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POCALayer and CGGradientRef anti-aliasing?
 

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  1. POCALayer and CGGradientRef anti-aliasing?
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    <p>I'm having an odd issue with CALayer drawing for the iPhone. I have a root layer which adds a bunch of sublayers representing "bubbles". The end result is supposed to look something like this:</p> <p><a href="http://www.expensivedna.com/IMG_0018.PNG" rel="nofollow noreferrer">http://www.expensivedna.com/IMG_0018.PNG http://www.expensivedna.com/IMG_0018.PNG</a></p> <p>The problem is that I can't seem to get the layer to anti-alias (notice the jaggies on the bubbles). My code overwriting drawInContext for the bubble CALayer is as follows:</p> <pre><code>- (void)drawInContext:(CGContextRef)theContext{ CGContextSetAllowsAntialiasing(theContext, true); CGContextSetShouldAntialias(theContext, true); size_t num_locations = 2; CGFloat locations[2] = { 0.0, 1.0 }; CGFloat components[8] = { 1.0, 1.0, 1.0, 0.5, // Start color 1.0, 1.0, 1.0, 0.0 }; // End color CGColorSpaceRef rgbColorspace = CGColorSpaceCreateDeviceRGB(); CGGradientRef glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations); CGPoint topCenter = CGPointMake(25, 20); CGPoint midCenter = CGPointMake(25, 25); CGContextDrawRadialGradient(theContext, glossGradient, midCenter, 20, topCenter, 10, kCGGradientDrawsAfterEndLocation); </code></pre> <p>}</p> <p>Now the really odd thing is that if I slightly alter the drawing code to only draw normal red circles as follows:</p> <pre><code>- (void)drawInContext:(CGContextRef)theContext{ CGContextSetAllowsAntialiasing(theContext, true); CGContextSetShouldAntialias(theContext, true); CGContextSetFillColorWithColor(theContext, [UIColor redColor].CGColor); CGContextFillEllipseInRect(theContext, CGRectMake(0, 0, 40,40)); } </code></pre> <p>Everything seems to antialias OK:</p> <p><a href="http://www.expensivedna.com/IMG_0017.PNG" rel="nofollow noreferrer">http://www.expensivedna.com/IMG_0017.PNG http://www.expensivedna.com/IMG_0017.PNG</a></p> <p>I can't seem to figure out this seemingly odd behavior. Am I missing some difference between antialiasing gradients and normal circles?</p> <p>Thanks guys.</p>
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