image_tutorial.go

package main

import (
	"image"
	"image/color"
	"golang.org/x/tour/pic"
)

type Image struct{}

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

func (img Image) Bounds() image.Rectangle {
	return image.Rect(0, 0, 500, 500)
}

func (img Image) At(x, y int) color.Color {
	v := uint8((x*x + y*y) / 2)
	u := uint8(255-v)
	return color.RGBA{v, u, 0, 255}
}

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