Uint8ClampedArray shim

uint8clampedarray.js

if (!window.Uint8ClampedArray && window.Uint8Array && window.ImageData) {
window.Uint8ClampedArray = function(input,arg1,arg2) {
	var len = 0;
	if (typeof input == "undefined") { }
	else if (!isNaN(parseInt(input.length))) { //an array, yay
		len = input.length;
	}
	else if (input instanceof ArrayBuffer) {
		return new Uint8ClampedArray(new Uint8Array(input,arg1,arg2));
	}
	else {
		len = parseInt(input);
		if (isNaN(len) || len < 0) {
			throw new RangeError();
		}
		input = undefined;
	}
	len = Math.ceil(len / 4);
	
	if (len == 0) len = 1;
	
	var array = document.createElement("canvas")
	              .getContext("2d")
	              .createImageData(len, 1)
	              .data;
	
	if (typeof input != "undefined") {
		for (var i=0;i<input.length;i++) {
			array[i] = input[i];
		}
	}
	try {
		Object.defineProperty(array,"buffer",{
			get: function() {
				return new Uint8Array(this).buffer;
			}
		});
	} catch(e) { try {
		array.__defineGetter__("buffer",function() {
			return new Uint8Array(this).buffer;
		});
	} catch(e) {} }
	return array;
}
}

FWIW prior to version 12, the CanvasPixelArray in Opera was not clamped but clipped.

Sadly, this is only any good for the native clamping support. The buffer property is pretty much useless because CanvasPixelArray doesn't implement the ArrayBufferView interface.