go-chart/yaxis.go

131 lines
2.9 KiB
Go

package chart
import (
"math"
"sort"
)
// YAxis is a veritcal rule of the range.
// There can be (2) y-axes; a primary and secondary.
type YAxis struct {
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)
return ya.generateTicksWithStep(ra, step, vf)
}
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
}
func (ya YAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
tickCount := ya.getTickCount(r, ra, vf)
return ra.Delta() / float64(tickCount)
}
func (ya YAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
var ticks []Tick
for cursor := ra.Min; cursor < ra.Max; cursor += step {
ticks = append(ticks, Tick{
Value: cursor,
Label: vf(cursor),
})
if len(ticks) == 20 {
return ticks
}
}
return ticks
}
// Render renders the axis.
func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, axisType YAxisType, ticks []Tick) {
r.SetStrokeColor(ya.Style.GetStrokeColor(DefaultAxisColor))
r.SetStrokeWidth(ya.Style.GetStrokeWidth(DefaultAxisLineWidth))
fontColor := ya.Style.GetFontColor(DefaultAxisColor)
r.SetFontColor(fontColor)
fontSize := ya.Style.GetFontSize(DefaultFontSize)
r.SetFontSize(fontSize)
sort.Sort(Ticks(ticks))
var lx int
var tx int
if axisType == YAxisPrimary {
lx = canvasBox.Right
tx = canvasBox.Right + DefaultYAxisMargin
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()
}
} else if axisType == YAxisSecondary {
lx = canvasBox.Left
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
ptw, _ := r.MeasureText(t.Label)
tw := ptw
th := int(fontSize)
tx = lx - (int(tw) + (DefaultYAxisMargin >> 1))
ty := ly + th>>1
r.Text(t.Label, tx, ty)
r.MoveTo(lx, ly)
r.LineTo(lx-DefaultVerticalTickWidth, ly)
r.Stroke()
}
}
}