wayland: Fix resizing of windows with aspect ratio

After finishing interactive resize, the window needs to be gravitated.
However, it won't be gravitated because isInteractiveMoveResize() will
return false.

In order to fix that, every configure event needs to carry the gravity,
that way the window can be gravitated even after leaving interactive
resize.

src/xdgshellclient.cpp

@@ -137,6 +137,7 @@ void XdgSurfaceClient::sendConfigure()
         configureEvent->flags = previousEvent->flags;
     }
 
+    configureEvent->gravity = m_nextGravity;
     configureEvent->flags |= m_configureFlags;
     m_configureFlags = {};
 
@@ -199,6 +200,37 @@ void XdgSurfaceClient::maybeUpdateMoveResizeGeometry(const QRect &rect)
     setMoveResizeGeometry(rect);
 }
 
+static QRect gravitateGeometry(const QRect &rect, const QRect &bounds, Gravity gravity)
+{
+    QRect geometry = rect;
+
+    switch (gravity) {
+    case Gravity::TopLeft:
+        geometry.moveRight(bounds.right());
+        geometry.moveBottom(bounds.bottom());
+        break;
+    case Gravity::Top:
+    case Gravity::TopRight:
+        geometry.moveLeft(bounds.left());
+        geometry.moveBottom(bounds.bottom());
+        break;
+    case Gravity::Right:
+    case Gravity::BottomRight:
+    case Gravity::Bottom:
+    case Gravity::None:
+        geometry.moveLeft(bounds.left());
+        geometry.moveTop(bounds.top());
+        break;
+    case Gravity::BottomLeft:
+    case Gravity::Left:
+        geometry.moveRight(bounds.right());
+        geometry.moveTop(bounds.top());
+        break;
+    }
+
+    return geometry;
+}
+
 void XdgSurfaceClient::handleNextWindowGeometry()
 {
     const QRect boundingGeometry = surface()->boundingRect();
@@ -221,22 +253,13 @@ void XdgSurfaceClient::handleNextWindowGeometry()
     }
 
     QRect frameGeometry(pos(), clientSizeToFrameSize(m_windowGeometry.size()));
-
-    // We're not done yet. The xdg-shell spec allows clients to attach buffers smaller than
-    // we asked. Normally, this is not a big deal, but when the client is being interactively
-    // resized, it may cause the window contents to bounce. In order to counter this, we have
-    // to "gravitate" the new geometry according to the current move-resize pointer mode so
-    // the opposite window corner stays still.
-
-    if (isInteractiveMoveResize()) {
-        frameGeometry = adjustMoveResizeGeometry(frameGeometry);
-    } else {
     if (const XdgSurfaceConfigure *configureEvent = lastAcknowledgedConfigure()) {
         if (configureEvent->flags & XdgSurfaceConfigure::ConfigurePosition) {
-                frameGeometry.moveTopLeft(configureEvent->position);
+            frameGeometry = gravitateGeometry(frameGeometry, configureEvent->bounds, configureEvent->gravity);
         }
     }
 
+    if (!isInteractiveMoveResize()) {
         // Both the compositor and the client can change the window geometry. If the client
         // sets a new window geometry, the compositor's move-resize geometry will be invalid.
         maybeUpdateMoveResizeGeometry(frameGeometry);
@@ -260,37 +283,6 @@ void XdgSurfaceClient::resetHaveNextWindowGeometry()
     m_haveNextWindowGeometry = false;
 }
 
-QRect XdgSurfaceClient::adjustMoveResizeGeometry(const QRect &rect) const
-{
-    QRect geometry = rect;
-
-    switch (interactiveMoveResizeGravity()) {
-    case Gravity::TopLeft:
-        geometry.moveRight(moveResizeGeometry().right());
-        geometry.moveBottom(moveResizeGeometry().bottom());
-        break;
-    case Gravity::Top:
-    case Gravity::TopRight:
-        geometry.moveLeft(moveResizeGeometry().left());
-        geometry.moveBottom(moveResizeGeometry().bottom());
-        break;
-    case Gravity::Right:
-    case Gravity::BottomRight:
-    case Gravity::Bottom:
-    case Gravity::None:
-        geometry.moveLeft(moveResizeGeometry().left());
-        geometry.moveTop(moveResizeGeometry().top());
-        break;
-    case Gravity::BottomLeft:
-    case Gravity::Left:
-        geometry.moveRight(moveResizeGeometry().right());
-        geometry.moveTop(moveResizeGeometry().top());
-        break;
-    }
-
-    return geometry;
-}
-
 void XdgSurfaceClient::moveResizeInternal(const QRect &rect, MoveResizeMode mode)
 {
     if (areGeometryUpdatesBlocked()) {
@@ -866,7 +858,7 @@ XdgSurfaceConfigure *XdgToplevelClient::sendRoleConfigure() const
     const quint32 serial = m_shellSurface->sendConfigure(nextClientSize, m_nextStates);
 
     XdgToplevelConfigure *configureEvent = new XdgToplevelConfigure();
-    configureEvent->position = moveResizeGeometry().topLeft();
+    configureEvent->bounds = moveResizeGeometry();
     configureEvent->states = m_nextStates;
     configureEvent->decoration = m_nextDecoration;
     configureEvent->serial = serial;
@@ -1006,6 +998,7 @@ void XdgToplevelClient::doSetQuickTileMode()
 bool XdgToplevelClient::doStartInteractiveMoveResize()
 {
     if (interactiveMoveResizeGravity() != Gravity::None) {
+        m_nextGravity = interactiveMoveResizeGravity();
         m_nextStates |= XdgToplevelInterface::State::Resizing;
         scheduleConfigure();
     }
@@ -2031,7 +2024,7 @@ XdgSurfaceConfigure *XdgPopupClient::sendRoleConfigure() const
     const quint32 serial = m_shellSurface->sendConfigure(QRect(popupPosition, moveResizeGeometry().size()));
 
     XdgSurfaceConfigure *configureEvent = new XdgSurfaceConfigure();
-    configureEvent->position = moveResizeGeometry().topLeft();
+    configureEvent->bounds = moveResizeGeometry();
     configureEvent->serial = serial;
 
     return configureEvent;

src/xdgshellclient.h

@@ -41,7 +41,8 @@ public:
     };
     Q_DECLARE_FLAGS(ConfigureFlags, ConfigureFlag)
 
-    QPoint position;
+    QRect bounds;
+    Gravity gravity;
     qreal serial;
     ConfigureFlags flags;
 };
@@ -76,6 +77,7 @@ protected:
     QPointer<KWaylandServer::PlasmaShellSurfaceInterface> m_plasmaShellSurface;
 
     NET::WindowType m_windowType = NET::Normal;
+    Gravity m_nextGravity = Gravity::None;
 
 private:
     void setupPlasmaShellIntegration();
@@ -87,7 +89,6 @@ private:
     bool haveNextWindowGeometry() const;
     void setHaveNextWindowGeometry();
     void resetHaveNextWindowGeometry();
-    QRect adjustMoveResizeGeometry(const QRect &rect) const;
     void maybeUpdateMoveResizeGeometry(const QRect &rect);
 
     KWaylandServer::XdgSurfaceInterface *m_shellSurface;