basics of stacked bar.

chart.go

@@ -463,7 +463,7 @@ func (c Chart) styleDefaultsCanvas() Style {
 }
 
 func (c Chart) styleDefaultsSeries(seriesIndex int) Style {
-	strokeColor := GetDefaultSeriesStrokeColor(seriesIndex)
+	strokeColor := GetDefaultColor(seriesIndex)
 	return Style{
 		StrokeColor: strokeColor,
 		StrokeWidth: DefaultStrokeWidth,

defaults.go

@@ -159,16 +159,16 @@ var (
 	DashArrayDashesLarge = []int{10, 10}
 )
 
-// GetDefaultSeriesStrokeColor returns a color from the default list by index.
+// GetDefaultColor returns a color from the default list by index.
 // NOTE: the index will wrap around (using a modulo).
-func GetDefaultSeriesStrokeColor(index int) drawing.Color {
+func GetDefaultColor(index int) drawing.Color {
 	finalIndex := index % len(DefaultColors)
 	return DefaultColors[finalIndex]
 }
 
-// GetDefaultPieChartValueColor returns a color from the default list by index.
+// GetAlternateColor returns a color from the default list by index.
 // NOTE: the index will wrap around (using a modulo).
-func GetDefaultPieChartValueColor(index int) drawing.Color {
+func GetAlternateColor(index int) drawing.Color {
 	finalIndex := index % len(DefaultAlternateColors)
 	return DefaultAlternateColors[finalIndex]
 }

examples/pie_chart/main.go

@@ -14,13 +14,13 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			FillColor: chart.ColorLightGray,
 		},
 		Values: []chart.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: "!!"},
+			{Value: 5, Label: "Blue"},
+			{Value: 5, Label: "Green"},
+			{Value: 4, Label: "Gray"},
+			{Value: 4, Label: "Orange"},
+			{Value: 3, Label: "Test"},
+			{Value: 3, Label: "??"},
+			{Value: 1, Label: "!!"},
 		},
 	}
 

examples/stacked_bar/main.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/wcharczuk/go-chart"
+)
+
+func drawChart(res http.ResponseWriter, req *http.Request) {
+	sbc := chart.StackedBarChart{
+		Background: chart.Style{
+			Padding: chart.Box{Top: 50, Left: 50, Right: 50, Bottom: 50},
+		},
+		Bars: []chart.StackedBar{
+			{
+				Values: []chart.Value{
+					{Value: 5, Label: "Blue"},
+					{Value: 5, Label: "Green"},
+					{Value: 4, Label: "Gray"},
+					{Value: 4, Label: "Orange"},
+					{Value: 3, Label: "Test"},
+					{Value: 3, Label: "??"},
+					{Value: 1, Label: "!!"},
+				},
+			},
+			{
+				Values: []chart.Value{
+					{Value: 10, Label: "Blue"},
+					{Value: 5, Label: "Green"},
+					{Value: 1, Label: "Gray"},
+				},
+			},
+		},
+	}
+
+	res.Header().Set("Content-Type", "image/svg+xml")
+	err := sbc.Render(chart.SVG, res)
+	if err != nil {
+		fmt.Printf("Error rendering chart: %v\n", err)
+	}
+}
+
+func main() {
+	http.HandleFunc("/", drawChart)
+	log.Fatal(http.ListenAndServe(":8080", nil))
+}

pie_chart.go

@@ -217,7 +217,7 @@ func (pc PieChart) stylePieChartValue(index int) Style {
 	return Style{
 		StrokeColor: ColorWhite,
 		StrokeWidth: 5.0,
-		FillColor:   GetDefaultPieChartValueColor(index),
+		FillColor:   GetAlternateColor(index),
 		FontSize:    24.0,
 		FontColor:   ColorWhite,
 		Font:        pc.GetFont(),
@@ -232,16 +232,6 @@ func (pc PieChart) styleDefaultsBackground() Style {
 	}
 }
 
