[PSA] Non-layer backed views + scrolling + visual artifacts
[PSA] Non-layer backed views + scrolling + visual artifacts
- Subject: [PSA] Non-layer backed views + scrolling + visual artifacts
- From: Seth Willits <email@hidden>
- Date: Fri, 28 Nov 2014 13:14:50 -0800
UGH.
So my app was doing this:
http://www.sethwillits.com/temp/ScrollingWeirdness.mp4
… very often, and sometimes dramatically worse than that (but also sometimes much more subtle).
For subtle, stick these two images in separate tabs and switch back and forth:
http://sethwillits.com/temp/ScrollingWeirdnessSubtleA.png
http://sethwillits.com/temp/ScrollingWeirdnessSubtleB.png
The very first thing I tried was setting the window's content view to be layer-backed to see if that changed anything, and it didn't. So I then created a stripped down bare bones nothing-but-nibs project that was still exhibiting this behavior and then spent 3 hours exploring 6 or 7 different dead ends trying to find the cause.
It took me too long to figure out that my initial test was broken, since after setting the window's content view to be layer-backed, I then _replaced_ that content view with the view from another nib which wasn't layer-backed. *sigh* As soon as I turned on layer-backing for real, the problem went away.
Here's a project with two windows side by side so you can compare and see if you see them. For me it may take a lot of fiddling (scrolling, window activation changes, app changes, rain dancing, knocking on wood etc) to get it to start breaking really obviously. Other times it happens immediately and constantly. Otherwise you have to be paying attention reaaaally closely to see the subtle brokenness.
http://www.sethwillits.com/temp/ScrollingWeirdness.zip
For me, this is 100% repeatable, and 100% fixable by turning on layer-backing. I'm on 10.10.1, iMac14,2 NVIDIA 780M. I imagine it's a bug, but one that's worked around by using layer-backing.
I'll be filing a bug report…
--
Seth Willits
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