Due to being a compositor, kwin has to conform to some certain
interfaces. It means a lot of virtual functions and function tables to
integrate with C APIs. Naturally, we not always want to use every
argument in such functions.
Since we get -Wunused-parameter from -Wall, we have to plumb those
unused arguments in order to suppress compiler warnings at the moment.
However, I don't think that extra work is worth it. We cannot change or
alter prototypes in any way to fix the warning the desired way. Q_UNUSED
and similar macros are not good indicators of whether an argument is
used too, we tend to overlook putting or removing those macros. I've
also noticed that Q_UNUSED are not used to guide us with the removal no
longer needed parameters.
Therefore, I think it's worth adding -Wno-unused-parameter compiler
option to stop the compiler producing warnings about unused parameters.
It changes nothing except that we don't need to put Q_UNUSED anymore,
which can be really cumbersome sometimes. Note that it doesn't affect
unused variables, you'll still get a -Wunused-variable compiler warning
if a variable is unused.
Things such as Output, InputDevice and so on are made to be
multi-purpose. In order to make this separation more clear, this change
moves that code in the core directory. Some things still link to the
abstraction level above (kwin), they can be tackled in future refactors.
Ideally code in core/ should depend either on other code in core/ or
system libs.
Currently, the main user of these two functions is the X11 standalone
platform.
This change ports that code to Workspace::geometry(), which is not great
but the X11 backend already depends on the Workspace indirectly via the
Screens. Not sure if it's worth making the standalone X11 backend track
the xinerama rect internally.
At the moment, dmabuf importing is scattered all over the place in kwin.
It would be great if we had one function that takes dma-buf attributes
and returns an EGLImage if successful.
As the first step, make linux-dmabuf-v1 implementation provide dmabuf
attrs compatible with KWin::DmaBufAttributes.
There are a few benefits to using smart pointers from the standard library:
- std::unique_ptr has move semantics. With move semantics, transfer of ownership
can be properly expressed
- std::shared_ptr is more efficient than QSharedPointer
- more developers are used to them, making contributions for newcomers easier
We're also already using a mix of both; because Qt shared pointers provide
no benefits, porting to standard smart pointers improves consistency in
the code base. Because of that, this commit ports most of the uses of QSharedPointer
to std::shared_ptr, and some uses of QScopedPointer to std::unique_ptr
This makes KWin switch to in-tree copy of KWaylandServer codebase.
KWaylandServer namespace has been left as is. It will be addressed later
by renaming classes in order to fit in the KWin namespace.
AbstractOutput is not so Abstract and it's common to avoid the word
"Abstract" in class names as it doesn't contribute any new information.
It also significantly reduces the line width in some places.
GLRenderTarget doesn't provide a generic abstraction for framebuffer
objects, so let's call GLRenderTarget what it is - a framebuffer.
Renaming the GLRenderTarget class allows us to use the term "render
target" which abstracts fbos or shm images without creating confusion.
The .clang-format file is based on the one in ECM except the following
style options:
- AlwaysBreakBeforeMultilineStrings
- BinPackArguments
- BinPackParameters
- ColumnLimit
- BreakBeforeBraces
- KeepEmptyLinesAtTheStartOfBlocks
It's not possible to get the surface damage before calling
Scene::paint(), which is a big problem because it blocks proper surface
damage and buffer damage calculation when walking render layer tree.
This change reworks the scene compositing stages to allow getting the
next surface damage before calling Scene::paint().
The main challenge is that the effects can expand the surface damage. We
have to call prePaintWindow() and prePaintScreen() before actually
starting painting. However, prePaintWindow() is called after starting
rendering.
This change makes Scene call prePaintWindow() and prePaintScreen() so
it's possible to know the surface damage beforehand. Unfortunately, it's
also a breaking change. Some fullscreen effects will have to adapt to
the new Scene paint order. Paint hooks will be invoked in the following
order:
* prePaintScreen() once per frame
* prePaintWindow() once per frame
* paintScreen() can be called multiple times
* paintWindow() can be called as many times as paintScreen()
* postPaintWindow() once per frame
* postPaintScreen() once per frame
After walking the render layer tree, the Compositor will poke the render
backend for the back buffer repair region and combine it with the
surface damage to get the buffer damage, which can be passed to the
render backend (in order to optimize performance with tiled gpus) and
Scene::paint(), which will determine what parts of the scene have to
repainted based on the buffer damage.
The responsibilities of the Scene must be reduced to painting only so we
can move forward with the layer-based compositing.
This change moves direct scanout logic from the opengl scene to the base
scene class and the compositor. It makes the opengl scene less
overloaded and allows to share direct scanout logic.
