Overview

Package draw provides image composition functions.

See “The Go image/draw package” for an introduction to this package:
https://golang.org/doc/articles/image_draw.html

Index

draw.go

Draw calls DrawMask with a nil mask.

func 

  1. func DrawMask(dst , r image., src image., sp image., mask image., mp image., op Op)

DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the
rectangle r in dst with the result of a Porter-Duff composition. A nil mask is
treated as opaque.

type 

  1. type Drawer interface {
  2.     // Draw aligns r.Min in dst with sp in src and then replaces the
  3.     // rectangle r in dst with the result of drawing src on dst.
  4.     Draw(dst , r image., src image., sp image.)
  5. }

Drawer contains the Draw method.

FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error
diffusion.


Example:

  1. const width = 130
  3. im := image.NewGray(image.Rectangle{Max: image.Point{X: width, Y: height}})
  4. for x := 0; x < width; x++ {
  5.     for y := 0; y < height; y++ {
  6.         dist := math.Sqrt(math.Pow(float64(x-width/2), 2)/3+math.Pow(float64(y-height/2), 2)) / (height / 1.5) * 255
  7.         var gray uint8
  8.         if dist > 255 {
  9.             gray = 255
  11.             gray = uint8(dist)
  12.         }
  13.         im.SetGray(x, y, color.Gray{Y: 255 - gray})
  14.     }
  15. }
  16. pi := image.NewPaletted(im.Bounds(), []color.Color{
  17.     color.Gray{Y: 255},
  18.     color.Gray{Y: 160},
  19.     color.Gray{Y: 70},
  20.     color.Gray{Y: 35},
  21. })
  23. draw.FloydSteinberg.Draw(pi, im.Bounds(), im, image.ZP)
  24. shade := []string{" ", "░", "▒", "▓", "█"}
  25. for i, p := range pi.Pix {
  26.     fmt.Print(shade[p])
  27.     if (i+1)%width == 0 {
  28.         fmt.Print("\n")
  29.     }
  30. }

  1. type Image interface {
  2.     .Image
  3.     Set(x, y , c color.)
  4. }

type Op

Op is a Porter-Duff compositing operator.

  1. const (
  2.     // Over specifies ``(src in mask) over dst''.
  3.     Over Op = 
  4.     // Src specifies ``src in mask''.
  5.     Src

  1. func (op Op) Draw(dst , r image., src image., sp image.)

Draw implements the Drawer interface by calling the Draw function with this Op.

type Quantizer