Fix crash after moving clip with filter and undo twice

The trim command was also causing a spurious filter change
command which would cause crashing.

As reported here:
https://forum.shotcut.org/t/crash-after-moving-clip-with-filter/47467

Author: bmatherly

src/commands/timelinecommands.cpp

@@ -855,6 +855,7 @@ TrimClipInCommand::TrimClipInCommand(MultitrackModel &model,
 
 void TrimClipInCommand::redo()
 {
+    MAIN.filterController()->pauseUndoTracking();
     if (m_rippleMarkers) {
         // Remove and shift markers as appropriate
         bool markersModified = false;
@@ -911,16 +912,19 @@ void TrimClipInCommand::redo()
         m_undoHelper->recordAfterState();
         m_redo = true;
     }
+    MAIN.filterController()->resumeUndoTracking();
 }
 
 void TrimClipInCommand::undo()
 {
     LOG_DEBUG() << "trackIndex" << m_trackIndex << "clipIndex" << m_clipIndex << "delta" << m_delta;
     Q_ASSERT(m_undoHelper);
+    MAIN.filterController()->pauseUndoTracking();
     m_undoHelper->undoChanges();
     if (m_rippleMarkers && m_markerRemoveStart >= 0) {
         m_markersModel.doReplace(m_markers);
     }
+    MAIN.filterController()->resumeUndoTracking();
 }
 
 bool TrimClipInCommand::mergeWith(const QUndoCommand *other)
@@ -961,6 +965,7 @@ TrimClipOutCommand::TrimClipOutCommand(MultitrackModel &model,
 
 void TrimClipOutCommand::redo()
 {
+    MAIN.filterController()->pauseUndoTracking();
     if (m_rippleMarkers) {
         // Remove and shift markers as appropriate
         bool markersModified = false;
@@ -1019,16 +1024,19 @@ void TrimClipOutCommand::redo()
         m_undoHelper->recordAfterState();
         m_redo = true;
     }
+    MAIN.filterController()->resumeUndoTracking();
 }
 
 void TrimClipOutCommand::undo()
 {
     LOG_DEBUG() << "trackIndex" << m_trackIndex << "clipIndex" << m_clipIndex << "delta" << m_delta;
     Q_ASSERT(m_undoHelper);
+    MAIN.filterController()->pauseUndoTracking();
     m_undoHelper->undoChanges();
     if (m_rippleMarkers && m_markerRemoveStart >= 0) {
         m_markersModel.doReplace(m_markers);
     }
+    MAIN.filterController()->resumeUndoTracking();
 }
 
 bool TrimClipOutCommand::mergeWith(const QUndoCommand *other)
@@ -1262,9 +1270,11 @@ TrimTransitionInCommand::TrimTransitionInCommand(MultitrackModel &model,
 void TrimTransitionInCommand::redo()
 {
     if (m_redo) {
+        MAIN.filterController()->pauseUndoTracking();
         m_model.trimTransitionIn(m_trackIndex, m_clipIndex, m_delta);
         if (m_notify && m_clipIndex >= 0)
             m_model.notifyClipIn(m_trackIndex, m_clipIndex);
+        MAIN.filterController()->resumeUndoTracking();
     } else {
         m_redo = true;
     }
@@ -1274,9 +1284,11 @@ void TrimTransitionInCommand::undo()
 {
     LOG_DEBUG() << "trackIndex" << m_trackIndex << "clipIndex" << m_clipIndex << "delta" << m_delta;
     if (m_clipIndex >= 0) {
+        MAIN.filterController()->pauseUndoTracking();
         m_model.trimTransitionIn(m_trackIndex, m_clipIndex, -m_delta);
         m_model.notifyClipIn(m_trackIndex, m_clipIndex);
         m_notify = true;
+        MAIN.filterController()->resumeUndoTracking();
     } else
         LOG_WARNING() << "invalid clip index" << m_clipIndex;
 }
@@ -1311,9 +1323,11 @@ void TrimTransitionOutCommand::redo()
 {
     if (m_redo) {
         LOG_DEBUG() << "trackIndex" << m_trackIndex << "clipIndex" << m_clipIndex;
+        MAIN.filterController()->pauseUndoTracking();
         m_model.trimTransitionOut(m_trackIndex, m_clipIndex, m_delta);
         if (m_notify && m_clipIndex >= 0)
             m_model.notifyClipOut(m_trackIndex, m_clipIndex);
+        MAIN.filterController()->resumeUndoTracking();
     } else {
         m_redo = true;
     }
@@ -1324,9 +1338,11 @@ void TrimTransitionOutCommand::undo()
     if (m_clipIndex >= 0) {
         LOG_DEBUG() << "trackIndex" << m_trackIndex << "clipIndex" << m_clipIndex << "delta"
                     << m_delta;
+        MAIN.filterController()->pauseUndoTracking();
         m_model.trimTransitionOut(m_trackIndex, m_clipIndex, -m_delta);
         m_model.notifyClipOut(m_trackIndex, m_clipIndex);
         m_notify = true;
+        MAIN.filterController()->resumeUndoTracking();
     } else
         LOG_WARNING() << "invalid clip index" << m_clipIndex;
 }

src/controllers/filtercontroller.cpp

@@ -363,6 +363,20 @@ void FilterController::onProducerChanged()
     emit m_attachedModel.trackTitleChanged();
 }
 
