For the usage of KWin in Plasma Active many of KWin’s advanced features are just not needed. For example on Plasma Active we target OpenGL ES/EGL compositing, so the for desktop usage still useful XRender compositing is just unneccessary bloat added to the binary.
In 4.7 we started to add some build-options to remove unused parts from the build. We decided that on Plasma Active we do not need window decorations and added an option to exclude the decorations from the build and the basic functionality to start KWin without any decoration plugin present (which was not possible before).
Now with master open and a GSoC working on modularizing KWin, we were able to split out more stuff which can be disabled at compile time. There is a new build option to group all the settings for KWin on Plasma Active which currently includes:
- No window decorations
- No configuration modules
- Reduced set of effects
- No Alt+Tab (window switching)
- No Screenedge interaction
- No XRender Compositing
- Default build to OpenGL ES if available at compile time
Some of the removed parts also affect the size of the KWin binary and/or the KWin internal libraries. I was interested in the differences of size when building KWin for desktop and for Plasma Active. So today I did a release build of current master with “normal” build flags and with the active build flag and compared the size of:
- oxygen decoration
For the desktop this sums up here on my system to 3239.5 KB and for active it’s only 1987.3 KB. And this is without considering the size of the installed package where the difference is much bigger as we do not install any decorations and configuration modules on Active. I’m really quite impressed seeing that the size of KWin is so much decreased. The biggest impact has the removal of some desktop effects: the size of kwin_effects_builtins goes from 927 KB to 269 KB. And there is more to go like disabling window tiling support, desktop change OSD and so on and so on…
I hope to get some “real” numbers on comparing the package size once both builds based on master are available as a package.
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