import (
    "bytes"
    "image"
    "image/color"
    "image/draw"
    "image/png"
    "log"
    "math/rand"
)

func newImage() image.Image {
    sz := 50
    // create the whole image canvas
    canvas := image.Rect(0, 0, 2*sz, 2*sz)
    img := image.NewRGBA(canvas)
    
    
    // draw a gray background
    //bkg := color.RGBA{0x66, 0x66, 0x66, 0xff}
    bkg := color.RGBA{102, 102, 102, 255}
    draw.Draw(img, canvas, image.NewUniform(bkg), image.ZP, draw.Src)
    
    // create a randomly sized, randomly centered, red square
    x1 := rand.Intn(sz)
    y1 := rand.Intn(sz)
    x2 := rand.Intn(sz) + sz
    y2 := rand.Intn(sz) + sz
    
    // red foreground
    red := color.RGBA{255,0,0,255}
    draw.Draw(
        img, 
        image.Rect(x1, y1, x2, y2),
        image.NewUniform(red), 
        image.ZP, draw.Src,
    )
    return img
}

func getRaw(img image.Image) []byte {
    buf := bytes.Buffer{}
    err := png.Encode(&buf, img)
    if err != nil {
        log.Printf("could not encode to PNG: %v", err)
        return nil
    }
    return buf.Bytes()
}

img := newImage()

print(img)

print(getRaw(img))

import "encoding/hex"
print(hex.Dump(getRaw(img)))

img

getRaw(img)

print(1+2)

newImage()

func get() (int, int) { return 42, 666 }

get()

import "encoding/hex"
hex.Dump(getRaw(newImage()))