We use surfaceless contexts with internal windows. We also require
the EGL_KHR_surfaceless_context extension for making context current
without outputs.
Arguably, we could use pbuffers, but since mainstream drivers (Mesa and
NVIDIA) support surfaceless contexts, the extra complexity doesn't buy
us anything.
With per-screen rendering, every output may have different EGLConfig.
Having a single global EGLConfig doesn't work out well.
This change removes Platform::sceneEglConfig(). It's used primarily to
create the global share context. In hindsight, the global share context
can be created without EGLConfig as it's never made current.
EGL_NO_CONFIG_KHR is part of EGL_KHR_no_config_context extension, which
is supported by both Mesa and NVIDIA driver so it should be safe to make
it mandatory.
The Xrender backend was added at the time when OpenGL drivers were not
particularly stable. Nowadays though, it's a totally different situation.
The OpenGL render backend has been the default one for many years. It's
quite stable, and it allows implementing many advanced features that
other render backends don't.
Many features are not tested with it during the development cycle; the
only time when it is noticed is when changes in other parts of kwin break
the build in the xrender backend. Effectively, the xrender backend is
unmaintained nowadays.
Given that the xrender backend is effectively unmaintained and our focus
being shifted towards wayland, this change drops the xrender backend in
favor of the opengl backend.
Besides being de-facto unmaintained, another issue is that QtQuick does
not support and most likely will never support the Xrender API. This
poses a problem as we want thumbnail items to be natively integrated in
the qtquick scene graph.
The backend can now optionally wait for the scene to be created before
it updates its outputs, which is necessary for better atomic tests in
the DRM backend.
Currently, the implementation of the DecoratedClient and the decoration
renderer are strongly coupled. This poses a problem with the item based
design as the ultimate goal is to have scene items construct paint nodes
which are then fed to the renderer. The DecorationItem has to have
control over the decoration texture. Another issue is that the scene
cannot smoothly cross-fade between two window states if the decoration
is removed, e.g. from fullscreen mode to normal and vice versa.
This change moves the decoration renderer to the decoration item. With
the introduction of a generic scene texture atlas, we hope to get rid of
the decoration renderer altogether.
Platform::prepareShutdown() was introduced to work around the issue
where the platform accesses destroyed OutputDeviceInterface objects.
Since we no longer query OutputDeviceInterface for output info, the
Platform::prepareShutdown() function can be dropped.
At the moment, the session code is far from being extensible. If we
decide to add support for libseatd, it will be a challenging task with
the current design of session management code. The goal of this
refactoring is to fix that.
Another motivation behind this change is to prepare session related code
for upstreaming to kwayland-server where it belongs.
Once in a while, we receive complaints from other fellow KDE developers
about the file organization of kwin. This change addresses some of those
complaints by moving all of source code in a separate directory, src/,
thus making the project structure more traditional. Things such as tests
are kept in their own toplevel directories.
This change may wreak havoc on merge requests that add new files to kwin,
but if a patch modifies an already existing file, git should be smart
enough to figure out that the file has been relocated.
We may potentially split the src/ directory further to make navigating
the source code easier, but hopefully this is good enough already.
