feat: implement legend type with fixed length line on the left side

fixes #185
This commit is contained in:
Rico 2022-02-05 17:07:04 +01:00
parent c1468e8ae4
commit bbad84f537
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GPG key ID: 91F477359C5B7AD3

118
legend.go
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@ -118,6 +118,124 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
}
}
// LegendLineLeft is a legend with the line drawn left to the legend text.
func LegendLineLeft(c *Chart, userDefaults ...Style) Renderable {
return func(r Renderer, cb Box, chartDefaults Style) {
legendDefaults := Style{
FillColor: drawing.ColorWhite,
FontColor: DefaultTextColor,
FontSize: 8.0,
StrokeColor: DefaultAxisColor,
StrokeWidth: DefaultAxisLineWidth,
}
var legendStyle Style
if len(userDefaults) > 0 {
legendStyle = userDefaults[0].InheritFrom(chartDefaults.InheritFrom(legendDefaults))
} else {
legendStyle = chartDefaults.InheritFrom(legendDefaults)
}
// DEFAULTS
legendPadding := Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
}
lineTextGap := 5
lineLengthMinimum := 25
var labels []string
var lines []Style
for index, s := range c.Series {
if !s.GetStyle().Hidden {
if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
labels = append(labels, s.GetName())
lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))
}
}
}
legend := Box{
Top: cb.Top,
Left: cb.Left,
// bottom and right will be sized by the legend content + relevant padding.
}
legendContent := Box{
Top: legend.Top + legendPadding.Top,
Left: legend.Left + legendPadding.Left,
Right: legend.Left + legendPadding.Left,
Bottom: legend.Top + legendPadding.Top,
}
legendStyle.GetTextOptions().WriteToRenderer(r)
// measure
labelCount := 0
for x := 0; x < len(labels); x++ {
if len(labels[x]) > 0 {
tb := r.MeasureText(labels[x])
if labelCount > 0 {
legendContent.Bottom += DefaultMinimumTickVerticalSpacing
}
legendContent.Bottom += tb.Height()
right := legendContent.Left + tb.Width() + lineTextGap + lineLengthMinimum
legendContent.Right = MaxInt(legendContent.Right, right)
labelCount++
}
}
legend = legend.Grow(legendContent)
legend.Right = legendContent.Right + legendPadding.Right
legend.Bottom = legendContent.Bottom + legendPadding.Bottom
Draw.Box(r, legend, legendStyle)
legendStyle.GetTextOptions().WriteToRenderer(r)
ycursor := legendContent.Top
lx := legendContent.Left
legendCount := 0
var label string
for x := 0; x < len(labels); x++ {
label = labels[x]
if len(label) > 0 {
if legendCount > 0 {
ycursor += DefaultMinimumTickVerticalSpacing
}
// Calculate text dimensions
tb := r.MeasureText(label)
ty := ycursor + tb.Height()
th2 := tb.Height() >> 1
// Calculate line x and y coordinates
ly := ty - th2
// Calculate line ending x coordinate
lx2 := lx + lineLengthMinimum
r.SetStrokeColor(lines[x].GetStrokeColor())
r.SetStrokeWidth(lines[x].GetStrokeWidth())
r.SetStrokeDashArray(lines[x].GetStrokeDashArray())
r.MoveTo(lx, ly)
r.LineTo(lx2, ly)
r.Stroke()
// Calculate Text starting coordinates
textX := lx2 + lineTextGap
r.Text(label, textX, ty)
ycursor += tb.Height()
legendCount++
}
}
}
}
// LegendThin is a legend that doesn't obscure the chart area.
func LegendThin(c *Chart, userDefaults ...Style) Renderable {
return func(r Renderer, cb Box, chartDefaults Style) {