Fix crash on mix group move, fix mix sometimes refusing to be created

src/timeline2/model/timelinemodel.cpp

@@ -703,12 +703,13 @@ bool TimelineModel::requestClipMove(int clipId, int trackId, int position, bool
                 // Insert mix on new track
                 bool result = getTrackById_const(trackId)->createMix(mixData.first, mixParams, finalMove);
                 // Remove mix on old track
-                getTrackById_const(previous_track)->syncronizeMixes(finalMove);
+                getTrackById_const(previous_track)->removeMix(mixData.first);
                 return result;
             };
             simple_restore_mix = [this, previous_track, trackId, finalMove, mixData, mixParams]() {
                 bool result = getTrackById_const(previous_track)->createMix(mixData.first, mixParams, finalMove);
-                getTrackById_const(trackId)->syncronizeMixes(finalMove);
+                // Remove mix on old track
+                getTrackById_const(trackId)->removeMix(mixData.first);
                 return result;
             };
         }

src/timeline2/model/trackmodel.cpp

@@ -719,6 +719,7 @@ Fun TrackModel::requestClipResize_lambda(int clipId, int in, int out, bool right
                 }
                 return err == 0;
             };
+        } else {
         }
         blank = target_clip + 1;
     } else {
@@ -730,7 +731,7 @@ Fun TrackModel::requestClipResize_lambda(int clipId, int in, int out, bool right
     }
     if (m_playlists[target_track].is_blank(blank)) {
         int blank_length = m_playlists[target_track].clip_length(blank);
-        if (blank_length + delta >= 0 && (hasMix || other_blank_end >= out)) {
+        if (blank_length + delta >= 0 && (hasMix || other_blank_end >= out - in)) {
             return [blank_length, blank, right, clipId, delta, update_snaps, this, in, out, target_clip, target_track]() {
                 if (isLocked()) return false;
                 int target_clip_mutable = target_clip;
@@ -2198,6 +2199,18 @@ void TrackModel::setMixDuration(int cid, int mixDuration, int mixCut)
     m_sameCompositions[cid]->dataChanged(QModelIndex(), QModelIndex(), {AssetParameterModel::ParentDurationRole});
 }
 
+void TrackModel::removeMix(MixInfo info)
+{
+    Q_ASSERT(m_sameCompositions.count(info.secondClipId) > 0);
+    Mlt::Transition &transition = *static_cast<Mlt::Transition*>(m_sameCompositions[info.secondClipId]->getAsset());
+    QScopedPointer<Mlt::Field> field(m_track->field());
+    field->lock();
+    field->disconnect_service(transition);
+    field->unlock();
+    m_sameCompositions.erase(info.secondClipId);
+    m_mixList.remove(info.firstClipId);
+}
+
 void TrackModel::syncronizeMixes(bool finalMove)
 {
     QList<int>toDelete;

src/timeline2/model/trackmodel.hpp

@@ -140,6 +140,8 @@ public:
     void switchMix(int cid, const QString composition, Fun &undo, Fun &redo);
     /** @brief Ensure we don't have unsynced mixes in the playlist (mixes without owner clip) */
     void syncronizeMixes(bool finalMove);
+    /** @brief Remove a mix in the track (if its clip was removed) */
+    void removeMix(MixInfo info);
     /** @brief Switch a clip from one playlist to the other */
     bool switchPlaylist(int clipId, int position, int sourcePlaylist, int destPlaylist);
     /** @brief Load a same track transition from project */