Summary:
QPainter doesn't render decoration shadows. It renders only
shadows provided through ShadowInterface.
With this change, painting of shadows is done in similar way OpenGL backend is
currently doing.
Before
{F5734867, layout=center, size=full}
After
{F5734870, layout=center, size=full}
Depends on D10811 (dummy decoration with shadows in autotests)
Test Plan:
* start kwin with QPainter backend enabled:
```
KWIN_COMPOSE=Q kwin_wayland --xwayland --windowed
```
* open konsole and kate:
```
DISPLAY=:1 konsole
DISPLAY=:1 kate
```
Reviewers: #kwin, graesslin, davidedmundson
Reviewed By: davidedmundson
Subscribers: abetts, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D10943
This change is similar to D7232 and moves the scene_qpainter into a
dedicated plugin. Compared to the XRender case it's more complicated as
the platform plugins need to implement a platform specific backend.
The base implementation for this part used to be in scene_qpainter. As
the idea is to completly move it away from KWin core it would be point
less to still have the backend definition in KWin core, but it cannot
be in the scene plugin as otherwise all platforms need to link the
plugin.
To solve this a new platformsupport subdirectory is added which contains
the scene platform backend as a static library. For the OpenGL scene such
a static library will also be required.
Test Plan: SceneQPainter test still passes, nested compositor still works
Reviewers: #kwin, #plasma
Subscribers: plasma-devel
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D7259
