CATiledLayer draws same tile multiple times

Originator:felix.lamouroux
Number:rdar://11382508 Date Originated:04-May-2012 02:31 PM
Status:Open Resolved:
Product:iPhone SDK Product Version:5.1
Classification:Performance Reproducible:Alwazs
 
Summary:
A CATiledLayer draws the same tile multiple times (mostly two times one right after the other). This creates huge drawbacks for the performance for rendering intensive apps.

This happens both for UIViews that are backed by a CATiledLayer (drawRect:) as well as for pure CATiledLayers (drawInContext:).

Steps to Reproduce:
Build & Run the attached demo app and observe the logs. This is a simple Xcode-Template (Single View) with a view backed by a CATiledLayer and a single CATiledLayer added in addition to illustrate the bug in both scenarios.

Expected Results:
The respective drawing methods should be called once for each tile and CATiledLayer.

Actual Results:
The drawing methods are called twice for each tile and CATiledLayer.

Regression:
This has been reproduced on iOS 5.1 on device supporting multithreaded rendering via CATiledLayers (ie. this is not observable on iPhone 3GS).

Notes:

'CATiledLayerDuplicateDraws.zip' was successfully uploaded

Comments


Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at bugreport.apple.com before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!