QPointer is a really useful way to store a pointer over time.
It doesn't make have any value as a return value used by a short-lived
method.
There isn't a good copy constructor, it's effectively the same as
creating a new QWeakPointer reference that has to be cleaned up.
Testing if something is null is still the same. A new QPointer can be
made by the caller if it actually is needed.
Input handling is a very hot path called many times a frame, so it's
important to keep this light. focus() and at() are called a lot which
added up to slightly over 1% of CPU time when moving the mouse about.
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:
Uses the tablet classes introduced in kwayland.
Depends on D26858
Test Plan:
Scratched my tablet with a magic stick and it did things depending on the pressure.
https://youtu.be/GGx0TlNJlzs
Reviewers: #kwin, #plasma, zzag, davidedmundson
Reviewed By: #kwin, #plasma, zzag, davidedmundson
Subscribers: davidedmundson, zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D26859
Summary:
This includes support for them on libinput and turns it into fake
pointer actions.
This doesn't implement zwp_tablet, this will have to happen in an
iteration later.
Test Plan:
Been playing around with it, see video.
https://www.youtube.com/watch?v=GF1WbO8FVvU
Reviewers: #plasma, #kwin, romangg
Reviewed By: #plasma, #kwin, romangg
Subscribers: zzag, davidedmundson, romangg, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D25663
Summary:
There is no point in using quint32 and casting back and forth in numerous places.
Fix a bunch of compiler warnings that we implicitly cast between signed and unsigned.
This makes things consistent with what we get from libinput.
Reviewers: #kwin, romangg
Reviewed By: #kwin, romangg
Subscribers: zzag, romangg, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D23086
Summary:
So far we were following a bit unique and rare doxygen comment style:
/**
* Contents of the comment.
**/
Doxygen comments with this style look balanced and neat, but many people
that contribute to KWin don't follow this style. Instead, they prefer
more traditional doxygen comment style, i.e.
/**
* Contents of the comment.
*/
Reviewing such changes has been a bit frustrating for me (so selfish!)
and for other contributors.
This change switches doxygen comment style in KWin to a more traditional
style. The main reason for doing this is to make code review process easier
for new contributors as well us.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D22812
Summary:
Currently code base of kwin can be viewed as two pieces. One is very
ancient, and the other one is more modern, which uses new C++ features.
The main problem with the ancient code is that it was written before
C++11 era. So, no override or final keywords, lambdas, etc.
Quite recently, KDE compiler settings were changed to show a warning if
a virtual method has missing override keyword. As you might have already
guessed, this fired back at us because of that ancient code. We had
about 500 new compiler warnings.
A "solution" was proposed to that problem - disable -Wno-suggest-override
and the other similar warning for clang. It's hard to call a solution
because those warnings are disabled not only for the old code, but also
for new. This is not what we want!
The main argument for not actually fixing the problem was that git
history will be screwed as well because of human factor. While good git
history is a very important thing, we should not go crazy about it and
block every change that somehow alters git history. git blame allows to
specify starting revision for a reason.
The other argument (human factor) can be easily solved by using tools
such as clang-tidy. clang-tidy is a clang-based linter for C++. It can
be used for various things, e.g. fixing coding style(e.g. add missing
braces to if statements, readability-braces-around-statements check),
or in our case add missing override keywords.
Test Plan: Compiles.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, apol, romangg, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D22371
Summary:
XWayland clients have a surface associated with them asynchronously. In this
case we don't directly want to set focus on this Toplevel, but wait until the
surface is set.
This patch aims in conjunction with an unrelated fix to SDL at improving Steam
Big Picture Mode in our Wayland session.
Test Plan: Steam BPM regains focus on game close.
Reviewers: #kwin, zzag
Reviewed By: #kwin, zzag
Subscribers: anthonyfieroni, davidedmundson, zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D19262
Summary:
So far KWin didn't send axis_source, axis_discrete, and axis_stop. Even
though most of those events are optional, clients need them to work as
expected. For example, one needs axis_source and axis_stop to implement
kinetic scrolling; Xwayland needs axis_discrete to prevent multiple
scroll events when the compositor sends axis deltas greater than 10, etc.
BUG: 404152
FIXED-IN: 5.17.0
Test Plan:
* Content of a webpage in Firefox is moved by one line per each mouse
wheel "click";
* Scrolled gedit using 2 fingers on GNOME Shell, sway, and KDE Plasma;
in all three cases wayland debug looked the same (except diagonal scroll
motions).
