random-bitmap.go

package main

import (
	cryptorand "crypto/rand"
	"fmt"
	"image"
	"image/color"
	"image/png"
	"math/big"
	"math/rand"
	"os"
	"time"
)

const (
	MIN_X = 0
	MIN_Y = 0

	MAX_X = 512
	MAX_Y = 512
)

func createMathRandom() {
	fmt.Print("Generating math.png...\n")

	mathRandImage := image.NewGray(image.Rectangle{
		Min: image.Point{X: MIN_X, Y: MIN_Y},
		Max: image.Point{X: MAX_X, Y: MAX_Y},
	})

	for x := MIN_X; x <= MAX_X; x++ {
		for y := MIN_Y; y <= MAX_Y; y++ {
			generatedInt := rand.Intn(2)

			var generatedColor uint8
			if generatedInt == 0 {
				generatedColor = 0
			} else {
				generatedColor = 255
			}

			mathRandImage.SetGray(x, y, color.Gray{Y: generatedColor})
		}
	}

	mathImageFile, err := os.Create("math.png")
	if err != nil {
		fmt.Printf("Failed to open math.png: %s\n", err)
		return
	}
	defer mathImageFile.Close()

	err = png.Encode(mathImageFile, mathRandImage)
	if err != nil {
		fmt.Printf("Failed to write math.png: %s\n", err)
		return
	}

	fmt.Print("Generated math.png\n")
}

var (
	CRYPTO_MAX  = big.NewInt(2)
	CRYPTO_ZERO = big.NewInt(0)
)

func createCryptoRandom() {
	fmt.Print("Generating crypto.png...\n")

	cryptoRandImage := image.NewGray(image.Rectangle{
		Min: image.Point{X: MIN_X, Y: MIN_Y},
		Max: image.Point{X: MAX_X, Y: MAX_Y},
	})

	for x := MIN_X; x <= MAX_X; x++ {
		for y := MIN_Y; y <= MAX_Y; y++ {
			generatedInt, err := cryptorand.Int(cryptorand.Reader, CRYPTO_MAX)
			if err != nil {
				fmt.Printf("Failed to generate a random number for crypto.png: %s\n", err)
				return
			}

			var generatedColor uint8
			if generatedInt.Cmp(CRYPTO_ZERO) == 0 {
				generatedColor = 0
			} else {
				generatedColor = 255
			}

			cryptoRandImage.SetGray(x, y, color.Gray{Y: generatedColor})
		}
	}

	cryptoImageFile, err := os.Create("crypto.png")
	if err != nil {
		fmt.Printf("Failed to open crypto.png: %s\n", err)
		return
	}
	defer cryptoImageFile.Close()

	err = png.Encode(cryptoImageFile, cryptoRandImage)
	if err != nil {
		fmt.Printf("Failed to write crypto.png: %s\n", err)
		return
	}

	fmt.Print("Generated crypto.png\n")
}

func main() {
	rand.Seed(time.Now().UnixNano())

	createMathRandom()
	createCryptoRandom()
}