D18633: [kcmkwin/kwindecoration] Draw decoration buttons over the decoration palette

davidedmundson created this revision.
davidedmundson added a reviewer: KWin.
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davidedmundson requested review of this revision.

REVISION SUMMARY
  The breeze buttons adapt to the used colour scheme. They expect to be drawn over
  the "Active Titlebar" colour defined by the user.
  
  In the KCM we're mixing roles from the window deco with classic window palette roles.
  This leads to a situation where we can draw white on white (or black on black etc)
  
  The KCM currently attempts to resolve this by blending the current decorated button 
  with the foreground colour text. Unfortunately if you have a white decoration button, 
  black text and a grey window this ultimately just ends up being grey-on-grey.
  
  This patch instead renders the buttons over the same background used in the 
  actual window decoration for maximum contrast.

TEST PLAN
  Opened KCM

REPOSITORY
  R108 KWin

BRANCH
  origin-master (branched from master)

REVISION DETAIL
  https://phabricator.kde.org/D18633

AFFECTED FILES
  kcmkwin/kwindecoration/declarative-plugin/plugin.cpp
  kcmkwin/kwindecoration/declarative-plugin/previewbutton.cpp
  kcmkwin/kwindecoration/declarative-plugin/previewbutton.h
  kcmkwin/kwindecoration/declarative-plugin/previewsettings.cpp
  kcmkwin/kwindecoration/declarative-plugin/previewsettings.h
  kcmkwin/kwindecoration/package/contents/ui/ButtonGroup.qml
  kcmkwin/kwindecoration/package/contents/ui/Buttons.qml

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