Bug 189999

Summary:	Wobbly windows causes excessive painting when (not) moving windows
Product:	[Plasma] kwin	Reporter:	Mike <mike>
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED WORKSFORME
Severity:	normal	CC:	Lukasz.Kurylo, vlad.zahorodnii, yg
Priority:	LO
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Mike 2009-04-18 21:24:26 UTC

Version:            (using Devel)
OS:                Linux
Installed from:    Compiled sources

When using wobbly windows and the show paint plugin I can see that when you grab a window to move it, it repaints the entire screen repeatedly.  This happens if you move the window or not.

To replicate, enable those plugins and then grab and move a window by 1 pixel.  The screen will flash.  This does not happen if wobbly is disabled.

Do not try to replicate if you suffer from photo-induced epilepsy!

Comment 1 Martin Flöser 2009-04-27 16:54:23 UTC

just tried around a little bit. When restricting the paint region wobbly causes artefacts. 

Don't know if it is worth the effort to restrict the painting when the window is pressed but not moved.

Comment 2 Martin Flöser 2009-11-10 11:03:45 UTC

*** Bug 213946 has been marked as a duplicate of this bug. ***

Comment 3 Martin Flöser 2010-08-04 20:32:44 UTC

With SVN rev 1159203 only changed regions are repainted. But as soon as you moved the window by one pixel the window will continue to repaint even if there is no movement.

It would be possible to test for that case that the window is not moved, but I fear it will break the effect as wobbly information are only updated while repainting and not when the window is moved.

Comment 4 Lukasz 2011-02-02 15:51:36 UTC

(In reply to comment #3)
The test should be then: 
repaint if(window moved || transformation matrix changed)

Comment 5 Martin Flöser 2011-03-09 20:22:02 UTC

*** Bug 186192 has been marked as a duplicate of this bug. ***

Comment 6 Vlad Zahorodnii 2018-08-09 09:31:27 UTC

@Martin
Can we mark this bug as RESOLVED?

It looks like the Wobbly Windows effect is doing its the best to reduce repaints. Also, I personally don't experience excessive CPU usage.

Comment 7 Martin Flöser 2018-08-09 18:39:12 UTC

Constant repaints are no longer an issue as sever as ~10 years ago. KWin got way more optimized and on the other hand CPUs got faster.