getOpaqueBounds() function added to InteractivePNG

InteractivePNGTest.as

		/**
		 * Returns a rectangle around the opaque area of the png.
		 * 
		 * @author Mims H. Wright
		 */
		public function getOpaqueBounds():Rectangle {
			if (_bitmapForHitDetection==null)
				drawBitmapHitArea();
			
			var left:uint = 0;
			var top:uint = 0;
			var right:uint = width;
			var bottom:uint = height;
			
			// Start on the narrowest side because it will reduce the number of 
			// recursions on the longer side.
			if (width > height) {
				left = getLeft();
				right = getRight();
				top = getTop(left, right);
				bottom = getBottom(left, right);
			} else {
				top = getTop();
				bottom = getBottom();
				left = getLeft(top, bottom);
				right = getRight(top, bottom);
			}
			
			var opaqueBounds:Rectangle = new Rectangle();
			opaqueBounds.left = left;
			opaqueBounds.right = right - left;
			opaqueBounds.top = top;
			opaqueBounds.bottom = bottom - top;
			return opaqueBounds;
			
			function getLeft(startY:uint=0, endY:uint=0):uint {
				// if endY isn't defined, use the height.
				endY = endY == 0 ? height : endY; 
				
				var left:uint = 0;
				var y:uint;
				while (left < width) {
					y = startY;
					while (y < endY) {
						if (isPixelOpaque(left, y)) return left;
						y += 1;
					}
					left += 1;
				} 
				
				// if there are no visible pixels, return the bounds.
				return 0;
			}
			function getRight(startY:uint=0, endY:uint=0):uint {
				// if endY isn't defined, use the height.
				endY = endY == 0 ? height : endY; 
				
				var right:uint = width;
				var y:uint;
				while (right > 0) {
					y = startY;
					while (y < endY) {
						if (isPixelOpaque(right, y)) return right;
						y += 1;
					}
					right -= 1;
				} 
				
				// if there are no visible pixels, return the bounds.
				return width;
			}
			function getTop(startX:uint=0, endX:uint=0):uint {
				// if endX isn't defined, use the width.
				endX = endX == 0 ? width : endX; 
				
				var top:uint = 0;
				var x:uint;
				while (top < height) {
					x = startX;
					while (x < endX) {
						if (isPixelOpaque(x, top)) return top;
						x += 1;
					}
					top += 1;
				} 
				// if there are no visible pixels, return the bounds.
				return 0
			}
			function getBottom(startX:uint=0, endX:uint=0):uint {
				// if endX isn't defined, use the width.
				endX = endX == 0 ? width : endX; 
				
				var bottom:uint = height;
				var x:uint;
				while (x < endX) {
					x = endX
					while (x > startX) {
						if (isPixelOpaque(x, bottom)) return bottom;
						x -= 1;
					}
					bottom -= 1;
				}
				
				// if there are no visible pixels, return the bounds.
				return height;
			}
		}