blog-instashred

Image.go

type Image interface {
    image.Image
    Set(x, y int, c image.Color)
}

image.Image.go

type Image interface {
    // ColorModel returns the Image's ColorModel.
    ColorModel() ColorModel
    // Bounds returns the domain for which At can return non-zero color.
    // The bounds do not necessarily contain the point (0, 0).
    Bounds() Rectangle
    // At returns the color of the pixel at (x, y).
    // At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
    // At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.
    At(x, y int) Color
}
type ColorModel interface {
    Convert(c Color) Color
}
type Color interface {
    RGBA() (r, g, b, a uint32)
}
type Rectangle struct {
    Min, Max Point
}
type Point struct {
    X, Y int
}

main.go

func main() {
  random_image := new(RandomColorImage)
  output_image := image.NewRGBA(256, 256)
  draw.Draw(output_image, output_image.Bounds(), random_image, image.ZP, draw.Src)
  WritePNGFile("random_image.png", output_image)
}

RandomColorImage.go

type RandomColorImage struct{}

func (rcm *RandomColorImage) ColorModel() image.ColorModel { 
  return image.RGBAColorModel
}

func (rcm *RandomColorImage) Bounds() image.Rectangle {
  return image.Rectangle{image.Point{-1e9,-1e9}, image.Point{1e9,1e9}}
}

func (rcm *RandomColorImage) Opaque() bool {
  return true
}

func (rcm *RandomColorImage) At(x, y int) image.Color {
  seed := rand.Uint32()
  r := uint8((seed << 24) >> 24)
  g := uint8((seed << 16) >> 24)
  b := uint8((seed << 8) >> 24)
  a := uint8(0xFF)
  return image.NRGBAColor{r,g,b,a}
}

WritePNGFile.go

func WritePNGFile(filename string, image image.Image) {
	f, err := os.Create(filename)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	err = png.Encode(f, image)
	if err != nil {
		log.Fatal(err)
	}
}