core-graphics

问题 Trying to animatie an ellipse masked on a UIView to be scale transformed remaining in the center position. I have found CALayer - CABasicAnimation not scaling around center/anchorPoint, and followed by adding a bounds property to the maskLayer CAShapeLayer however, this ends with the mask being positioned in the left corner with only 1/4 of it showing. I would like the mask to remain within the center of the screen. @synthesize maskedView; - (void)viewDidLoad { [super viewDidLoad];

问题 What is the equivalent of CGImageCreateWithImageInRect iOS method in MonoTouch? I'm trying to convert this Objective-C line in C#: CGImageRef sampleImageRef = CGImageCreateWithImageInRect(self.CGImage, fillRect); Thanks in advance! 回答1: The CoreGrapphics function CGImageCreateWithImageInRect correspond to the WithImageInRect method of CGImage . API signature is: public CGImage WithImageInRect (RectangleF rect) Once translated from ObjectiveC your source code should look like: CGImage

问题 What is the equivalent of CGImageCreateWithImageInRect iOS method in MonoTouch? I'm trying to convert this Objective-C line in C#: CGImageRef sampleImageRef = CGImageCreateWithImageInRect(self.CGImage, fillRect); Thanks in advance! 回答1: The CoreGrapphics function CGImageCreateWithImageInRect correspond to the WithImageInRect method of CGImage . API signature is: public CGImage WithImageInRect (RectangleF rect) Once translated from ObjectiveC your source code should look like: CGImage

问题 I am trying to draw a ruler on top of UIScrollView. The way I do it is by adding a custom view called RulerView. I add this rulerView to superview of scrollView setting its frame to be same as frame of scrollView. I then do custom drawing to draw lines as scrollView scrolls. But the drawing is not smooth, it stutters as I scroll and the end or begin line suddenly appears/disappears. What's wrong in my drawRect? class RulerView: UIView { public var contentOffset = CGFloat(0) { didSet { self

问题 In my application I am rendering graphics into a block of main memory using the CPU (please don't challenge this requirement). When it is time to draw this on the screen, the following code is used in order to blit a rectangular portion of this memory to the screen via "attaching" a NSBitmapImageRep to it: void* offsetBuffer = reinterpret_cast<void*>(_buffer + sourceY * bpr + sourceX * 4); unsigned char** planes = (unsigned char**)&offsetBuffer; NSRect destRect; destRect.origin.x = destX;

问题 I wish to have the following view respond to the magnification gestures, but it only works the first time. The view can be magnified as expected, but after the view is released, subsequent touches do not trigger the gesture. Is there a way to have the gesture work continuously? struct Card: View { @State var magScale: CGFloat = 1 var magnification: some Gesture { MagnificationGesture().onChanged { gesture in magScale = gesture } } var body: some View { Rectangle() .frame(width: 200, height:

问题 I recently got a new macbook pro (2020 13-inch, running Big Sur v 11.1) and am using Rstudio (V 1.3.1093 with R version 4.0.3). On my old computer, I often used the quartz() function to view my plots in the external graphics viewer. On my old mac, this would allow me to dynamically resize, keep fonts consistent, save directly from the resized version, etc. Now, on my new computer, it is behaving... strangely. For example, when I run quartz() and a window opens, then I run a ggplot , the

问题 In Objective-C I was able to use CGBitmapContextCreate to create an empty context. I am trying to to the same in Swift 3, but for some reason it is nil. What am I missing? let inImage: UIImage = ... let width = Int(inImage.size.width) let height = Int(inImage.size.height) let bitmapBytesPerRow = width * 4 let bitmapByteCount = bitmapBytesPerRow * height let pixelData = UnsafeMutablePointer<UInt8>.allocate(capacity: bitmapByteCount) let context = CGContext(data: pixelData, width: width, height

问题 In Objective-C I was able to use CGBitmapContextCreate to create an empty context. I am trying to to the same in Swift 3, but for some reason it is nil. What am I missing? let inImage: UIImage = ... let width = Int(inImage.size.width) let height = Int(inImage.size.height) let bitmapBytesPerRow = width * 4 let bitmapByteCount = bitmapBytesPerRow * height let pixelData = UnsafeMutablePointer<UInt8>.allocate(capacity: bitmapByteCount) let context = CGContext(data: pixelData, width: width, height

问题 I am trying to convert my custom UIView into UIImage using core graphic, but sometimes it turns to black, my whole UIImage looks like a black image. What I noticed is that if the height of my UIView is exceeding 4096 regardless what the width is then the produced UIImage will be black! Note 1: my custom UIView is loaded from a nib file. Here is my code: func getImageWithScale(_ scale: CGFloat) -> UIImage { let size = self.bounds.size.applying(CGAffineTransform(scaleX: scale, y: scale))