If I create a bitmap image and then try to get ready to draw into it, like so: NSBitmapImageRep* newRep = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes: nullptr pixelsWide: 128 pixelsHigh: 128 bitsPerSample: 8 samplesPerPixel: 4 hasAlpha: YES isPlanar: NO colorSpaceName: NSDeviceRGBColorSpace bitmapFormat: NSBitmapFormatAlphaNonpremultiplied | NSBitmapFormatThirtyTwoBitBigEndian bytesPerRow: 4 * 128 bitsPerPixel: 32]; [NSGraphicsContext setCurrentContext: [NSGraphicsContext graphicsContextWithBitmapImageRep: newRep]]; then the log shows this error: CGBitmapContextCreate: unsupported parameter combination: RGB 8 bits/component, integer 512 bytes/row kCGImageAlphaLast kCGImageByteOrderDefault kCGImagePixelFormatPacked Valid parameters for RGB color space model are: 16 bits per pixel, 5 bits per component, kCGImageAlphaNoneSkipFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaNoneSkipFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaNoneSkipLast 32 bits per pixel, 8 bits per component, kCGImageAlphaPremultipliedFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaPremultipliedLast 32 bits per pixel, 10 bits per component, kCGImageAlphaNone|kCGImagePixelFormatRGBCIF10|kCGImageByteOrder16Little 64 bits per pixel, 16 bits per component, kCGImageAlphaPremultipliedLast 64 bits per pixel, 16 bits per component, kCGImageAlphaNoneSkipLast 64 bits per pixel, 16 bits per component, kCGImageAlphaPremultipliedLast|kCGBitmapFloatComponents|kCGImageByteOrder16Little 64 bits per pixel, 16 bits per component, kCGImageAlphaNoneSkipLast|kCGBitmapFloatComponents|kCGImageByteOrder16Little 128 bits per pixel, 32 bits per component, kCGImageAlphaPremultipliedLast|kCGBitmapFloatComponents 128 bits per pixel, 32 bits per component, kCGImageAlphaNoneSkipLast|kCGBitmapFloatComponents See Quartz 2D Programming Guide (available online) for more information. If I don't use NSBitmapFormatAlphaNonpremultiplied as part of the format, I don't get the error message. My question is, why does the constant NSBitmapFormatAlphaNonpremultiplied exist if you can't use it like this? If you're wondering why I wanted to do this: I want to extract the RGBA pixel data from an image, which might have non-premultiplied alpha. And elsewhere online, I saw advice that if you want to look at the pixels of an image, draw it into a bitmap whose format you know and look at those pixels. And I don't want the process of drawing to premultiply my alpha.

