wip: wayland: Add xdg-toplevel-drag support

code.code-workspace

@@ -66,19 +66,28 @@
         "request": "launch",
         "program": "${command:cmake.launchTargetPath}",
         "args": [
-          "tst_affinityWithPersistentCentralGroup"
+          "--wayland-toplevel-drag",
+          "-platform",
+          "wayland"
         ],
         "cwd": "${command:cmake.buildDirectory}",
-        "env": {}
+        "env": {
+          "XDG_RUNTIME_DIR": "/run/user/1000"
+        }
       },
       {
         "name": "Current Target (GDB)",
         "type": "cppdbg",
         "request": "launch",
         "program": "${command:cmake.launchTargetPath}",
         "args": [
-          "tst_affinityWithPersistentCentralGroup"
+          "--wayland-toplevel-drag",
+          "-platform",
+          "wayland"
         ],
+        "env": {
+          "XDG_RUNTIME_DIR": "/run/user/1000"
+        },
         "cwd": "${command:cmake.buildDirectory}",
         "MIMode": "gdb",
         "setupCommands": [

examples/dockwidgets/main.cpp

@@ -236,6 +236,13 @@ int main(int argc, char **argv)
         QCoreApplication::translate("main", "Ctrl key toggles drop indicators"));
     parser.addOption(ctrlTogglesDropIndicators);
 
+#ifdef Q_OS_LINUX
+    QCommandLineOption waylandToplevelDrag(
+        "wayland-toplevel-drag",
+        QCoreApplication::translate("main", "Use xdg-toplevel-drag on Wayland so the actual window drags instead of a pixmap"));
+    parser.addOption(waylandToplevelDrag);
+#endif
+
 #if defined(DOCKS_DEVELOPER_MODE)
     parser.addOption(centralFrame);
 
@@ -369,6 +376,11 @@ int main(int argc, char **argv)
     if (parser.isSet(doubleClickMaximize))
         flags |= KDDockWidgets::Config::Flag_DoubleClickMaximizes;
 
+#ifdef Q_OS_LINUX
+    if (parser.isSet(waylandToplevelDrag))
+        flags |= KDDockWidgets::Config::Flag_WaylandToplevelDrag;
+#endif
+
     if (parser.isSet(incompatibleMainWindows) && !parser.isSet(multipleMainWindows)) {
         qWarning() << "Error: Argument -i requires -m";
         return 1;

src/Config.cpp

@@ -361,7 +361,7 @@ void Config::Private::fixFlags()
     }
 
 #if defined(Q_OS_LINUX)
-    if (KDDockWidgets::isWayland()) {
+    if (KDDockWidgets::isWayland() && !(m_flags & Config::Flag_WaylandToplevelDrag)) {
         // Native title bar is forced on Wayland. Needed for moving the window.
         // The inner KDDW title bar is used for DnD.
         m_flags |= Flag_NativeTitleBar;

src/Config.h

@@ -132,6 +132,7 @@ class DOCKS_EXPORT Config
                                                   ///< right clicking on the tab area
         Flag_AutoHideAsTabGroups = 0x100000, ///< If tabbed dockwidgets are sent to/from sidebar, they're all sent and restored together
         Flag_DisableDoubleClick = 0x200000, ///< Do not maximize of float if a title or tab is double-clicked.
+        Flag_WaylandToplevelDrag = 0x400000, ///< EXPERIMENTAL. Uses xdg-toplevel-drag on Wayland so the actual window drags instead of a pixmap. Requires compositor support.
         Flag_Default = Flag_AeroSnapWithClientDecos ///< The defaults
     };
     Q_DECLARE_FLAGS(Flags, Flag)

src/core/DragController.cpp

@@ -596,10 +596,13 @@ namespace {
 StateDragging *createDraggingState(DragController *parent)
 {
 #ifdef KDDW_FRONTEND_QT
-    return isWayland() ? new StateDraggingWayland(parent) : new StateDragging(parent);
-#else
-    return new StateDragging(parent);
+    if (isWayland()) {
+        if (Config::self().flags() & Config::Flag_WaylandToplevelDrag)
+            return new StateDraggingWaylandToplevel(parent);
+        return new StateDraggingWayland(parent);
+    }
 #endif
+    return new StateDragging(parent);
 }
 
 }

src/core/DragController_p.h

@@ -153,6 +153,7 @@ class DOCKS_EXPORT_FOR_UNIT_TESTS DragController : public MinimalStateMachine, p
     friend class StateInternalMDIDragging;
     friend class StateDropped;
     friend class StateDraggingWayland;
+    friend class StateDraggingWaylandToplevel;
     friend class ::TestQtWidgets;
 
     explicit DragController(Core::Object * = nullptr);

src/core/Utils_p.h

@@ -30,6 +30,16 @@ inline bool isWayland()
     return Core::Platform::instance()->displayType() == Core::Platform::DisplayType::Wayland;
 }
 
