wayland: Implement xdg-shell v5

In v5, the xdg_toplevel.wm_capabilities event had been introduced which
specifies a list of actions allowed by the compositors. Mainly useful to
client-side decorated apps.

src/wayland/xdgshell_interface.cpp

@@ -16,7 +16,7 @@
 
 namespace KWaylandServer
 {
-static const int s_version = 4;
+static const int s_version = 5;
 
 XdgShellInterfacePrivate::XdgShellInterfacePrivate(XdgShellInterface *shell)
     : q(shell)
@@ -595,6 +595,32 @@ void XdgToplevelInterface::sendConfigureBounds(const QSize &size)
     }
 }
 
+void XdgToplevelInterface::sendWmCapabilities(Capabilities capabilities)
+{
+    if (d->resource()->version() < XDG_TOPLEVEL_WM_CAPABILITIES_SINCE_VERSION) {
+        return;
+    }
+    // Note that the capabilities listed in the event must be an array of uint32_t.
+
+    uint32_t capabilitiesData[4] = {0};
+    int i = 0;
+
+    if (capabilities & Capability::WindowMenu) {
+        capabilitiesData[i++] = QtWaylandServer::xdg_toplevel::wm_capabilities_window_menu;
+    }
+    if (capabilities & Capability::Maximize) {
+        capabilitiesData[i++] = QtWaylandServer::xdg_toplevel::wm_capabilities_maximize;
+    }
+    if (capabilities & Capability::FullScreen) {
+        capabilitiesData[i++] = QtWaylandServer::xdg_toplevel::wm_capabilities_fullscreen;
+    }
+    if (capabilities & Capability::Minimize) {
+        capabilitiesData[i++] = QtWaylandServer::xdg_toplevel::wm_capabilities_minimize;
+    }
+
+    d->send_wm_capabilities(QByteArray::fromRawData(reinterpret_cast<char *>(capabilitiesData), sizeof(uint32_t) * i));
+}
+
 XdgToplevelInterface *XdgToplevelInterface::get(::wl_resource *resource)
 {
     if (auto toplevelPrivate = resource_cast<XdgToplevelInterfacePrivate *>(resource)) {

src/wayland/xdgshell_interface.h

@@ -224,6 +224,14 @@ public:
     };
     Q_ENUM(ResizeAnchor)
 
+    enum class Capability {
+        WindowMenu = 0x1,
+        Maximize = 0x2,
+        FullScreen = 0x4,
+        Minimize = 0x8,
+    };
+    Q_DECLARE_FLAGS(Capabilities, Capability)
+
     /**
      * Constructs an XdgToplevelInterface for the given xdg-surface \a surface.
      */
@@ -297,6 +305,11 @@ public:
      */
     void sendConfigureBounds(const QSize &size);
 
+    /**
+     * Sends an event to the client specifying allowed actions by the compositor.
+     */
+    void sendWmCapabilities(Capabilities capabilities);
+
     /**
      * Returns the XdgToplevelInterface for the specified wayland resource object \a resource.
      */
@@ -585,5 +598,6 @@ private:
 } // namespace KWaylandServer
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(KWaylandServer::XdgToplevelInterface::States)
+Q_DECLARE_OPERATORS_FOR_FLAGS(KWaylandServer::XdgToplevelInterface::Capabilities)
 Q_DECLARE_METATYPE(KWaylandServer::XdgToplevelInterface::State)
 Q_DECLARE_METATYPE(KWaylandServer::XdgToplevelInterface::States)

src/xdgshellwindow.cpp

@@ -643,6 +643,12 @@ bool XdgToplevelWindow::supportsWindowRules() const
     return true;
 }
 
+void XdgToplevelWindow::applyWindowRules()
+{
+    WaylandWindow::applyWindowRules();
+    updateCapabilities();
+}
+
 void XdgToplevelWindow::closeWindow()
 {
     if (isCloseable()) {
@@ -1120,11 +1126,13 @@ void XdgToplevelWindow::handlePongReceived(quint32 serial)
 
 void XdgToplevelWindow::handleMaximumSizeChanged()
 {
+    updateCapabilities();
     Q_EMIT maximizeableChanged(isMaximizable());
 }
 
 void XdgToplevelWindow::handleMinimumSizeChanged()
 {
+    updateCapabilities();
     Q_EMIT maximizeableChanged(isMaximizable());
 }
 
@@ -1207,6 +1215,7 @@ void XdgToplevelWindow::initialize()
     configureDecoration();
     scheduleConfigure();
     updateColorScheme();
+    updateCapabilities();
     setupWindowManagementInterface();
 
     m_isInitialized = true;
@@ -1234,6 +1243,26 @@ void XdgToplevelWindow::updateFullScreenMode(bool set)
     Q_EMIT fullScreenChanged();
 }
 
+void XdgToplevelWindow::updateCapabilities()
+{
+    KWaylandServer::XdgToplevelInterface::Capabilities caps = KWaylandServer::XdgToplevelInterface::Capability::WindowMenu;
+
+    if (isMaximizable()) {
+        caps.setFlag(KWaylandServer::XdgToplevelInterface::Capability::Maximize);
+    }
+    if (isFullScreenable()) {
+        caps.setFlag(KWaylandServer::XdgToplevelInterface::Capability::FullScreen);
+    }
+    if (isMinimizable()) {
+        caps.setFlag(KWaylandServer::XdgToplevelInterface::Capability::Minimize);
+    }
+
+    if (m_capabilities != caps) {
+        m_capabilities = caps;
+        m_shellSurface->sendWmCapabilities(caps);
+    }
+}
+
 QString XdgToplevelWindow::preferredColorScheme() const
 {
     if (m_paletteInterface) {

src/xdgshellwindow.h

@@ -150,6 +150,7 @@ public:
     void invalidateDecoration() override;
     QString preferredColorScheme() const override;
     bool supportsWindowRules() const override;
+    void applyWindowRules() override;
     bool takeFocus() override;
     bool wantsInput() const override;
     bool dockWantsInput() const override;
@@ -209,6 +210,7 @@ private:
     void configureXdgDecoration(DecorationMode decorationMode);
     void configureServerDecoration(DecorationMode decorationMode);
     void clearDecoration();
+    void updateCapabilities();
 
     QPointer<KWaylandServer::AppMenuInterface> m_appMenuInterface;
     QPointer<KWaylandServer::ServerSideDecorationPaletteInterface> m_paletteInterface;
@@ -218,6 +220,7 @@ private:
     KWaylandServer::XdgToplevelInterface::States m_nextStates;
     KWaylandServer::XdgToplevelInterface::States m_acknowledgedStates;
     KWaylandServer::XdgToplevelInterface::States m_initialStates;
+    KWaylandServer::XdgToplevelInterface::Capabilities m_capabilities;
     QMap<quint32, PingReason> m_pings;
     MaximizeMode m_maximizeMode = MaximizeRestore;
     MaximizeMode m_requestedMaximizeMode = MaximizeRestore;