core-graphics

I draw a circle in the drawRect method and fill it with a color. Now i need to add a glowing effect to the circle. When i click on a button, the circle needs to glow. How can i do this? Any help will be greatly appreciated! Thanks in advance!!! If you are using Quartz 2D, you can simply add a white shadow to the circle. See the Quartz 2D Programming Guide for Shadows Apple's Sample code for setting up a shadow taken from the link above: void MyDrawWithShadows (CGContextRef myContext, // 1 float wd, float ht); { CGSize myShadowOffset = CGSizeMake (-15, 20);// 2 float myColorValues[] = {1.0, 1.0

I create a CGPath area as shown green circle. The CGPath area need to be clear, and the rest of image will be applied blurry or translucent effect, I can clip image inside CGPath with following code: UIGraphicsBeginImageContext(view.frame.size); CGContextAddPath(ctx, path); CGContextClip(ctx); [view.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *clipImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); UIImageWriteToSavedPhotosAlbum(clipImage, nil, nil, nil); CGPathRelease(path); but I don't know how to apply blurry or translucent effect with CGPath

I'm getting a clipped LineJoin in a UIBezierPath when one line comes back exactly over the previous line. If I adjust the second line by one pixel, the LineJoin behaves as expected. Here's the code: UIBezierPath *path = [UIBezierPath bezierPath]; [path setLineWidth:10.0f]; [path setLineCapStyle:kCGLineCapRound]; [path setLineJoinStyle:kCGLineJoinRound]; [path moveToPoint:CGPointMake(100, 100)]; [path addLineToPoint:CGPointMake(200, 100)]; [path addLineToPoint:CGPointMake(150, 100)]; [path moveToPoint:CGPointMake(100, 120)]; [path addLineToPoint:CGPointMake(200, 120)]; [path addLineToPoint

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? Joerg Simon When you would have something like: +(UITextView *)textView:(UITextView *)textView withCuttedRect:(CGRect)r { } you actually can simply access the textview's layer from core animation with textView.layer What you then can to is set a mask for

I'm creating an bitmap context using CGBitmapContextCreate with the kCGImageAlphaPremultipliedFirst option. I made a 5 x 5 test image with some major colors (pure red, green, blue, white, black), some mixed colors (i.e. purple) combined with some alpha variations. Every time when the alpha component is not 255, the color value is wrong. I found that I could re-calculate the color when I do something like: almostCorrectRed = wrongRed * (255 / alphaValue); almostCorrectGreen = wrongGreen * (255 / alphaValue); almostCorrectBlue = wrongBlue * (255 / alphaValue); But the problem is, that my

I'm trying to figure out how to draw an arc in CoreGraphics. I understand which method calls to make and how to compute the angles in the following scenario. ---------- | | *--------* When the points are both in the bottom of the rect. However when two points are in other locations, I don't know how to calculate the correct angle. ---------* | | *--------- See bottom portion of my image. Ray Wenderlich has a great tutorial about creating arcs for only in the first mentioned point positions. // sample code for creating arc for path from bottom of rect CGMutablePathRef

I'm doing a series of translations and rotations on the CTM and at some point I need to reset it to identity before going further with transformations. I can't find any proper way to do it (obviously, there should have been a function named CGContextSetCTM or so) and since efficiency is the key, I don't want to use CGContextSaveGState/CGContextRestoreGState... Get current transformation matrix via CGContextGetCTM , invert it with CGAffineTransformInvert and multiply the current matrix by the inverted one (that's important!) with CGContextConcatCTM . CTM is now identity. Note that inverting the