"A Tour of Go"

Images.go

/*
Exercise: Images

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 call pic.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 main

import (
    "code.google.com/p/go-tour/pic"
    "image"
    "image/color"
)

type Image struct{
    W,H int
    V uint8
}

func (im Image) Bounds() image.Rectangle{
    return image.Rect(0,0,im.W,im.H)
}

func (im Image) ColorModel() color.Model {
    return color.RGBAModel;
}

func (im Image) At(x,y int) color.Color {
    return color.RGBA{im.V,im.V,255,255}
}

func main() {
    m := Image{256,256,128}
    pic.ShowImage(m)
}