-func (pc PieChart) styleDefaultsSeries(seriesIndex int) Style {
-	strokeColor := GetDefaultSeriesStrokeColor(seriesIndex)
-	return Style{
-		StrokeColor: strokeColor,
-		StrokeWidth: DefaultStrokeWidth,
-		Font:        pc.GetFont(),
-		FontSize:    DefaultFontSize,
-	}
-}
-
 func (pc PieChart) styleDefaultsElements() Style {
 	return Style{
 		Font: pc.GetFont(),

stacked_bar_chart.go

@@ -0,0 +1,209 @@
+package chart
+
+import (
+	"errors"
+	"io"
+
+	"github.com/golang/freetype/truetype"
+)
+
+// StackedBar is a bar within a StackedBarChart.
+type StackedBar struct {
+	Name   string
+	Width  int
+	Values []Value
+}
+
+// GetWidth returns the width of the bar.
+func (sb StackedBar) GetWidth() int {
+	if sb.Width == 0 {
+		return 20
+	}
+	return sb.Width
+}
+
+// StackedBarChart is a chart that draws sections of a bar based on percentages.
+type StackedBarChart struct {
+	Title      string
+	TitleStyle Style
+
+	Width  int
+	Height int
+	DPI    float64
+
+	Background Style
+	Canvas     Style
+
+	BarSpacing int
+
+	Font        *truetype.Font
+	defaultFont *truetype.Font
+
+	Bars     []StackedBar
+	Elements []Renderable
+}
+
+// GetDPI returns the dpi for the chart.
+func (sbc StackedBarChart) GetDPI(defaults ...float64) float64 {
+	if sbc.DPI == 0 {
+		if len(defaults) > 0 {
+			return defaults[0]
+		}
+		return DefaultDPI
+	}
+	return sbc.DPI
+}
+
+// GetFont returns the text font.
+func (sbc StackedBarChart) GetFont() *truetype.Font {
+	if sbc.Font == nil {
+		return sbc.defaultFont
+	}
+	return sbc.Font
+}
+
+// GetWidth returns the chart width or the default value.
+func (sbc StackedBarChart) GetWidth() int {
+	if sbc.Width == 0 {
+		return DefaultChartWidth
+	}
+	return sbc.Width
+}
+
+// GetHeight returns the chart height or the default value.
+func (sbc StackedBarChart) GetHeight() int {
+	if sbc.Height == 0 {
+		return DefaultChartWidth
+	}
+	return sbc.Height
+}
+
+// GetBarSpacing returns the spacing between bars.
+func (sbc StackedBarChart) GetBarSpacing() int {
+	if sbc.BarSpacing == 0 {
+		return 100
+	}
+	return sbc.BarSpacing
+}
+
+// Render renders the chart with the given renderer to the given io.Writer.
+func (sbc StackedBarChart) Render(rp RendererProvider, w io.Writer) error {
+	if len(sbc.Bars) == 0 {
+		return errors.New("Please provide at least one bar.")
+	}
+
+	r, err := rp(sbc.GetWidth(), sbc.GetHeight())
+	if err != nil {
+		return err
+	}
+
+	if sbc.Font == nil {
+		defaultFont, err := GetDefaultFont()
+		if err != nil {
+			return err
+		}
+		sbc.defaultFont = defaultFont
+	}
+	r.SetDPI(sbc.GetDPI(DefaultDPI))
+
+	canvasBox := sbc.getAdjustedCanvasBox(sbc.getDefaultCanvasBox())
+	sbc.drawBars(r, canvasBox)
+
+	sbc.drawTitle(r)
+	for _, a := range sbc.Elements {
+		a(r, canvasBox, sbc.styleDefaultsElements())
+	}
+
+	return r.Save(w)
+}
+
+func (sbc StackedBarChart) drawBars(r Renderer, canvasBox Box) {
+	xoffset := canvasBox.Left
+	for _, bar := range sbc.Bars {
+		sbc.drawBar(r, canvasBox, xoffset, bar)
