[server] Add a signal SeatInterface::focusedPointerChanged

Summary:
The signal gets emitted whenever the focused PointerInterfaces gets
newly set or reset to nullptr. This is needed to better track the
current cursor image in the compositor.

Reviewers: #plasma, sebas

Subscribers: plasma-devel

Projects: #plasma

Differential Revision: https://phabricator.kde.org/D1007

src/wayland/autotests/client/test_wayland_seat.cpp

@@ -296,8 +296,13 @@ void TestWaylandSeat::testPointer()
     SurfaceInterface *serverSurface = surfaceCreatedSpy.first().first().value<KWayland::Server::SurfaceInterface*>();
     QVERIFY(serverSurface);
 
+    QSignalSpy focusedPointerChangedSpy(m_seatInterface, &SeatInterface::focusedPointerChanged);
+    QVERIFY(focusedPointerChangedSpy.isValid());
+
     m_seatInterface->setPointerPos(QPoint(20, 18));
     m_seatInterface->setFocusedPointerSurface(serverSurface, QPoint(10, 15));
+    QCOMPARE(focusedPointerChangedSpy.count(), 1);
+    QVERIFY(!focusedPointerChangedSpy.first().first().value<PointerInterface*>());
     // no pointer yet
     QVERIFY(m_seatInterface->focusedPointerSurface());
     QVERIFY(!m_seatInterface->focusedPointer());
@@ -311,8 +316,12 @@ void TestWaylandSeat::testPointer()
     QVERIFY(pointerCreatedSpy.wait());
     QVERIFY(m_seatInterface->focusedPointer());
     QCOMPARE(pointerCreatedSpy.first().first().value<PointerInterface*>(), m_seatInterface->focusedPointer());
+    QCOMPARE(focusedPointerChangedSpy.count(), 2);
+    QCOMPARE(focusedPointerChangedSpy.last().first().value<PointerInterface*>(), m_seatInterface->focusedPointer());
 
     m_seatInterface->setFocusedPointerSurface(nullptr);
+    QCOMPARE(focusedPointerChangedSpy.count(), 3);
+    QVERIFY(!focusedPointerChangedSpy.last().first().value<PointerInterface*>());
     serverSurface->client()->flush();
     QTest::qWait(100);
 
@@ -342,6 +351,8 @@ void TestWaylandSeat::testPointer()
     QVERIFY(serverPointer);
     QCOMPARE(p->enteredSurface(), s);
     QCOMPARE(cp.enteredSurface(), s);
+    QCOMPARE(focusedPointerChangedSpy.count(), 4);
+    QCOMPARE(focusedPointerChangedSpy.last().first().value<PointerInterface*>(), serverPointer);
 
     // test motion
     m_seatInterface->setTimestamp(1);
@@ -411,6 +422,7 @@ void TestWaylandSeat::testPointer()
 
     // leave the surface
     m_seatInterface->setFocusedPointerSurface(nullptr);
+    QCOMPARE(focusedPointerChangedSpy.count(), 5);
     QVERIFY(leftSpy.wait());
     QCOMPARE(leftSpy.first().first().value<quint32>(), m_display->serial());
     QVERIFY(!p->enteredSurface());
@@ -418,13 +430,15 @@ void TestWaylandSeat::testPointer()
 
     // enter it again
     m_seatInterface->setFocusedPointerSurface(serverSurface, QPoint(0, 0));
+    QCOMPARE(focusedPointerChangedSpy.count(), 6);
     QVERIFY(enteredSpy.wait());
     QCOMPARE(p->enteredSurface(), s);
     QCOMPARE(cp.enteredSurface(), s);
 
     delete s;
     wl_display_flush(m_connection->display());
-    QTest::qWait(100);
+    QVERIFY(focusedPointerChangedSpy.wait());
+    QCOMPARE(focusedPointerChangedSpy.count(), 7);
     QVERIFY(!m_seatInterface->focusedPointerSurface());
 }
 

src/wayland/seat_interface.cpp

@@ -322,6 +322,7 @@ void SeatInterface::Private::getPointer(wl_client *client, wl_resource *resource
         if (!globalPointer.focus.pointer) {
             globalPointer.focus.pointer = pointer;
             pointer->setFocusedSurface(globalPointer.focus.surface, globalPointer.focus.serial);
+            emit q->focusedPointerChanged(pointer);
         }
     }
     QObject::connect(pointer, &QObject::destroyed, q,
@@ -329,6 +330,7 @@ void SeatInterface::Private::getPointer(wl_client *client, wl_resource *resource
             pointers.removeAt(pointers.indexOf(pointer));
             if (globalPointer.focus.pointer == pointer) {
                 globalPointer.focus.pointer = nullptr;
+                emit q->focusedPointerChanged(nullptr);
             }
         }
     );
@@ -514,12 +516,14 @@ void SeatInterface::setFocusedPointerSurface(SurfaceInterface *surface, const QM
             [this] {
                 Q_D();
                 d->globalPointer.focus = Private::Pointer::Focus();
+                emit focusedPointerChanged(nullptr);
             }
         );
         d->globalPointer.focus.offset = QPointF();
         d->globalPointer.focus.transformation = transformation;
         d->globalPointer.focus.serial = serial;
     }
+    emit focusedPointerChanged(p);
     if (!p) {
         return;
     }

src/wayland/seat_interface.h

@@ -373,6 +373,12 @@ Q_SIGNALS:
     void keyboardCreated(KWayland::Server::KeyboardInterface*);
     void touchCreated(KWayland::Server::TouchInterface*);
 
+    /**
+     * Emitted whenever the focused pointer changes
+     * @since 5.6
+     **/
+    void focusedPointerChanged(KWayland::Server::PointerInterface*);
+
 private:
     friend class Display;
     friend class DataDeviceManagerInterface;