go-chart/raster_renderer.go

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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) {
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println("SetStrokeColor")
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rr.gc.SetStrokeColor(c)
}
// SetFillColor implements the interface method.
func (rr *rasterRenderer) SetFillColor(c color.RGBA) {
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println("SetFillColor")
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rr.gc.SetFillColor(c)
}
// SetLineWidth implements the interface method.
func (rr *rasterRenderer) SetLineWidth(width int) {
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println("SetLineWidth", width)
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rr.gc.SetLineWidth(float64(width))
}
// MoveTo implements the interface method.
func (rr *rasterRenderer) MoveTo(x, y int) {
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println("MoveTo", x, y)
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rr.gc.MoveTo(float64(x), float64(y))
}
// LineTo implements the interface method.
func (rr *rasterRenderer) LineTo(x, y int) {
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println("LineTo", x, y)
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rr.gc.LineTo(float64(x), float64(y))
}
// Close implements the interface method.
func (rr *rasterRenderer) Close() {
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println("Close")
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rr.gc.Close()
}
// Stroke implements the interface method.
func (rr *rasterRenderer) Stroke() {
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println("Stroke")
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rr.gc.Stroke()
}
// FillStroke implements the interface method.
func (rr *rasterRenderer) FillStroke() {
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println("FillStroke")
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rr.gc.FillStroke()
}
// Circle implements the interface method.
func (rr *rasterRenderer) Circle(radius float64, x, y int) {
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println("Circle", radius, x, y)
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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) {
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println("SetFont")
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rr.font = f
rr.gc.SetFont(f)
}
// SetFontSize implements the interface method.
func (rr *rasterRenderer) SetFontSize(size float64) {
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println("SetFontSize", size)
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rr.fontSize = size
rr.gc.SetFontSize(size)
}
// SetFontColor implements the interface method.
func (rr *rasterRenderer) SetFontColor(c color.RGBA) {
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println("SetFontColor")
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rr.fontColor = c
rr.gc.SetStrokeColor(c)
}
// Text implements the interface method.
func (rr *rasterRenderer) Text(body string, x, y int) {
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println("Text", body, x, y)
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rr.gc.CreateStringPath(body, float64(x), float64(y))
}
// MeasureText implements the interface method.
func (rr *rasterRenderer) MeasureText(body string) int {
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println("MeasureText", body)
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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 {
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println("Save")
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return png.Encode(w, rr.i)
}