Clipping for GUI

example.java

public boolean beginClipping(int x, int y, int w, int h) {
	IDevice dev = Age.Device;
	if (!dev.isEnabled(Feature.Scissor)) {
		dev.setFeatures(true, Feature.Scissor);
	}
	if (!clipRectStack.isEmpty()) {
		Rectangle parent = clipRectStack.lastElement();
		int minX = Math.max(parent.x, x);
		int maxX = Math.min(parent.x + parent.width, x + w);
		if (maxX - minX < 1) return false;

		int minY = Math.max(parent.y, y);
		int maxY = Math.min(parent.y + parent.height, y + h);
		if (maxY - minY < 1) return false;

		x = minX;
		y = minY;
		w = maxX - minX;
		h = Math.max(1, maxY - minY);
	}
	clipRectStack.push(new Rectangle(x, y, w, h));
	dev.setScissor(x, y, w, h);
	return true;
}

public void endClipping() {
	IDevice dev = Age.Device;
	if (!clipRectStack.isEmpty()) {
		clipRectStack.pop();
	}
	if (!clipRectStack.isEmpty()) {
		Rectangle scissor = clipRectStack.peek();
		dev.setScissor(scissor.x, scissor.y, scissor.width, scissor.height);
	} else {
		dev.setScissor(0, 0, width, height);
		if (dev.isEnabled(Feature.Scissor)) {
			dev.setFeatures(false, Feature.Scissor);
		}
	}
}