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: davidedmundson, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D19000
Summary:
Building upon the generic X Selection support this patch establishes another
selection class representing the XDND selection and provides interfaces
to communicate drags originating from Xwayland windows to the Wayland
server KWin and drags originating from Wayland native drags to Xwayland.
For Wayland native drags KWin will claim the XDND selection as owner and
will simply translate all relevant events to the XDND protocol and receive
alike messages by X clients.
When an X client claims the XDND selection KWin is notified via the X protocol
and it decides if it allows the X drag to transcend into the Wayland protocol.
If this is the case the mouse position is tracked and on entering a Wayland
native window a proxy X Window is mapped to the top of the window stack. This
proxy window acts as a drag destination for the drag origin window and again
X messages will be translated into respective Wayland protocol calls. If the
cursor leaves the Wayland window geometry before a drop is registered, the
proxy window is unmapped, what triggers a subsequent drag leave event.
In both directions the necessary core integration is minimal. There is a single
call to be done in the drag and drop event filter through the Xwayland
interface class.
From my tests this patch facilitates drags between any Qt/KDE apps. What needs
extra care are the browsers, which use target formats, that are not directly
compatible with the Wayland protocol's MIME representation. For Chromium an
additional integration step must be done in order to provide it with a net
window stack containing the proxy window.
Test Plan: Manually. Auto tests planned.
Reviewers: #kwin
Subscribers: zzag, kwin, alexde
Tags: #kwin
Maniphest Tasks: T4611
Differential Revision: https://phabricator.kde.org/D15627
Summary:
We have a mix of different doxygen comment styles, e.g.
/*!
Foo bar.
*/
/**
* Foo bar.
*/
/** Foo bar.
*/
/**
* Foo bar.
*/
/**
* Foo bar.
**/
To make the code more consistent, this change updates the style of all
doxygen comments to the last one.
Test Plan: Compiles.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D18683
Summary:
Certain input devices like touch screens can be in a state of having no input
target at all. In case of touch screens when there are no current touch points.
In this case unset and block at-surface targets until a touch point is
available again.
Test Plan: Auto test window-selection passes again.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: graesslin, davidedmundson, zzag, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D17537
Summary:
This patch aims at improving the Toplevel, internal window and decoration
focus tracking.
In detail the goals are:
* Clean tracking of beneath and focus Toplevel as well as decoration and
internal windows. Splitting this up in well defined sub routines.
* Minimal find Toplevel operations on window stack.
* Reduce code duplication in pointer and touch child classes.
* Reuse tracking in drag operations.
* Allow direct usage of Wayland input interfaces for decoration and internal
windows in the future.
* Update touch focus on external events like VD switches correctly.
Test Plan: Manually and existing autotests.
Reviewers: #kwin
Subscribers: kwin, zzag
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D15595
Summary:
Some members were declared protected. Better style is to have them private
with public or protected getters and setters.
This also removes the unnecessary m_input variable.
Test Plan: Builds and runs.
Reviewers: #kwin, davidedmundson
Reviewed By: #kwin, davidedmundson
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D15519
Summary:
With 2694839099, 0bd5eff862 and f0ba436c72 it is now possible to
unconstrain a pointer by killing the client or deactivating the window, for
example by switching the window via the TabBox.
A user should always be able to do it therefore without needing to explicitly
break the pointer constrain as in the past with the Esc key.
Therefore remove the functionality and also remove the OSD announcing it,
which was often shown at the wrong time.
Test Plan: Manually and auto test adapted.
Reviewers: #kwin, #vdg, hein
Reviewed By: hein
Subscribers: ngraham, hein, kwin
Tags: #kwin
Maniphest Tasks: T8923
Differential Revision: https://phabricator.kde.org/D15234
Summary:
expose in the libinput wrapper a property that tells whether
a tablet mode switch input device is present on the machine,
expose it trough dbus
Test Plan:
still not complete, I need a way to either access the connection
from TabletModeManager or setting to TabletModeManager from input.cpp
Reviewers: #kwin, #plasma, graesslin
Reviewed By: #kwin, #plasma, graesslin
Subscribers: graesslin, ngraham, davidedmundson, plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D9944
Summary:
This change introduces a new SwitchEvent and passes it through the
InputEventSpy and InputEventFilter. The DebugConsoleFilter implements it
so that the events can be monitored in the debug console.
Test Plan: Untested as my only device with such switches has too old libinput
Reviewers: #kwin, #plasma
Subscribers: plasma-devel, kwin
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D9521
Summary:
Thanks to std::bind we don't need that many different slots to setup the
global shortcut connections. Instead we can have one shared
implementation which takes the argument and passes it to the window.
