If all you want is the alpha value of a single point, all you need is an alpha-only single-point buffer. I believe this should suffice: // assume im is a UIImage, point is the CGPoint to test CGImageRef cgim = im.CGImage; unsigned char pixel[1] = {0}; CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 1, NULL, … Read more
Note that the following method creates just a bitmap of the view; it does not create actual typography. (void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename { // Creates a mutable data object for updating with binary data, like a byte array NSMutableData *pdfData = [NSMutableData data]; // Points the pdf converter to the mutable data object and to the UIView … Read more
The following blog post is where I got my answer when I had issues with modifying and saving Exif data Caffeinated Cocoa. This works on iOS. Here is my test code for writing Exif and GPS data. It pretty much a copy and paste of the code from the above blog. I am using this … Read more
Here is code that works … – (IBAction) renderScrollViewToImage { UIImage* image = nil; UIGraphicsBeginImageContext(_scrollView.contentSize); { CGPoint savedContentOffset = _scrollView.contentOffset; CGRect savedFrame = _scrollView.frame; _scrollView.contentOffset = CGPointZero; _scrollView.frame = CGRectMake(0, 0, _scrollView.contentSize.width, _scrollView.contentSize.height); [_scrollView.layer renderInContext: UIGraphicsGetCurrentContext()]; image = UIGraphicsGetImageFromCurrentImageContext(); _scrollView.contentOffset = savedContentOffset; _scrollView.frame = savedFrame; } UIGraphicsEndImageContext(); if (image != nil) { [UIImagePNGRepresentation(image) writeToFile: @”/tmp/test.png” … Read more
I needed the same thing – in my case, to pick the dimension that fits once scaled, and then crop each end to fit the rest to the width. (I’m working in landscape, so might not have noticed any deficiencies in portrait mode.) Here’s my code – it’s part of a categeory on UIImage. Target … Read more
I believe the easiest way (and thread safe too) is to do: //assume that the image is loaded in landscape mode from disk UIImage * landscapeImage = [UIImage imageNamed:imgname]; UIImage * portraitImage = [[UIImage alloc] initWithCGImage: landscapeImage.CGImage scale: 1.0 orientation: UIImageOrientationRight]; Note: As Brainware said this only modifies the orientation data of the image – … Read more
FYI, I combined Keremk’s answer with my original outline, cleaned-up the typos, generalized it to return an array of colors and got the whole thing to compile. Here is the result: + (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)x andY:(int)y count:(int)count { NSMutableArray *result = [NSMutableArray arrayWithCapacity:count]; // First get the image into your data buffer CGImageRef imageRef = [image … Read more