102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
package chart
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import (
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"math"
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"sort"
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"github.com/wcharczuk/go-chart/drawing"
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)
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// XAxis represents the horizontal axis.
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type XAxis struct {
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Name string
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Style Style
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ValueFormatter ValueFormatter
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Range Range
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Ticks []Tick
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}
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// GetName returns the name.
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func (xa XAxis) GetName() string {
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return xa.Name
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}
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// GetStyle returns the style.
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func (xa XAxis) GetStyle() Style {
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return xa.Style
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}
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// GetTicks returns the ticks for a series. It coalesces between user provided ticks and
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// generated ticks.
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func (xa XAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
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if len(xa.Ticks) > 0 {
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return xa.Ticks
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}
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return xa.generateTicks(r, ra, vf)
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}
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func (xa XAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
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step := xa.getTickStep(r, ra, vf)
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return xa.generateTicksWithStep(ra, step, vf)
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}
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func (xa XAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
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fontSize := xa.Style.GetFontSize(DefaultFontSize)
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r.SetFontSize(fontSize)
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// take a cut at determining the 'widest' value.
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l0 := vf(ra.Min)
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ln := vf(ra.Max)
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ll := l0
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if len(ln) > len(l0) {
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ll = ln
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}
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llw, _ := r.MeasureText(ll)
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textWidth := drawing.PointsToPixels(r.GetDPI(), float64(llw))
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width := textWidth + DefaultMinimumTickHorizontalSpacing
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count := int(math.Ceil(float64(ra.Domain) / float64(width)))
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return count
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}
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func (xa XAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
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tickCount := xa.getTickCount(r, ra, vf)
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step := ra.Delta() / float64(tickCount)
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return step
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}
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func (xa XAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
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var ticks []Tick
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for cursor := ra.Min; cursor < ra.Max; cursor += step {
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ticks = append(ticks, Tick{
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Value: cursor,
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Label: vf(cursor),
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})
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}
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return ticks
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}
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// Render renders the axis
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func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, ticks []Tick) {
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tickFontSize := xa.Style.GetFontSize(DefaultFontSize)
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tickHeight := drawing.PointsToPixels(r.GetDPI(), tickFontSize)
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ty := canvasBox.Bottom + DefaultXAxisMargin + int(tickHeight)
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r.SetStrokeColor(xa.Style.GetStrokeColor(DefaultAxisColor))
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r.SetStrokeWidth(xa.Style.GetStrokeWidth(DefaultAxisLineWidth))
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r.MoveTo(canvasBox.Left, canvasBox.Bottom)
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r.LineTo(canvasBox.Right, canvasBox.Bottom)
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r.Stroke()
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r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
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r.SetFontSize(tickFontSize)
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sort.Sort(Ticks(ticks))
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for _, t := range ticks {
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v := t.Value
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x := ra.Translate(v)
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tx := canvasBox.Right - x
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r.Text(t.Label, tx, ty)
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}
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}
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