+		xoffset += sbc.GetBarSpacing()
+	}
+}
+
+func (sbc StackedBarChart) drawBar(r Renderer, canvasBox Box, xoffset int, bar StackedBar) int {
+	bxl := xoffset
+	bxr := xoffset + bar.GetWidth()
+
+	normalizedBarComponents := Values(bar.Values).Normalize()
+	yoffset := canvasBox.Top
+	for index, bv := range normalizedBarComponents {
+		barHeight := int(bv.Value * float64(canvasBox.Height()))
+		barBox := Box{Top: yoffset, Left: bxl, Right: bxr, Bottom: yoffset + barHeight}
+		DrawBox(r, barBox, bv.Style.InheritFrom(sbc.styleDefaultsStackedBarValue(index)))
+		yoffset += barHeight
+	}
+
+	return bxr
+}
+
+func (sbc StackedBarChart) drawTitle(r Renderer) {
+	if len(sbc.Title) > 0 && sbc.TitleStyle.Show {
+		r.SetFont(sbc.TitleStyle.GetFont(sbc.GetFont()))
+		r.SetFontColor(sbc.TitleStyle.GetFontColor(DefaultTextColor))
+		titleFontSize := sbc.TitleStyle.GetFontSize(DefaultTitleFontSize)
+		r.SetFontSize(titleFontSize)
+
+		textBox := r.MeasureText(sbc.Title)
+
+		textWidth := textBox.Width()
+		textHeight := textBox.Height()
+
+		titleX := (sbc.GetWidth() >> 1) - (textWidth >> 1)
+		titleY := sbc.TitleStyle.Padding.GetTop(DefaultTitleTop) + textHeight
+
+		r.Text(sbc.Title, titleX, titleY)
+	}
+}
+
+func (sbc StackedBarChart) getDefaultCanvasBox() Box {
+	return sbc.Box()
+}
+
+func (sbc StackedBarChart) getAdjustedCanvasBox(canvasBox Box) Box {
+	var totalWidth int
+	for index, bar := range sbc.Bars {
+		totalWidth += bar.GetWidth()
+		if index < len(sbc.Bars)-1 {
+			totalWidth += sbc.GetBarSpacing()
+		}
+	}
+
+	return canvasBox.OuterConstrain(sbc.Box(), Box{
+		Top:    canvasBox.Top,
+		Left:   canvasBox.Left,
+		Right:  canvasBox.Left + totalWidth,
+		Bottom: canvasBox.Bottom,
+	})
+}
+
+// Box returns the chart bounds as a box.
+func (sbc StackedBarChart) Box() Box {
+	dpr := sbc.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
+	dpb := sbc.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
+
+	return Box{
+		Top:    sbc.Background.Padding.GetTop(DefaultBackgroundPadding.Top),
+		Left:   sbc.Background.Padding.GetLeft(DefaultBackgroundPadding.Left),
+		Right:  sbc.GetWidth() - dpr,
+		Bottom: sbc.GetHeight() - dpb,
+	}
+}
+
+func (sbc StackedBarChart) styleDefaultsStackedBarValue(index int) Style {
+	return Style{
+		StrokeColor: GetAlternateColor(index),
+		StrokeWidth: 3.0,
+		FillColor:   GetAlternateColor(index),
+	}
+}
+
+func (sbc StackedBarChart) styleDefaultsElements() Style {
+	return Style{
+		Font: sbc.GetFont(),
+	}
+}

util.go

@@ -109,7 +109,7 @@ func Normalize(values ...float64) []float64 {
 	}
 	output := make([]float64, len(values))
 	for x, v := range values {
-		output[x] = RoundDown(v/total, 0.001)
+		output[x] = RoundDown(v/total, 0.00001)
 	}
 	return output
 }

value.go

@@ -32,7 +32,7 @@ func (vs Values) Normalize() []Value {
 		output[index] = Value{
 			Style: v.Style,
 			Label: v.Label,
-			Value: RoundDown(v.Value/total, 0.001),
+			Value: RoundDown(v.Value/total, 0.00001),
 		}
 	}
 	return output