Introduce AbstractDropHandler

This abstract class represents an object that receives drag and drop
events.
This roughly maps to some of DataDevice's receiving methods, but by
being abstract
also allows us to use the same code from xwayland in a manner
transparent to all
code paths.

Preivous xwayland support with "proxy surfaces" have been removed.

--
In future it will be extended to have the mouse move events, so that we
can
avoid spying on the seat both in dataDevice and kwin's internal filter

src/wayland/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(SERVER_LIB_SRCS
     abstract_data_source.cpp
+    abstract_drop_handler.cpp
     appmenu_interface.cpp
     blur_interface.cpp
     clientbuffer.cpp
@@ -319,6 +320,7 @@ install(TARGETS KWaylandServer EXPORT KWaylandServerTargets ${KF5_INSTALL_TARGET
 set(SERVER_LIB_HEADERS
   ${CMAKE_CURRENT_BINARY_DIR}/KWaylandServer/kwaylandserver_export.h
   abstract_data_source.h
+  abstract_drop_handler.h
   appmenu_interface.h
   blur_interface.h
   clientbuffer.h

src/wayland/abstract_drop_handler.cpp

@@ -0,0 +1,17 @@
+/*
+    SPDX-FileCopyrightText: 2020 David Edmundson <davidedmundson@kde.org>
+    SPDX-FileCopyrightText: 2021 David Redondo <kde@david-redondo.de>
+
+    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+*/
+
+#include "abstract_drop_handler.h"
+
+namespace KWaylandServer
+{
+AbstractDropHandler::AbstractDropHandler(QObject *parent)
+    : QObject(parent)
+{
+}
+
+}

src/wayland/abstract_drop_handler.h

@@ -0,0 +1,26 @@
+/*
+    SPDX-FileCopyrightText: 2020 David Edmundson <davidedmundson@kde.org>
+    SPDX-FileCopyrightText: 2021 David Redondo <kde@david-redondo.de>
+
+    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+*/
+
+#pragma once
+
+#include <KWaylandServer/kwaylandserver_export.h>
+
+#include <QObject>
+
+namespace KWaylandServer
+{
+class SurfaceInterface;
+
+class KWAYLANDSERVER_EXPORT AbstractDropHandler : public QObject
+{
+    Q_OBJECT
+public:
+    AbstractDropHandler(QObject *parent = nullptr);
+    virtual void updateDragTarget(SurfaceInterface *surface, quint32 serial) = 0;
+    virtual void drop() = 0;
+};
+}

src/wayland/datadevice_interface.cpp

@@ -91,10 +91,6 @@ void DataDeviceInterfacePrivate::data_device_start_drag(Resource *resource,
         dataSource = DataSourceInterface::get(sourceResource);
     }
 
-    if (proxyRemoteSurface) {
-        // origin is a proxy surface
-        focusSurface = proxyRemoteSurface.data();
-    }
     const bool pointerGrab = seat->hasImplicitPointerGrab(serial) && seat->focusedPointerSurface() == focusSurface;
     if (!pointerGrab) {
         // Client doesn't have pointer grab.
@@ -171,7 +167,7 @@ void DataDeviceInterfacePrivate::data_device_destroy_resource(QtWaylandServer::w
 }
 
 DataDeviceInterface::DataDeviceInterface(SeatInterface *seat, wl_resource *resource)
-    : QObject(nullptr)
+    : AbstractDropHandler(nullptr)
     , d(new DataDeviceInterfacePrivate(seat, this, resource))
 {
     SeatInterfacePrivate *seatPrivate = SeatInterfacePrivate::get(seat);

src/wayland/datadevice_interface.h

@@ -11,6 +11,8 @@
 
 #include <KWaylandServer/kwaylandserver_export.h>
 
+#include "abstract_drop_handler.h"
+
 struct wl_client;
 struct wl_resource;
 
@@ -65,7 +67,7 @@ private:
  * @see SeatInterface
  * @see DataSourceInterface
  */
-class KWAYLANDSERVER_EXPORT DataDeviceInterface : public QObject
+class KWAYLANDSERVER_EXPORT DataDeviceInterface : public AbstractDropHandler
 {
     Q_OBJECT
 public:
@@ -80,7 +82,7 @@ public:
     /**
      * The event is sent when a drag-and-drop operation is ended because the implicit grab is removed.
      */
-    void drop();
+    void drop() override;
     /**
      * Updates the SurfaceInterface to which drag motion events are sent.
      *
@@ -92,7 +94,7 @@ public:
      * @param surface The SurfaceInterface which gets motion events
      * @param serial The serial to be used for enter/leave
      */
-    void updateDragTarget(SurfaceInterface *surface, quint32 serial);
+    void updateDragTarget(SurfaceInterface *surface, quint32 serial) override;
     void updateProxy(SurfaceInterface *remote);
 
     wl_client *client();

src/wayland/seat_interface.cpp

@@ -189,6 +189,15 @@ void SeatInterfacePrivate::registerDataDevice(DataDeviceInterface *dataDevice)
     }
 }
 
