xcb: Implement support for touchpad gestures

They map to the data exposed by libinput exactly the same way as
touchpad gestures on Wayland. The implementation is functionally the
same and follows the same patterns to preserve similar behavior across
X11 and Wayland.

For example, we use the last known pointer position as the position for
gestures, even though on X11 this data is available as part of events.

The new implementation is only enabled if the used xcb supports the
required APIs.

[ChangeLog][Platform Specific Changes][X11] Touchpads can now detect
multi-finger gestures and send RotateNativeGesture, ZoomNativeGesture
and PanNativeGesture events, since XInput 2.4 and X Server 21.1.

Change-Id: If404dcf8385210deadeb7e7c6d29171e9abc9e50
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbwindow.h b/src/plugins/platforms/xcb/qxcbwindow.h
index f7bed7f67b..01aabfc429 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.h
+++ b/src/plugins/platforms/xcb/qxcbwindow.h
@@ -175,6 +175,9 @@ public:
 
     QXcbScreen *xcbScreen() const;
 
+    QPoint lastPointerPosition() const { return m_lastPointerPosition; }
+    QPoint lastPointerGlobalPosition() const { return m_lastPointerGlobalPosition; }
+
     bool startSystemMoveResize(const QPoint &pos, int edges);
     void doStartSystemMoveResize(const QPoint &globalPos, int edges);
 
@@ -271,6 +274,7 @@ protected:
     QRegion m_exposeRegion;
     QSize m_oldWindowSize;
     QPoint m_lastPointerPosition;
+    QPoint m_lastPointerGlobalPosition;
 
     xcb_visualid_t m_visualId = 0;
     // Last sent state. Initialized to an invalid state, on purpose.