initial commit.

chart.go

@@ -0,0 +1,210 @@
+package chart
+
+import (
+	"image/color"
+	"io"
+
+	"github.com/golang/freetype/truetype"
+)
+
+// Chart is what we're drawing.
+/*
+	The chart box model is as follows:
+	0,0									width,0
+			cl,ct					cr,ct
+			cl,cb					cr,cb
+	0, height							width,height
+*/
+type Chart struct {
+	Title         string
+	TitleFontSize float64
+
+	Width   int
+	Height  int
+	Padding int
+
+	BackgroundColor       color.RGBA
+	CanvasBackgroundColor color.RGBA
+
+	AxisShow     bool
+	AxisStyle    Style
+	AxisFontSize float64
+
+	CanvasBorderShow  bool
+	CanvasBorderStyle Style
+
+	FinalValueLabelShow bool
+	FinalValueStyle     Style
+
+	FontColor color.RGBA
+	Font      *truetype.Font
+
+	Series []Series
+}
+
+// GetTitleFontSize calculates or returns the title font size.
+func (c Chart) GetTitleFontSize() float64 {
+	if c.TitleFontSize != 0 {
+		if c.TitleFontSize > DefaultMinimumFontSize {
+			return c.TitleFontSize
+		}
+	}
+	fontSize := float64(c.Height >> 3)
+	if fontSize > DefaultMinimumFontSize {
+		return fontSize
+	}
+	return DefaultMinimumFontSize
+}
+
+// GetCanvasTop gets the top corner pixel.
+func (c Chart) GetCanvasTop() int {
+	return c.Padding
+}
+
+// GetCanvasLeft gets the left corner pixel.
+func (c Chart) GetCanvasLeft() int {
+	return c.Padding
+}
+
+// GetCanvasBottom gets the bottom corner pixel.
+func (c Chart) GetCanvasBottom() int {
+	return c.Height - c.Padding
+}
+
+// GetCanvasRight gets the right corner pixel.
+func (c Chart) GetCanvasRight() int {
+	return c.Width - c.Padding
+}
+
+// GetCanvasWidth returns the width of the canvas.
+func (c Chart) GetCanvasWidth() int {
+	if c.Padding > 0 {
+		return c.Width - (c.Padding << 1)
+	}
+	return c.Width
+}
+
+// GetCanvasHeight returns the height of the canvas.
+func (c Chart) GetCanvasHeight() int {
+	if c.Padding > 0 {
+		return c.Height - (c.Padding << 1)
+	}
+	return c.Height
+}
+
+// GetBackgroundColor returns the chart background color.
+func (c Chart) GetBackgroundColor() color.RGBA {
+	if ColorIsZero(c.BackgroundColor) {
+		c.BackgroundColor = DefaultBackgroundColor
+	}
+	return c.BackgroundColor
+}
+
+// GetCanvasBackgroundColor returns the canvas background color.
+func (c Chart) GetCanvasBackgroundColor() color.RGBA {
+	if ColorIsZero(c.CanvasBackgroundColor) {
+		c.CanvasBackgroundColor = DefaultCanvasColor
+	}
+	return c.CanvasBackgroundColor
+}
+
+// GetTextFont returns the text font.
+func (c Chart) GetTextFont() (*truetype.Font, error) {
+	if c.Font != nil {
+		return c.Font, nil
+	}
+	return GetDefaultFont()
+}
+
+// GetTextFontColor returns the text font color.
+func (c Chart) GetTextFontColor() color.RGBA {
+	if ColorIsZero(c.FontColor) {
+		c.FontColor = DefaultTextColor
+	}
+	return c.FontColor
+}
+
+// Render renders the chart with the given renderer to the given io.Writer.
+func (c Chart) Render(provider RendererProvider, w io.Writer) error {
+	r := provider(c.Width, c.Height)
+	c.drawBackground(r)
+	c.drawCanvas(r)
+	c.drawAxes(r)
+
+	for _, series := range c.Series {
+		c.drawSeries(r, series)
+	}
+	err := c.drawTitle(r)
+	if err != nil {
+		return err
+	}
+	return r.Save(w)
+}
+
+func (c Chart) drawBackground(r Renderer) {
+	r.SetStrokeColor(c.GetBackgroundColor())
+	r.SetFillColor(c.GetBackgroundColor())
+	r.SetLineWidth(0)
+	r.MoveTo(0, 0)
+	r.LineTo(c.Width, 0)
+	r.LineTo(c.Width, c.Height)
+	r.LineTo(0, c.Height)
+	r.LineTo(0, 0)
+	r.FillStroke()
+	r.Close()
+}
+
+func (c Chart) drawCanvas(r Renderer) {
+	if !c.CanvasBorderStyle.IsZero() {
+		r.SetStrokeColor(c.CanvasBorderStyle.GetStrokeColor())
+		r.SetLineWidth(c.CanvasBorderStyle.GetStrokeWidth())
+	} else {
+		r.SetStrokeColor(c.GetCanvasBackgroundColor())
+		r.SetLineWidth(0)
+	}
+	r.SetFillColor(c.GetCanvasBackgroundColor())
+	r.MoveTo(c.GetCanvasLeft(), c.GetCanvasTop())
+	r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
+	r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
+	r.LineTo(c.GetCanvasLeft(), c.GetCanvasBottom())
+	r.LineTo(c.GetCanvasLeft(), c.GetCanvasTop())
+	r.FillStroke()
+	r.Close()
+}
+
+func (c Chart) drawAxes(r Renderer) {
+	if c.AxisShow {
+		if !c.AxisStyle.IsZero() {
+			r.SetStrokeColor(c.AxisStyle.GetStrokeColor())
+			r.SetLineWidth(c.AxisStyle.GetStrokeWidth())
+		} else {
+			r.SetStrokeColor(DefaultAxisColor)
+			r.SetLineWidth(DefaultLineWidth)
+		}
+		r.MoveTo(c.GetCanvasLeft(), c.GetCanvasBottom())
+		r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
+		r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
+		r.Stroke()
+	}
+}
+
+func (c Chart) drawSeries(r Renderer, s Series) {
+
+}
+
+func (c Chart) drawTitle(r Renderer) error {
+	if len(c.Title) > 0 {
+		font, err := c.GetTextFont()
+		if err != nil {
+			return err
+		}
+		r.SetFontColor(c.GetTextFontColor())
+		r.SetFont(font)
+		r.SetFontSize(c.GetTitleFontSize())
+		textWidth := r.MeasureText(c.Title)
+		titleX := (c.Width >> 1) - (textWidth >> 1)
+		titleY := c.GetCanvasTop() + int(c.GetTitleFontSize()/2.0)
+		r.Text(c.Title, titleX, titleY)
+	}
+	return nil
+}