go-chart/yaxis.go

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package chart
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import (
"math"
"sort"
)
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// YAxis is a veritcal rule of the range.
// There can be (2) y-axes; a primary and secondary.
type YAxis struct {
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Name string
Style Style
ValueFormatter ValueFormatter
Range Range
Ticks []Tick
}
// GetName returns the name.
func (ya YAxis) GetName() string {
return ya.Name
}
// GetStyle returns the style.
func (ya YAxis) GetStyle() Style {
return ya.Style
}
// GetTicks returns the ticks for a series. It coalesces between user provided ticks and
// generated ticks.
func (ya YAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
if len(ya.Ticks) > 0 {
return ya.Ticks
}
return ya.generateTicks(r, ra, vf)
}
func (ya YAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
step := ya.getTickStep(r, ra, vf)
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return GenerateTicksWithStep(ra, step, vf)
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}
func (ya YAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
tickCount := ya.getTickCount(r, ra, vf)
return ra.Delta() / float64(tickCount)
}
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func (ya YAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
textHeight := int(ya.Style.GetFontSize(DefaultFontSize))
height := textHeight + DefaultMinimumTickVerticalSpacing
count := int(math.Ceil(float64(ra.Domain) / float64(height)))
return count
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}
// Render renders the axis.
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func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, axisType YAxisType, ticks []Tick) {
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r.SetStrokeColor(ya.Style.GetStrokeColor(DefaultAxisColor))
r.SetStrokeWidth(ya.Style.GetStrokeWidth(DefaultAxisLineWidth))
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fontColor := ya.Style.GetFontColor(DefaultAxisColor)
r.SetFontColor(fontColor)
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fontSize := ya.Style.GetFontSize(DefaultFontSize)
r.SetFontSize(fontSize)
sort.Sort(Ticks(ticks))
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var lx int
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var tx int
if axisType == YAxisPrimary {
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lx = canvasBox.Right
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tx = canvasBox.Right + DefaultYAxisMargin
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r.MoveTo(lx, canvasBox.Bottom)
r.LineTo(lx, canvasBox.Top)
r.Stroke()
for _, t := range ticks {
v := t.Value
ly := ra.Translate(v) + canvasBox.Top
th := int(fontSize) >> 1
ty := ly + th
r.Text(t.Label, tx, ty)
r.MoveTo(lx, ly)
r.LineTo(lx+DefaultVerticalTickWidth, ly)
r.Stroke()
}
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} else if axisType == YAxisSecondary {
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lx = canvasBox.Left
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r.MoveTo(lx, canvasBox.Bottom)
r.LineTo(lx, canvasBox.Top)
r.Stroke()
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for _, t := range ticks {
v := t.Value
ly := ra.Translate(v) + canvasBox.Top
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ptw, _ := r.MeasureText(t.Label)
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tw := ptw
th := int(fontSize)
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tx = lx - (int(tw) + (DefaultYAxisMargin >> 1))
ty := ly + th>>1
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r.Text(t.Label, tx, ty)
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r.MoveTo(lx, ly)
r.LineTo(lx-DefaultVerticalTickWidth, ly)
r.Stroke()
}
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}
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}