// Example_functions draws some functions. func Example_functions() *plot.Plot { p, err := plot.New() if err != nil { panic(err) } p.Title.Text = "Functions" p.X.Label.Text = "X" p.Y.Label.Text = "Y" quad := plotter.NewFunction(func(x float64) float64 { return x * x }) quad.Color = color.RGBA{B: 255, A: 255} exp := plotter.NewFunction(func(x float64) float64 { return math.Pow(2, x) }) exp.Dashes = []vg.Length{vg.Points(2), vg.Points(2)} exp.Width = vg.Points(2) exp.Color = color.RGBA{G: 255, A: 255} sin := plotter.NewFunction(func(x float64) float64 { return 10*math.Sin(x) + 50 }) sin.Dashes = []vg.Length{vg.Points(4), vg.Points(5)} sin.Width = vg.Points(4) sin.Color = color.RGBA{R: 255, A: 255} p.Add(quad, exp, sin) p.Legend.Add("x^2", quad) p.Legend.Add("2^x", exp) p.Legend.Add("10*sin(x)+50", sin) p.Legend.ThumbnailWidth = vg.Inches(0.5) p.X.Min = 0 p.X.Max = 10 p.Y.Min = 0 p.Y.Max = 100 return p }
// NewImage returns a new image canvas // that draws to the given image. The // minimum point of the given image // should probably be 0,0. func NewImage(img draw.Image) *Canvas { w := float64(img.Bounds().Max.X - img.Bounds().Min.X) h := float64(img.Bounds().Max.Y - img.Bounds().Min.Y) draw.Draw(img, img.Bounds(), image.White, image.ZP, draw.Src) gc := draw2d.NewGraphicContext(img) gc.SetDPI(dpi) gc.Scale(1, -1) gc.Translate(0, -h) c := &Canvas{ gc: gc, img: img, w: vg.Inches(w / dpi), h: vg.Inches(h / dpi), color: []color.Color{color.Black}, } vg.Initialize(c) return c }
// Save saves the plot to an image file. Width and height // are specified in inches, and the file format is determined // by the extension. Supported extensions are // .eps, .jpg, .jpeg, .pdf, .png, .svg, and .tiff. func (p *Plot) Save(width, height float64, file string) (err error) { w, h := vg.Inches(width), vg.Inches(height) var c interface { vg.Canvas Size() (w, h vg.Length) io.WriterTo } switch ext := strings.ToLower(filepath.Ext(file)); ext { case ".eps": c = vgeps.NewTitle(w, h, file) case ".jpg", ".jpeg": c = vgimg.JpegCanvas{Canvas: vgimg.New(w, h)} case ".pdf": c = vgpdf.New(w, h) case ".png": c = vgimg.PngCanvas{Canvas: vgimg.New(w, h)} case ".svg": c = vgsvg.New(w, h) case ".tiff": c = vgimg.TiffCanvas{Canvas: vgimg.New(w, h)} default: return fmt.Errorf("Unsupported file extension: %s", ext) } p.Draw(MakeDrawArea(c)) f, err := os.Create(file) if err != nil { return err } if _, err = c.WriteTo(f); err != nil { return err } return f.Close() }