+void FilterController::pauseUndoTracking()
+{
+    if (m_currentFilter && !m_attachedModel.isSourceClip()) {
+        m_currentFilter->stopUndoTracking();
+    }
+}
+
+void FilterController::resumeUndoTracking()
+{
+    if (m_currentFilter && !m_attachedModel.isSourceClip()) {
+        m_currentFilter->startUndoTracking();
+    }
+}
+
 void FilterController::addMetadata(QmlMetadata *meta)
 {
     m_metadataModel.add(meta);

src/controllers/filtercontroller.h

@@ -66,6 +66,8 @@ public slots:
     void onServiceOutChanged(int delta, Mlt::Service *service = 0);
     void removeCurrent();
     void onProducerChanged();
+    void pauseUndoTracking();
+    void resumeUndoTracking();
 
 private slots:
     void handleAttachedModelChange();

src/docks/timelinedock.cpp

@@ -2685,6 +2685,7 @@ void TimelineDock::commitTrimCommand()
     }
     m_trimDelta = 0;
     m_transitionDelta = 0;
+    emit trimEnded();
 }
 
 void TimelineDock::onRowsInserted(const QModelIndex &parent, int first, int last)
@@ -3202,6 +3203,7 @@ void TimelineDock::onClipMoved(int fromTrack, int toTrack, int clipIndex, int po
 
 bool TimelineDock::trimClipIn(int trackIndex, int clipIndex, int oldClipIndex, int delta, bool ripple)
 {
+    emit trimStarted();
     if (dynamic_cast<Timeline::RemoveTransitionByTrimInCommand *>(m_trimCommand.get())) {
         if (delta < 0) {
             // Do not trim past the removed tansition
@@ -3292,6 +3294,7 @@ bool TimelineDock::trimClipIn(int trackIndex, int clipIndex, int oldClipIndex, i
 
 bool TimelineDock::trimClipOut(int trackIndex, int clipIndex, int delta, bool ripple)
 {
+    emit trimStarted();
     if (dynamic_cast<Timeline::RemoveTransitionByTrimOutCommand *>(m_trimCommand.get())) {
         if (delta < 0) {
             // Do not trim past the removed tansition

src/docks/timelinedock.h

@@ -128,6 +128,8 @@ class TimelineDock : public QDockWidget
     void warnTrackLocked(int trackIndex);
     void refreshWaveforms();
     void updateThumbnails(int trackIndex, int clipIndex);
+    void trimStarted();
+    void trimEnded();
 
 public slots:
     int addAudioTrack();

src/mainwindow.cpp

@@ -666,6 +666,14 @@ void MainWindow::setupAndConnectDocks()
             m_filterController->motionTrackerModel(),
             &MotionTrackerModel::removeFromService);
     connect(this, SIGNAL(audioChannelsChanged()), m_filterController, SLOT(setProducer()));
+    connect(m_timelineDock,
+            &TimelineDock::trimStarted,
+            m_filterController,
+            &FilterController::pauseUndoTracking);
+    connect(m_timelineDock,
+            &TimelineDock::trimEnded,
+            m_filterController,
+            &FilterController::resumeUndoTracking);
 
     m_markersDock = new MarkersDock(this);
     m_markersDock->hide();

src/qmltypes/qmlfilter.cpp

@@ -801,6 +801,15 @@ void QmlFilter::startUndoTracking()
     }
 }
 
+void QmlFilter::stopUndoTracking()
+{
+    if (!m_previousState.count()) {
+        LOG_DEBUG() << "Undo tracking has not started yet";
+        return;
+    }
+    m_previousState = Mlt::Properties();
+}
+
 void QmlFilter::startUndoParameterCommand(const QString &desc)
 {
     if (!m_previousState.count()) {

src/qmltypes/qmlfilter.h

@@ -141,6 +141,7 @@ class QmlFilter : public QObject
 
     // Functions for undo/redo
     void startUndoTracking();
+    void stopUndoTracking();
     Q_INVOKABLE void startUndoParameterCommand(const QString &desc = QString());
     void startUndoAddKeyframeCommand();
     void startUndoRemoveKeyframeCommand();