initial commit.

raster_renderer.go

@@ -0,0 +1,131 @@
+package chart
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"io"
+
+	"golang.org/x/image/font"
+
+	"github.com/golang/freetype/truetype"
+	drawing "github.com/llgcode/draw2d/draw2dimg"
+)
+
+// PNG returns a new png/raster renderer.
+func PNG(width, height int) Renderer {
+	i := image.NewRGBA(image.Rect(0, 0, width, height))
+	return &rasterRenderer{
+		i:  i,
+		gc: drawing.NewGraphicContext(i),
+	}
+}
+
+// RasterRenderer renders chart commands to a bitmap.
+type rasterRenderer struct {
+	i  *image.RGBA
+	gc *drawing.GraphicContext
+	fc *font.Drawer
+
+	font      *truetype.Font
+	fontColor color.RGBA
+	fontSize  float64
+}
+
+// SetStrokeColor implements the interface method.
+func (rr *rasterRenderer) SetStrokeColor(c color.RGBA) {
+	rr.gc.SetStrokeColor(c)
+}
+
+// SetFillColor implements the interface method.
+func (rr *rasterRenderer) SetFillColor(c color.RGBA) {
+	rr.gc.SetFillColor(c)
+}
+
+// SetLineWidth implements the interface method.
+func (rr *rasterRenderer) SetLineWidth(width int) {
+	rr.gc.SetLineWidth(float64(width))
+}
+
+// MoveTo implements the interface method.
+func (rr *rasterRenderer) MoveTo(x, y int) {
+	rr.gc.MoveTo(float64(x), float64(y))
+}
+
+// LineTo implements the interface method.
+func (rr *rasterRenderer) LineTo(x, y int) {
+	rr.gc.LineTo(float64(x), float64(y))
+}
+
+// Close implements the interface method.
+func (rr *rasterRenderer) Close() {
+	rr.gc.Close()
+}
+
+// Stroke implements the interface method.
+func (rr *rasterRenderer) Stroke() {
+	rr.gc.Stroke()
+}
+
+// FillStroke implements the interface method.
+func (rr *rasterRenderer) FillStroke() {
+	rr.gc.FillStroke()
+}
+
+// Circle implements the interface method.
+func (rr *rasterRenderer) Circle(radius float64, x, y int) {
+	xf := float64(x)
+	yf := float64(y)
+	rr.gc.MoveTo(xf-radius, yf)              //9
+	rr.gc.QuadCurveTo(xf, yf, xf, yf-radius) //12
+	rr.gc.QuadCurveTo(xf, yf, xf+radius, yf) //3
+	rr.gc.QuadCurveTo(xf, yf, xf, yf+radius) //6
+	rr.gc.QuadCurveTo(xf, yf, xf-radius, yf) //9
+	rr.gc.Close()
+	rr.gc.FillStroke()
+}
+
+// SetFont implements the interface method.
+func (rr *rasterRenderer) SetFont(f *truetype.Font) {
+	rr.font = f
+	rr.gc.SetFont(f)
+}
+
+// SetFontSize implements the interface method.
+func (rr *rasterRenderer) SetFontSize(size float64) {
+	rr.fontSize = size
+	rr.gc.SetFontSize(size)
+}
+
+// SetFontColor implements the interface method.
+func (rr *rasterRenderer) SetFontColor(c color.RGBA) {
+	rr.fontColor = c
+	rr.gc.SetStrokeColor(c)
+}
+
+// Text implements the interface method.
+func (rr *rasterRenderer) Text(body string, x, y int) {
+	rr.gc.CreateStringPath(body, float64(x), float64(y))
+}
+
+// MeasureText implements the interface method.
+func (rr *rasterRenderer) MeasureText(body string) int {
+	if rr.fc == nil && rr.font != nil {
+		rr.fc = &font.Drawer{
+			Face: truetype.NewFace(rr.font, &truetype.Options{
+				DPI:  DefaultDPI,
+				Size: rr.fontSize,
+			}),
+		}
+	}
+	if rr.fc != nil {
+		dimensions := rr.fc.MeasureString(body)
+		return dimensions.Floor()
+	}
+	return 0
+}
+
+// Save implements the interface method.
+func (rr *rasterRenderer) Save(w io.Writer) error {
+	return png.Encode(w, rr.i)
+}