Function erodeMask

kinetic.js:4760–4792

(mask, sw, sh)

	}

	function erodeMask(mask, sw, sh) {

		var weights = [1, 1, 1, 1, 0, 1, 1, 1, 1];
		var side = Math.round(Math.sqrt(weights.length));
		var halfSide = Math.floor(side / 2);

		var maskResult = [];
		for (var y = 0; y < sh; y++) {
			for (var x = 0; x < sw; x++) {

				var so = y * sw + x;
				var a = 0;
				for (var cy = 0; cy < side; cy++) {
					for (var cx = 0; cx < side; cx++) {
						var scy = y + cy - halfSide;
						var scx = x + cx - halfSide;

						if (scy >= 0 && scy < sh && scx >= 0 && scx < sw) {

							var srcOff = scy * sw + scx;
							var wt = weights[cy * side + cx];

							a += mask[srcOff] * wt;
						}
					}
				}

				maskResult[so] = (a === 255 * 8) ? 255 : 0;
			}
		}

		return maskResult;
	}

	function dilateMask(mask, sw, sh) {