This allows us to make the GLRenderTarget a bit nicer when using it to
wrap the default fbo as we don't know what the color attachment texture
is besides its size.
This means that the responsibility of ensuring that the color attachment
outlives the fbo is now up to the caller. However, most of kwin code
has been written that way, so it's not an issue.
Because the GLRenderTarget and the GLVertexBuffer use the global
coordinate system, they are not ergonomic in render layers.
Assigning the device pixel ratio to GLRenderTarget and GLVertexBuffer is
an interesting api design choice too. Scaling is a window system
abstraction, which is absent in OpenGL or Vulkan. For example, it's not
possible to create an OpenGL texture with a scale factor of 2. It only
works with device pixels.
This change makes the GLRenderTarget and the GLVertexBuffer more
ergonomic for usages other than rendering the workspace by removing all
the global coordinate system and scaling stuff. That's the
responsibility of the users of those two classes.
In order to support layered rendering and tiled outputs KWin needs to be
able to split rendering of outputs into multiple surfaces. This commit
prepares the drm backend for that, by moving most of the code in EglGbmBackend
out to a EglGbmSurface class, which will later be used for overlay surfaces
and rendering to multiple connectors side by side.
In doing that, this commit also cleans up the code a bit, removes a lot of
now unnecessary multi-gpu stuff and potentially makes modesets a little
bit more efficient by re-using resources more often.
KWin loads glGetGraphicsResetStatus() on its own to handle ARB and EXT
extensions. After moving graphics reset handling to the RenderBackend,
kwin doesn't use its own glGetGraphicsResetStatus() function, but instead
uses the one provided by libepoxy, which panics if
glGetGraphicsResetStatus() is not in core spec. This change makes the
OpenGLBackend use kwin's glGetGraphicsResetStatus() function instead of
the one provided by libepoxy to avoid a crash.
Instead of only allowing the current format, send the default tranches modified
to only contain formats and modifiers suitable for scanout.
In order to not fail when we can't do direct scanout with a given format
(because that may require a modeset, which we don't allow), keep a blacklist
of attempted formats and modifiers for the current client.
This makes the Scene less overloaded and it's needed for things such as
render layers.
In hindsight, it would be great to merge checkGraphicsReset() and
beginFrame(), e.g. make beginFrame() return the status like in QRhi or
VkSwapchain. If it's OUT_OF_DATE or something, reinitialize the
compositor.
This commit makes 10 bits per color channel the default color depth, which
should reduce banding on outputs that support color formats with more than
8 bits per color channel. In order to support this the commit also removes
the dependency of the EglGbmBackend on a specific format and EglConfig and
instead makes those per-Output properties.
dmabuf-feedback allows the compositor to give the clients better feedback on what
formats and modifiers they should use, and for which device they should allocate.
This way they can reallocate for scanout whenever the compositor tells them to,
which makes direct scanout work for a lot more devices and applications.
This enables kwin to get notified when a memory has been lost in the
system, allowing the driver to purge all the memory and have kwin create
new contexts.
This matches what we do on GLX.
The current code for creating the root shared context is very naive and
does not take into account aspects like robustness or versions.
It is not always possible to mix attributes, in particular robustness
meaning we are unable to opt into these features in future contexts.
This refactors everything to use a common path to make all contexts.
This unifies frame hooks for OpenGL and QPainter render backends. There
are a couple of reasons why it's a good idea - it provides one mental
framework to start painting a frame, the Compositor will be able to
start and submit frames. The last one is very cool because it gives the
Compositor more power over compositing.
Besides unifying frame hooks, this cleans up a bit the arg naming mess
in endFrame(). As is, "damage" and "damagedRegion" are very confusing
names. "damage" arg has been renamed to "renderedRegion," because that's
what it is. The renderedRegion arg specifies the region that has been
repainted by the Scene. It's different from the damagedRegion as that
one specifies the surface damage, i.e. the difference between the
current and the next frame, while the renderedRegion may include a
region that had to be repainted to repair the back buffer. The main
reason why we need renderedRegion is the X11 platform. On Wayland, it's
unused.
In the future, we will need to extend this api with output layers.
The main idea behind the render backend is to decouple low level bits
from scenes. The end goal is to make the render backend provide render
targets where the scene can render.
Design-wise, such a split is more flexible than the current state, for
example we could start experimenting with using qtquick (assuming that
the legacy scene is properly encapsulated) or creating multiple scenes,
for example for each output layer, etc.
So far, the RenderBackend class only contains one getter, more stuff will
be moved from the Scene as it makes sense.
This allows using base opengl backends in libkwin, which can be useful
later on for the purpose of moving the ownership of render backends from
the Scene class to the Compositor class.
