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POHow get a High Performance UIWebView -> UIImage on ipad retina?
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copied!<p>Have page flip type application that needs to convert the contents of a fullscreen UIWebView to a UIImage very quickly (e.g. 200ms tops). Sacrificing quality for speed is OK. Having a real tough time getting anywhere near this on a iPad3 retina. </p> <p>Do create a UIImage i am doing the common renderInContext method:</p> <pre><code>UIGraphicsBeginImageContextWithOptions(frame.size, YES, 0); CGContextRef context = UIGraphicsGetCurrentContext(); [view.layer renderInContext:context]; UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext(); </code></pre> <p>On a ipad3 retina display I typically see 400-500ms. Interestingly the second time the method is run it is much quicker (around 100ms), which doesn't help but suggests some sort of caching is happening.</p> <p>I have tried the following things:</p> <ol> <li><p>I have tried playing with the scale and opaque parameters UIGraphicsBeginImageContextWithOptions to ever possible combination. Setting the scale to say .5 or 1.0 actually makes it even slower.</p></li> <li><p>Adding CGContextSetInterpolationQuality(context, kCGInterpolationNone). No change to performance.</p></li> <li><p>webview.shouldRasterize=YES. No change to performance.</p></li> <li><p>Shrinking the UIWebView in half and then scaling to fullscreen . This does help but is still around 300ms. </p></li> </ol> <p>Any other ideas? Running this on a ipad1-2 is ok - but the ipad3 retina just kills the performance. </p>

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