Remember the picture generator you wrote earlier? Let‘s write another one, but this time it will return an implementation of image.Image instead of a slice of data.

Define your own Image type, implement the necessary methods, and callpic.ShowImage.

Bounds should return a image.Rectangle, like image.Rect(0, 0, w, h).

ColorModel should return color.RGBAModel.

At should return a color; the value v in the last picture generator corresponds to color.RGBA{v, v, 255, 255} in this one.

package mainimport (    "code.google.com/p/go-tour/pic"    "image"    "image/color")type Image struct{}func (img Image) ColorModel() color.Model {    return color.RGBAModel}func (img Image) Bounds() image.Rectangle {    return image.Rect(0, 0, 100, 100)}func (img Image) At(x, y int) color.Color {    return color.RGBA{uint8(x), uint8(y), 255, 255}}func main() {    m := Image{}    pic.ShowImage(m)}

A Tour of Go Exercise: Images