+KWaylandServer::AbstractDropHandler *SeatInterface::dropHandlerForSurface(SurfaceInterface *surface) const
+{
+    auto list = d->dataDevicesForSurface(surface);
+    if (list.isEmpty()) {
+        return nullptr;
+    };
+    return list.first();
+}
+
 void SeatInterfacePrivate::registerDataControlDevice(DataControlDeviceV1Interface *dataDevice)
 {
     Q_ASSERT(dataDevice->seat() == q);
@@ -275,7 +284,7 @@ void SeatInterfacePrivate::endDrag(quint32 serial)
 {
     QObject::disconnect(drag.dragSourceDestroyConnection);
 
-    DataDeviceInterface *dragTargetDevice = drag.target;
+    AbstractDropHandler *dragTargetDevice = drag.target.data();
     AbstractDataSource *dragSource = drag.source;
     if (dragSource) {
         // TODO: Also check the current drag-and-drop action.
@@ -487,7 +496,10 @@ void SeatInterface::setTimestamp(quint32 time)
     Q_EMIT timestampChanged(time);
 }
 
-void SeatInterface::setDragTarget(SurfaceInterface *surface, const QPointF &globalPosition, const QMatrix4x4 &inputTransformation)
+void SeatInterface::setDragTarget(AbstractDropHandler *dropTarget,
+                                  SurfaceInterface *surface,
+                                  const QPointF &globalPosition,
+                                  const QMatrix4x4 &inputTransformation)
 {
     if (surface == d->drag.surface) {
         // no change
@@ -501,10 +513,7 @@ void SeatInterface::setDragTarget(SurfaceInterface *surface, const QPointF &glob
     // TODO: technically we can have mulitple data devices
     // and we should send the drag to all of them, but that seems overly complicated
     // in practice so far the only case for mulitple data devices is for clipboard overriding
-    d->drag.target = nullptr;
-    if (d->dataDevicesForSurface(surface).size() > 0) {
-        d->drag.target = d->dataDevicesForSurface(surface).first();
-    }
+    d->drag.target = dropTarget;
 
     if (d->drag.mode == SeatInterfacePrivate::Drag::Mode::Pointer) {
         notifyPointerMotion(globalPosition);
@@ -523,13 +532,13 @@ void SeatInterface::setDragTarget(SurfaceInterface *surface, const QPointF &glob
     return;
 }
 
-void SeatInterface::setDragTarget(SurfaceInterface *surface, const QMatrix4x4 &inputTransformation)
+void SeatInterface::setDragTarget(AbstractDropHandler *target, SurfaceInterface *surface, const QMatrix4x4 &inputTransformation)
 {
     if (d->drag.mode == SeatInterfacePrivate::Drag::Mode::Pointer) {
-        setDragTarget(surface, pointerPos(), inputTransformation);
+        setDragTarget(target, surface, pointerPos(), inputTransformation);
     } else {
         Q_ASSERT(d->drag.mode == SeatInterfacePrivate::Drag::Mode::Touch);
-        setDragTarget(surface, d->globalTouch.focus.firstTouchPos, inputTransformation);
+        setDragTarget(target, surface, d->globalTouch.focus.firstTouchPos, inputTransformation);
     }
 }
 

src/wayland/seat_interface.h

@@ -18,6 +18,7 @@ struct wl_resource;
 namespace KWaylandServer
 {
 class AbstractDataSource;
+class AbstractDropHandler;
 class DragAndDropIcon;
 class DataDeviceInterface;
 class Display;
@@ -216,16 +217,18 @@ public:
      * Sends a drag leave event to the current target and an enter event to @p surface.
      * The enter position is derived from @p globalPosition and transformed by @p inputTransformation.
      */
-    void setDragTarget(SurfaceInterface *surface, const QPointF &globalPosition, const QMatrix4x4 &inputTransformation);
+    void setDragTarget(AbstractDropHandler *dropTarget, SurfaceInterface *surface, const QPointF &globalPosition, const QMatrix4x4 &inputTransformation);
     /**
      * Sets the current drag target to @p surface.
      *
      * Sends a drag leave event to the current target and an enter event to @p surface.
      * The enter position is derived from current global position and transformed by @p inputTransformation.
      */
-    void setDragTarget(SurfaceInterface *surface, const QMatrix4x4 &inputTransformation = QMatrix4x4());
+    void setDragTarget(AbstractDropHandler *dropTarget, SurfaceInterface *surface, const QMatrix4x4 &inputTransformation = QMatrix4x4());
     ///@}
 
+    AbstractDropHandler *dropHandlerForSurface(SurfaceInterface *surface) const;
+
     /**
      * @name Pointer related methods
      */

src/wayland/seat_interface_p.h

@@ -123,7 +123,7 @@ public:
         Mode mode = Mode::None;
         AbstractDataSource *source = nullptr;
         QPointer<SurfaceInterface> surface;
-        QPointer<DataDeviceInterface> target;
+        QPointer<AbstractDropHandler> target;
         QPointer<DragAndDropIcon> dragIcon;
         QMatrix4x4 transformation;
         quint32 dragImplicitGrabSerial = -1;