tweaks.

chart.go

@@ -29,32 +29,36 @@ type Chart struct {
 
 // GetCanvasTop gets the top corner pixel.
 func (c Chart) GetCanvasTop() int {
-	return c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
+	return c.Background.Padding.GetTop(DefaultBackgroundPadding.Top)
 }
 
 // GetCanvasLeft gets the left corner pixel.
 func (c Chart) GetCanvasLeft() int {
-	return c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left)
+	return c.Background.Padding.GetLeft(DefaultBackgroundPadding.Left)
 }
 
 // GetCanvasBottom gets the bottom corner pixel.
 func (c Chart) GetCanvasBottom() int {
-	return c.Height - c.Canvas.Padding.GetBottom(DefaultCanvasPadding.Bottom)
+	return c.Height - c.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
 }
 
 // GetCanvasRight gets the right corner pixel.
 func (c Chart) GetCanvasRight() int {
-	return c.Width - c.Canvas.Padding.GetRight(DefaultCanvasPadding.Right)
+	return c.Width - c.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
 }
 
 // GetCanvasWidth returns the width of the canvas.
 func (c Chart) GetCanvasWidth() int {
-	return c.Width - (c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left) + c.Canvas.Padding.GetRight(DefaultCanvasPadding.Right))
+	pl := c.Background.Padding.GetLeft(DefaultBackgroundPadding.Left)
+	pr := c.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
+	return c.Width - (pl + pr)
 }
 
 // GetCanvasHeight returns the height of the canvas.
 func (c Chart) GetCanvasHeight() int {
-	return c.Height - (c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top) + c.Canvas.Padding.GetBottom(DefaultCanvasPadding.Bottom))
+	pt := c.Background.Padding.GetTop(DefaultBackgroundPadding.Top)
+	pb := c.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
+	return c.Height - (pt + pb)
 }
 
 // GetFont returns the text font.
@@ -79,8 +83,8 @@ func (c *Chart) Render(provider RendererProvider, w io.Writer) error {
 	c.drawBackground(r)
 	c.drawCanvas(r)
 	c.drawAxes(r, xrange, yrange)
-	for _, series := range c.Series {
+	for index, series := range c.Series {
-		c.drawSeries(r, series, xrange, yrange)
+		c.drawSeries(r, index, series, xrange, yrange)
 	}
 	c.drawTitle(r)
 	return r.Save(w)
@@ -162,7 +166,7 @@ func (c Chart) drawCanvas(r Renderer) {
 func (c Chart) drawAxes(r Renderer, xrange, yrange Range) {
 	if c.Axes.Show {
 		r.SetStrokeColor(c.Axes.GetStrokeColor(DefaultAxisColor))
-		r.SetLineWidth(c.Axes.GetStrokeWidth(DefaultLineWidth))
+		r.SetLineWidth(c.Axes.GetStrokeWidth(DefaultStrokeWidth))
 		r.MoveTo(c.GetCanvasLeft(), c.GetCanvasBottom())
 		r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
 		r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
@@ -173,46 +177,46 @@ func (c Chart) drawAxes(r Renderer, xrange, yrange Range) {
 }
 
 func (c Chart) drawAxesLabels(r Renderer, xrange, yrange Range) {
-
+	// do x axis
+	// do y axis
 }
 
-func (c Chart) drawSeries(r Renderer, s Series, xrange, yrange Range) {
+func (c Chart) drawSeries(r Renderer, index int, s Series, xrange, yrange Range) {
-	r.SetStrokeColor(s.GetStyle().GetStrokeColor(DefaultLineColor))
+	r.SetStrokeColor(s.GetStyle().GetStrokeColor(GetDefaultSeriesStrokeColor(index)))
-	r.SetLineWidth(s.GetStyle().GetStrokeWidth(DefaultLineWidth))
+	r.SetLineWidth(s.GetStyle().GetStrokeWidth(DefaultStrokeWidth))
 
 	if s.Len() == 0 {
 		return
 	}
 
-	px := c.Canvas.Padding.GetLeft(DefaultCanvasPadding.Left)
+	cx := c.GetCanvasLeft()
-	py := c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
+	cy := c.GetCanvasTop()
-
 	cw := c.GetCanvasWidth()
 