I have filed a bug report for this (FB17734946), but I'm posting it here verbatim in case others have the same issue and in hopes of getting attention from an Apple engineer sooner. When calling setNeedsDisplayInRect on a CATiledLayer - or a UIView whose backing layer is CATiledLayer - one would expect to re-draw only a region identified by the rect passed to the method. This is even written in the documentation for the class: "Regions of the layer may be invalidated using the setNeedsDisplayInRect: method however the update will be asynchronous. While the next display update will most likely not contain the updated content, a future update will." However, upon calling this method, CATiledLayer redraws whole contents instead of just the tile at the specified rect, and it flashes when doing so. It behaves exactly the same as if one had called setNeedsDisplay without passing any rect; all contents are cleared and re-drawn again. I'm 100% sure I've passed in the correct rect of the exact tile that I need to redraw. I have even tried passing much smaller rects, but still the same. (And yes, the rect I've passed accounts for the current level of detail.) I have found this GitHub repo https://github.com/frankus/NetPhotoScroller, which based on discussion from here https://forums.macrumors.com/threads/catiledlayer-blanks-out-tiles-when-redrawing.1333948/ aims at solving these issues by using two private methods on CATiledLayer class: (void)setNeedsDisplayInRect:(CGRect)r levelOfDetail:(int)level; (BOOL)canDrawRect:(CGRect)rect levelOfDetail:(int)level; I have explored the repo in detail, however I wasn't able to test exactly this code from the GitHub repo. I have tried using those two private methods myself (through an Objective-C class that defines the methods in the header file and then a swift class which inherits it), but I couldn't solve the issue; the flashing and the full re-draw is still there. After doing a lot of research, the conclusion seems to be that one cannot use CATiledLayer with contents that are downloaded remotely, on demand, as tiles are being requested. I have, however, found one interesting thing which seems to work so far: before calling setNeedsDisplayInRect (or just setNeedsDisplay, as they behave the same for CATiledLayer in my testing), cache the current layer's contents, and after calling setNeedsDisplay (or setNeedsDisplayInRect), restore the contents back to the layer. This prevents flashing and preserves any tiles that were drawn at the time of the re-draw. let c = tiledLayer.contents tiledLayer.setNeedsDisplay(tileRect) tiledLayer.contents = c However! Docs clearly state the warning: Do not attempt to directly modify the contents property of a CATiledLayer object. Doing so disables the ability of a tiled layer to asynchronously provide tiled content, effectively turning the layer into a regular CALayer object. I believe this message implies modifying the contents property with some raw content, like image data, and that it may be safe to re-apply the existing contents (which are in my testing of type CAImageProvider) -- but I can't rely on an implementation detail in my production app. I have tested this and confirmed that the bug appears on: iPhone 14 Pro, iOS 18.5 iPhone 13 Pro, iOS 17.5.1 iPhone 5s, iOS 15.8.3 iPad Pro 1st gen, iPadOS 18.4.1 a couple simulator versions I can also confirm that the fix (to re-apply contents property) is also working properly on all these versions. Is this expected behavior, that tiled layer redraws itself entirely instead of redrawing specific tiles? Is it safe to modify contents of a CATiledLayer by re-applying the existing contents? If not, is there an alternative to avoid flashing?

I am new to Xcode and trying to learn how to use Metal for my internship. I am trying to link the binaries of Foundation.framework, Metal.framework, and Quartcore.framework. But whenever I try to build it always fails to find any of them. I have my Header Search Path as $(PROJECT_DIR)/metal-cpp, I tried adding some for the Frameworks but that did not work either. I do have the binaries linked in the Build Phases, so I don't know what else I could be missing.

