BitmapData.js

var BitmapData = (function() {

	function BitmapData(width, height) {
		this.width = width;
		this.height = height;

		this.canvas = document.createElement('canvas');
		this.canvas.setAttribute('width', this.width + 'px');
		this.canvas.setAttribute('height', this.height + 'px');

		this.context = this.canvas.getContext('2d');
		this.imageData = this.context.createImageData(this.canvas.width, this.canvas.height);
		this.byteArray = this.imageData.data;
	}

	BitmapData.prototype.setPixel32 = function(x, y, r, g, b, a) {
		var idx;

		if (x >= 0 && x < this.width && y >= 0 && y < this.height) {
			idx = ((x | 0) + (y | 0) * this.width) * 4;
			this.byteArray[idx + 0] = r;
			this.byteArray[idx + 1] = g;
			this.byteArray[idx + 2] = b;
			this.byteArray[idx + 3] = a;
		}
	};

	BitmapData.prototype.toImage = function() {
		var img;

		this.context.putImageData(this.imageData, 0, 0);

		img = document.createElement('img');
		img.setAttribute('width', this.width + 'px');
		img.setAttribute('height', this.height + 'px');
		img.setAttribute('src', this.canvas.toDataURL());

		return img;
	};

	return BitmapData;

})();