OpaqueRegion subtract()

in wicket-extensions/src/main/java/org/apache/wicket/extensions/captcha/kittens/OpaqueRegion.java [181:284]
70 lines of code
16 McCabe index (conditional complexity)

	OpaqueRegion subtract(final OpaqueRegion removeRegion, final Point offset)
	{
		// Create new rectangle list
		final List<Rectangle> newRectangles = new ArrayList<>();

		// For each rectangle
		for (final Rectangle rectangle : rectangles)
		{
			// Get y
			final int y = rectangle.y;

			// Work list starts with the current rectangle in this opaque region
			final List<Rectangle> workList = new ArrayList<>();
			workList.add(new Rectangle(rectangle));

			// For each rectangle in the region to remove
			for (final Rectangle remove : removeRegion.rectangles)
			{
				// Offset the rectangle
				final Rectangle offsetRemove = new Rectangle(remove);
				offsetRemove.translate(offset.x, offset.y);

				// If we've gone past a possible match
				if (offsetRemove.y > y)
				{
					// quit
					break;
				}

				// If we're processing a rectangle on the right scan-line
				if (offsetRemove.y == y)
				{
					// Get rectangle x1 and x2
					int rx1 = offsetRemove.x;
					int rx2 = offsetRemove.x + offsetRemove.width;

					// Go through work list to remove the given rectangle
					for (int i = 0; i < workList.size(); i++)
					{
						// Get rectangle from work list
						final Rectangle work = workList.get(i);

						// Get work x1, x2
						int x1 = work.x;
						int x2 = work.x + work.width;

						// Compare left and right sides
						if ((rx1 <= x1) && (rx2 >= x2))
						{
							// Whole rectangle is obscured
							workList.remove(i);
							i -= 1;
						}
						else
						{
							// Check which sides are in
							boolean leftIn = (rx1 >= x1) && (rx1 < x2);
							boolean rightIn = (rx2 > x1) && (rx2 <= x2);

							if (leftIn)
							{
								if (rightIn)
								{
									// Split in two
									if (rx1 - x1 > 0)
									{
										workList.set(i, new Rectangle(x1, y, rx1 - x1, 1));
									}

									if (x2 - rx2 > 0)
									{
										workList.add(i + 1, new Rectangle(rx2, y, x2 - rx2, 1));
									}

								}
								else
								{
									// Chop off right side
									if (rx1 - x1 > 0)
									{
										workList.set(i, new Rectangle(x1, y, rx1 - x1, 1));
									}
								}
							}
							else if (rightIn)
							{
								// Chop off left side
								if (x2 - rx2 > 0)
								{
									workList.set(i, new Rectangle(rx2, y, x2 - rx2, 1));
								}
							}
						}
					}
				}
			}

			// Add the rectangle(s) to the new list
			newRectangles.addAll(workList);
		}

		// Return new opaque region
		return new OpaqueRegion(newRectangles);
	}