Question

I’ve load an image into narrow UIImageView – the width is 3px, the height is approx. 10

Then I’ve rotate the view – and I’ve got not pleasant picture, with visual distortion (like http://upload.wikimedia.org/wikipedia/commons/f/fd/Anti-aliased-diamonds.png on the left part of picture).
Is any way to fix it? Does Quartz let anti-alias pictures?

Answer 1

if you are rotating using UIView’s transform property or rotating via the view’s layer: you can produce superior looking results with quartz’s apis directly.

you can create a higher quality image using a quartz image process which creates a new image and specify high quality with anti-aliasing for the transform and rendering.

this image process could be implemented many ways, such as CGContextRotateCTM followed by CGContextDrawImage, then accessing the new image with CGBitmapContextCreateImage.

alternatively, you may prefer to draw the image directly to the context rather than creating an intermediate.