D18042: WIP: Add high DPI support to internal KWin windows

davidedmundson created this revision.
davidedmundson added a reviewer: KWin.
Herald added a project: KWin.
Herald added a subscriber: kwin.
davidedmundson requested review of this revision.

REVISION SUMMARY
  So far we didn't try to do high DPI on kwin internal windows, such as
  the user context menu and tab bars and whatever.
  
  Due to wayland scaling they were the correct phyiscal size but upscaled.
  This patch fixes our QPA to enable Qt's high-dpi support.
  
  BUG: 402853
  
  I've tagged it as a WIP because:
  
  - There's a hack for with icons. See screen.cpp I don't see how this can be fixed without Qt changes.
  
  Patch would still make sense without it as it will make text and
  everything else crisper
  
  - It's quite an invasive change, it needs some thorough testing

TEST PLAN
  Ran at 2x on my normal DPI screen (as that's easier to see anything)
  
  - User action menu is high DPI
  - Window deco tooltips are still fine
  - Tab switcher is high DPI

REPOSITORY
  R108 KWin

BRANCH
  internal_scale

REVISION DETAIL
  https://phabricator.kde.org/D18042

AFFECTED FILES
  main_wayland.cpp
  plugins/qpa/backingstore.cpp
  plugins/qpa/backingstore.h
  plugins/qpa/screen.cpp
  plugins/qpa/window.cpp
  plugins/qpa/window.h
  shell_client.cpp

To: davidedmundson, #kwin
Cc: kwin, kvanton, jraleigh, GB_2, mkulinski, ragreen, jackyalcine, Pitel, iodelay, bwowk, ZrenBot, ngraham, lesliezhai, ali-mohamed, hardening, jensreuterberg, abetts, sebas, apol, mart