1
  2// DOMRect
  3(function (global) {
  4	function number(v) {
  5		return v === undefined ? 0 : Number(v);
  6	}
  7
  8	function different(u, v) {
  9		return u !== v && !(isNaN(u) && isNaN(v));
 10	}
 11
 12	function DOMRect(xArg, yArg, wArg, hArg) {
 13		var x, y, width, height, left, right, top, bottom;
 14
 15		x = number(xArg);
 16		y = number(yArg);
 17		width = number(wArg);
 18		height = number(hArg);
 19
 20		Object.defineProperties(this, {
 21			x: {
 22				get: function () { return x; },
 23				set: function (newX) {
 24					if (different(x, newX)) {
 25						x = newX;
 26						left = right = undefined;
 27					}
 28				},
 29				enumerable: true
 30			},
 31			y: {
 32				get: function () { return y; },
 33				set: function (newY) {
 34					if (different(y, newY)) {
 35						y = newY;
 36						top = bottom = undefined;
 37					}
 38				},
 39				enumerable: true
 40			},
 41			width: {
 42				get: function () { return width; },
 43				set: function (newWidth) {
 44					if (different(width, newWidth)) {
 45						width = newWidth;
 46						left = right = undefined;
 47					}
 48				},
 49				enumerable: true
 50			},
 51			height: {
 52				get: function () { return height; },
 53				set: function (newHeight) {
 54					if (different(height, newHeight)) {
 55						height = newHeight;
 56						top = bottom = undefined;
 57					}
 58				},
 59				enumerable: true
 60			},
 61			left: {
 62				get: function () {
 63					if (left === undefined) {
 64						left = x + Math.min(0, width);
 65					}
 66					return left;
 67				},
 68				enumerable: true
 69			},
 70			right: {
 71				get: function () {
 72					if (right === undefined) {
 73						right = x + Math.max(0, width);
 74					}
 75					return right;
 76				},
 77				enumerable: true
 78			},
 79			top: {
 80				get: function () {
 81					if (top === undefined) {
 82						top = y + Math.min(0, height);
 83					}
 84					return top;
 85				},
 86				enumerable: true
 87			},
 88			bottom: {
 89				get: function () {
 90					if (bottom === undefined) {
 91						bottom = y + Math.max(0, height);
 92					}
 93					return bottom;
 94				},
 95				enumerable: true
 96			}
 97		});
 98	}
 99
100	global.DOMRect = DOMRect;
101}(self));
102