[wayland] Add support for ServerSideDecorationManager

We announce support for it and depending on whether we have a plugin
or not set the default mode to Server or None.

When a decoration interface is created it gets installed on the
ShellClient. But there it isn't properly used yet as we don't have
support for decorations in ShellClient yet.

decorations/decorationbridge.cpp

@@ -26,6 +26,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "client.h"
 #include "composite.h"
 #include "scene.h"
+#include "wayland_server.h"
 #include "workspace.h"
 
 // KDecoration
@@ -33,6 +34,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <KDecoration2/DecoratedClient>
 #include <KDecoration2/DecorationSettings>
 
+// KWayland
+#include <KWayland/Server/server_decoration_interface.h>
+
 // Frameworks
 #include <KPluginMetaData>
 #include <KPluginLoader>
@@ -82,8 +86,12 @@ QString DecorationBridge::readTheme() const
 
 void DecorationBridge::init()
 {
+    using namespace KWayland::Server;
     m_noPlugin = readNoPlugin();
     if (m_noPlugin) {
+        if (waylandServer()) {
+            waylandServer()->decorationManager()->setDefaultMode(ServerSideDecorationManagerInterface::Mode::None);
+        }
         return;
     }
     m_plugin = readPlugin();
@@ -101,6 +109,9 @@ void DecorationBridge::init()
             initPlugin();
         }
     }
+    if (waylandServer()) {
+        waylandServer()->decorationManager()->setDefaultMode(m_factory ? ServerSideDecorationManagerInterface::Mode::Server : ServerSideDecorationManagerInterface::Mode::None);
+    }
 }
 
 void DecorationBridge::initPlugin()

shell_client.cpp

@@ -34,6 +34,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <KWayland/Server/buffer_interface.h>
 #include <KWayland/Server/plasmashell_interface.h>
 #include <KWayland/Server/shadow_interface.h>
+#include <KWayland/Server/server_decoration_interface.h>
 #include <KWayland/Server/qtsurfaceextension_interface.h>
 #include <KWayland/Server/plasmawindowmanagement_interface.h>
 
@@ -148,6 +149,10 @@ ShellClient::ShellClient(ShellSurfaceInterface *surface)
             updateCursor();
         }
     );
+    // check whether we have a ServerSideDecoration
+    if (ServerSideDecorationInterface *deco = ServerSideDecorationInterface::get(surface->surface())) {
+        installServerSideDecoration(deco);
+    }
 }
 
 ShellClient::~ShellClient() = default;
@@ -847,4 +852,29 @@ QMatrix4x4 ShellClient::inputTransformation() const
     return m;
 }
 
+void ShellClient::installServerSideDecoration(KWayland::Server::ServerSideDecorationInterface *deco)
+{
+    if (m_serverDecoration == deco) {
+        return;
+    }
+    m_serverDecoration = deco;
+    connect(m_serverDecoration, &ServerSideDecorationInterface::destroyed, this,
+        [this] {
+            // TODO: update decoration
+            m_serverDecoration = nullptr;
+        }
+    );
+    // TODO: update decoration
+    connect(m_serverDecoration, &ServerSideDecorationInterface::modeRequested, this,
+        [this] (ServerSideDecorationManagerInterface::Mode mode) {
+            const bool changed = mode != m_serverDecoration->mode();
+            // always acknowledge the requested mode
+            m_serverDecoration->setMode(mode);
+            if (changed) {
+                // TODO: update decoration
+            }
+        }
+    );
+}
+
 }

shell_client.h

@@ -27,6 +27,7 @@ namespace KWayland
 namespace Server
 {
 class ShellSurfaceInterface;
+class ServerSideDecorationInterface;
 class PlasmaShellSurfaceInterface;
 class QtExtendedSurfaceInterface;
 }
@@ -109,6 +110,7 @@ public:
 
     void installPlasmaShellSurface(KWayland::Server::PlasmaShellSurfaceInterface *surface);
     void installQtExtendedSurface(KWayland::Server::QtExtendedSurfaceInterface *surface);
+    void installServerSideDecoration(KWayland::Server::ServerSideDecorationInterface *decoration);
 
     bool isInitialPositionSet() const;
 
@@ -161,6 +163,7 @@ private:
     NET::WindowType m_windowType = NET::Normal;
     QPointer<KWayland::Server::PlasmaShellSurfaceInterface> m_plasmaShellSurface;
     QPointer<KWayland::Server::QtExtendedSurfaceInterface> m_qtExtendedSurface;
+    KWayland::Server::ServerSideDecorationInterface *m_serverDecoration = nullptr;
     bool m_fullScreen = false;
     bool m_transient = false;
 };

wayland_server.cpp

@@ -42,6 +42,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <KWayland/Server/plasmawindowmanagement_interface.h>
 #include <KWayland/Server/qtsurfaceextension_interface.h>
 #include <KWayland/Server/seat_interface.h>
+#include <KWayland/Server/server_decoration_interface.h>
 #include <KWayland/Server/shadow_interface.h>
 #include <KWayland/Server/blur_interface.h>
 #include <KWayland/Server/shell_interface.h>
@@ -219,6 +220,16 @@ void WaylandServer::init(const QByteArray &socketName, InitalizationFlags flags)
     shadowManager->create();
 
     m_display->createDpmsManager(m_display)->create();
+
+    m_decorationManager = m_display->createServerSideDecorationManager(m_display);
+    connect(m_decorationManager, &ServerSideDecorationManagerInterface::decorationCreated, this,
+        [this] (ServerSideDecorationInterface *deco) {
+            if (ShellClient *c = findClient(deco->surface())) {
+                c->installServerSideDecoration(deco);
+            }
+        }
+    );
+    m_decorationManager->create();
 }
 
 void WaylandServer::initWorkspace()

wayland_server.h

@@ -43,6 +43,7 @@ class CompositorInterface;
 class Display;
 class ShellInterface;
 class SeatInterface;
+class ServerSideDecorationManagerInterface;
 class SurfaceInterface;
 class OutputInterface;
 class PlasmaShellInterface;
@@ -89,6 +90,9 @@ public:
     KWayland::Server::PlasmaWindowManagementInterface *windowManagement() {
         return m_windowManagement;
     }
+    KWayland::Server::ServerSideDecorationManagerInterface *decorationManager() const {
+        return m_decorationManager;
+    }
     QList<ShellClient*> clients() const {
         return m_clients;
     }
@@ -164,6 +168,7 @@ private:
     KWayland::Server::PlasmaShellInterface *m_plasmaShell = nullptr;
     KWayland::Server::PlasmaWindowManagementInterface *m_windowManagement = nullptr;
     KWayland::Server::QtSurfaceExtensionInterface *m_qtExtendedSurface = nullptr;
+    KWayland::Server::ServerSideDecorationManagerInterface *m_decorationManager = nullptr;
     struct {
         KWayland::Server::ClientConnection *client = nullptr;
         QMetaObject::Connection destroyConnection;