Disabling composition for full-screen applications

[es20490446e]

I figured out another way of disabling composition for full-screen applications.

The trick is simple: instantly disabling composition on full screen, and if the full-screen application loses focus just waiting 10 seconds before re-enabling composition. That prevents 95% of glitches.

Better than that: no need to constantly poll the current window to see if it is full-screen, wasting computer resources. It only checks full-screen status on a window change.

Here you have the algorithms, in case you find that useful.

[es20490446e]

By the way I have figured out an even better algorithm to do this. Now:

• Entering or leaving full-screen instantly toggles composition. You can't even see the transition.
• Composition isn't re-enabled if the full-screen window loses focus, till that window is closed.
• Applications started as windowed don't automatically block composition when maximized, for example web-browsers.
• No perceivable use of CPU or IO on the system monitor.

The trick was simple: only re-test for full-screen if the last known full-screen window is no longer full-screen.

Everything is done in memory for maximum performance, and only iterated on window focus change.

[es20490446e]

@tildearrow Ported to kwinscript on the KDE Store.

[tildearrow]

Full-screen unredirection now available with the latest KWin-lowlatency release I just pushed a bit ago.