Use runtime detection of XInput 2.1 to disable legacy wheel events

Ensure we fall back to using wheel button events if xinput 2.1
scroll events are not available. Handles lack of xinput 2.1
support in the server or in the input devices drivers.

Task-number: QTBUG-38169
Change-Id: Ie4ad9069f648d0ab02d8f9540ed01ad58fd9e9d8
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 13a0280baf..1933b89a19 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -402,6 +402,12 @@ public:
 #elif defined(XCB_USE_XINPUT2)
     void xi2Select(xcb_window_t window);
 #endif
+#ifdef XCB_USE_XINPUT21
+    bool isUsingXInput21() { return m_xi2Enabled && m_xi2Minor >= 1; }
+#else
+    bool isUsingXInput21() { return false; }
+#endif
+
 
     void sync();
     void flush() { xcb_flush(m_connection); }
@@ -511,11 +517,12 @@ private:
     QVector<TabletData> m_tabletData;
 #endif
     struct ScrollingDevice {
-        ScrollingDevice() : deviceId(0), verticalIndex(0), horizontalIndex(0), orientations(0) { }
+        ScrollingDevice() : deviceId(0), verticalIndex(0), horizontalIndex(0), orientations(0), legacyOrientations(0) { }
         int deviceId;
         int verticalIndex, horizontalIndex;
         double verticalIncrement, horizontalIncrement;
         Qt::Orientations orientations;
+        Qt::Orientations legacyOrientations;
         QPointF lastScrollPosition;
     };
     void xi2HandleScrollEvent(void *event, ScrollingDevice &scrollingDevice);
@@ -525,6 +532,7 @@ private:
 #if defined(XCB_USE_XINPUT2) || defined(XCB_USE_XINPUT2_MAEMO)
     static bool xi2GetValuatorValueIfSet(void *event, int valuatorNum, double *value);
     static bool xi2PrepareXIGenericDeviceEvent(xcb_ge_event_t *event, int opCode);
+    static bool xi2GetButtonState(void *event, int buttonNum);
 #endif
 
     xcb_connection_t *m_connection;