Effects are given the interval between two consecutive frames. The main
flaw of this approach is that if the Compositor transitions from the idle
state to "active" state, i.e. when there is something to repaint,
effects may see a very large interval between the last painted frame and
the current. In order to address this issue, the Scene invalidates the
timer that is used to measure time between consecutive frames before the
Compositor is about to become idle.
While this works perfectly fine with Xinerama-style rendering, with per
screen rendering, determining whether the compositor is about to idle is
rather a tedious task mostly because a single output can't be used for
the test.
Furthermore, since the Compositor schedules pointless repaints just to
ensure that it's idle, it might take several attempts to figure out
whether the scene timer must be invalidated if you use (true) per screen
rendering.
Ideally, all effects should use a timeline helper that is aware of the
underlying render loop and its timings. However, this option is off the
table because it will involve a lot of work to implement it.
Alternative and much simpler option is to pass the expected presentation
time to effects rather than time between consecutive frames. This means
that effects are responsible for determining how much animation timelines
have to be advanced. Typically, an effect would have to store the
presentation timestamp provided in either prePaint{Screen,Window} and
use it in the subsequent prePaint{Screen,Window} call to estimate the
amount of time passed between the next and the last frames.
Unfortunately, this is an API incompatible change. However, it shouldn't
take a lot of work to port third-party binary effects, which don't use the
AnimationEffect class, to the new API. On the bright side, we no longer
need to be concerned about the Compositor getting idle.
We do still try to determine whether the Compositor is about to idle,
primarily, because the OpenGL render backend swaps buffers on present,
but that will change with the ongoing compositing timing rework.
The buffer offset for client-side decorated windows is not 0, this plus
mixing the frame position and the client size may result in clipped
thumbnails of client-side decorated applications, such as gedit, etc.
BUG: 428595
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.
QGraphicsRotation and Scale are QObject wrappers. It's not useful in
data structures where we're creating mulitple of these every frame. It's
large enough to appear in hotspot as taking over 1% of a regular frame.
We don't even use the QGraphicsRotation mapping inside scene for a
reason, so it's not giving us much.
It's technically an API break in libkwineffects. Pragamatically no-one
would use these. We also lose QGraphicsScale's origin, but we never
exposed this in PaintData's public header.
If window thumbnails have to be downscaled, it's up to the application
what filter must be used. Also, we don't really use the lanczos filter
because both x and y scale factors are 1.
AnimationEffect schedules repaints in postPaintWindow() and performs
cleanup in preScreenPaint(). With the X11-style rendering, this doesn't
have any issues, scheduled repaints will be reset during the next
compositing cycle.
But with per screen rendering, we might hit the following case
- Paint screen 0
- Reset scheduled repaints
- AnimationEffect::prePaintScreen(): update the timeline
- AnimationEffect::postPaintScreen(): schedule a repaint
- Paint screen 1
- Reset scheduled repaints
- AnimationEffect::prePaintScreen(): destroy the animation
- AnimationEffect::postPaintScreen(): no repaint is scheduled
- Return to the event loop
In this scenario, the repaint region scheduled by AnimationEffect will
be lost when compositing is performed on screen 1.
There is no any other way to fix this issue but maintain repaint regions
per each individual screen if per screen rendering is enabled.
BUG: 428439
We use the GL_LINEAR magnification filter. This means that GL_REPEAT
wrap mode cannot be used for the software cursor because sampling texels
beyond the right texture edge is the same as sampling texels on the
left edge. This may produce undesired visual artifacts.
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 you play some video and the software cursor doesn't hover it, then
the shadow cast by the cursor will be getting darker and darker with
every frame.
The main reason for that is that kwin paints the software cursor even
if the rect behind it hasn't been damaged or repainted.
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.
GLTexture::width() and GLTexture::height() return the size of the cursor
texture in native pixels, but we need a size in device independent pixels.
CCBUG: 424589
Currently, we use glFinish() to ensure that stream consumers don't see
corrupted or rather incomplete buffers. This is a serious issue because
glFinish() not only prevents the gpu from processing new GL commands,
but it also blocks the compositor.
This change addresses the blocking issue by using native fences. With
the proposed change, after finishing recording a frame, a fence is
inserted in the command stream. When the native fence is signaled, the
pending pipewire buffer will be enqueued.
