package chart import ( "errors" "fmt" "io" "math" "git.gutmet.org/golang-freetype.git/truetype" "git.gutmet.org/go-chart.git/util" ) const ( _pi = math.Pi _pi2 = math.Pi / 2.0 _pi4 = math.Pi / 4.0 ) // PieChart is a chart that draws sections of a circle based on percentages. type PieChart 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 PieChart) 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 PieChart) GetFont() *truetype.Font { if pc.Font == nil { return pc.defaultFont } return pc.Font } // GetWidth returns the chart width or the default value. func (pc PieChart) GetWidth() int { if pc.Width == 0 { return DefaultChartWidth } return pc.Width } // GetHeight returns the chart height or the default value. func (pc PieChart) 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 PieChart) 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 PieChart) drawBackground(r Renderer) { Draw.Box(r, Box{ Right: pc.GetWidth(), Bottom: pc.GetHeight(), }, pc.getBackgroundStyle()) } func (pc PieChart) drawCanvas(r Renderer, canvasBox Box) { Draw.Box(r, canvasBox, pc.getCanvasStyle()) } func (pc PieChart) drawTitle(r Renderer) { if len(pc.Title) > 0 && pc.TitleStyle.Show { Draw.TextWithin(r, pc.Title, pc.Box(), pc.styleDefaultsTitle()) } } func (pc PieChart) drawSlices(r Renderer, canvasBox Box, values []Value) { cx, cy := canvasBox.Center() diameter := util.Math.MinInt(canvasBox.Width(), canvasBox.Height()) radius := float64(diameter >> 1) labelRadius := (radius * 2.0) / 3.0 // draw the pie slices var rads, delta, delta2, total float64 var lx, ly int if len(values) == 1 { pc.stylePieChartValue(0).WriteToRenderer(r) r.MoveTo(cx, cy) r.Circle(radius, cx, cy) } else { for index, v := range values { v.Style.InheritFrom(pc.stylePieChartValue(index)).WriteToRenderer(r) r.MoveTo(cx, cy) rads = util.Math.PercentToRadians(total) delta = util.Math.PercentToRadians(v.Value) r.ArcTo(cx, cy, radius, radius, rads, delta) r.LineTo(cx, cy) r.Close() r.FillStroke() total = total + v.Value } } // draw the labels total = 0 for index, v := range values { v.Style.InheritFrom(pc.stylePieChartValue(index)).WriteToRenderer(r) if len(v.Label) > 0 { delta2 = util.Math.PercentToRadians(total + (v.Value / 2.0)) delta2 = util.Math.RadianAdd(delta2, _pi2) lx, ly = util.Math.CirclePoint(cx, cy, labelRadius, delta2) tb := r.MeasureText(v.Label) lx = lx - (tb.Width() >> 1) ly = ly + (tb.Height() >> 1) if lx < 0 { lx = 0 } if ly < 0 { lx = 0 } r.Text(v.Label, lx, ly) } total = total + v.Value } } func (pc PieChart) finalizeValues(values []Value) ([]Value, error) { finalValues := Values(values).Normalize() if len(finalValues) == 0 { return nil, fmt.Errorf("pie chart must contain at least (1) non-zero value") } return finalValues, nil } func (pc PieChart) getDefaultCanvasBox() Box { return pc.Box() } func (pc PieChart) getCircleAdjustedCanvasBox(canvasBox Box) Box { circleDiameter := util.Math.MinInt(canvasBox.Width(), canvasBox.Height()) square := Box{ Right: circleDiameter, Bottom: circleDiameter, } return canvasBox.Fit(square) } func (pc PieChart) getBackgroundStyle() Style { return pc.Background.InheritFrom(pc.styleDefaultsBackground()) } func (pc PieChart) getCanvasStyle() Style { return pc.Canvas.InheritFrom(pc.styleDefaultsCanvas()) } func (pc PieChart) styleDefaultsCanvas() Style { return Style{ FillColor: pc.GetColorPalette().CanvasColor(), StrokeColor: pc.GetColorPalette().CanvasStrokeColor(), StrokeWidth: DefaultStrokeWidth, } } func (pc PieChart) styleDefaultsPieChartValue() Style { return Style{ StrokeColor: pc.GetColorPalette().TextColor(), StrokeWidth: 5.0, FillColor: pc.GetColorPalette().TextColor(), } } func (pc PieChart) stylePieChartValue(index int) Style { return pc.SliceStyle.InheritFrom(Style{ StrokeColor: ColorWhite, StrokeWidth: 5.0, FillColor: pc.GetColorPalette().GetSeriesColor(index), FontSize: pc.getScaledFontSize(), FontColor: pc.GetColorPalette().TextColor(), Font: pc.GetFont(), }) } func (pc PieChart) getScaledFontSize() float64 { effectiveDimension := util.Math.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 PieChart) styleDefaultsBackground() Style { return Style{ FillColor: pc.GetColorPalette().BackgroundColor(), StrokeColor: pc.GetColorPalette().BackgroundStrokeColor(), StrokeWidth: DefaultStrokeWidth, } } func (pc PieChart) styleDefaultsElements() Style { return Style{ Font: pc.GetFont(), } } func (pc PieChart) 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 PieChart) getTitleFontSize() float64 { effectiveDimension := util.Math.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 PieChart) GetColorPalette() ColorPalette { if pc.ColorPalette != nil { return pc.ColorPalette } return AlternateColorPalette } // Box returns the chart bounds as a box. func (pc PieChart) 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, } }