generate_w_pool.go

package rndimage

import (
	"image"
	"image/color"
	"math/rand"
	"sync"
)

const numWorkers = 10

func setPointWorker(rgba *image.RGBA, points <-chan image.Point, wg *sync.WaitGroup) {
	rnd := rand.New(rand.NewSource(rand.Int63()))
	defer wg.Done()

	for p := range points {
		rgba.Set(p.X, p.Y, color.RGBA{
			R: uint8(rnd.Intn(256)),
			G: uint8(rnd.Intn(256)),
			B: uint8(rnd.Intn(256)),
			A: uint8(rnd.Intn(256)),
		})
	}
}

// Generate - generates `image.RGBA` of given `width` and `height` filling it with random pixel colors
func Generate(width, height int) *image.RGBA {
	rgba := image.NewRGBA(image.Rectangle{Min: image.Point{0, 0}, Max: image.Point{width, height}})
	points := make(chan image.Point, width*height)
	var wg sync.WaitGroup

	wg.Add(numWorkers)

	for i := 0; i < numWorkers; i++ {
		go setPointWorker(rgba, points, &wg)
	}

	for i := 0; i < width; i++ {
		for k := 0; k < height; k++ {
			points <- image.Point{i, k}
		}
	}

	close(points)

	wg.Wait()

	return rgba
}