If the EGL_ANDROID_native_fence_sync extension is not supported, we'll
fall back to using glFinish().
Every time Platform::supportsQpaContext() is called, we go through the
list of supported extensions and perform a string comparison op. This is
not really cheap.
Summary:
Notify the driver about the parts of the screen that will be repainted.
In some cases this can be benefitial. This is especially useful on lima
and panfrost devices (e.g. pinephone, pinebook, pinebook pro).
Test Plan:
Tested on a pinebook pro with a late mesa version.
Basically I implemented it, then it didn't work and I fixed it.
Maybe next step we want to look into our damage algorithm.
The main advantage of SPDX license identifiers over the traditional
license headers is that it's more difficult to overlook inappropriate
licenses for kwin, for example GPL 3. We also don't have to copy a
lot of boilerplate text.
In order to create this change, I ran licensedigger -r -c from the
toplevel source directory.
Summary: Don't include the \n at the end of the debug messages
Test Plan: Now I can see the debug errors without an empty line below
Reviewers: #kwin, zzag
Reviewed By: #kwin, zzag
Subscribers: zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D29684
No window quads are generated for sub-surfaces right now. This leads to
issues with effects that operate on window quads, e.g. magic lamp and
wobbly windows. Furthermore, the OpenGL scene needs window quads to
properly clip windows during the rendering process.
The best way to render sub-surfaces would be with a little help from a
scene graph. Contrary to GNOME, KDE hasn't developed any scene graph
implementation that we could use in kwin. As a short term solution, this
change adjusts the scene to generate window quads.
Window quads are generated as we traverse the current window pixmap tree
in the depth-first search manner. In order to match a list of quads with
a particular WindowPixmap, we assign an id to each quad.
BUG: 387313
FIXED-IN: 5.19.0
Differential Revision: https://phabricator.kde.org/D29131
In order to generate window quads for sub-surfaces, we need a valid
window pixmap tree. The problem is that the window pixmap tree is
created too late in the rendering process. This change adjusts the
scene so it creates window pixmap trees before buildQuads().
Differential Revision: https://phabricator.kde.org/D29131
Summary:
The screenshot made on screens with scale factor were downscaled by their scale factor making them blurry.
It prevents taking screenshots of missing Hidpi related bugs showing the issues under Wayland.
This fix the case of a single screenshot, but not the rest:
Multiscreen screenshot downscales the screen using scale factor.
Spectacle rectangular selection screenshot is broken as soon as some scale factor different than 1 is used on any screen.
Test Plan:
Under Wayland with a scale factor on a screen, take a screenshot using spectacle.
The output image is not downscaled and has the same size as the screen resolution.
No other change to any other screenshot mode, or under X.
Reviewers: davidedmundson, #kwin
Reviewed By: davidedmundson, #kwin
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D29010
Summary:
As is KWin only had 1 Cursor which was a singleton. This made it impossible for
us to properly implement the tablet (as in drawing tablets) support and show where
we're drawing.
This patch makes it possible to have different Cursors in KWin, it makes all the
current code still follow the mouse but the tablet can still render a cursor.
Test Plan: Tests pass, been using it and works as well as before but with beautiful tablet cursors.
Reviewers: #kwin, cblack, davidedmundson
Reviewed By: #kwin, cblack, davidedmundson
Subscribers: davidedmundson, cblack, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D28155
Summary:
This may help with debugging why compositing is suspended.
CCBUG: 418951
Test Plan: Compiles.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D28139
Summary: No need to keep them around for no reason.
Test Plan: Tested the plugins I thought could be affected. Have been using it for a couple of days without problems
Reviewers: #kwin, zzag
Reviewed By: #kwin, zzag
Subscribers: zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D28062
Summary:
This will save the copy of some objects, especially PaintData classes that are
not copy-on-write.
It also follows the practice on other parts of the system.
Test Plan: Running it right now
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D28031
Summary:
If a client has been resized, it doesn't necessarily mean that the
decoration theme will schedule full repaint of the window frame. In
OpenGL and Xrender scene, we have a little hack that forces a full
repaint of window borders. However, we don't have one in QPainter
scene which causes all sorts of weird looking artifacts when resizing
a server-side decorated client.
