CreateLegend() returns a renderable for a legend.
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@ -1,5 +1,7 @@
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package chart
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import "github.com/wcharczuk/go-chart/drawing"
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// DrawLineSeries draws a line series with a renderer.
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func DrawLineSeries(r Renderer, canvasBox Box, xrange, yrange Range, s Style, vs ValueProvider) {
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if vs.Len() == 0 {
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@ -165,3 +167,83 @@ func DrawTextCentered(r Renderer, text string, x, y int, s Style) {
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ty := y - (tb.Height() >> 1)
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r.Text(text, tx, ty)
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}
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func CreateLegend(c *Chart) Renderable {
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return func(r Renderer, cb Box, defaults Style) {
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// DEFAULTS
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legendPadding := 5
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lineTextGap := 5
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lineLengthMinimum := 25
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var labels []string
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var lines []Style
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for _, s := range c.Series {
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if s.GetStyle().IsZero() || s.GetStyle().Show {
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if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
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labels = append(labels, s.GetName())
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lines = append(lines, s.GetStyle())
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}
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}
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}
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legend := Box{
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Top: cb.Top, //padding
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Left: cb.Left,
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}
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legendContent := Box{
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Top: legend.Top + legendPadding,
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Left: legend.Left + legendPadding,
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}
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r.SetFontColor(DefaultTextColor)
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r.SetFontSize(8.0)
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// measure
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for x := 0; x < len(labels); x++ {
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if len(labels[x]) > 0 {
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tb := r.MeasureText(labels[x])
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legendContent.Bottom += (tb.Height() + DefaultMinimumTickVerticalSpacing)
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rowRight := tb.Width() + legendContent.Left + lineLengthMinimum + lineTextGap
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legendContent.Right = MaxInt(legendContent.Right, rowRight)
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}
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}
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legend = legend.Grow(legendContent)
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DrawBox(r, legend, Style{
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FillColor: drawing.ColorWhite,
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StrokeColor: DefaultAxisColor,
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StrokeWidth: 1.0,
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})
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legendContent.Right = legend.Right - legendPadding
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legendContent.Bottom = legend.Bottom - legendPadding
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ycursor := legendContent.Top
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tx := legendContent.Left
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for x := 0; x < len(labels); x++ {
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if len(labels[x]) > 0 {
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tb := r.MeasureText(labels[x])
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ycursor += tb.Height()
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//r.SetFillColor(DefaultTextColor)
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r.Text(labels[x], tx, ycursor)
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th2 := tb.Height() >> 1
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lx := tx + tb.Width() + lineTextGap
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ly := ycursor - th2
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lx2 := legendContent.Right - legendPadding
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r.SetStrokeColor(lines[x].GetStrokeColor())
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r.SetStrokeWidth(lines[x].GetStrokeWidth())
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r.SetStrokeDashArray(lines[x].GetStrokeDashArray())
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r.MoveTo(lx, ly)
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r.LineTo(lx2, ly)
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r.Stroke()
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ycursor += DefaultMinimumTickVerticalSpacing
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}
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}
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}
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}
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