Add a touchscreen generic qpa plugin.

Change-Id: Iaf79df05eb4f60d254d95f5d0f280a8f8f8a8de8
Reviewed-on: http://codereview.qt.nokia.com/941
Reviewed-by: Jørgen Lind <jorgen.lind@nokia.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/src/plugins/generic/touchscreen/README b/src/plugins/generic/touchscreen/README
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+Generic plug-in for evdev touch events
+
+(a) Using as a QPA generic plug-in
+
+1. set up the touch device
+2. sudo apt-get install libmtdev-dev libudev-dev
+3. build this plug-in (qmake && make)
+4. sudo cp 70-qtouchscreen.rules /etc/udev/rules.d
+5. sudo udevadm trigger --subsystem-match=input
+6. run apps like this: app -platform xcb -plugin LinuxTouchScreen
+
+If automatic detection does not work, use -plugin
+LinuxTouchScreen:/dev/input/eventN to explicitly set the device file
+name.
+
+By default the surface of the touch device is mapped to the entire
+screen. If this is not desired, define FORCE_TO_ACTIVE_WINDOW in
+qtoucheventsenderqpa.cpp. This will map the touch surface to the
+active window instead.
+
+Only touch events are generated (via
+QWindowSystemInterface::handleTouchEvent), mouse events are not. This
+is because on desktop the touch device will usually act as a
+single-touch mouse replacement anyway. For pointer-less systems the
+code needs to be extended to generate also mouse events (by calling
+handleMouseEvent too).
+
+(b) Using in a compositor
+
+The classes (QTouchScreenHandler, QTouchScreenHandlerThread) are also
+suitable for direct inclusion into an application, e.g. a Wayland
+compositor. The compositor will then usually register its own
+QTouchScreenObserver because relying on the QTouchEvents generated by
+the QPA event sender is often not satisfactory, as some low-level
+details may get lost, and due to performance reasons.
+
+
+Known issues:
+
+The udev rule matches any touchpad device. If there are multiple ones,
+specify the device as described above.
+
+On recent distributions (e.g. Ubuntu 11.04) you may need to remove
+50-synaptics.conf from /usr/share/X11/xorg.conf.d (followed by
+logout/login) otherwise no evdev events can be read.