Use locked cursor position hint

Summary:
Listen for cursor position hint changes and set cursor position to the hint
on unlock if a valid position hint was set.

Test Plan: With pointer constraints test app.

Reviewers: #kwin, graesslin

Reviewed By: #kwin, graesslin

Subscribers: graesslin, kwin

Tags: #kwin

Maniphest Tasks: T4693

Differential Revision: https://phabricator.kde.org/D14176

pointer_input.cpp

@@ -594,6 +594,12 @@ void PointerInputRedirection::disconnectConfinedPointerRegionConnection()
     m_confinedPointerRegionConnection = QMetaObject::Connection();
 }
 
+void PointerInputRedirection::disconnectLockedPointerAboutToBeUnboundConnection()
+{
+    disconnect(m_lockedPointerAboutToBeUnboundConnection);
+    m_lockedPointerAboutToBeUnboundConnection = QMetaObject::Connection();
+}
+
 void PointerInputRedirection::disconnectPointerConstraintsConnection()
 {
     disconnect(m_constraintsConnection);
@@ -689,8 +695,13 @@ void PointerInputRedirection::updatePointerConstraints()
     if (lock) {
         if (lock->isLocked()) {
             if (!canConstrain) {
+                const auto hint = lock->cursorPositionHint();
                 lock->setLocked(false);
                 m_locked = false;
+                disconnectLockedPointerAboutToBeUnboundConnection();
+                if (! (hint.x() < 0 || hint.y() < 0) && m_window) {
+                    processMotion(m_window->pos() - m_window->clientContentPos() + hint, waylandServer()->seat()->timestamp());
+                }
             }
             return;
         }
@@ -698,6 +709,24 @@ void PointerInputRedirection::updatePointerConstraints()
         if (canConstrain && r.contains(m_pos.toPoint())) {
             lock->setLocked(true);
             m_locked = true;
+
+            // The client might cancel pointer locking from its side by unbinding the LockedPointerInterface.
+            // In this case the cached cursor position hint must be fetched before the resource goes away
+            m_lockedPointerAboutToBeUnboundConnection = connect(lock.data(), &KWayland::Server::LockedPointerInterface::aboutToBeUnbound, this,
+                [this, lock]() {
+                    const auto hint = lock->cursorPositionHint();
+                    if (hint.x() < 0 || hint.y() < 0 || !m_window) {
+                        return;
+                    }
+                    auto globalHint = m_window->pos() - m_window->clientContentPos() + hint;
+
+                    // When the resource finally goes away, reposition the cursor according to the hint
+                    connect(lock.data(), &KWayland::Server::LockedPointerInterface::unbound, this,
+                        [this, globalHint]() {
+                            processMotion(globalHint, waylandServer()->seat()->timestamp());
+                    });
+                }
+            );
             OSD::show(i18nc("notification about mouse pointer locked",
                             "Pointer locked to current position.\nTo end pointer lock hold Escape for 3 seconds."),
                       QStringLiteral("preferences-desktop-mouse"), 5000);
@@ -705,6 +734,7 @@ void PointerInputRedirection::updatePointerConstraints()
         }
     } else {
         m_locked = false;
+        disconnectLockedPointerAboutToBeUnboundConnection();
     }
 }
 

pointer_input.h

@@ -155,6 +155,7 @@ private:
     void warpXcbOnSurfaceLeft(KWayland::Server::SurfaceInterface *surface);
     QPointF applyPointerConfinement(const QPointF &pos) const;
     void disconnectConfinedPointerRegionConnection();
+    void disconnectLockedPointerAboutToBeUnboundConnection();
     void disconnectPointerConstraintsConnection();
     void breakPointerConstraints(KWayland::Server::SurfaceInterface *surface);
     bool areButtonsPressed() const;
@@ -169,6 +170,7 @@ private:
     QMetaObject::Connection m_constraintsConnection;
     QMetaObject::Connection m_constraintsActivatedConnection;
     QMetaObject::Connection m_confinedPointerRegionConnection;
+    QMetaObject::Connection m_lockedPointerAboutToBeUnboundConnection;
     QMetaObject::Connection m_decorationGeometryConnection;
     bool m_confined = false;
     bool m_locked = false;

tests/pointerconstraintstest.cpp

@@ -142,8 +142,14 @@ void WaylandBackend::lockRequest(bool persistent, QRect region)
     }
     m_lockedPointer = lockedPointer;
     m_lockedPointerPersistent = persistent;
+
     connect(lockedPointer, &LockedPointer::locked, this, [this]() {
         qDebug() << "------ LOCKED! ------";
+        if(lockHint()) {
+            m_lockedPointer->setCursorPositionHint(QPointF(10., 10.));
+            forceSurfaceCommit();
+        }
+
         Q_EMIT lockChanged(true);
     });
     connect(lockedPointer, &LockedPointer::unlocked, this, [this]() {

tests/pointerconstraintstest.h

@@ -49,6 +49,7 @@ public:
     Backend(QObject *parent = nullptr) : QObject(parent) {}
 
     Q_PROPERTY(int mode READ mode CONSTANT)
+    Q_PROPERTY(bool lockHint MEMBER m_lockHint NOTIFY lockHintChanged)
     Q_PROPERTY(bool errorsAllowed READ errorsAllowed WRITE setErrorsAllowed NOTIFY errorsAllowedChanged)
 
     virtual void init(QQuickView *view) {
@@ -57,6 +58,10 @@ public:
     int mode() const {
         return (int)m_mode;
     }
+
+    bool lockHint() const {
+        return m_lockHint;
+    }
     bool errorsAllowed() const {
         return m_errorsAllowed;
     }
@@ -87,7 +92,9 @@ public:
 Q_SIGNALS:
     void confineChanged(bool confined);
     void lockChanged(bool locked);
+    void lockHintChanged();
     void errorsAllowedChanged();
+    void forceSurfaceCommit();
 
 protected:
     enum class Mode {
@@ -105,6 +112,8 @@ protected:
 private:
     QQuickView *m_view;
     Mode m_mode;
+
+    bool m_lockHint = true;
     bool m_errorsAllowed = false;
 };
 

tests/pointerconstraintstest.qml

@@ -79,6 +79,28 @@ ColumnLayout {
         return activArea.rect();
     }
 
+    Connections {
+        target: org_kde_kwin_tests_pointerconstraints_backend
+        onForceSurfaceCommit: {
+            forceCommitRect.visible = true
+        }
+    }
+
+    Rectangle {
+        id: forceCommitRect
+        width: 10
+        height: 10
+        color: "red"
+        visible: false
+
+        Timer {
+            interval: 500
+            running: forceCommitRect.visible
+            repeat: false
+            onTriggered: forceCommitRect.visible = false;
+        }
+    }
+
     GridLayout {
         columns: 2
         rowSpacing: 10
@@ -120,6 +142,13 @@ ColumnLayout {
         }
     }
 
+    CheckBox {
+        id: lockHintChck
+        text: "Send position hint on lock"
+        checked: root.waylandNative
+        enabled: root.waylandNative
+        onCheckedChanged: org_kde_kwin_tests_pointerconstraints_backend.lockHint = checked;
+    }
     CheckBox {
         id: restrAreaChck
         text: "Restrict input area (not yet implemented)"