core-graphics

i want to create a path.something like i touch the screen and draw line in touchmove event.when line intersect from starting point.fill that path using any colour. now see in the image i've drawn a line.i just want to detect if line intersects again to start point.then fill that path with my own desired color.also i m using core graphics to draw line but it's very slow on real device.could you tell me a way to improve speed? Header: #import <UIKit/UIKit.h> @interface myView : UIView { CGMutablePathRef path; CGPathRef drawingPath; CGRect start; BOOL outsideStart; } @end Implementation: #import

I would like to create a UIBezierPath with 10px rounded corners and with gradient fill. How can I acheive this effect? Here's an image of what I want to do: As you can see, this square has: 2px black border 10px rounded corners red to green linear gradient fill How can I do this programatically without using pattern image color ? Here's how I create the path: UIBezierPath *border = [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius:10.0f]; [border setLineWidth:2]; [[UIColor blackColor] setStroke]; [border stroke]; [[UIColor redColor] setFill]; <-- what should I put here? [border

I search all the question and answer in StackOverflow but can not get the result I want. I would like to use a PNG file, to display as a stroke at the point user touch and move. This is the PNG file: But I did all the ways on StackOverflow, even using CGPatternRef, but I don't have the result I want. The result I have is here: But the result I want to have is here: This result I have done in OpenGL ES, but I can not do that in Core Graphics. I think I can use CGContextDrawImage at each point, but this way cause poor performance because I must draw image all the points between 2 points user

I want to draw a UIView in my current CGGraphicsContext . I draw the UIView via renderInContext: , but it's not positioned correctly (always in the top left corner). I have all values of the UIView available for drawing the UIView . CGRect frame; CGRect bound; CGPoint center; CGAffineTransform transform; I currently set the position and rotation of the layer like this: CGContextTranslateCTM(context, frame.origin.x, frame.origin.y); CGContextRotateCTM(context, (CGFloat) atan2(transform.b, transform.a)); But the position is, due to the rotation, not correct and differs from the original position

The article https://www.objc.io/issues/12-animations/animating-custom-layer-properties/ has this to say about doing completely custom animations with Core Animation: Suppose that instead of implementing our clock face using individual layers, we wanted to draw the clock using Core Graphics. (In general this will have inferior performance , but it’s possible to imagine that there are complex drawing operations that we might want to implement that would be hard to replicate using ordinary layer properties and transforms.) How would we do that? In other words, we draw each frame of the CA

I'm reading this tutorial on getting pixel data from the iPhone camera. While I have no issue running and using this code, I need to take the output of the camera data (which comes in BGRA) and convert it to ARGB so that I can use it with an external library. How do I do this? If you're on iOS 5.0, you can use vImage within the Accelerate framework to do a NEON-optimized color component swap using code like the following (drawn from Apple's WebCore source code ): vImage_Buffer src; src.height = height; src.width = width; src.rowBytes = srcBytesPerRow; src.data = srcRows; vImage_Buffer dest;