D28623: [WIP] Sync titlebar button appearance with GTK CSD apps

[Mikhail Zolotukhin]

gikari created this revision.
Herald added a project: Plasma.
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gikari requested review of this revision.

REVISION SUMMARY
  Currently GTK applications with Client Side Decoration always use
  decorations from the respected GTK CSS theme. Because of CSS nature
  different themes may handle decorations in the headerbars differently,
  therefore making modifying them via user css a very hard task. However,
  what we can do is to use decoration appearance syncing in our own theme
  
  - Breeze GTK.
  
  Breeze GTK uses images (.svg and .png) for representing decoration
  buttons (close, minimize, maximize) appearance. So to achieve the goal
  what we can do (hypothetically) is the following:
  
  1. Ask KWin to render current decoration buttons to custom QPainters. For each button we must export every state (clicked, hovered, normal).
  2. QPainters then export decoration buttons to pixmaps or/and svg.
  3. Then we will save those images to assets folder in `~/.config/gtk-3.0/assets` or something like that.
  4. Then we will create custom .css for Breeze GTK, that tells the theme to use these saved images for decorations.
  
  I am currently having trouble with the first part, trying to ask KWin to
  do QPainter stuff. Currently it crashes, without any understandable for
  me reason. If someone can, please help.

REPOSITORY
  R99 KDE Gtk Configuration Tool

BRANCH
  decorations-appearance (branched from master)

REVISION DETAIL
  https://phabricator.kde.org/D28623

AFFECTED FILES
  CMakeLists.txt
  kded/CMakeLists.txt
  kded/configvalueprovider.cpp
  kded/configvalueprovider.h
  kded/gtkconfig.cpp
  kded/gtkconfig.h
  kded/kwin_bridge/CMakeLists.txt
  kded/kwin_bridge/dummydecoratedclient.cpp
  kded/kwin_bridge/dummydecoratedclient.h
  kded/kwin_bridge/dummydecorationbridge.cpp
  kded/kwin_bridge/dummydecorationbridge.h

To: gikari
Cc: plasma-devel, Orage, LeGast00n, The-Feren-OS-Dev, cblack, jraleigh, zachus, fbampaloukas, GB_2, ragreen, ZrenBot, ngraham, himcesjf, lesliezhai, ali-mohamed, jensreuterberg, abetts, sebas, apol, ahiemstra, mart
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