go-chart/xaxis.go
Will Charczuk 29ffceeec0 tweaks.
2016-07-11 00:05:48 -07:00

98 lines
2.3 KiB
Go

package chart
import (
"math"
"sort"
"github.com/wcharczuk/go-chart/drawing"
)
// XAxis represents the horizontal axis.
type XAxis struct {
Name string
Style Style
ValueFormatter ValueFormatter
Range Range
Ticks []Tick
}
// 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)
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
}
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
}
llw, _ := r.MeasureText(ll)
textWidth := drawing.PointsToPixels(r.GetDPI(), float64(llw))
width := textWidth + DefaultMinimumTickHorizontalSpacing
count := int(math.Ceil(float64(ra.Domain) / float64(width)))
return count
}
// Render renders the axis
func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, ticks []Tick) {
tickFontSize := xa.Style.GetFontSize(DefaultFontSize)
r.SetStrokeColor(xa.Style.GetStrokeColor(DefaultAxisColor))
r.SetStrokeWidth(xa.Style.GetStrokeWidth(DefaultAxisLineWidth))
r.MoveTo(canvasBox.Left, canvasBox.Bottom)
r.LineTo(canvasBox.Right, canvasBox.Bottom)
r.Stroke()
r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
r.SetFontSize(tickFontSize)
sort.Sort(Ticks(ticks))
var textHeight int
for _, t := range ticks {
_, th := r.MeasureText(t.Label)
if th > textHeight {
textHeight = th
}
}
ty := canvasBox.Bottom + DefaultXAxisMargin + int(textHeight)
for _, t := range ticks {
v := t.Value
x := ra.Translate(v)
tx := canvasBox.Right - x
r.Text(t.Label, tx, ty)
}
}