To support std::bind arguments in kwinbindings the initShortcut method
and dependencies are adjusted as well as a new macro is added.
As I don't want to include abstract_client.h in workspace.h a new enum
is created for the quick tiling flags used in Workspace. This caused a
larger refactoring as the change to an enum class also caused quite some
changes.
Test Plan: Affected test cases still pass
Reviewers: #kwin, #plasma
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D6783
Summary:
Making QActions with the Connection as a parent is dangerous as it gets
moved to a new thread, moving all child objects to that thread.
KGlobalAccel and QAction aren't thread safe and we shouldn't be using it
in two threads. This was notably seen when runnng invokeShortcut over
DBus which then invokes it on the main thread. Something my laptop was
doing when I closed the lid.
This patch simply moves the code to the Input class, where we set up the
libinput connection.
Test Plan:
Closed lid, kwin_wayland was still there when I resumed
Set manual shortcut for toggling touchpad, that still worked
Reviewers: #plasma
Subscribers: plasma-devel, kwin, #kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D5733
Summary:
There are a few places where KWin needs to read values from kcminputrc.
As I need to add yet another one it makes more sense to properly
structure it like in other cases and have only one kcminputrc hold in
the application. This also allows to better mock the config values in
the integration tests.
Reviewers: #kwin, #plasma
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D5540
Summary:
This change adds global touchpad swipe gestures to the
GlobalShortcutsManager and hooks up the swipe gestures as defined at the
Plasma Affenfels sprint:
* swipe up: Desktop Grid
* swipe down: Present Windows
* swipe left: previous virtual desktop
* swipe right: next virtual desktop
The main work is handled by two new classes: SwipeGesture and
GestureRecognizer. This is implemented in a way that it can be extended
to also recognize touch screen gestures and pinch gestures.
The SwipeGesture defines what is required for the gesture to trigger.
Currently this includes the minimum and maximum number of fingers
participating in the gesture and the direction. The gesture gets
registered in the GestureRecognizer.
The events for the gesture are fed into the GestureRecognizer. It
evaluates which gestures could trigger and tracks them for every update
of the gesture. In the process of the gesture tracking the
GestureRecognizer emits signals on the Gesture:
* started: when the Gesture gets considered for a sequence
* cancelled: the Gesture no longer matches the sequence
* triggered: the sequence ended and the Gesture still matches
The remaining changes are related to hook up the existing shortcut
framework with the new touchpad gestures. The GlobalShortcutManager
gained support for it, InputRedirection and EffectsHandler offer methods
to register a QAction. VirtualDesktopManager, PresentWindows and
DesktopGrid are adjusted to support the gesture.
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel
Tags: #plasma_on_wayland
Differential Revision: https://phabricator.kde.org/D5097
Summary:
InputRedirection has a workaround to add a connect on a QAction which
is used for a global shortcut. This is specific to the X11 platform as
the xtime needs to be updated.
This change adds a new virtual method to the Platform and moves the
implementation into the X11 standalone platform. Thus it does no longer
gets called on Wayland.
Reviewers: #kwin, #plasma
Subscribers: plasma-devel
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D4168
Summary:
An improvement from the introduction of InputEventSpy. Instead of
specifying a std::function as argument, we let the compiler decide what
is the best argument.
Reviewers: #kwin, #plasma, mart
Reviewed By: mart
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D3877
Summary:
So far KWin's input event processing is mostly based on
InputEventFilters. A filter can - as the name suggest - filter out an
input event from further processing. Our code shows that this is not
sufficient for all input event processing.
We have several areas inside KWin where we need to have access to all
input events, where the processing needs to happen on all events and
filtering is not allowed. This results in sub-optimal code which has
classes which know too much and do too much.
Examples:
* key-repeat handling done in KeyboardInputRedirection
* Layout change OSD in Xkb
* modifier only shortcuts in Xkb
* emitting signals for Cursor class in KeyboardInputRedirection
Also there are misuses of the InputEventFilters and internal API
* DebugConsole keyboard state (uses wrong information)
* DebugConsole input events tab (uses Filter, should be a spy)
This change introduces the API needed to fix these problems. It
introduces an InputEventSpy which is modelled after the InputEventFilter
with the difference that it has only void messages and uses the KWin
introduced event classes.
The spies are always processed prior to the filters, thus we know it can
have all events.
