304 lines
7 KiB
Go
304 lines
7 KiB
Go
package chart
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import (
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"errors"
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"fmt"
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"io"
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"math"
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"github.com/golang/freetype/truetype"
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"github.com/wcharczuk/go-chart/util"
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)
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const (
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_pi2 = math.Pi / 2.0
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_pi4 = math.Pi / 4.0
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)
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// PieChart is a chart that draws sections of a circle based on percentages.
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type PieChart struct {
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Title string
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TitleStyle Style
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ColorPalette ColorPalette
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Width int
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Height int
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DPI float64
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Background Style
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Canvas Style
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SliceStyle Style
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Font *truetype.Font
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defaultFont *truetype.Font
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Values []Value
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Elements []Renderable
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}
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// GetDPI returns the dpi for the chart.
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func (pc PieChart) GetDPI(defaults ...float64) float64 {
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if pc.DPI == 0 {
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if len(defaults) > 0 {
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return defaults[0]
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}
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return DefaultDPI
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}
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return pc.DPI
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}
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// GetFont returns the text font.
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func (pc PieChart) GetFont() *truetype.Font {
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if pc.Font == nil {
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return pc.defaultFont
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}
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return pc.Font
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}
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// GetWidth returns the chart width or the default value.
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func (pc PieChart) GetWidth() int {
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if pc.Width == 0 {
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return DefaultChartWidth
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}
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return pc.Width
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}
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// GetHeight returns the chart height or the default value.
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func (pc PieChart) GetHeight() int {
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if pc.Height == 0 {
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return DefaultChartWidth
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}
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return pc.Height
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}
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// Render renders the chart with the given renderer to the given io.Writer.
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func (pc PieChart) Render(rp RendererProvider, w io.Writer) error {
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if len(pc.Values) == 0 {
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return errors.New("please provide at least one value")
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}
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r, err := rp(pc.GetWidth(), pc.GetHeight())
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if err != nil {
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return err
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}
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if pc.Font == nil {
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defaultFont, err := GetDefaultFont()
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if err != nil {
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return err
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}
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pc.defaultFont = defaultFont
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}
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r.SetDPI(pc.GetDPI(DefaultDPI))
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canvasBox := pc.getDefaultCanvasBox()
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canvasBox = pc.getCircleAdjustedCanvasBox(canvasBox)
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pc.drawBackground(r)
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pc.drawCanvas(r, canvasBox)
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finalValues, err := pc.finalizeValues(pc.Values)
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if err != nil {
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return err
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}
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pc.drawSlices(r, canvasBox, finalValues)
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pc.drawTitle(r)
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for _, a := range pc.Elements {
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a(r, canvasBox, pc.styleDefaultsElements())
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}
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return r.Save(w)
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}
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func (pc PieChart) drawBackground(r Renderer) {
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Draw.Box(r, Box{
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Right: pc.GetWidth(),
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Bottom: pc.GetHeight(),
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}, pc.getBackgroundStyle())
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}
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func (pc PieChart) drawCanvas(r Renderer, canvasBox Box) {
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Draw.Box(r, canvasBox, pc.getCanvasStyle())
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}
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func (pc PieChart) drawTitle(r Renderer) {
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if len(pc.Title) > 0 && pc.TitleStyle.Show {
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Draw.TextWithin(r, pc.Title, pc.Box(), pc.styleDefaultsTitle())
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}
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}
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func (pc PieChart) drawSlices(r Renderer, canvasBox Box, values []Value) {
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cx, cy := canvasBox.Center()
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diameter := util.Math.MinInt(canvasBox.Width(), canvasBox.Height())
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radius := float64(diameter >> 1)
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labelRadius := (radius * 2.0) / 3.0
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// draw the pie slices
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var rads, delta, delta2, total float64
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var lx, ly int
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for index, v := range values {
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v.Style.InheritFrom(pc.stylePieChartValue(index)).WriteToRenderer(r)
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r.MoveTo(cx, cy)
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rads = util.Math.PercentToRadians(total)
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delta = util.Math.PercentToRadians(v.Value)
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r.ArcTo(cx, cy, radius, radius, rads, delta)
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r.LineTo(cx, cy)
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r.Close()
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r.FillStroke()
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total = total + v.Value
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}
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// draw the labels
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total = 0
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for index, v := range values {
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v.Style.InheritFrom(pc.stylePieChartValue(index)).WriteToRenderer(r)
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if len(v.Label) > 0 {
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delta2 = util.Math.PercentToRadians(total + (v.Value / 2.0))
