core-graphics

问题 On Mac OS X, I know in Cocoa I can set up a observer for detecting future screen saver events or workspace lock events, like this: - (id)init { if ((self = [super init])) { NSDistributedNotificationCenter* distCenter = [NSDistributedNotificationCenter defaultCenter]; [distCenter addObserver:self selector:@selector(onScreenSaverStarted:) name:@"com.apple.screensaver.didstart" object:nil]; [distCenter addObserver:self selector:@selector(onScreenSaverStopped:) name:@"com.apple.screensaver

问题 For an app, I have to place a MKCircle annotation on a MKMapView. However, the circle needs to be moved/resized. I know this has been asked, e.g. Moving MKCircle in MKMapView where removing/adding the annotation is suggested to get that behavior. However, I consider the drawing being very slow, like the user in this post: Smooth resizing of MKCircle. Since there are now answers to this question, the question seemed to use YHAnimatedCircleView . By slow I mean, when I use a UISlider to change

问题 I'm trying to draw a quarter circle in iOS. In Mac OS, it seems you can use appendBezierPathWithArcWithCenter but this doesn't seem to work in iOS. Does anyone know how to simply draw a quarter circle in iOS? Thanks 回答1: There are two iOS equivalents, one for UIBezierPath and one for CGPath : UIBezierPath equivalent UIBezierPath *path = [UIBezierPath bezierPath]; [path addArcWithCenter:centerPoint radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES]; CGPath equivalent

问题 how to create this 2D look How to I create this. Thanks a lot. 回答1: Try this class TwoDView : UIView { public var xDiff : CGFloat = 5.0 public var yDiff : CGFloat = 5.0 override func draw(_ rect: CGRect) { let ctx = UIGraphicsGetCurrentContext() ctx?.move(to: CGPoint(x: 0, y: rect.height - yDiff)) ctx?.addLines(between: [ CGPoint(x: rect.width - xDiff, y: rect.height - yDiff), CGPoint(x: rect.width, y: rect.height), CGPoint(x: xDiff, y: rect.height), CGPoint(x: 0, y: rect.height - yDiff) ])

问题 I wonder if is possible to animate the fill color of a path I have drawn using CoreGraphics? I am drawing this: Simple drawing with Quartz - Core Graphics and I want to change its fill color from white to let's say gray. Is this possible? I know the existence of view.layer.content property but Is this useful here? Though, I am not sure how can I use it in this case. Thanks in advance. Update I am trying this approach (its buggy, hence I can tell if its going to work) basically I am creating a

问题 I wonder if is possible to animate the fill color of a path I have drawn using CoreGraphics? I am drawing this: Simple drawing with Quartz - Core Graphics and I want to change its fill color from white to let's say gray. Is this possible? I know the existence of view.layer.content property but Is this useful here? Though, I am not sure how can I use it in this case. Thanks in advance. Update I am trying this approach (its buggy, hence I can tell if its going to work) basically I am creating a

问题 I used codes below to draw a dashed line // get the current CGContextRef for the view CGContextRef currentContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort]; // grab some useful view size numbers NSRect bounds = [self bounds]; float width = NSWidth( bounds ); float height = NSHeight( bounds ); float originX = NSMinX( bounds ); float originY = NSMinY( bounds ); float maxX = NSMaxX( bounds ); float maxY = NSMaxY( bounds ); float middleX = NSMidX( bounds ); float middleY =

问题 I'm trying to generate a graph with gradient/shading effect. Now I'm able to draw line graph and applied gradient effect to that graph. It is applying to whole view not to the graph. Now I'm getting image like this. But I want like this. I want gradient effect just under the graph. Please help me in this. Thanks in advance. The code that I'm using is: UIGraphicsBeginImageContext(self.graphView.frame.size); [graphView.image drawInRect:CGRectMake(0, 0, self.graphView.frame.size.width, self

问题 I have an iPhone application and I need to implement the following method: +(UITextView *)textView:(UITextView *) withCuttedRect:(CGRect)r This method must cut (fill with [UIColor clearColor] ) the rect r from UITextView and return UITextView object. The user will see the view behind UITextView from the cutted holes. How can it be done? 回答1: When you would have something like: +(UITextView *)textView:(UITextView *)textView withCuttedRect:(CGRect)r { } you actually can simply access the

问题 I have the following situation in my multi-monitor setup: In this example I want to position a window exactly at the coordinates depicted with the yellow arrow. All I do have however, are the coordinates of an NSView that is a subview of the contentView of an NSWindow that spans the entire (bigger,upper) secondary monitor. Here's how the global coordinate space is defined: {0,0} is the coordinate of the upper left corner of my laptop screen. (green) {-296, -1080} is the coordinate of the