 	v0x, v0y := s.GetValue(0)
 	x0 := cw - xrange.Translate(v0x)
 	y0 := yrange.Translate(v0y)
-	r.MoveTo(x0+px, y0+py)
+	r.MoveTo(x0+cx, y0+cy)
 
 	var vx, vy float64
 	var x, y int
-	for index := 1; index < s.Len(); index++ {
+	for i := 1; i < s.Len(); i++ {
-		vx, vy = s.GetValue(index)
+		vx, vy = s.GetValue(i)
 		x = cw - xrange.Translate(vx)
 		y = yrange.Translate(vy)
-		r.LineTo(x+px, y+py)
+		r.LineTo(x+cx, y+cy)
 	}
 	r.Stroke()
 
-	c.drawFinalValueLabel(r, s, yrange)
+	c.drawFinalValueLabel(r, index, s, yrange)
 }
 
-func (c Chart) drawFinalValueLabel(r Renderer, s Series, yrange Range) {
+func (c Chart) drawFinalValueLabel(r Renderer, index int, s Series, yrange Range) {
 	if c.FinalValueLabel.Show {
 		_, lv := s.GetValue(s.Len() - 1)
 		_, ll := s.GetLabel(s.Len() - 1)
 
-		py := c.Canvas.Padding.GetTop(DefaultCanvasPadding.Top)
+		py := c.GetCanvasTop()
 		ly := yrange.Translate(lv) + py
 
 		r.SetFontSize(c.FinalValueLabel.GetFontSize(DefaultFinalLabelFontSize))
@@ -245,7 +249,7 @@ func (c Chart) drawFinalValueLabel(r Renderer, s Series, yrange Range) {
 
 		//draw the shape...
 		r.SetFillColor(c.FinalValueLabel.GetFillColor(DefaultFinalLabelBackgroundColor))
-		r.SetStrokeColor(c.FinalValueLabel.GetStrokeColor(s.GetStyle().GetStrokeColor(DefaultLineColor)))
+		r.SetStrokeColor(c.FinalValueLabel.GetStrokeColor(s.GetStyle().GetStrokeColor(GetDefaultSeriesStrokeColor(index))))
 		r.SetLineWidth(c.FinalValueLabel.GetStrokeWidth(DefaultAxisLineWidth))
 		r.MoveTo(cx, ly)
 		r.LineTo(ltlx, ltly)

defaults.go

@@ -12,8 +12,8 @@ const (
 	DefaultChartHeight = 400
 	// DefaultChartWidth is the default chart width.
 	DefaultChartWidth = 200
-	// DefaultLineWidth is the default chart line width.
+	// DefaultStrokeWidth is the default chart line/stroke width.
-	DefaultLineWidth = 2.0
+	DefaultStrokeWidth = 1.0
 	// DefaultAxisLineWidth is the line width of the axis lines.
 	DefaultAxisLineWidth = 1.0
 	//DefaultDPI is the default dots per inch for the chart.
@@ -24,26 +24,18 @@ const (
 	DefaultFontSize = 10.0
 	// DefaultTitleFontSize is the default title font size.
 	DefaultTitleFontSize = 18.0
-	// DefaultDateFormat is the default date format.
-	DefaultDateFormat = "2006-01-02"
-)
-
-const (
 	// DefaultFinalLabelDeltaWidth is the width of the left triangle out of the final label.
 	DefaultFinalLabelDeltaWidth = 10
 	// DefaultFinalLabelFontSize is the font size of the final label.
 	DefaultFinalLabelFontSize = 10.0
-)
+	// DefaultDateFormat is the default date format.
-
+	DefaultDateFormat = "2006-01-02"
-var (
-	// DefaultFinalLabelPadding is the padding around the final label.
-	DefaultFinalLabelPadding = Box{Top: 5, Left: 0, Right: 5, Bottom: 5}
 )
 