Hello! I’m experiencing a crash in my iOS/iPadOS app related to a CALayer rendering process. The crash occurs when attempting to render a UIImage on a background thread. The crashes are occurring in our production app, and while we can monitor them through Crashlytics, we are unable to reproduce the issue in our development environment. Relevant Code I have a custom view controller that handles rendering CALayers onto images. This method creates a CALayer on the main thread and then starts a detached task to render this CALayer into a UIImage. The whole idea is learnt from this StackOverflow post: https://stackoverflow.com/a/77834613/9202699 Here are key parts of my implementation: class MyViewController: UIViewController { @MainActor func renderToUIImage(size: CGSize, itemsToDraw: [MyDrawingItem], transform: CGAffineTransform) async -> UIImage? { // Create CALayer and add it to the view. CATransaction.begin() let customLayer = MyDrawingLayer() customLayer.setupContent(itemsToDraw: itemsToDraw) // Position the frame off-screen to it hidden. customLayer.frame = CGRect( origin: CGPoint(x: -100 - size.width, y: -100 - size.height), size: size) customLayer.masksToBounds = true customLayer.drawsAsynchronously = true view.layer.addSublayer(customLayer) CATransaction.commit() // Render CALayer to UIImage in background thread. let image = await Task.detached { customLayer.setNeedsDisplay() let renderer = UIGraphicsImageRenderer(size: size) let image = renderer.image { // CRASH happens on this line let cgContext = $0.cgContext cgContext.saveGState() cgContext.concatenate(transform) customLayer.render(in: cgContext) cgContext.restoreGState() } return image }.value // Remove the CALayer from the view. CATransaction.begin() customLayer.removeFromSuperlayer() CATransaction.commit() return image } } class MyDrawingLayer: CALayer { var itemsToDraw: [MyDrawingItem] = [] func setupContent(itemsToDraw: [MyDrawingItem]) { self.itemsToDraw = itemsToDraw } override func draw(in ctx: CGContext) { for item in itemsToDraw { // Render the item to the context (example pseudo-code). // All items are thread-safe to use. // Things to draw may include CGPath, CGImages, UIImages, NSAttributedString, etc. item.draw(in: ctx) } } } Crash Log The crash occurs at the following location: Crashed: com.apple.root.default-qos.cooperative 0 MyApp 0x5cb300 closure #1 in closure #1 in MyViewController.renderToUIImage(size: CGSize, itemsToDraw: [MyDrawingItem], transform: CGAffineTransform) + 4313002752 (<compiler-generated>:4313002752) 1 MyApp 0x5cb300 closure #1 in closure #1 in MyViewController.renderToUIImage(size: CGSize, itemsToDraw: [MyDrawingItem], transform: CGAffineTransform) + 4313002752 (<compiler-generated>:4313002752) 2 MyApp 0x1a4578 AnyModifier.modified(for:) + 4308649336 (<compiler-generated>:4308649336) 3 MyApp 0x7b4e64 thunk for @escaping @callee_guaranteed (@guaranteed UIGraphicsPDFRendererContext) -> () + 4315008612 (<compiler-generated>:4315008612) 4 UIKitCore 0x1489c0 -[UIGraphicsRenderer runDrawingActions:completionActions:format:error:] + 324 5 UIKitCore 0x14884c -[UIGraphicsRenderer runDrawingActions:completionActions:error:] + 92 6 UIKitCore 0x148778 -[UIGraphicsImageRenderer imageWithActions:] + 184 7 MyApp 0x5cb1c0 closure #1 in MyViewController.renderToUIImage(size: CGSize, itemsToDraw: [MyDrawingItem], transform: CGAffineTransform) + 100 (FileName.swift:100) 8 libswift_Concurrency.dylib 0x60f5c swift::runJobInEstablishedExecutorContext(swift::Job*) + 252 9 libswift_Concurrency.dylib 0x62514 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 144 10 libdispatch.dylib 0x15ec0 _dispatch_root_queue_drain + 392 11 libdispatch.dylib 0x166c4 _dispatch_worker_thread2 + 156 12 libsystem_pthread.dylib 0x3644 _pthread_wqthread + 228 13 libsystem_pthread.dylib 0x1474 start_wqthread + 8 Questions Is it safe to run UIGraphicsImageRenderer.image on the background thread? Given that I want to leverage GPU rendering, what are some best practices for rendering images off the main thread while ensuring stability? Are there alternatives to using UIGraphicsImageRenderer for background rendering that can still take advantage of GPU rendering? It is particularly interesting that the crash logs indicate the error may be related to UIGraphicsPDFRendererContext (crash log line number 3). It would be very helpful if someone could explain the connection between starting and drawing on a UIGraphicsImageRenderer and UIGraphicsPDFRendererContext. Any insights or guidance on this issue would be greatly appreciated. Thanks!!!

I’m trying to create a CGContext that matches my screen using the following code let context = CGContext( data: pixelBuffer, width: pixelWidth, // 3456 height: pixelHeight, // 2234 bitsPerComponent: 10, // PixelEncoding = "--RRRRRRRRRRGGGGGGGGGGBBBBBBBBBB" bytesPerRow: bytesPerRow, // 13824 space: CGColorSpace(name: CGColorSpace.extendedSRGB)!, bitmapInfo: CGImageAlphaInfo.none.rawValue | CGImagePixelFormatInfo.RGBCIF10.rawValue | CGImageByteOrderInfo.order16Little.rawValue ) But it fails with an error CGBitmapContextCreate: unsupported parameter combination: RGB 10 bits/component, integer 13824 bytes/row kCGImageAlphaNone kCGImageByteOrder16Little kCGImagePixelFormatRGBCIF10 Valid parameters for RGB color space model are: 16 bits per pixel, 5 bits per component, kCGImageAlphaNoneSkipFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaNoneSkipFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaNoneSkipLast 32 bits per pixel, 8 bits per component, kCGImageAlphaPremultipliedFirst 32 bits per pixel, 8 bits per component, kCGImageAlphaPremultipliedLast 32 bits per pixel, 10 bits per component, kCGImageAlphaNone|kCGImagePixelFormatRGBCIF10|kCGImageByteOrder16Little 64 bits per pixel, 16 bits per component, kCGImageAlphaPremultipliedLast 64 bits per pixel, 16 bits per component, kCGImageAlphaNoneSkipLast 64 bits per pixel, 16 bits per component, kCGImageAlphaPremultipliedLast|kCGBitmapFloatComponents|kCGImageByteOrder16Little 64 bits per pixel, 16 bits per component, kCGImageAlphaNoneSkipLast|kCGBitmapFloatComponents|kCGImageByteOrder16Little 128 bits per pixel, 32 bits per component, kCGImageAlphaPremultipliedLast|kCGBitmapFloatComponents 128 bits per pixel, 32 bits per component, kCGImageAlphaNoneSkipLast|kCGBitmapFloatComponents See Quartz 2D Programming Guide (available online) for more information. Why is it unsupported if it matches the 6th option? (32 bits per pixel, 10 bits per component, kCGImageAlphaNone|kCGImagePixelFormatRGBCIF10|kCGImageByteOrder16Little)

