package chart import ( "image" "image/color" "image/png" "io" "math" "github.com/golang/freetype/truetype" "github.com/wcharczuk/go-chart/drawing" ) // PNG returns a new png/raster renderer. func PNG(width, height int) (Renderer, error) { i := image.NewRGBA(image.Rect(0, 0, width, height)) gc, err := drawing.NewRasterGraphicContext(i) if err == nil { return &rasterRenderer{ i: i, gc: gc, }, nil } return nil, err } // rasterRenderer renders chart commands to a bitmap. type rasterRenderer struct { i *image.RGBA gc *drawing.RasterGraphicContext fontSize float64 fontColor color.RGBA f *truetype.Font } // SetDPI implements the interface method. func (rr *rasterRenderer) SetDPI(dpi float64) { rr.gc.SetDPI(dpi) } // 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) SetStrokeWidth(width float64) { rr.gc.SetLineWidth(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() } // Fill implements the interface method. func (rr *rasterRenderer) Fill() { rr.gc.Fill() } // 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.f = 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.SetFillColor(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)) rr.gc.Fill() } // MeasureText returns the height and width in pixels of a string. func (rr *rasterRenderer) MeasureText(body string) (width int, height int) { l, t, r, b, err := rr.gc.GetStringBounds(body) if err != nil { return } dw := r - l dh := b - t width = int(math.Ceil(dw * (4.0 / 3.0))) height = int(math.Ceil(dh * (4.0 / 3.0))) return } // Save implements the interface method. func (rr *rasterRenderer) Save(w io.Writer) error { return png.Encode(w, rr.i) }