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