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}

Obfuscated Canvas Commands

  1. const oCan = (
  2.   d = document,
  3.   b = d.body,
  4.   canvas = b.appendChild(document.createElement('canvas')),
  5.   c = canvas.getContext('2d'),
  6.   props = [],
  7.   o = {},
  8.   docs = {},
  9.   cmds = [],
  10.   L,
  11.   k,
  12.   du,
  13.   j,
  14.   draw,
  15.   id
  16. ) => {
  17.   ;(onresize = () => {
  18.     canvas.width = innerWidth
  19.     canvas.height = innerHeight
  20.     if (draw) {
  21.       clearTimeout(id)
  22.       id = setTimeout(() => cmds.forEach(v => draw(v)), 500)
  23.     }
  24.   })()
  25.  
  26.   Object.assign(b.style, { margin: 0, height: '100%' })
  27.  
  28.   // longer way: console.log(Object.getOwnPropertyNames(Object.getPrototypeOf(c)));
  29.   for (let i in c) props.push(i)
  30.  
  31.   // make alphabetical since object keys have
  32.   // no order
  33.   props.sort().map(i => {
  34.     L = i.match(/[A-Z]/)
  35.     k = i[0]
  36.     if (L) k += L[0]
  37.     du = 0
  38.     if (o[k]) {
  39.       j = 0
  40.       while (o[k]) k += i[++j]
  41.     }
  42.  
  43.     o[k] =
  44.       (typeof c[i])[0] == 'f'
  45.         ? (...args) => c[i].apply(c, args)
  46.         : v => (c[i] = v)
  47.     docs[i] = k
  48.   })
  49.  
  50.   console.log('docs:', JSON.stringify(docs, null, 2))
  51.  
  52.   return (draw = (s, cmd, currFn, args = [], part, fn, num) => {
  53.     cmd = s.split(/\s+/)
  54.     cmds.push(s)
  55.     c.save()
  56.     for (let i = 0; i < cmd.length; i++) {
  57.       part = cmd[i]
  58.       fn = o[part]
  59.       if (fn && currFn != fn) {
  60.         currFn && currFn.apply(c, args)
  61.         currFn = fn
  62.         args = []
  63.       } else {
  64.         num = parseFloat(part)
  65.         args.push(!isNaN(num) ? num : part)
  66.       }
  67.     }
  68.     currFn && currFn.apply(c, args)
  69.     c.restore()
  70.   })
  71. }
  72.  
  73. const c = oCan()
  74. // `font` & text not suppoted
  75. // make str a function so resize works?
  76. c(`
  77.   fS #ccc
  78.   fR 0 0 400 ${innerHeight}
  79.   fS blue
  80.   fR 40 0 20 20
  81.   gCl difference
  82.   ro .25
  83.   fR 50 0 30 30
  84.   gCl source-over
  85.   fS rgba(200,100,9)
  86.   fR 100 100 40 40
  87.   `)

I’ve had this idea for a long time, never bothered doing it until now. I wrote it in a semi-golfed style for no reason… Anyway, this lets you write canvas code in a strange obfuscated syntax that looks like this:

  1. c(`
  2.   fS #ccc
  3.   fR 0 0 400 ${innerHeight}
  4.   fS blue
  5.   fR 40 0 20 20
  6.   gCl difference
  7.   ro .25
  8.   fR 50 0 30 30
  9.   gCl source-over
  10.   fS rgba(200,100,9)
  11.   fR 100 100 40 40
  12.   `)

This snippet logs out some JSON that shows all the method aliases for the canvas context.

Pretty Print JSON in Console

  1.   const obj = {
  2.     x: 1, y: 2,
  3.     data: { test: 'xyz' }
  4.   };
  5.   console.log(JSON.stringify(obj, null, 2));

JSON.stringify has two more arguments that allow for pretty printing and processing of the object in question. The second argument is a “replacer” function and the third argument is for indentation. Read more details here.

I am pretty sure I first learned this from this stack overflow post.

I used this technique in yesterdays console hijacking post.

snippet.zone ~ 2021-24 /// {s/z}