81 lines
2 KiB
Go
81 lines
2 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(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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// GenerateContinuousTicksWithStep generates a set of ticks.
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func GenerateContinuousTicksWithStep(ra Range, step float64, vf ValueFormatter, includeMax bool) []Tick {
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var ticks []Tick
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min, max := ra.GetMin(), ra.GetMax()
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for cursor := min; cursor <= 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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// this guard is in place in case step is super, super small.
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if len(ticks) > DefaultTickCountSanityCheck {
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return ticks
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}
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}
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if includeMax {
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ticks = append(ticks, Tick{
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Value: ra.GetMax(),
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Label: vf(ra.GetMax()),
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})
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}
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return ticks
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}
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// CalculateContinuousTickStep calculates the continous range interval between ticks.
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func CalculateContinuousTickStep(r Renderer, ra Range, isVertical bool, style Style, vf ValueFormatter) float64 {
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r.SetFont(style.GetFont())
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r.SetFontSize(style.GetFontSize())
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if isVertical {
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label := vf(ra.GetMin())
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tb := r.MeasureText(label)
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count := int(math.Ceil(float64(ra.GetDomain()) / float64(tb.Height()+DefaultMinimumTickVerticalSpacing)))
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return ra.GetDelta() / float64(count)
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}
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// take a cut at determining the 'widest' value.
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l0 := vf(ra.GetMin())
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ln := vf(ra.GetMax())
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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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llb := r.MeasureText(ll)
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textWidth := llb.Width()
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width := textWidth + DefaultMinimumTickHorizontalSpacing
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count := int(math.Ceil(float64(ra.GetDomain()) / float64(width)))
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return ra.GetDelta() / float64(count)
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}
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