QPlatformWindow: add startSystemMove()

It can be used by custom widgets or for example by
the Breeze style from KDE, which allows to drag windows
by some widgets.

It's important on X11 because _NET_WM_MOVERESIZE requests
induced by touch sequences require support from Qt.

Task-number: QTBUG-58044
Change-Id: I31c37534555a9050cf361cad85bdef13c2808572
Reviewed-by: Johan Helsing <johan.helsing@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 19 insertions, 0 deletions

diff --git a/src/gui/kernel/qplatformwindow.cpp b/src/gui/kernel/qplatformwindow.cpp
index 4bf96e277f..a66420c364 100644
--- a/src/gui/kernel/qplatformwindow.cpp
+++ b/src/gui/kernel/qplatformwindow.cpp
@@ -475,6 +475,25 @@ bool QPlatformWindow::startSystemResize(const QPoint &pos, Qt::Corner corner)
 }
 
 /*!
+    Reimplement this method to start a system move operation if
+    the system supports it and return true to indicate success.
+
+    The \a pos is a position of MouseButtonPress event or TouchBegin
+    event from a sequence of mouse events that triggered the movement.
+    It must be specified in window coordinates.
+
+    The default implementation is empty and does nothing with \a pos.
+
+    \since 5.11
+*/
+
+bool QPlatformWindow::startSystemMove(const QPoint &pos)
+{
+    Q_UNUSED(pos)
+    return false;
+}
+
+/*!
     Reimplement this method to set whether frame strut events
     should be sent to \a enabled.