Wayland: can drag a window by its titlebar using the touchscreen

It was already possible to drag it via the mouse but not via touch.

Task-number: QTBUG-41085
Change-Id: Ia52c7124fb2f1aa0331897bd072fcf09fb78aa1a
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

src/plugins/platforms/wayland/qwaylanddecoration.cpp

@@ -335,6 +335,19 @@ bool QWaylandDecoration::handleMouse(QWaylandInputDevice *inputDevice, const QPo
     return true;
 }
 
+bool QWaylandDecoration::handleTouch(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global, Qt::TouchPointState state, Qt::KeyboardModifiers mods)
+{
+    Q_UNUSED(inputDevice);
+    Q_UNUSED(global);
+    Q_UNUSED(mods);
+
+    if (state == Qt::TouchPointPressed && local.y() <= m_margins.top()) {
+        m_wayland_window->shellSurface()->move(inputDevice);
+        return true;
+    }
+    return false;
+}
+
 bool QWaylandDecoration::inMouseButtonPressedState() const
 {
     return m_mouseButtons & Qt::NoButton;

src/plugins/platforms/wayland/qwaylanddecoration_p.h

@@ -75,6 +75,7 @@ public:
     bool isDirty() const;
 
     bool handleMouse(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global,Qt::MouseButtons b,Qt::KeyboardModifiers mods);
+    bool handleTouch(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global, Qt::TouchPointState state, Qt::KeyboardModifiers mods);
     bool inMouseButtonPressedState() const;
 
     void startResize(QWaylandInputDevice *inputDevice,enum wl_shell_surface_resize resize, Qt::MouseButtons buttons);

src/plugins/platforms/wayland/qwaylandinputdevice.cpp

@@ -853,8 +853,8 @@ void QWaylandInputDevice::Touch::touch_down(uint32_t serial,
                                      wl_fixed_t x,
                                      wl_fixed_t y)
 {
-    Q_UNUSED(serial);
+    mParent->mTime = time;
-    Q_UNUSED(time);
+    mParent->mSerial = serial;
     mFocus = QWaylandWindow::fromWlSurface(surface);
     mParent->handleTouchPoint(id, wl_fixed_to_double(x), wl_fixed_to_double(y), Qt::TouchPointPressed);
 }
@@ -966,6 +966,12 @@ void QWaylandInputDevice::Touch::touch_frame()
 
     QWindow *window = mFocus ? mFocus->window() : 0;
 
+    if (mFocus) {
+        const QWindowSystemInterface::TouchPoint &tp = mTouchPoints.last();
+        QPointF localPos(window->mapFromGlobal(tp.area.center().toPoint()));
+        if (mFocus->touchDragDecoration(mParent, localPos, tp.area.center(), tp.state, mParent->modifiers()))
+            return;
+    }
     QWindowSystemInterface::handleTouchEvent(window, mParent->mTouchDevice, mTouchPoints);
 
     const bool allReleased = allTouchPointsReleased();

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -583,6 +583,13 @@ void QWaylandWindow::handleMouseLeave(QWaylandInputDevice *inputDevice)
     restoreMouseCursor(inputDevice);
 }
 
+bool QWaylandWindow::touchDragDecoration(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global, Qt::TouchPointState state, Qt::KeyboardModifiers mods)
+{
+    if (!mWindowDecoration)
+        return false;
+    return mWindowDecoration->handleTouch(inputDevice, local, global, state, mods);
+}
+
 void QWaylandWindow::handleMouseEventWithDecoration(QWaylandInputDevice *inputDevice, ulong timestamp, const QPointF &local, const QPointF &global, Qt::MouseButtons b, Qt::KeyboardModifiers mods)
 {
     if (mWindowDecoration->handleMouse(inputDevice,local,global,b,mods))

src/plugins/platforms/wayland/qwaylandwindow_p.h

@@ -156,6 +156,9 @@ public:
     void handleMouseEnter(QWaylandInputDevice *inputDevice);
     void handleMouseLeave(QWaylandInputDevice *inputDevice);
 
+    bool touchDragDecoration(QWaylandInputDevice *inputDevice, const QPointF &local, const QPointF &global,
+                             Qt::TouchPointState state, Qt::KeyboardModifiers mods);
+
     bool createDecoration();
 
     inline bool isMaximized() const { return mState == Qt::WindowMaximized; }