 var (
 	// DefaultBackgroundColor is the default chart background color.
 	// It is equivalent to css color:white.
-	DefaultBackgroundColor = color.RGBA{R: 239, G: 239, B: 239, A: 255} //color.RGBA{R: 255, G: 255, B: 255, A: 255}
+	DefaultBackgroundColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
 	// DefaultCanvasColor is the default chart canvas color.
 	// It is equivalent to css color:white.
 	DefaultCanvasColor = color.RGBA{R: 255, G: 255, B: 255, A: 255}
@@ -56,9 +48,6 @@ var (
 	// DefaultStrokeColor is the default chart border color.
 	// It is equivalent to #efefef.
 	DefaultStrokeColor = color.RGBA{R: 239, G: 239, B: 239, A: 255}
-	// DefaultLineColor is the default (1st) series line color.
-	// It is equivalent to #0074d9.
-	DefaultLineColor = color.RGBA{R: 0, G: 116, B: 217, A: 255}
 	// DefaultFillColor is the default fill color.
 	// It is equivalent to #0074d9.
 	DefaultFillColor = color.RGBA{R: 0, G: 217, B: 116, A: 255}
@@ -67,8 +56,26 @@ var (
 )
 
 var (
-	// DefaultCanvasPadding is the default canvas padding config.
+	// DefaultSeriesStrokeColors are a couple default series colors.
-	DefaultCanvasPadding = Box{Top: 5, Left: 5, Right: 15, Bottom: 15}
+	DefaultSeriesStrokeColors = []color.RGBA{
+		color.RGBA{R: 0, G: 116, B: 217, A: 255},
+		color.RGBA{R: 0, G: 217, B: 116, A: 255},
+		color.RGBA{R: 217, G: 0, B: 116, A: 255},
+	}
+)
+
+// GetDefaultSeriesStrokeColor returns a color from the default list by index.
+// NOTE: the index will wrap around (using a modulo).g
+func GetDefaultSeriesStrokeColor(index int) color.RGBA {
+	finalIndex := index % len(DefaultSeriesStrokeColors)
+	return DefaultSeriesStrokeColors[finalIndex]
+}
+
+var (
+	// DefaultFinalLabelPadding is the padding around the final label.
+	DefaultFinalLabelPadding = Box{Top: 5, Left: 0, Right: 5, Bottom: 5}
+	// DefaultBackgroundPadding is the default canvas padding config.
+	DefaultBackgroundPadding = Box{Top: 5, Left: 5, Right: 40, Bottom: 40}
 )
 
 var (

style.go

@@ -24,7 +24,7 @@ func (s Style) GetStrokeColor(defaults ...color.RGBA) color.RGBA {
 		if len(defaults) > 0 {
 			return defaults[0]
 		}
-		return DefaultLineColor
+		return DefaultStrokeColor
 	}
 	return s.StrokeColor
 }
@@ -46,7 +46,7 @@ func (s Style) GetStrokeWidth(defaults ...float64) float64 {
 		if len(defaults) > 0 {
 			return defaults[0]
 		}
-		return DefaultLineWidth
+		return DefaultStrokeWidth
 	}
 	return s.StrokeWidth
 }

testserver/main.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"image/color"
 	"log"
 	"time"
 
@@ -34,31 +33,15 @@ func main() {
 				Show:        true,
 				StrokeWidth: 1.0,
 			},
-			YRange: chart.Range{
-				Min: 0.0,
-				Max: 7.0,
-			},
 			FinalValueLabel: chart.Style{
 				Show: true,
 			},
 			Series: []chart.Series{
 				chart.TimeSeries{
 					Name:    "goog",
-					Style: chart.Style{
-						StrokeWidth: 1.0,
-					},
 					XValues: []time.Time{now.AddDate(0, 0, -4), now.AddDate(0, 0, -3), now.AddDate(0, 0, -2), now.AddDate(0, 0, -1)},
 					YValues: []float64{2.5, 5.0, 2.0, 3.0},
 				},
-				chart.TimeSeries{
-					Name: "aapl",
-					Style: chart.Style{
-						StrokeWidth: 1.0,
-						StrokeColor: color.RGBA{R: 0, G: 217, B: 116, A: 255},
-					},
-					XValues: []time.Time{now.AddDate(0, 0, -5), now.AddDate(0, 0, -4), now.AddDate(0, 0, -2), now.AddDate(0, 0, -1)},
-					YValues: []float64{3.0, 2.7, 2.0, 1.1},
-				},
 			},
 		}