cglayer

I have a UIPanGestureRecognizer attached to a view in my iOS app. I copied the code from the Touches sample app for the pan handler. When the gesture starts, my code: Records the original anchor point and center. Changes the anchor point and center to be around the user's fingers, like so: CGPoint locationInView = [gestureRecognizer locationInView:target]; CGPoint locationInSuperview = [gestureRecognizer locationInView:target.superview]; target.layer.anchorPoint = CGPointMake( locationInView.x / target.bounds.size.width, locationInView.y / target.bounds.size.height ); target.center =

I have a loop that fires a function 30 times per second. The function changes the position of a couple of points that I use to animate. I draw lines through all the points, meaning that the lines will change 30 times per second. I draw these lines to a CGLayer, which then is drawn to a UIView in the drawRect: method. I do this because I understand that performance is improved when drawing offscreen. However, it seems that the CGLayer saves all actual lines instead of drawn pixels, since even if I clear it, the program runs slower and slower over time when more lines are drawn. I'm asking for

I am caching some graphics onto CGLayers and then storing them in NSValue objects using @encode (so as to store them in an array). I just wanted to make sure that I handle the retain/release correctly... I cache the graphics and store them in the array something like this: // Create an NSMutableArray "newCache" CGLayerRef drawingLayer = CGLayerCreateWithContext(context, bounds.size, NULL); CGContextRef drawingContext = CGLayerGetContext(drawingLayer); // Do some drawing... [newCache addObject:[NSValue valueWithBytes:&drawingLayer objCType:@encode(CGLayerRef)]]; CGLayerRelease(drawingLayer); //

I am working on a drawing application, I am using CGlayers for drawing, So I open my canvas for drawing on click of a button, I am using UIBezierPath and then converting it to CGPath in touchesMoved below and then using it to draw -(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { if (ctr == 4) { m_touchMoved = true; self.currentPath = [[DrawingPath alloc] init]; [self.currentPath setPathColor:self.lineColor]; self.currentPath.pathWidth = [NSString stringWithFormat:@"%f",self.lineWidth]; pts[3] = midPoint(pts[2], pts[4]);// move the endpoint to the middle of the line joining the

I am working with unod redo operations on CgLayer, I have tried some code, but not able to get it working, dont know , where I am getting wrong, below is my code, which i have written this is my drawRect function - (void)drawRect:(CGRect)rect { m_backgroundImage = [UIImage imageNamed:@"bridge.jpg"]; CGPoint drawingTargetPoint = CGPointMake(0,0); [m_backgroundImage drawAtPoint:drawingTargetPoint]; switch(drawStep) { case DRAW: { CGContextRef context = UIGraphicsGetCurrentContext(); if(myLayerRef == nil) { myLayerRef = CGLayerCreateWithContext(context, self.bounds.size, NULL); }

I'm confusing CGLayer and CALayer . They look similar, so why are there separate implementations? What's the difference between, and compatibility of, CGLayer and CALayer ? Joe Blow They are completely different, and not compatible. To be absolutely clear: it is strictly a coincidence that the word "layer" is used in both names ; they are completely unrelated . CGLayers are a "special" "high performance" thingy. You could consider them "like bitmaps, but better." Apple sat down and said "We're sick of people using bitmaps, let's make something better!" :-) Indeed, you only work with CGLayers

I am working with a drawing app, I am using CGlayers for drawing. On touches ended, I get image out of the layer and store it in a Array, which I use to undo operation. My touches ended function -(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { NSLog(@"Touches ended"); UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextDrawLayerInRect(context, self.bounds, self.drawingLayer); m_curImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); [m_undoArray addObject: m_curImage]; }