Hi Plasma devs, a small reminder: if you want to animate windows use KWin. You should not animate your windows yourself. Why you might ask?
X11 sucks. If you animate using X11 you are moving the window. With each animation step you perform a configure event on the X server. This is then sent to all listening applications (e.g. KWin, Plasma, many more) which are woken up, process, etc. You cannot in no reasonable way know when the frame gets rendered. So if you animate yourself you pick a "frame rate" which might be anywhere from stuttering to too fast. You just cannot know, because you have no introspection into X. If you send too many events, you just block everything due to too many wakeups and you get stuttering and in worst case even tearing. Oh and you increase the CPU usage significantly. Which again slows down your animation. How does this change when you use KWin? Well KWin for starters doesn't need to move the window. All it needs to do is move a window texture around. For that it uses OpenGL and there is one thing OpenGL is really good at: that's texture mapping. So with KWin you don't have to send configure requests, you don't wake up completely uninterested applications. The animation is controlled (KWin knows its framerate and how long it took to render the last frame), it never renders more frames than the screen could show. It cannot stall due to too many frames rendered. If you have a problem where you want to animate windows and do so by moving the window position: talk to me. But please, pretty please never animate windows yourself. X sucks for that and Wayland makes it impossible. So please don't do it. Talk to me. The same goes for opacity btw. Don't change the window opacity with Qt's mechanism, but use KWin. It's pretty much the same: QWindow's opacity goes through an X property, you have no control when it goes on the screen. KWin can animate opacity without going through X. That's how our fade effect works. So if you want to animate any aspect of the window: talk to me. If you have code which animates: get rid of it. Cheers Martin
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