quartz-2d

i have a big jpeg image that i want to load in tiles asynchronously in my opengl engine. Everything works well if its done on the main thread but its slow. When i try to put the tile loading on an NSOperationBlock, it always crashes when trying to access the shared image data pointer that i previously loaded on the main thread. There must be something i don't get with background operation because i assume i can access memory sections that i created on the main thread. What i try to do is the following : @interface MyViewer { } @property (atomic, assign) CGImageRef imageRef; @property (atomic,

I am doing PDF based application for iPad. It supports thumbnail view, Free hand comment, And annotations (Notes). Ya and I searched lot on net but I didnt find any relevant answer for making annotation on PDF using Quartz 2d. We can get PDF page info using CGPDFDictionaryRef CGPDFPageGetDictionary ( CGPDFPageRef page ); And using Annots key. bool CGPDFDictionaryGetArray ( CGPDFDictionaryRef dict, "Annots", CGPDFArrayRef *value ); you can get annotation for particular page. If I am right what is key for Notes and if it is there how to update page dictionary. If i am wrong at all in above

My app uses core graphics for custom finger paint drawing. I allow the user to change the alpha of the line and a new line is continuously drawn on touches moved. When I make the alpha lower than 1.0 the point of overlap is darker than the rest of the line. I know why this occurs but how can I stop this? Kris Van Bael I suppose you want a single stroke not to darken itself, but still to darken previous strokes (that's how most painting apps work). For this to work, you need two views/buffers, one for the 'current background' and one for the current stroke. Merge the latter with the background

This question already has an answer here: Assigning an existing CGColor to a CGColor property works in iOS Simulator, not iOS device. Why? 3 answers I have a custom UIButton class that adds a gradient and a gloss effect to the UIButton the code works perfectly in iOS 4 and on iOS5 simulator but when i run it on iOS 5 devices it gives me the exception EXC_BAD_ACCESS , the exception is triggered by the line : CGContextStrokePath(context); any help is really appreciated , here's my code - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGFloat actualBrightness

I'm struggling with a pdf export method that's was running just fine until I ported the app to the arm64 achitecture. Bacisally, the method opens an existing PDF, it creates a new pdf file, and draws the content of the first pdf into the newly created one before adding more content pages. When the method tries to create a new pdf page to the document (after the first pdf was integrated to the new pdf) the app crashes with a EXC_BAD_ACCESS warning on UIGraphicsBeginPDFPage(); call . It only happens with some PDF files, not all and only on 64 bit devices. Here's the stacktrace which shows the

I have an UIView where I was drawing some stuff inside -drawRect:. Now I need a CGImageRef from this graphics context or bitmap of the UIView. Is there an easy way to get that? Like this (typed from memory, so it might not be 100% correct): // Get a UIImage from the view's contents UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, view.contentScaleFactor); CGContextRef context = UIGraphicsGetCurrentContext(); [view.layer renderInContext:context]; UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); // Convert UIImage to CGImage