Golang現在標準函式庫裡有 image,
可以讓使用者輸出jpg/png等格式的圖形.

來看一個簡單的建立png檔的程式.

// hello80
package main

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"os"
)

func main() {
	width, height := 128, 128
	m := image.NewRGBA(image.Rect(0, 0, width, height))
	drawGradient(*m)
	outFilename := "gradient.png"
	outfile, err := os.Create(outFilename)
	if err != nil {
		fmt.Println(err)
	}
	defer outfile.Close()
	fmt.Printf("Saving image to: %s\n", outFilename)
	png.Encode(outfile, m)
}

func drawGradient(m image.RGBA) {
	size := m.Bounds().Size()
	for x := 0; x < size.X; x++ {
		for y := 0; y < size.Y; y++ {
			mcolor := color.RGBA{
				uint8(255 * x / size.X),
				uint8(255 * y / size.Y),
				55,
				255}
			m.Set(x, y, mcolor)
		}
	}
}

執行結果:

/hello80 
Saving image to: gradient.png

圖形如: