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) }