5 files changed, 43 insertions, 1 deletions
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 10a8f26614..a7c60cac84 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -257,6 +257,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     , has_shape_extension(false)
     , has_randr_extension(false)
     , has_input_shape(false)
+    , has_touch_without_mouse_emulation(false)
     , m_buttons(0)
     , m_focusWindow(0)
 {
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 44c0e28dd5..1d6f09a2bc 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -401,6 +401,7 @@ public:
     bool hasXShape() const { return has_shape_extension; }
     bool hasXRandr() const { return has_randr_extension; }
     bool hasInputShape() const { return has_input_shape; }
+    bool hasTouchWithoutMouseEmulation() const { return has_touch_without_mouse_emulation; }
 
     bool supportsThreadedRendering() const { return m_reader->isRunning(); }
 
@@ -543,6 +544,7 @@ private:
     bool has_shape_extension;
     bool has_randr_extension;
     bool has_input_shape;
+    bool has_touch_without_mouse_emulation;
 
     Qt::MouseButtons m_buttons;
 
diff --git a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
index dfd4feb254..991c82eaaa 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
@@ -92,6 +92,9 @@ void QXcbConnection::initializeXInput2()
             // Tablet support: Find the stylus-related devices.
             xi2SetupTabletDevices();
 #endif // QT_NO_TABLETEVENT
+#ifdef XI2_TOUCH_DEBUG
+            qDebug("XInput version %d.%d is supported", xiMajor, m_xi2Minor);
+#endif
         }
     }
 }
@@ -118,7 +121,16 @@ void QXcbConnection::xi2Select(xcb_window_t window)
     mask.deviceid = XIAllMasterDevices;
     mask.mask_len = sizeof(bitMask);
     mask.mask = xiBitMask;
-    XISelectEvents(xDisplay, window, &mask, 1);
+    Status result = XISelectEvents(xDisplay, window, &mask, 1);
+    // If we have XInput 2.2 and successfully enable touch on the master
+    // devices, then evdev touchscreens will provide touch only. In most other
+    // cases, there will be emulated mouse events, because true X11 touch
+    // support is so new that for the older drivers, mouse emulation was the
+    // only way; and it's still the fallback even with the modern evdev driver.
+    // But if neither Qt nor X11 does mouse emulation, it will not be possible
+    // to interact with mouse-oriented QWidgets; so we have to let Qt do it.
+    if (m_xi2Minor >= 2 && result == Success)
+        has_touch_without_mouse_emulation = true;
 #endif
 
 #ifndef QT_NO_TABLETEVENT
diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index dd1466d23c..de26353e1b 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -337,4 +337,30 @@ QPlatformTheme *QXcbIntegration::createPlatformTheme(const QString &name) const
     return QGenericUnixTheme::createUnixTheme(name);
 }
 
+QVariant QXcbIntegration::styleHint(QPlatformIntegration::StyleHint hint) const
+{
+    switch (hint) {
+    case QPlatformIntegration::CursorFlashTime:
+    case QPlatformIntegration::KeyboardInputInterval:
+    case QPlatformIntegration::MouseDoubleClickInterval:
+    case QPlatformIntegration::StartDragDistance:
+    case QPlatformIntegration::StartDragTime:
+    case QPlatformIntegration::KeyboardAutoRepeatRate:
+    case QPlatformIntegration::PasswordMaskDelay:
+    case QPlatformIntegration::FontSmoothingGamma:
+    case QPlatformIntegration::StartDragVelocity:
+    case QPlatformIntegration::UseRtlExtensions:
+        // TODO using various xcb, gnome or KDE settings
+        break; // Not implemented, use defaults
+    case QPlatformIntegration::ShowIsFullScreen:
+        // X11 always has support for windows, but the
+        // window manager could prevent it (e.g. matchbox)
+        return false;
+    case QPlatformIntegration::SynthesizeMouseFromTouchEvents:
+        // We do not want Qt to synthesize mouse events if X11 already does it.
+        return m_connections.at(0)->hasTouchWithoutMouseEmulation();
+    }
+    return QPlatformIntegration::styleHint(hint);
+}
+
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/xcb/qxcbintegration.h b/src/plugins/platforms/xcb/qxcbintegration.h
index 451dc43475..fad5222049 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.h
+++ b/src/plugins/platforms/xcb/qxcbintegration.h
@@ -94,6 +94,7 @@ public:
 
     QStringList themeNames() const;
     QPlatformTheme *createPlatformTheme(const QString &name) const;
+    QVariant styleHint(StyleHint hint) const;
 
     QXcbConnection *defaultConnection() const { return m_connections.first(); }