???

xaxis.go

@@ -3,8 +3,6 @@ package chart
 import (
 	"math"
 	"sort"
-
-	"github.com/wcharczuk/go-chart/drawing"
 )
 
 // XAxis represents the horizontal axis.
@@ -57,13 +55,46 @@ func (xa XAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
 	if len(ln) > len(l0) {
 		ll = ln
 	}
-	llw, _ := r.MeasureText(ll)
-	textWidth := drawing.PointsToPixels(r.GetDPI(), float64(llw))
+	llb := r.MeasureText(ll)
+	textWidth := llb.Width
 	width := textWidth + DefaultMinimumTickHorizontalSpacing
 	count := int(math.Ceil(float64(ra.Domain) / float64(width)))
 	return count
 }
 
+// Measure returns the bounds of the axis.
+func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, ticks []Tick) Box {
+	defaultFont, _ := GetDefaultFont()
+	r.SetFont(xa.Style.GetFont(defaultFont))
+	r.SetFontSize(xa.Style.GetFontSize(DefaultFontSize))
+
+	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
+
+		top = MinInt(top, canvasBox.Bottom)
+		left = MinInt(left, tx-(tb.Width>>1))
+		right = MaxInt(right, tx+(tb.Width>>1))
+		bottom = MaxInt(bottom, ty)
+	}
+
+	return Box{
+		Top:    top,
+		Left:   left,
+		Right:  right,
+		Bottom: bottom,
+		Width:  right - left,
+		Height: bottom - top,
+	}
+}
+
 // Render renders the axis
 func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, ticks []Tick) {
 	tickFontSize := xa.Style.GetFontSize(DefaultFontSize)
@@ -80,18 +111,16 @@ func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, ticks []Tick) {
 
 	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)
+		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)
+
+		r.MoveTo(tx, canvasBox.Bottom)
+		r.LineTo(tx, canvasBox.Bottom+DefaultVerticalTickHeight)
+		r.Stroke()
 	}
 }