Reviewers: #kwin, #plasma
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D3863
Summary:
Prior to this change various event filters performed deep calls into
Xkb class to figure out the modifiers relevant for global shortcuts (aka
consumed modifiers). This shows that this is a general useful
information which should be available to all input event filters
directly.
Thus it's now added to the input events and exposed directly in
InputRedirection so that the calls into Xkb are no longer needed.
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D3810
Summary:
For every input event we have similar code. We go through all
InputFilters, invoke a method with some arguments and check whether
the filter returns true.
Instead of duplicating that logic everywhere, there is now one method
in InputRedirection which takes a std::function to call on the input
filters. The std::function is supposed to be generated with a std::bind
on the InputFilter::method with all the required arguments.
Reviewers: #kwin, #plasma
Subscribers: plasma-devel, kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D3806
Summary:
There are two types of constraints supported:
1. Pointer confinement
2. Pointer locking
In the case of confinement the pointer is confined to a given region of
the surface. This is comparable to general operation where the pointer
is confined to the screen region.
In the second case the pointer gets locked. That means it cannot move at
all. No further position updates are provided, only relative motion
events can go to the application. There is a hint about cursor position
update on unlock which is not yet implemented in KWayland::Server, thus
also not in this change.
The implementation in KWin grants the requests for pointer constraints
when the pointer enters the constrained region, either by pointer
movement or by e.g. stacking order changes. There is no confirmation
from user required to enter that mode. But we want to show an OSD when
the pointer gets constrained, this is not yet implemented, though.
Breaking an active constraint is relatively easy. E.g. changing the
stacking order will break the constraint if another surface is under the
cursor. Also (in case of confinement) moving the pointer to an
overlapping window breaks the confinement. But as soon as one moves the
pointer back to the window a constraint might get honoured again.
To properly break there is a dedicated event filter. It listens for a
long press of the Escape key. If hold for 3sec the pointer constraint is
broken and not activated again till the pointer got moved out of the
window. Afterward when moving in the pointer might activate again.
The escape filter ensures that the key press is forwarded to the
application if it's a short press or if another key gets pressed during
the three seconds. If the three seconds way fires, the later escape
release is not sent to the application.
This basic interaction is also ensured through an added auto test.
This change implements T4605.
Test Plan: Added auto test and nested KWin Wayland with D3488
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D3506
Summary:
A second interactive selection mode gets added to select a position on
the screen. This is handled by the same input event filter as for the
window selection. Just that instead of returning a window, it returns a
QPoint.
This allows to pick a point on the screen which we need to screenshot
the screen under the mouse cursor and in future for color picking.
The screenshot effect provides two new dbus methods to (interactively)
select a screen or fullscreen. This allows spectacle to screenshot the
(full) screen with still having the user in control.
Reviewers: #kwin, #plasma_on_wayland, bgupta
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D3475
Summary:
The interactive window selection is implemented in InputRedirection
through a dedicated InputEventFilter. The InputEventFilter so far takes
care of pointer input and keyboard input. In addition it ensures that
keyboard and pointer focus is reset on start and on end.
With this change KillWindow now also works on Wayland, but only for X11
windows, as the Wayland variant is not yet implemented.
Test Plan: Tested in nested setup, auto-tests still needed
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D3365
A new protected method is added to InputEventFilter to forward a
QKeyEvent to the Wayland server. Several input filters need to forward
the event to have a proper state of the events. E.g. the TabBox filter,
but also the internal window filter and effects filter. It's important
to update all events even if the events are not forwarded to a surface.
This new method takes care of the general handling like ignoring key
repeats, etc.
Reviewed-By: bshah
Summary:
Gesture events are swipe or pinch events on a touch pad.
This change implements basic support by:
* wrapping them in LibInput::Event
* processing them in LibInput::Connection and emitting
dedicated signals
* Forwarding them in InputRedirection to PointerInputRedirection
* Support them in the internal input event filter
* Printing debug information in DebugConsole
Further handling is not yet done. In future the following should be
implemented:
* activating e.g. zoom and present windows on pinch/swipe gesture
* forwarding non global gestures to KWayland
Note that forwarding to KWayland is not yet useful as QtWayland does
not yet have support for the unstable protocol. No Qt application could
make use of it yet. So for the moment just global gestures is the best
we can get.
Test Plan: Looked at output of DebugConsole when triggering gestures
Reviewers: #kwin, #plasma_on_wayland
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D2359
Summary:
This is a workaround for QTBUG-54371 resulting in QtWayland never
requesting the input methods panel without having keyboard focus.
Thus also the virtual keyboard is not working.
