// 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()
}