wayland: Implement xdg-shell v6

This change adds support for xdg_wm_base v6, which introduces
xdg_toplevel suspended state.

The suspended state is tied to the visibility of the window item so the
effects could possibily "resume" window content updates.

src/scene/windowitem.cpp

@@ -168,7 +168,12 @@ bool WindowItem::computeVisibility() const
 
 void WindowItem::updateVisibility()
 {
-    setVisible(computeVisibility());
+    const bool visible = computeVisibility();
+    setVisible(visible);
+
+    if (m_window->readyForPainting()) {
+        m_window->setSuspended(!visible);
+    }
 }
 
 void WindowItem::updatePosition()

src/wayland/xdgshell_interface.cpp

@@ -16,7 +16,7 @@
 
 namespace KWaylandServer
 {
-static const int s_version = 5;
+static const int s_version = 6;
 
 XdgShellInterfacePrivate::XdgShellInterfacePrivate(XdgShellInterface *shell)
     : q(shell)
@@ -540,7 +540,7 @@ quint32 XdgToplevelInterface::sendConfigure(const QSize &size, const States &sta
 {
     // Note that the states listed in the configure event must be an array of uint32_t.
 
-    uint32_t statesData[8] = {0};
+    uint32_t statesData[9] = {0};
     int i = 0;
 
     if (states & State::MaximizedHorizontal && states & State::MaximizedVertical) {
@@ -571,6 +571,12 @@ quint32 XdgToplevelInterface::sendConfigure(const QSize &size, const States &sta
         }
     }
 
+    if (d->resource()->version() >= XDG_TOPLEVEL_STATE_SUSPENDED_SINCE_VERSION) {
+        if (states & State::Suspended) {
+            statesData[i++] = QtWaylandServer::xdg_toplevel::state_suspended;
+        }
+    }
+
     const QByteArray xdgStates = QByteArray::fromRawData(reinterpret_cast<char *>(statesData), sizeof(uint32_t) * i);
     const quint32 serial = xdgSurface()->shell()->display()->nextSerial();
 

src/wayland/xdgshell_interface.h

@@ -207,6 +207,7 @@ public:
         TiledTop = 0x40,
         TiledRight = 0x80,
         TiledBottom = 0x100,
+        Suspended = 0x200,
         Maximized = MaximizedHorizontal | MaximizedVertical,
     };
     Q_DECLARE_FLAGS(States, State)

src/window.cpp

@@ -4256,6 +4256,26 @@ void Window::setHiddenByShowDesktop(bool hidden)
     }
 }
 
+bool Window::isSuspended() const
+{
+    return m_suspended;
+}
+
+void Window::setSuspended(bool suspended)
+{
+    if (isDeleted()) {
+        return;
+    }
+    if (m_suspended != suspended) {
+        m_suspended = suspended;
+        doSetSuspended();
+    }
+}
+
+void Window::doSetSuspended()
+{
+}
+
 } // namespace KWin
 
 #include "moc_window.cpp"

src/window.h

@@ -988,6 +988,9 @@ public:
     }
     virtual bool isMinimizable() const;
 
+    bool isSuspended() const;
+    void setSuspended(bool suspended);
+
     QRectF fullscreenGeometryRestore() const;
     virtual bool isFullScreenable() const;
     virtual bool isFullScreen() const;
@@ -1502,6 +1505,7 @@ protected:
     virtual void doSetQuickTileMode();
     virtual void doSetHidden();
     virtual void doSetHiddenByShowDesktop();
+    virtual void doSetSuspended();
 
     void setupWindowManagementInterface();
     void destroyWindowManagementInterface();
@@ -1753,6 +1757,7 @@ protected:
     bool m_keepBelow = false;
     bool m_demandsAttention = false;
     bool m_minimized = false;
+    bool m_suspended = false;
     QTimer *m_autoRaiseTimer = nullptr;
     QTimer *m_shadeHoverTimer = nullptr;
     ShadeMode m_shadeMode = ShadeNone;

src/xdgshellwindow.cpp

@@ -836,6 +836,17 @@ void XdgToplevelWindow::doFinishInteractiveMoveResize()
     }
 }
 
+void XdgToplevelWindow::doSetSuspended()
+{
+    if (isSuspended()) {
+        m_nextStates |= XdgToplevelInterface::State::Suspended;
+    } else {
+        m_nextStates &= ~XdgToplevelInterface::State::Suspended;
+    }
+
+    scheduleConfigure();
+}
+
 bool XdgToplevelWindow::takeFocus()
 {
     if (wantsInput()) {

src/xdgshellwindow.h

@@ -178,6 +178,7 @@ protected:
     bool acceptsFocus() const override;
     Layer layerForDock() const override;
     void doSetQuickTileMode() override;
+    void doSetSuspended() override;
 
 private:
     void handleWindowTitleChanged();