+inline bool isWaylandXDGTopLevelDrag()
+{
+    return isWayland() && (Config::self().flags() & Config::Flag_WaylandToplevelDrag);
+}
+
+inline bool isWaylandNonXDGTopLevelDrag()
+{
+    return isWayland() && !isWaylandXDGTopLevelDrag();
+}
+
 inline bool isOffscreen()
 {
     return Core::Platform::instance()->displayType() == Core::Platform::DisplayType::QtOffscreen;
@@ -58,7 +68,7 @@ inline bool usesNativeTitleBar()
 inline bool usesClientTitleBar()
 {
     if (isWayland()) {
-        // Wayland has both client and native title bars, due to limitations.
+        // Wayland always has the client title-bar, since the native one doesn't emit events when moved
         return true;
     }
 

src/qtcommon/DragControllerWayland_p.cpp

@@ -14,6 +14,12 @@
 #include "core/ScopedValueRollback_p.h"
 #include "kddockwidgets/core/Platform.h"
 #include "kddockwidgets/core/DropArea.h"
+#include "kddockwidgets/core/FloatingWindow.h"
+#include "qtcommon/Window_p.h"
+#include "Config.h"
+
+#include <QWindow>
+#include <QDataStream>
 
 using namespace KDDockWidgets::Core;
 
@@ -127,3 +133,77 @@ bool StateDraggingWayland::handleDragMove(DragMoveEvent *ev, DropArea *dropArea,
 
     return true;
 }
+
+StateDraggingWaylandToplevel::StateDraggingWaylandToplevel(DragController *parent)
+    : StateDraggingWayland(parent)
+{
+}
+
+StateDraggingWaylandToplevel::~StateDraggingWaylandToplevel()
+{
+}
+
+void StateDraggingWaylandToplevel::onEntry()
+{
+    KDDW_DEBUG("StateDraggingWaylandToplevel entered");
+
+    if (DragController::instance()->m_inQDrag) {
+        KDDW_ERROR("Impossible!");
+        return;
+    }
+
+    ScopedValueRollback guard(DragController::instance()->m_inQDrag, true);
+
+    q->m_windowBeingDragged = q->m_draggable->makeWindow();
+    if (!q->m_windowBeingDragged) {
+        KDDW_ERROR("StateDraggingWaylandToplevel: Failed to create window");
+        q->dragCanceled.emit();
+        return;
+    }
+
+    auto fw = q->m_windowBeingDragged->floatingWindow();
+    if (!fw) {
+        KDDW_ERROR("StateDraggingWaylandToplevel: No FloatingWindow");
+        q->dragCanceled.emit();
+        return;
+    }
+
+    auto window = fw->view()->window();
+    if (!window) {
+        KDDW_ERROR("StateDraggingWaylandToplevel: No window");
+        q->dragCanceled.emit();
+        return;
+    }
+
+    auto qtWindow = static_cast<QtCommon::Window *>(window.get())->qtWindow();
+    if (!qtWindow) {
+        KDDW_ERROR("StateDraggingWaylandToplevel: No QWindow");
+        q->dragCanceled.emit();
+        return;
+    }
+
+    auto serialize = [](const auto &object) {
+        QByteArray data;
+        QDataStream dataStream(&data, QIODevice::WriteOnly);
+        dataStream << object;
+        return data;
+    };
+
+    auto mimeData = new WaylandMimeData();
+    mimeData->setData(QStringLiteral("application/x-qt-mainwindowdrag-window"),
+                      serialize(reinterpret_cast<qintptr>(qtWindow))); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
+    mimeData->setData(QStringLiteral("application/x-qt-mainwindowdrag-position"),
+                      serialize(QCursor::pos()));
+
+    Drag drag(this);
+    drag.setMimeData(mimeData);
+
+    Platform::instance()->installGlobalEventFilter(q);
+    KDDW_DEBUG("Started QDrag (toplevel)");
+    const Qt::DropAction result = drag.exec();
+    KDDW_DEBUG("QDrag (toplevel) finished with result={}", int(result));
+
+    Platform::instance()->removeGlobalEventFilter(q);
+    if (result == Qt::IgnoreAction)
+        q->dragCanceled.emit();
+}

src/qtcommon/DragControllerWayland_p.h

@@ -44,5 +44,14 @@ class WaylandMimeData : public QMimeData
 public:
 };
 
+class StateDraggingWaylandToplevel : public StateDraggingWayland
+{
+    Q_OBJECT
+public:
+    explicit StateDraggingWaylandToplevel(DragController *parent);
+    ~StateDraggingWaylandToplevel() override;
+    void onEntry() override;
+};
+
 }
 }

src/qtwidgets/views/ClassicIndicatorsWindow.cpp

@@ -152,7 +152,6 @@ QString Indicator::iconFileName(bool active) const
 static QWidget *parentForIndicatorWindow(ClassicDropIndicatorOverlay *classicIndicators_)
 {
     // On Wayland it can't be a top-level, as we have no way of positioning it
-
     return isWayland() ? QtCommon::View_qt::asQWidget(classicIndicators_->view()) : nullptr;
 }