Re: Ugly flickering in some views

[Eric Wasylishen]

On 2012-01-25, at 12:21 PM, Fred Kiefer wrote:

> Hi Eric,
> 
> On 25.01.2012 20:02, Eric Wasylishen wrote:
>>>> Ok, thanks for testing. I'm not sure what we should do; I asked Fred's 
>>>> opinion.
>>>> 
>>>> If we end up keeping copy-on-scroll on for the release you can put in this 
>>>> hack for the problematic scroll view:
>>>> 
>>>> [[aScrollView contentView] setCopiesOnScroll: NO];
>>>> 
>>>> Not ideal, but debugging flickering problems tends to be very difficult.
>>> 
>>> German's problem was before you applied r34614, how did that change affect 
>>> this problem? But that patch seems to have its own problems.
>>> 
>>> My main problem is when resizing a whole window, this flickers horribly, 
>>> but I am not sure whether GNUstep is causing this or my driver for the 
>>> graphic card. But it happens only with GNUstep windows.
>>> 
>>> 
>>> What are our options here?
>>> 
>>> - Find a proper solution within the next few days.
>>> 
>>> - Disable copy-on-scroll in all scroll views.
>>> 
>>> - Revert to the old cairo surface.
>>> 
>>> - Ignore the problem as it only happens for some views.
>>> 
>>> None of that (apart from the first one, which isn't that realistic) sounds 
>>> too attractive. Disabling copy-on-scroll will make scroll views horribly 
>>> slow and affect everybody, even people not using cairo. I think I hate the 
>>> option to revert the standard cairo surface the least. This should send us 
>>> back to the way GNUstep was about a year ago, but we can revert this step 
>>> if we find a proper fix for the open issues.
>>> 
>>> Fred
>>> 
>> 
>> I thought a bit about this. First, sorry for putting us in this situation!
>> 
>> The conclusion I came to is I should have strictly followed the code freeze. 
>> Only bugfixes that have a localized effect should be allowed in during the 
>> freeze… we should be shipping code that was tested over the last 8 months 
>> and not doing large last-minute changes like I did.
>> 
>> So my preference is to revert the two commits to gui I made since the freeze 
>> (r34606 and r34614). This is, in other words, the "Disable copy-on-scroll in 
>> all scroll views." option. I know scrolling will be slower than it should, 
>> but on the other hand it took almost 8 months to realize I had introduced a 
>> bug that was disabling it, and AFAIK no one complained to the mailing list.
>> 
>> If I find solution to the scrolling flickering (or the general window resize 
>> flickering) in the next few weeks after the release, we could always do a 
>> bugfix release.
> 
> Wouldn't it be simpler to just turn off copy on scroll in the NSScrollView?

Do you mean instead of reverting r34606, just turn off copy on scroll in 
NSScrollView? I guess that should be safe.

I think r34614 should be reverted until after the release, though.

>> btw, but is it KDE4 where you are having very bad flickering when resizing? 
>> Which video card do you have?
> 
> It is KDE4 and I am using a AMD graphics card. Maybe I should play a bit with 
> the configuration program.
> 
> Fred

Ok, thanks for the info. I have a nvidia 9400m, and just did a native install 
of Ubunutu on my laptop (was using VirtualBox before) - so I'll try kde4 too.

Eric