Summary:
If a window is being slided in and for some reason it gets closed, the
window will be slided out. The problem is that there is a jump between
the slide in animation and the slide out animation.
The reason for that is we cancel the slide in animation when the slide
out animation is started.
It makes sense to cancel previously active animations because they have
different durations. But visually, it doesn't look good.
TimeLine tries to preserve progress value when changing duration. Thus,
let's utilize that to fix the jump.
This change matters only with animation speed factor > 1.0.
CCBUG: 264276
Test Plan: Manually.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: abetts, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D15626
66a91f0861