Warning messages are not the kind of messages that should be ignored,
they indicate that something is off or wrong.
Also, this makes triaging bugs easier as we no longer have to ask people
to run kwin with the QT_LOGGING_RULES environment variable set.
If there is a pending frame, the RenderLoop will delay all schedule
repaint requests to the next vblank event. This means that the render
loop needs to be notified when a frame has been presented or failed.
At the moment, the RenderLoop is notified only about successfully
presented frames. If some frame fails, no repaints will be scheduled
on that output.
In order to make frame scheduling robust, the RenderLoop has to be
notified if a frame has failed.
At the moment, our frame scheduling infrastructure is still heavily
based on Xinerama-style rendering. Specifically, we assume that painting
is driven by a single timer, etc.
This change introduces a new type - RenderLoop. Its main purpose is to
drive compositing on a specific output, or in case of X11, on the
overlay window.
With RenderLoop, compositing is synchronized to vblank events. It
exposes the last and the next estimated presentation timestamp. The
expected presentation timestamp can be used by effects to ensure that
animations are synchronized with the upcoming vblank event.
On Wayland, every outputs has its own render loop. On X11, per screen
rendering is not possible, therefore the platform exposes the render
loop for the overlay window. Ideally, the Scene has to expose the
RenderLoop, but as the first step towards better compositing scheduling
it's good as is for the time being.
The RenderLoop tries to minimize the latency by delaying compositing as
close as possible to the next vblank event. One tricky thing about it is
that if compositing is too close to the next vblank event, animations
may become a little bit choppy. However, increasing the latency reduces
the choppiness.
Given that, there is no any "silver bullet" solution for the choppiness
issue, a new option has been added in the Compositing KCM to specify the
amount of latency. By default, it's "Medium," but if a user is not
satisfied with the upstream default, they can tweak it.
We want to get notified when the next page flip occurs. The problem is
that kwin will avoid queueing a page flip if nothing has been changed on
the screen. From performance point of view, that is expected behavior,
but for frame scheduling and some wayland clients that create frame
callbacks to get notified about the next vblank, it's not suitable.
The compositing timing algorithm assumes that glXSwapBuffers() and
eglSwapBuffers() block. While this was true long time ago with NVIDIA
drivers, nowadays, it's not the case. The NVIDIA driver queues
several buffers in advance and if the application runs out of them,
it will block. With Mesa driver, swapping buffer was never blocking.
This change makes the render backends swap buffers right after ending
a compositing cycle. This may potentially block, but it shouldn't be
an issue with modern drivers. In case it gets proven, we can move
glXSwapBuffers() and eglSwapBuffers() in a separate thread.
Note that this change breaks the compositing timing algorithm, but
it's already sort of broken with Mesa drivers.
Since the Screens class is a convenience wrapper around AbstractOutput
objects that come from the Platform, it should not be platform-specific.
By dropping createScreens(), output-related code becomes simpler.
One of the annoying things about EGL headers is that they include
platform headers by default, e.g. on X11, it's Xlib.h, etc.
The problem with Xlib.h is that it uses the define compiler directive to
declare constants and those constants have very generic names, e.g.
'None', which typically conflict with enums, etc.
In order to work around bad things coming from Xlib.h, we include
fixx11.h file that contains some workarounds to redefine some Xlib's
types.
There's a flag or rather two flags (EGL_NO_PLATFORM_SPECIFIC_TYPES and
EGL_NO_X11) that are cross-vendor and they can be used to prevent EGL
headers from including platform specific headers, such as Xlib.h [1]
The benefit of setting those two flags is that you can simply include
EGL/egl.h or epoxy/egl.h and the world won't explode due to Xlib.h
MESA_EGL_NO_X11_HEADERS is set to support older versions of Mesa.
[1] https://github.com/KhronosGroup/EGL-Registry/pull/111
These signals can be useful if you want to know what output exactly has
been disabled or enabled.
The outputEnabled signal is emitted after the outputAdded signal, and
the outputDisabled signal is emitted before the outputRemoved signal.
In case hardware transforms can be used again, the shadow framebuffer
must be destroyed; otherwise rendered results will be distorted due to a
mismatch between the dimensions of the shadow framebuffer and the mode
size.
At the moment, the gbm_device for the primary device is destroyed before
the EGLDisplay is destroyed. This results in a crash in Mesa.
In order to fix the crash, this change ensures that the EGLDisplay is
destroyed before the gbm device.
Currently, the OpenGLBackend and the QPainterBackend have hooks to
indicate the start and the end of compositing cycle, but in both cases,
the hooks have different names. This change fixes that inconsistency.
In order to allow per screen rendering, we need the Compositor to be
able to drive rendering on each screen. Currently, it's not possible
because Scene::paint() paints all screen.
With this change, the Compositor will be able to ask the Scene to paint
only a screen with the specific id.
Listen to logind for resume notification and turn the outputs on when it
happens, much like we do when pressing a key.
This way laptops come back on when the lid opens.
BUG: 428424
They would override KScreen in case we were using a dock station that
brings 2 displays.
We'd get:
- udev: event for the first hotplughed screen
- kwin: process all screens properly (both)
- kscreen: would offer the right configuration for such displays
- udev: process the event for the second hotplug udev event
- kwin: restore the configuration
- kscreen: would think this is a conscious decision and embrace it as a
configuration
With this change we are only re-reading the configuration in case the
outputs changed.
At the moment, despite the protocol supporting it, we were not feeding
the EDIDs. KScreen was falling back to the output name so it didn't fail
horribly but it's still a good idea to provide all the data.
When dragging files on the desktop, the cursor image might be just too
big for the cursor plane, in which case we need to abandon hardware
cursors for a brief moment and use a software cursor. Once the files
have been dropped and the cursor image is small enough, we can go back
to using hw cursors.
BUG: 424589
Currently, if there is no pointer, only the hardware cursor will be
hidden. If the software cursor is forced, you are going to see a dead
immovable cursor.
If an output is rotated, we will compute a transform matrix for the
cursor plane to rotate its contents.
In order to compute that matrix we need the rect of the cursor in the
device-independent pixels, the scale factor and the output transform.
The problem is that we provide a rect of the cursor in the native
pixels. This may result in the cursor being partially or fully clipped.
CCBUG: 424589
If a cursor animation is driven purely by frame callbacks and kwin
uses hardware cursors, the cpu usage may spike to 100%.
This change addresses that issue by sending frame callbacks after a
compositing cycle has been performed.