We could add yet another hack in the QPainter scene, but a better
approach to tackle this problem would be to make DecoratedClient
schedule a full repaint of the decoration. It makes code in scene
plugins more straightforward and prevents us from repeating the same
mistake again.
Test Plan:
No longer able to see invisible decoration borders when
using QPainter render backend.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D26927
Summary:
Legacy OpenGL 1 compositing backend had been dropped quite a while ago
so some of OpenGL scene classes can be merged back.
Test Plan: Compiles, windows are rendered as before.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D26700
Summary:
Scene opengl has a callback for when we have a GL error. One of the
handlers for an error calls scheduleVboReInit the history shows it was a
forerunner to the GLX_NV_robustness_video_memory_purge but resetting
only one tiny part based on debug output.
When we get here we schedule a reset of the vertex buffer, via a timer.
When the timer is caled we have no idea what GL context was last
current, if it's not the currect context then the main scene
GLVertexBuffer will be deleted but not correctly re-initialised.
We have two very common crashes with a corrupted
GLVertexBuffer::streamingBuffer() which would match up perfectly.
Given that we now have a proper mechanism to reset the entire scene, we
don't need this timer based hack and resolve that problem.
BUG: 399499
BUG: 372305
Reviewers: #kwin
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D26556
Summary:
Quite long time ago, window decorations were painted on real X11 windows.
The nicest thing about that approach is that we get both contents of the
client and the frame window at the same time. However, somewhere around
KDE 4.2 - 4.3 times, decoration rendering architecture had been changed
to what we have now.
I've mentioned the previous decoration rendering design because it didn't
have a problem that the new design has, namely the texture bleeding issue.
In the name of better performance, opengl scene puts all decoration parts
to an atlas. This is totally reasonable, however we must be super cautious
about things such as the GL_LINEAR filter.
The GL_LINEAR filter may need to sample a couple of neighboring texels
in order to produce the final texel value. However, since all decoration
parts now live in a single texture, we have to make sure that we don't
sample texels that belong to another decoration part.
This patch fixes the texture bleeding problem by padding each individual
decoration part in the atlas. There is another solution for this problem
though. We could render a window into an offscreen texture and then map
that texture on the transformed window geometry. This would work well and
we definitely need an offscreen rendering path in the opengl scene,
however it's not feasible at the moment since we need to break the window
quads API. Also, it would be great to have as less as possible stuff going
on between invocation of Scene::Window::performPaint() and getting the
corresponding pixel data on the screen.
There is a good chance that the new padding stuff may make you vomit. If
it does so, I'm all ears for the suggestions how to make the code more
nicer.
BUG: 257566
BUG: 360549
CCBUG: 412573
FIXED-IN: 5.18.0
Reviewers: #kwin
Subscribers: fredrik, kwin, fvogt
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D25611
Summary:
We currently see a gap on transformed windows between the window and the
top decoration.
This is partly the atlas bleed on the decoration, and partly a bleed on
the window content itself.
On X11, the window we composite is the frame window - which is a larger
texture containing a transparent border where the frame normally would
be. When we sample with a linear filter we include these texels. Hence
GL_CLAMP_TO_EDGE doesn't work.
Vlad's patch to composite the correct window, not the frame was my
preferred approach, but we had to revert it as it caused an issue with
xwayland :(
Half pixel correction nearly worked, but caused blurry fonts.
This patch resolves it in the fragment shader used by effects doing
transforms. We pass the real texture geometry of the window to the
client with a half pixel correction. Any samples outside the outer half
pixel are then clamped within bounds.
Arguably a hack, but solves the problem in a comparatively
non-invasive way.
BUG: 360549
BUG: 257566
Test Plan:
X11:
Using Vlad's atlas padding for decoration
Slowed animations, wobbled a dark window over a light background
No artifacts
Wayland:
This isn't needed. Now tested that everything still renders the same.
Reviewers: #kwin, zzag
Reviewed By: #kwin, zzag
Subscribers: zzag, jgrulich, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D25737
Summary:
Add a small getter to query information internally if the backend supports
swap events. Defaults to true as it is the default in the GBM Wayland backend.
Test Plan: i915
Reviewers: #kwin
Subscribers: kwin
Tags: #kwin
Maniphest Tasks: T11071
Differential Revision: https://phabricator.kde.org/D25298