With this change we go back to always announcing a keyboard and
binding the virtual keyboard to whether we don't have an alpha-numeric
keyboard instead of whether there is a keyboard on the seat.
Reviewers: #kwin, #plasma_on_wayland, bshah
Subscribers: plasma-devel, kwin
Tags: #plasma_on_wayland, #kwin
Differential Revision: https://phabricator.kde.org/D2343
Summary:
Qt's touch event API is rather difficult and complex to implement.
As none of KWin's internal windows supports multi-touch gestures yet,
this is going the easy route and just simulates a left mouse button
press. If in future need arises for touch gesture support on KWin's
internal windows, this can be added.
Test Plan: Tested on exopc with DebugConsole and auto test
Reviewers: #plasma
Subscribers: plasma-devel
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D1661
Summary:
Touch events are emulating mouse events, in particular left mouse
button.
With this change one can move windows through the decoration, use
the decoration buttons and also support the double click action.
As finding the decoration is pretty much exactly the same as for
pointer events, a new base class is introduces which provides the
functionality of updating the decoration and the shared common
variables.
Reviewers: #plasma
Subscribers: plasma-devel
Projects: #plasma
Differential Revision: https://phabricator.kde.org/D1604
Summary:
The configuration file kcminput, group Mouse is parsed to decide whether
pointer devices should be in left handed mode. The config is applied
whenever a new device is added.
In addition the Connection listens to KGlobalSettings for a mouse
settings changed signal which might be emitted by the mouse KCM.
When such a signal is emitted, all pointer devices are reconfigured.
This allows to change the mouse handed settings on Wayland.
Reviewers: #plasma
Subscribers: plasma-devel
Projects: #plasma
Differential Revision: https://phabricator.kde.org/D1543
As a Wayland server KWin does not have to emit additional key repeat
events (unlike X11). The clients are responsible for handling this based
on the provided key repeat information.
Internally KWin needs key repeat, though. E.g. the effects need key
repeat (filtering in Present Windows), window moving by keyboard needs
repeat, etc. etc.
This change introduces the internal key repeat. For each key press a
QTimer is started which gets canceled again on the key release. If the
timer fires it invoked processKey with a new KeyboardKeyAutoRepeat state.
This is handled just like a KeyPress, but states are not updated and
the QKeyEvent has autorepeat set to true.
The event filters check for the autorepeat state and filter the event
out if they are not interested in it. E.g. the filters passing the event
to the Wayland client need to filter it out.
Currently auto-repeat is bound to using libinput. This needs to be
modified. The only backend sending repeated events is X11, thus for
other backends it should be enabled.
Whether creating a timer on each key event is a good idea is something to
evaluate in future.
Reviewed-By: Bhushan Shah
So far the DrmOutput connected to all input events when going into
power saving. As we now have the input filters it's better to just
install a filter when an output goes into powersave and remove the
input filter again when all outputs are enabled again.
To make this work InputRedirection gains a new method to add a new
filter as the first filter. This is a potentially dangerous method
as it allows to have a filter before LockScreenFilter gets the
events. But in case of DPMS it's something we actually want.
A nice new feature possible with the input filter is that we can
filter out the event which re-enables the outputs. Thus when getting
on a system with output off and screen locked, the first key hit
doesn't go to the lock screen.
Reviewed-By: Bhushan Shah
BUG: 341201
Fixed-in: 5.6.0 (Wayland-only)
Similar to the change regarding pointer and touch a
KeyboardInputRedirection is created. The Xkb class is also moved to
the new files keyboard_input.h and keyboard_input.cpp.
Just like in the case of PointerInputRedirection no signals are added,
but the existing signals in InputRedirection are directly invoked.
All pointer related code is moved into a new class called
PointerInputRedirection.
The main idea is to simplify the code and make it easier to maintain.
Therefore also a few changes in the setup were performed:
* before init() is called, no processing is performed
* init() is only called on Wayland and after Workspace is created
* init property is set to false once Workspace or WaylandServer is
destroyed
Thus code can operate on the following assumptions:
* Workspace is valid
* WaylandServer is valid
* ScreenLocker integration is used
The various checks whether there is a waylandServer() and whether
there is a seat are no longer needed.
Some of the checks have been reordered to be faster in the most common
use case of using libinput. E.g. whether warping is supported is first
evaluated by the variable bound to whether we have libinput and only if
that is false the backend is checked.
The new class doesn't have signals but invokes the signals provided
by InputRedirection. I didn't want to add new signals as I consider
them as not needed. The areas in KWin needing those signals should
be ported to InputEventFilters.
