rgba -> png example

gistfile1.js

#!/usr/bin/env node

var Png = require('png').Png; // https://github.com/pkrumins/node-png
var fs = require('fs');

var size = 256;
var rgba = new Buffer(size*size*4);
var x, y;
var png;

for (y = 0; y < size; y++) {
  for (x = 0; x < size; x++) {
    rgba.writeUInt8(y&x, (y*size+x)*4 + 0);
    rgba.writeUInt8(y&x, (y*size+x)*4 + 1);
    rgba.writeUInt8(y&x, (y*size+x)*4 + 2);
    rgba.writeUInt8(y&x, (y*size+x)*4 + 3);
  }
}

png = new Png(rgba, size, size, 'rgba');
png.encode(function(data,err) {
  if (err) {
    console.error(err);
    process.exit(1);
  }
  fs.writeFileSync('wat.png', data.toString('binary'), 'binary');
});