart.Style{
+				Show: true,
+			},
 			Series: []chart.Series{
 				chart.TimeSeries{
 					Name: "goog",
@@ -44,6 +50,15 @@ func main() {
 					XValues: []time.Time{now.AddDate(0, 0, -4), now.AddDate(0, 0, -3), now.AddDate(0, 0, -2), now.AddDate(0, 0, -1)},
 					YValues: []float64{2.5, 5.0, 2.0, 3.0},
 				},
+				chart.TimeSeries{
+					Name: "aapl",
+					Style: chart.Style{
+						StrokeWidth: 1.0,
+						StrokeColor: color.RGBA{R: 0, G: 217, B: 116, A: 255},
+					},
+					XValues: []time.Time{now.AddDate(0, 0, -5), now.AddDate(0, 0, -4), now.AddDate(0, 0, -2), now.AddDate(0, 0, -1)},
+					YValues: []float64{3.0, 2.7, 2.0, 1.1},
+				},
 			},
 		}
 

util.go

@@ -3,6 +3,7 @@ package chart
 import (
 	"fmt"
 	"image/color"
+	"math"
 	"time"
 )
 
@@ -54,3 +55,14 @@ func MinAndMaxOfTime(values ...time.Time) (min time.Time, max time.Time) {
 	}
 	return
 }
+
+// Slices generates N slices that span the total.
+// The resulting array will be intermediate indexes until total.
+func Slices(count, total int) []int {
+	var values []int
+	sliceWidth := int(math.Floor(float64(total) / float64(count)))
+	for cursor := 0; cursor < total; cursor += sliceWidth {
+		values = append(values, cursor)
+	}
+	return values
+}

util_test.go

@@ -64,3 +64,14 @@ func TestMinAndMaxOfTimeEmpty(t *testing.T) {
 	assert.Equal(time.Time{}, min)
 	assert.Equal(time.Time{}, max)
 }
+
+func TestSlices(t *testing.T) {
+	assert := assert.New(t)
+
+	s := Slices(10, 100)
+	assert.Len(s, 10)
+	assert.Equal(0, s[0])
+	assert.Equal(10, s[1])
+	assert.Equal(20, s[2])
+	assert.Equal(90, s[9])
+}