{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import (\n",
    "    \"bytes\"\n",
    "    \"image\"\n",
    "    \"image/color\"\n",
    "    \"image/draw\"\n",
    "    \"image/png\"\n",
    "    \"log\"\n",
    "    \"math/rand\"\n",
    ")\n",
    "\n",
    "func newImage() image.Image {\n",
    "    sz := 50\n",
    "    // create the whole image canvas\n",
    "    canvas := image.Rect(0, 0, 2*sz, 2*sz)\n",
    "    img := image.NewRGBA(canvas)\n",
    "    \n",
    "    \n",
    "    // draw a gray background\n",
    "    //bkg := color.RGBA{0x66, 0x66, 0x66, 0xff}\n",
    "    bkg := color.RGBA{102, 102, 102, 255}\n",
    "    draw.Draw(img, canvas, image.NewUniform(bkg), image.ZP, draw.Src)\n",
    "    \n",
    "    // create a randomly sized, randomly centered, red square\n",
    "    x1 := rand.Intn(sz)\n",
    "    y1 := rand.Intn(sz)\n",
    "    x2 := rand.Intn(sz) + sz\n",
    "    y2 := rand.Intn(sz) + sz\n",
    "    \n",
    "    // red foreground\n",
    "    red := color.RGBA{255,0,0,255}\n",
    "    draw.Draw(\n",
    "        img, \n",
    "        image.Rect(x1, y1, x2, y2),\n",
    "        image.NewUniform(red), \n",
    "        image.ZP, draw.Src,\n",
    "    )\n",
    "    return img\n",
    "}\n",
    "\n",
    "func getRaw(img image.Image) []byte {\n",
    "    buf := bytes.Buffer{}\n",
    "    err := png.Encode(&buf, img)\n",
    "    if err != nil {\n",
    "        log.Printf(\"could not encode to PNG: %v\", err)\n",
    "        return nil\n",
    "    }\n",
    "    return buf.Bytes()\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "img := newImage()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(img)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(getRaw(img))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import \"encoding/hex\"\n",
    "print(hex.Dump(getRaw(img)))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "img"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "getRaw(img)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(1+2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "newImage()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "func get() (int, int) { return 42, 666 }"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "get()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import \"encoding/hex\"\n",
    "hex.Dump(getRaw(newImage()))"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Go",
   "language": "go",
   "name": "go"
  },
  "language_info": {
   "codemirror_mode": "go",
   "file_extension": ".go",
   "mimetype": "",
   "name": "go",
   "nbconvert_exporter": "",
   "pygments_lexer": "go",
   "version": "unreleased"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}