//
// Created by Gabriel Handford on 3/1/09.
// Copyright 2009-2013. All rights reserved.
// Created by John Boiles on 10/20/11.
// Copyright (c) 2011. All rights reserved
// Modified by Felix Schulze on 2/11/13.
// Copyright 2013. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//

#import "UIImage+Diff.h"

@implementation UIImage (Diff)

- (UIImage *)diffWithImage:(UIImage *)image
{
if (!image) {
return nil;
}
CGSize imageSize = CGSizeMake(MAX(self.size.width, image.size.width), MAX(self.size.height, image.size.height));
UIGraphicsBeginImageContextWithOptions(imageSize, YES, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
[self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];
CGContextSetAlpha(context, 0.5f);
CGContextBeginTransparencyLayer(context, NULL);
[image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
CGContextSetBlendMode(context, kCGBlendModeDifference);
CGContextSetFillColorWithColor(context,[UIColor whiteColor].CGColor);
CGContextFillRect(context, CGRectMake(0, 0, self.size.width, self.size.height));
CGContextEndTransparencyLayer(context);
UIImage *returnImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return returnImage;
}

@end