Merge branch 'master' of github.com:wcharczuk/go-chart

README.md

@@ -91,6 +91,13 @@ graph := chart.Chart{
 graph.Render(chart.PNG, buffer)
 ```
 
+# 2 Y-Axis Charts 
+
+ ![](https://raw.githubusercontent.com/wcharczuk/go-chart/master/images/two_axis.png)
+
+It is also possible to draw series against 2 separate y-axis with their own ranges (usually good for comparison charts).
+In order to map the series to an alternate axis make sure to set the `YAxis` property of the series to `YAxisSecondary`.
+
 # Design Philosophy
 
 I wanted to make a charting library that used only native golang, that could be stood up on a server (i.e. it had built in fonts).

style.go

@@ -149,3 +149,35 @@ func (s Style) SVG(dpi float64) string {
 	}
 	return strings.Join([]string{strokeWidthText, strokeText, fillText, fontSizeText}, ";")
 }
+
+// SVGStroke returns the stroke components.
+func (s Style) SVGStroke() Style {
+	return Style{
+		StrokeColor: s.StrokeColor,
+		StrokeWidth: s.StrokeWidth,
+	}
+}
+
+// SVGFill returns the fill components.
+func (s Style) SVGFill() Style {
+	return Style{
+		FillColor: s.FillColor,
+	}
+}
+
+// SVGFillAndStroke returns the fill and stroke components.
+func (s Style) SVGFillAndStroke() Style {
+	return Style{
+		FillColor:   s.FillColor,
+		StrokeColor: s.StrokeColor,
+		StrokeWidth: s.StrokeWidth,
+	}
+}
+
+// SVGText returns just the text components of the style.
+func (s Style) SVGText() Style {
+	return Style{
+		FontColor: s.FontColor,
+		FontSize:  s.FontSize,
+	}
+}

testserver/main.go

@@ -35,12 +35,12 @@ func chartHandler(rc *web.RequestContext) web.ControllerResult {
 		Height: 400,
 		XAxis: chart.XAxis{
 			Style: chart.Style{
-				Show: false,
+				Show: true,
 			},
 		},
 		YAxis: chart.YAxis{
 			Style: chart.Style{
-				Show: false,
+				Show: true,
 			},
 			Range: chart.Range{
 				Min: 0.0,
@@ -49,7 +49,7 @@ func chartHandler(rc *web.RequestContext) web.ControllerResult {
 		},
 		YAxisSecondary: chart.YAxis{
 			Style: chart.Style{
-				Show: false,
+				Show: true,
 			},
 			Range: chart.Range{
 				Min: 0.8,

vector_renderer.go

@@ -77,28 +77,22 @@ func (vr *vectorRenderer) Close() {
 
 // Stroke draws the path with no fill.
 func (vr *vectorRenderer) Stroke() {
-	vr.s.FillColor = drawing.ColorTransparent
-	vr.s.FontColor = drawing.ColorTransparent
-	vr.drawPath()
+	vr.drawPath(vr.s.SVGStroke())
 }
 
 // Fill draws the path with no stroke.
 func (vr *vectorRenderer) Fill() {
-	vr.s.StrokeColor = drawing.ColorTransparent
-	vr.s.StrokeWidth = 0
-	vr.s.FontColor = drawing.ColorTransparent
-	vr.drawPath()
+	vr.drawPath(vr.s.SVGFill())
 }
 
 // FillStroke draws the path with both fill and stroke.
 func (vr *vectorRenderer) FillStroke() {
-	vr.s.FontColor = drawing.ColorTransparent
-	vr.drawPath()
+	vr.drawPath(vr.s.SVGFillAndStroke())
 }
 
-func (vr *vectorRenderer) drawPath() {
-	vr.c.Path(strings.Join(vr.p, "\n"), vr.s.SVG(vr.dpi))
-	vr.p = []string{}
+func (vr *vectorRenderer) drawPath(s Style) {
+	vr.c.Path(strings.Join(vr.p, "\n"), s.SVG(vr.dpi))
+	vr.p = []string{} // clear the path
 }
 
 // Circle implements the interface method.
@@ -134,10 +128,8 @@ func (vr *vectorRenderer) svgFontFace() string {
 
 // Text draws a text blob.
 func (vr *vectorRenderer) Text(body string, x, y int) {
-	vr.s.FillColor = drawing.ColorTransparent
-	vr.s.StrokeColor = drawing.ColorTransparent
-	vr.s.StrokeWidth = 0
-	vr.c.Text(x, y, body, vr.s.SVG(vr.dpi)+";"+vr.svgFontFace())
+	s := vr.s.SVGText()
+	vr.c.Text(x, y, body, s.SVG(vr.dpi)+";"+vr.svgFontFace())
 }
 
 // MeasureText uses the truetype font drawer to measure the width of text.

yaxis.go

@@ -69,7 +69,9 @@ func (ya YAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter)
 func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, axisType YAxisType, ticks []Tick) {
 	r.SetStrokeColor(ya.Style.GetStrokeColor(DefaultAxisColor))
 	r.SetStrokeWidth(ya.Style.GetStrokeWidth(DefaultAxisLineWidth))
-	r.SetFontColor(ya.Style.GetFontColor(DefaultAxisColor))
+
+	fontColor := ya.Style.GetFontColor(DefaultAxisColor)
+	r.SetFontColor(fontColor)
 	fontSize := ya.Style.GetFontSize(DefaultFontSize)
 	r.SetFontSize(fontSize)