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delta2 = util.Math.RadianAdd(delta2, _pi2)
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lx, ly = util.Math.CirclePoint(cx, cy, labelRadius, delta2)
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tb := r.MeasureText(v.Label)
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lx = lx - (tb.Width() >> 1)
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ly = ly + (tb.Height() >> 1)
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r.Text(v.Label, lx, ly)
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}
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total = total + v.Value
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}
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}
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func (pc PieChart) finalizeValues(values []Value) ([]Value, error) {
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finalValues := Values(values).Normalize()
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if len(finalValues) == 0 {
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return nil, fmt.Errorf("pie chart must contain at least (1) non-zero value")
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}
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return finalValues, nil
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}
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func (pc PieChart) getDefaultCanvasBox() Box {
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return pc.Box()
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}
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func (pc PieChart) getCircleAdjustedCanvasBox(canvasBox Box) Box {
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circleDiameter := util.Math.MinInt(canvasBox.Width(), canvasBox.Height())
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square := Box{
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Right: circleDiameter,
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Bottom: circleDiameter,
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}
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return canvasBox.Fit(square)
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}
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func (pc PieChart) getBackgroundStyle() Style {
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return pc.Background.InheritFrom(pc.styleDefaultsBackground())
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}
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func (pc PieChart) getCanvasStyle() Style {
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return pc.Canvas.InheritFrom(pc.styleDefaultsCanvas())
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}
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func (pc PieChart) styleDefaultsCanvas() Style {
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return Style{
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FillColor: pc.GetColorPalette().CanvasColor(),
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StrokeColor: pc.GetColorPalette().CanvasStrokeColor(),
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StrokeWidth: DefaultStrokeWidth,
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}
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}
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func (pc PieChart) styleDefaultsPieChartValue() Style {
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return Style{
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StrokeColor: pc.GetColorPalette().TextColor(),
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StrokeWidth: 5.0,
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FillColor: pc.GetColorPalette().TextColor(),
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}
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}
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func (pc PieChart) stylePieChartValue(index int) Style {
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return pc.SliceStyle.InheritFrom(Style{
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StrokeColor: ColorWhite,
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StrokeWidth: 5.0,
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FillColor: pc.GetColorPalette().GetSeriesColor(index),
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FontSize: pc.getScaledFontSize(),
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FontColor: pc.GetColorPalette().TextColor(),
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Font: pc.GetFont(),
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})
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}
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func (pc PieChart) getScaledFontSize() float64 {
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effectiveDimension := util.Math.MinInt(pc.GetWidth(), pc.GetHeight())
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if effectiveDimension >= 2048 {
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return 48.0
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} else if effectiveDimension >= 1024 {
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return 24.0
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} else if effectiveDimension > 512 {
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return 18.0
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} else if effectiveDimension > 256 {
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return 12.0
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}
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return 10.0
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}
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func (pc PieChart) styleDefaultsBackground() Style {
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return Style{
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FillColor: pc.GetColorPalette().BackgroundColor(),
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StrokeColor: pc.GetColorPalette().BackgroundStrokeColor(),
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StrokeWidth: DefaultStrokeWidth,
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}
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}
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func (pc PieChart) styleDefaultsElements() Style {
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return Style{
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Font: pc.GetFont(),
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}
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}
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func (pc PieChart) styleDefaultsTitle() Style {
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return pc.TitleStyle.InheritFrom(Style{
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FontColor: pc.GetColorPalette().TextColor(),
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Font: pc.GetFont(),
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FontSize: pc.getTitleFontSize(),
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TextHorizontalAlign: TextHorizontalAlignCenter,
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TextVerticalAlign: TextVerticalAlignTop,
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TextWrap: TextWrapWord,
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})
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}
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func (pc PieChart) getTitleFontSize() float64 {
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effectiveDimension := util.Math.MinInt(pc.GetWidth(), pc.GetHeight())
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if effectiveDimension >= 2048 {
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return 48
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} else if effectiveDimension >= 1024 {
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return 24
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} else if effectiveDimension >= 512 {
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return 18
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} else if effectiveDimension >= 256 {
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return 12
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}
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return 10
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}
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// GetColorPalette returns the color palette for the chart.
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func (pc PieChart) GetColorPalette() ColorPalette {
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if pc.ColorPalette != nil {
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return pc.ColorPalette
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}
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return AlternateColorPalette
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}
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// Box returns the chart bounds as a box.
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func (pc PieChart) Box() Box {
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dpr := pc.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
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dpb := pc.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
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return Box{
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Top: pc.Background.Padding.GetTop(DefaultBackgroundPadding.Top),
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Left: pc.Background.Padding.GetLeft(DefaultBackgroundPadding.Left),
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Right: pc.GetWidth() - dpr,
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Bottom: pc.GetHeight() - dpb,
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}
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}
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