go-chart/xaxis.go

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package chart
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import (
"math"
"sort"
)
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// XAxis represents the horizontal axis.
type XAxis struct {
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Name string
Style Style
ValueFormatter ValueFormatter
Range Range
Ticks []Tick
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GridLines []GridLine
GridMajorStyle Style
GridMinorStyle Style
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}
// GetName returns the name.
func (xa XAxis) GetName() string {
return xa.Name
}
// GetStyle returns the style.
func (xa XAxis) GetStyle() Style {
return xa.Style
}
// GetTicks returns the ticks for a series. It coalesces between user provided ticks and
// generated ticks.
func (xa XAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
if len(xa.Ticks) > 0 {
return xa.Ticks
}
return xa.generateTicks(r, ra, vf)
}
func (xa XAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
step := xa.getTickStep(r, ra, vf)
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return GenerateTicksWithStep(ra, step, vf)
}
func (xa XAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
tickCount := xa.getTickCount(r, ra, vf)
step := ra.Delta() / float64(tickCount)
return step
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}
func (xa XAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
fontSize := xa.Style.GetFontSize(DefaultFontSize)
r.SetFontSize(fontSize)
// take a cut at determining the 'widest' value.
l0 := vf(ra.Min)
ln := vf(ra.Max)
ll := l0
if len(ln) > len(l0) {
ll = ln
}
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llb := r.MeasureText(ll)
textWidth := llb.Width()
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width := textWidth + DefaultMinimumTickHorizontalSpacing
count := int(math.Ceil(float64(ra.Domain) / float64(width)))
return count
}
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// GetGridLines returns the gridlines for the axis.
func (xa XAxis) GetGridLines(ticks []Tick) []GridLine {
if len(xa.GridLines) > 0 {
return xa.GridLines
}
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return GenerateGridLines(ticks, true)
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}
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// Measure returns the bounds of the axis.
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func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) Box {
r.SetStrokeColor(xa.Style.GetStrokeColor(defaults.StrokeColor))
r.SetStrokeWidth(xa.Style.GetStrokeWidth(defaults.StrokeWidth))
r.SetFont(xa.Style.GetFont(defaults.GetFont()))
r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
r.SetFontSize(xa.Style.GetFontSize(defaults.GetFontSize()))
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sort.Sort(Ticks(ticks))
var left, right, top, bottom = math.MaxInt32, 0, math.MaxInt32, 0
for _, t := range ticks {
v := t.Value
lx := ra.Translate(v)
tb := r.MeasureText(t.Label)
tx := canvasBox.Left + lx
ty := canvasBox.Bottom + DefaultXAxisMargin + tb.Height()
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top = MinInt(top, canvasBox.Bottom)
left = MinInt(left, tx-(tb.Width()>>1))
right = MaxInt(right, tx+(tb.Width()>>1))
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bottom = MaxInt(bottom, ty)
}
return Box{
Top: top,
Left: left,
Right: right,
Bottom: bottom,
}
}
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// Render renders the axis
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func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) {
r.SetStrokeColor(xa.Style.GetStrokeColor(defaults.StrokeColor))
r.SetStrokeWidth(xa.Style.GetStrokeWidth(defaults.StrokeWidth))
r.SetFont(xa.Style.GetFont(defaults.GetFont()))
r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
r.SetFontSize(xa.Style.GetFontSize(defaults.GetFontSize()))
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r.MoveTo(canvasBox.Left, canvasBox.Bottom)
r.LineTo(canvasBox.Right, canvasBox.Bottom)
r.Stroke()
sort.Sort(Ticks(ticks))
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for _, t := range ticks {
v := t.Value
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lx := ra.Translate(v)
tb := r.MeasureText(t.Label)
tx := canvasBox.Left + lx
ty := canvasBox.Bottom + DefaultXAxisMargin + tb.Height()
r.Text(t.Label, tx-tb.Width()>>1, ty)
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r.MoveTo(tx, canvasBox.Bottom)
r.LineTo(tx, canvasBox.Bottom+DefaultVerticalTickHeight)
r.Stroke()
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}
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if xa.GridMajorStyle.Show || xa.GridMinorStyle.Show {
for _, gl := range xa.GetGridLines(ticks) {
if (gl.IsMinor && xa.GridMinorStyle.Show) ||
(!gl.IsMinor && xa.GridMajorStyle.Show) {
gl.Render(r, canvasBox, ra)
}
}
}
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}