CALayer+TUIExtensions.m

//
//	CALayer+TUIExtensions.m
//
//	Created by Josh Vera on 11/26/11.
//	Copyright (c) 2011 Bitswift. All rights reserved.
//

#import "CALayer+TUIExtensions.h"

static CGRect convertAndClipRectFromSuperlayers (CGRect rect, CALayer *layer);

static CGRect convertAndClipRectFromSuperlayers (CGRect rect, CALayer *layer) {
	CALayer *superlayer = layer.superlayer;
	if (superlayer) {
		rect = convertAndClipRectFromSuperlayers(rect, superlayer);
		if (CGRectIsNull(rect))
			return CGRectNull;

		rect = [layer convertRect:rect fromLayer:superlayer];
	}

	if (layer.masksToBounds) {
		rect = CGRectIntersection(rect, layer.visibleRect);
	}

	return rect;
}

@implementation CALayer (TUIExtensions)
- (CGRect)tui_convertAndClipRect:(CGRect)rect toLayer:(CALayer *)layer {
	CALayer *clippingLayer = self.superlayer;
	CALayer *lastLayer = self;
	while (clippingLayer) {
		if (lastLayer.masksToBounds) {
			rect = CGRectIntersection(rect, lastLayer.visibleRect);
			if (CGRectIsNull(rect))
				return CGRectNull;
		}

		rect = [clippingLayer convertRect:rect fromLayer:lastLayer];

		lastLayer = clippingLayer;
		clippingLayer = clippingLayer.superlayer;
	}

	// 'rect' is in the coordinate system of the root layer, and has been
	// clipped accordingly
	return convertAndClipRectFromSuperlayers(rect, layer);
}

- (CGRect)tui_convertAndClipRect:(CGRect)rect fromLayer:(CALayer *)layer {
	return [layer tui_convertAndClipRect:rect toLayer:self];
}

@end