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POCropping image with transparency in iPhone
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copied!<p>I am working on Jigsaw type of game where i have two images for masking, I have implemented this code for masking</p> <pre><code>- (UIImage*) maskImage:(UIImage *)image withMaskImage:(UIImage*)maskImage { CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGImageRef maskImageRef = [maskImage CGImage]; CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast); if (mainViewContentContext==NULL) return NULL; CGFloat ratio = 0; ratio = maskImage.size.width/ image.size.width; if(ratio * image.size.height < maskImage.size.height) { ratio = maskImage.size.height/ image.size.height; } CGRect rect1 = {{0, 0}, {maskImage.size.width, maskImage.size.height}}; CGRect rect2 = {{-((image.size.width*ratio)-maskImage.size.width)/2,-((image.size.height*ratio)-maskImage.size.height)/2},{image.size.width*ratio, image.size.height*ratio}}; CGContextClipToMask(mainViewContentContext, rect1, maskImageRef); CGContextDrawImage(mainViewContentContext, rect2, image.CGImage); CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext); CGContextRelease(mainViewContentContext); UIImage *theImage = [UIImage imageWithCGImage:newImage]; CGImageRelease(newImage); return theImage; } </code></pre> <p><img src="https://i.stack.imgur.com/Jd7ji.png" alt="enter image description here"></p> <p>+</p> <p><img src="https://i.stack.imgur.com/QYttC.png" alt="enter image description here"></p> <p>=</p> <p>This is final result i got after masking.</p> <p><img src="https://i.stack.imgur.com/34MA9.png" alt="enter image description here"></p> <p>now i would like to crop image in piece like <img src="https://i.stack.imgur.com/e8YBT.png" alt="enter image description here"> and <img src="https://i.stack.imgur.com/6o2xd.png" alt="enter image description here"> and so on parametrically(crop an image by transparency).</p> <p>if any one has implemented such code or any idea on this scenario please share.</p> <p>Thanks.</p> <p>I am using this line of code for as <strong>Guntis Treulands's</strong> suggestion </p> <pre><code>int i=1; for (int x=0; x<=212; x+=106) { for (int y=0; y<318; y+=106) { CGRect rect = CGRectMake(x, y, 106, 106); CGRect rect2x = CGRectMake(x*2, y*2, 212, 212); UIImage *orgImg = [UIImage imageNamed:@"cat@2x.png"]; UIImage *frmImg = [UIImage imageNamed:[NSString stringWithFormat:@"%d@2x.png",i]]; UIImage *cropImg = [self cropImage:orgImg withRect:rect2x]; UIImageView *tmpImg = [[UIImageView alloc] initWithFrame:rect]; [tmpImg setUserInteractionEnabled:YES]; [tmpImg setImage:[self maskImage:cropImg withMaskImage:frmImg]]; [self.view addSubview:tmpImg]; i++; } } </code></pre> <p>orgImg is original cat image, frmImg frame for holding individual piece, masked in photoshop and cropImg is 106x106 cropped image of original cat@2x.png. </p> <p>my function for cropping is as following</p> <pre><code>- (UIImage *) cropImage:(UIImage*)originalImage withRect:(CGRect)rect { return [UIImage imageWithCGImage:CGImageCreateWithImageInRect([originalImage CGImage], rect)]; } </code></pre>

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