I have a 3х3 Matrix which I need to apply to UIImage and save it in Documents folder. I successfully converted the 3x3 Matrix (represented as [[Double]]) to CATrasform3D and then I have broken my head with trying to figure out how to apply it to UIImage. The only property where I can I apply it is UIView(or UIImageView in case with working with UIImage) transform property. But it has nothing to do with UIImage itself. I can't save the UIImage from transformed the UIImageView with all the transformations. And all the CoreGraphic methods (like concatenate for CGContext) only work with affine transformations which not suits for me. Please give me a hint what direction I should look. Does Apple has native methods or I have to use 3rd party frameworks for this functionality?

Hi Team, We are facing crash in CAMediaTimingCopyRenderTiming for production users. And we are unable to trace the crash. Below is the crash stack trace - Crashed: com.apple.main-thread 0 QuartzCore 0x14b9c CAMediaTimingCopyRenderTiming + 660 1 QuartzCore 0xfa9c -[CAAnimation _setCARenderAnimation:layer:] + 64 2 QuartzCore 0x146e4 -[CAAnimationGroup _copyRenderAnimationForLayer:] + 356 3 QuartzCore 0x12f3c CA::Layer::commit_animations(CA::Transaction*, double ()(CA::Layer, double, void*), void ()(CA::Layer, CA::Render::Animation*, void*), void ()(CA::Layer, __CFString const*, void*), CA::Render::TimingList* ()(CA::Layer, void*), void*) + 688 4 QuartzCore 0x277c invocation function for block in CA::Context::commit_transaction(CA::Transaction*, double, double*) + 176 5 QuartzCore 0x482bc CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 384 6 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 7 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 8 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 9 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 10 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 11 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 12 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 13 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 14 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 15 QuartzCore 0x48244 CA::Layer::commit_if_needed(CA::Transaction*, void (CA::Layer*, unsigned int, unsigned int) block_pointer) + 264 16 QuartzCore 0x2e078 CA::Context::commit_transaction(CA::Transaction*, double, double*) + 6224 17 QuartzCore 0x59dc0 CA::Transaction::commit() + 644 18 QuartzCore 0x44dbc CA::Transaction::flush_as_runloop_observer(bool) + 84 19 CoreFoundation 0x898e8 CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION + 32 20 CoreFoundation 0x1951c __CFRunLoopDoObservers + 552 21 CoreFoundation 0x75214 __CFRunLoopRun + 1004 22 CoreFoundation 0x79d20 CFRunLoopRunSpecific + 584 23 GraphicsServices 0x1998 GSEventRunModal + 160 24 UIKitCore 0x371448 -[UIApplication _run] + 868 25 UIKitCore 0x3710c0 UIApplicationMain + 312 26 SwiftUI 0x183c68 OUTLINED_FUNCTION_895 + 2184 27 SwiftUI 0xfdf1c block_copy_helper.1 + 452 28 SwiftUI 0xeaf6c OUTLINED_FUNCTION_901 + 2312 29 Evie Ring 0x2dd20c main + 10 (MovanoRingApp.swift:10) 30 ??? 0x1c7724344 (Missing)

Does anyone know why the following call fails? CGPDFOperatorTableSetCallback(operatorTable, "ID", &callback); The PDF specification seems to indicate that ID is an operator? BTW what is the proper topic/subtopic for questions about Quartz? Wasn't sure what topic on the new forums to post this under.