gistfile1.txt

- (BOOL) sourceImage:(UIImage*) sourceImage matchesImageNamed:(NSString*)imageName at:(CGPoint)at
{
    UIImage* comparisonImage = [UIImage imageNamed:imageName];
    
    CGImageRef comparisonImageRef = [comparisonImage CGImage];
    NSUInteger comparisonImageWidth = CGImageGetWidth(comparisonImageRef);
    NSUInteger comparisonImageHeight = CGImageGetHeight(comparisonImageRef);
    
    // NSLog(@"%@ Width: %d Height: %d", imageName, comparisonImageWidth, comparisonImageHeight);
    
    // The rectangle we want to draw
    CGRect sourceRect = CGRectMake(at.x, at.y, comparisonImageWidth, comparisonImageHeight);
    CGRect comparisonRect = CGRectMake(0, 0, comparisonImageWidth, comparisonImageHeight);
    
    // Create the data for the source pixels
    unsigned int *sourceImagePixels = (unsigned int*)malloc(comparisonImageHeight * comparisonImageWidth * 4);
    memset(sourceImagePixels, 0, comparisonImageHeight * comparisonImageWidth * 4);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef sourceImageRef = CGImageCreateWithImageInRect([sourceImage CGImage], sourceRect);
    CGContextRef sourceImageContext = CGBitmapContextCreate(sourceImagePixels, comparisonImageWidth, comparisonImageHeight, 8, comparisonImageWidth * 4, colorSpace, kCGBitmapByteOrder32Big | kCGImageAlphaNoneSkipLast);
    CGContextDrawImage(sourceImageContext, comparisonRect, sourceImageRef);
    
    
    // Create the data for the comparison image
    unsigned int* comparisonImagePixels = (unsigned int*)malloc(comparisonImageWidth * comparisonImageWidth * 4);
    memset(comparisonImagePixels, 0, comparisonImageHeight * comparisonImageWidth * 4);
    CGContextRef comparisonImageContext = CGBitmapContextCreate(comparisonImagePixels, comparisonImageWidth, comparisonImageHeight, 8, comparisonImageWidth * 4, colorSpace, kCGBitmapByteOrder32Big | kCGImageAlphaNoneSkipLast);
    CGContextDrawImage(comparisonImageContext, comparisonRect, comparisonImageRef);
    
    // Compare the two images
    BOOL match = NO;
    if (!memcmp(sourceImagePixels, comparisonImagePixels, comparisonImageHeight * comparisonImageWidth * 4)) {
        match = YES;
    }
    
    
    // Clean up memory
    free(comparisonImagePixels);
    free(sourceImagePixels);
    CGColorSpaceRelease(colorSpace);
    CGContextRelease(sourceImageContext);
    CGContextRelease(comparisonImageContext);
    CGImageRelease(sourceImageRef);
    
    return match;
}