Bitpacker = { function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } } /** * This is taken from a personal project of mine (Greg). * It efficently converts from a packed RGBA 32bit integer to red, green, blue, and alpha (and back again) * It's used for quickly and efficently looping over image data from a canvas */ var BitPacker = function () { /** * Creates the object */ function BitPacker() { _classCallCheck(this, BitPacker); // Since this class does a bunch of bit-manipulation, we need to heck endianess first this._isLittleEndian = this._checkIsLittleEndian(); } /** * Packs an RGBA value to a 32bit int. * This function is either-endian safe * * Note: Bounds are not checked for any of the values! * * @param {Uint8Clamped} red 0-255 * @param {Uint8Clamped} green 0-255 * @param {Uint8Clamped} blue 0-255 * @param {Uint8Clamped} alpha 0-255 * @return {Uint32} uint32 packed pixel color */ BitPacker.prototype.packPixel = function packPixel(red, green, blue, alpha) { if (alpha === 255 && red === 255 && green === 255 && blue === 255) { return 4294967295; } else if (this._isLittleEndian) { return alpha << 24 | blue << 16 | green << 8 | red; } else { return red << 24 | green << 16 | blue << 8 | alpha; } }; /** * Packs an RGBA value to a 32bit int. * This function is either-endian safe * * Note: Bounds are not checked for any of the values! * * @param {Uint32} packedPixel uint32 packed pixel color value * @return {array} [red,green,blue,alpha] array of 0-255 each */ BitPacker.prototype.unpackPixel = function unpackPixel(packedPixel) { if (this._isLittleEndian) { return [packedPixel & 0x000000ff, (packedPixel & 0x0000ff00) >>> 8, (packedPixel & 0x00ff0000) >>> 16, (packedPixel & 0xff000000) >>> 24]; } else { return [(packedPixel & 0xff000000) >>> 24, (packedPixel & 0x00ff0000) >>> 16, (packedPixel & 0x0000ff00) >>> 8, packedPixel & 0x000000ff]; } }; /** * Checks if the system is little or big endian * @return {Boolean} True if little endian, false if big endian */ BitPacker.prototype._checkIsLittleEndian = function _checkIsLittleEndian() { var buffer = new ArrayBuffer(12); var uInt32Array = new Uint32Array(buffer); uInt32Array[1] = 0x0a0b0c0d; if (buffer[4] === 0x0a && buffer[5] === 0x0b && buffer[6] === 0x0c && buffer[7] === 0x0d) { return false; } else { return true; } }; return BitPacker; } return BitPacker() }