83 lines
1.9 KiB
Go
83 lines
1.9 KiB
Go
package chart
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import "math"
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// TicksProvider is a type that provides ticks.
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type TicksProvider interface {
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GetTicks(r Renderer, defaults Style, vf ValueFormatter) []Tick
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}
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// Tick represents a label on an axis.
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type Tick struct {
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Value float64
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Label string
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}
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// Ticks is an array of ticks.
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type Ticks []Tick
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// Len returns the length of the ticks set.
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func (t Ticks) Len() int {
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return len(t)
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}
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// Swap swaps two elements.
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func (t Ticks) Swap(i, j int) {
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t[i], t[j] = t[j], t[i]
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}
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// Less returns if i's value is less than j's value.
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func (t Ticks) Less(i, j int) bool {
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return t[i].Value < t[j].Value
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}
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// GenerateContinuousTicks generates a set of ticks.
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func GenerateContinuousTicks(r Renderer, ra Range, isVertical bool, style Style, vf ValueFormatter) []Tick {
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if vf == nil {
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panic("vf is nil; did you remember to set a default value formatter?")
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}
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var ticks []Tick
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min, max := ra.GetMin(), ra.GetMax()
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ticks = append(ticks, Tick{
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Value: min,
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Label: vf(min),
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})
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minLabel := vf(min)
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style.GetTextOptions().WriteToRenderer(r)
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labelBox := r.MeasureText(minLabel)
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var tickSize float64
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if isVertical {
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tickSize = float64(labelBox.Height() + DefaultMinimumTickVerticalSpacing)
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} else {
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tickSize = float64(labelBox.Width() + DefaultMinimumTickHorizontalSpacing)
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}
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domain := float64(ra.GetDomain())
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domainRemainder := domain - (tickSize * 2)
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intermediateTickCount := int(math.Floor(float64(domainRemainder) / float64(tickSize)))
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rangeDelta := math.Abs(max - min)
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tickStep := rangeDelta / float64(intermediateTickCount)
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roundTo := Math.GetRoundToForDelta(rangeDelta) / 10
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intermediateTickCount = Math.MinInt(intermediateTickCount, 1<<10)
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for x := 1; x < intermediateTickCount; x++ {
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tickValue := min + Math.RoundUp(tickStep*float64(x), roundTo)
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ticks = append(ticks, Tick{
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Value: tickValue,
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Label: vf(tickValue),
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})
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}
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ticks = append(ticks, Tick{
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Value: max,
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Label: vf(max),
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})
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return ticks
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}
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