mostly works.

yaxis.go

@@ -1,28 +1,102 @@
 package chart
 
+import (
+	"math"
+	"sort"
+)
+
 // YAxis is a veritcal rule of the range.
 // There can be (2) y-axes; a primary and secondary.
 type YAxis struct {
-	axis
+	Name           string
+	Style          Style
+	ValueFormatter ValueFormatter
+	Range          Range
+	Ticks          []Tick
+}
+
+// GetName returns the name.
+func (ya YAxis) GetName() string {
+	return ya.Name
+}
+
+// GetStyle returns the style.
+func (ya YAxis) GetStyle() Style {
+	return ya.Style
+}
+
+// GetTicks returns the ticks for a series. It coalesces between user provided ticks and
+// generated ticks.
+func (ya YAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
+	if len(ya.Ticks) > 0 {
+		return ya.Ticks
+	}
+	return ya.generateTicks(r, ra, vf)
+}
+
+func (ya YAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
+	step := ya.getTickStep(r, ra, vf)
+	return ya.generateTicksWithStep(ra, step, vf)
+}
+
+func (ya YAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
+	textHeight := int(ya.Style.GetFontSize(DefaultFontSize))
+	height := textHeight + DefaultMinimumTickVerticalSpacing
+	count := int(math.Ceil(float64(ra.Domain) / float64(height)))
+	return count
+}
+
+func (ya YAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
+	tickCount := ya.getTickCount(r, ra, vf)
+	return ra.Delta() / float64(tickCount)
+}
+
+func (ya YAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
+	var ticks []Tick
+	for cursor := ra.Min; cursor < ra.Max; cursor += step {
+		ticks = append(ticks, Tick{
+			Value: cursor,
+			Label: vf(cursor),
+		})
+	}
+	return ticks
 }
 
 // Render renders the axis.
-func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, axisType YAxisType) {
+func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, axisType YAxisType, ticks []Tick) {
+	var lx int
 	var tx int
 	if axisType == YAxisPrimary {
+		lx = canvasBox.Right
 		tx = canvasBox.Right + DefaultYAxisMargin
 	} else if axisType == YAxisSecondary {
+		lx = canvasBox.Left
 		tx = canvasBox.Left - DefaultYAxisMargin
 	}
 
-	r.SetFontColor(ya.Style.GetFontColor(DefaultAxisColor))
-	r.SetFontSize(ya.Style.GetFontSize(DefaultFontSize))
+	r.SetStrokeColor(ya.Style.GetStrokeColor(DefaultAxisColor))
+	r.SetStrokeWidth(ya.Style.GetStrokeWidth(DefaultAxisLineWidth))
 
-	ticks := ya.getTicks(ra)
+	r.MoveTo(lx, canvasBox.Bottom)
+	r.LineTo(lx, canvasBox.Top)
+	r.Stroke()
+
+	r.SetFontColor(ya.Style.GetFontColor(DefaultAxisColor))
+	fontSize := ya.Style.GetFontSize(DefaultFontSize)
+	r.SetFontSize(fontSize)
+
+	sort.Sort(Ticks(ticks))
 	for _, t := range ticks {
 		v := t.Value
-		y := ra.Translate(v)
-		ty := int(y)
+		ly := ra.Translate(v) + canvasBox.Top
+
+		th := int(fontSize) >> 1
+		ty := ly + th
+
 		r.Text(t.Label, tx, ty)
+
+		r.MoveTo(lx, ly)
+		r.LineTo(lx+DefaultVerticalTickWidth, ly)
+		r.Stroke()
 	}
 }