feat(application): add WindowHints.resizeAroundCenter

application/tests/tst_windowhints.cpp

@@ -29,11 +29,17 @@ private slots:
         hints->setAlwaysOnTop(true);
         hints->setAlwaysOnTop(true);
         QCOMPARE(onTopChanged.count(), 1);
+        QVERIFY(!hints->resizeAroundCenter());
+        QSignalSpy anchorChanged(hints, &Cutefish::WindowHints::resizeAroundCenterChanged);
+        hints->setResizeAroundCenter(true);
+        hints->setResizeAroundCenter(true);
+        QCOMPARE(anchorChanged.count(), 1);
         window.create();
         window.destroy();
         window.create();
         QVERIFY(hints->skipTaskbar());
         QVERIFY(hints->alwaysOnTop());
+        QVERIFY(hints->resizeAroundCenter());
     }
 
     void qmlAndCppShareHintsAcrossSurfaceRecreation()
@@ -49,6 +55,7 @@ private slots:
                 height: 80
                 WindowHints.skipTaskbar: true
                 WindowHints.alwaysOnTop: true
+                WindowHints.resizeAroundCenter: true
                 property bool skipped: WindowHints.skipTaskbar
                 property bool onTop: WindowHints.alwaysOnTop
             }
@@ -67,6 +74,7 @@ private slots:
         QVERIFY(QTest::qWaitForWindowExposed(window));
         QVERIFY(hints->skipTaskbar());
         QVERIFY(hints->alwaysOnTop());
+        QVERIFY(hints->resizeAroundCenter());
         hints->setSkipTaskbar(false);
         QCOMPARE(object->property("skipped").toBool(), false);
         hints->setAlwaysOnTop(false);

application/waylandwindowhints.cpp

@@ -77,4 +77,15 @@ void WaylandWindowHints::setAlwaysOnTop(wl_surface *surface, bool alwaysOnTop)
     wl_display_flush(native->display());
 }
 
+void WaylandWindowHints::setResizeAroundCenter(wl_surface *surface, bool center)
+{
+    if (!m_manager || !surface)
+        return;
+    cutefish_window_hints_v1_set_resize_anchor(m_manager, surface,
+            center ? CUTEFISH_WINDOW_HINTS_V1_RESIZE_ANCHOR_CENTER
+                   : CUTEFISH_WINDOW_HINTS_V1_RESIZE_ANCHOR_TOP_LEFT);
+    auto *native = qGuiApp->nativeInterface<QNativeInterface::QWaylandApplication>();
+    wl_display_flush(native->display());
+}
+
 } // namespace Cutefish

application/waylandwindowhints_p.h

@@ -20,6 +20,7 @@ public:
     bool available() const { return m_manager != nullptr; }
     void setSkipTaskbar(wl_surface *surface, bool skip);
     void setAlwaysOnTop(wl_surface *surface, bool alwaysOnTop);
+    void setResizeAroundCenter(wl_surface *surface, bool center);
 
 Q_SIGNALS:
     void availableChanged();

application/windowhints.cpp

@@ -53,6 +53,15 @@ void WindowHints::setAlwaysOnTop(bool alwaysOnTop)
     Q_EMIT alwaysOnTopChanged();
 }
 
+void WindowHints::setResizeAroundCenter(bool center)
+{
+    if (m_resizeAroundCenter == center)
+        return;
+    m_resizeAroundCenter = center;
+    apply();
+    Q_EMIT resizeAroundCenterChanged();
+}
+
 bool WindowHints::available() const
 {
     return m_window && WaylandWindowHints::instance()->available();
@@ -102,6 +111,7 @@ void WindowHints::apply()
             native->nativeResourceForWindow(QByteArrayLiteral("surface"), m_window));
     WaylandWindowHints::instance()->setSkipTaskbar(surface, m_skipTaskbar);
     WaylandWindowHints::instance()->setAlwaysOnTop(surface, m_alwaysOnTop);
+    WaylandWindowHints::instance()->setResizeAroundCenter(surface, m_resizeAroundCenter);
 }
 
 } // namespace Cutefish

application/windowhints.h

@@ -13,6 +13,9 @@ class WindowHints : public QObject
     Q_OBJECT
     Q_PROPERTY(bool skipTaskbar READ skipTaskbar WRITE setSkipTaskbar NOTIFY skipTaskbarChanged)
     Q_PROPERTY(bool alwaysOnTop READ alwaysOnTop WRITE setAlwaysOnTop NOTIFY alwaysOnTopChanged)
+    // When the window resizes itself, keep its centre rather than its top-left corner.
+    Q_PROPERTY(bool resizeAroundCenter READ resizeAroundCenter WRITE setResizeAroundCenter
+                       NOTIFY resizeAroundCenterChanged)
     Q_PROPERTY(bool available READ available NOTIFY availableChanged)
 
 public:
@@ -24,11 +27,14 @@ public:
     void setSkipTaskbar(bool skip);
     bool alwaysOnTop() const { return m_alwaysOnTop; }
     void setAlwaysOnTop(bool alwaysOnTop);
+    bool resizeAroundCenter() const { return m_resizeAroundCenter; }
+    void setResizeAroundCenter(bool center);
     bool available() const;
 
 Q_SIGNALS:
     void skipTaskbarChanged();
     void alwaysOnTopChanged();
+    void resizeAroundCenterChanged();
     void availableChanged();
 
 protected:
@@ -43,6 +49,7 @@ private:
     QMetaObject::Connection m_destroyedConnection;
     bool m_skipTaskbar = false;
     bool m_alwaysOnTop = false;
+    bool m_resizeAroundCenter = false;
     bool m_surfaceDying = false;
 };
 

protocols/cutefish-window-hints-v1.xml

@@ -9,7 +9,11 @@
       These hints grant no focus or privileged shell role.
     </description>
     <enum name="error">
-      <entry name="invalid_value" value="0" summary="expected a boolean"/>
+      <entry name="invalid_value" value="0" summary="a value is out of range"/>
+    </enum>
+    <enum name="resize_anchor">
+      <entry name="top_left" value="0" summary="the top-left corner stays put"/>
+      <entry name="center" value="1" summary="the centre stays put"/>
     </enum>
     <request name="destroy" type="destructor"/>
     <request name="set_skip_taskbar">
@@ -32,5 +36,17 @@
       <arg name="surface" type="object" interface="wl_surface"/>
       <arg name="on_top" type="uint"/>
     </request>
+    <request name="set_resize_anchor">
+      <description summary="choose the point a client resize keeps in place">
+        When the client changes the size of a normal window on its own, with a
+        new buffer or window geometry rather than in answer to a configure, the
+        compositor keeps this point of the window where it was and then keeps
+        the window inside the work area. Resizes the compositor initiates,
+        interactive resizes and maximized, fullscreen or tiled windows are
+        unaffected. top_left is the default.
+      </description>
+      <arg name="surface" type="object" interface="wl_surface"/>
+      <arg name="anchor" type="uint" enum="resize_anchor"/>
+    </request>
   </interface>
 </protocol>