Fix some crashes with locked subtitle track

src/bin/model/subtitlemodel.cpp

@@ -1068,7 +1068,7 @@ void SubtitleModel::switchLocked()
     m_subtitleFilter->set("kdenlive:locked", isLocked ? 0 : 1);
     
     // En/disable snapping on lock
-    std::vector<std::weak_ptr<SnapInterface>> validSnapModels;
+    /*std::vector<std::weak_ptr<SnapInterface>> validSnapModels;
     for (const auto &snapModel : m_regSnaps) {
         if (auto ptr = snapModel.lock()) {
             validSnapModels.push_back(snapModel);
@@ -1093,7 +1093,7 @@ void SubtitleModel::switchLocked()
             int id = m_selected.takeFirst();
             updateSub(id, {SelectedRole});
         }
-    }
+    }*/
 }
 
 
@@ -1117,3 +1117,11 @@ void SubtitleModel::loadProperties(QMap<QString, QString> subProperties)
         ++i;
     }
 }
+
+void SubtitleModel::allSnaps(std::vector<int> &snaps)
+{
+    for (const auto &subtitle : m_subtitleList) {
+        snaps.push_back(subtitle.first.frames(pCore->getCurrentFps()));
+        snaps.push_back(subtitle.second.second.frames(pCore->getCurrentFps()));
+    }
+}

src/bin/model/subtitlemodel.hpp

@@ -137,6 +137,8 @@ public:
     bool isLocked() const;
     /** @brief Load some subtitle filter properties from file */
     void loadProperties(QMap<QString, QString> subProperties);
+    /** @brief Add all subtitle items to snaps */
+    void allSnaps(std::vector<int> &snaps);
 
 public slots:
     /** @brief Function that parses through a subtitle file */

src/timeline2/model/timelinemodel.cpp

@@ -1880,7 +1880,6 @@ bool TimelineModel::requestSubtitleDeletion(int clipId, Fun &undo, Fun &redo, bo
         UPDATE_UNDO_REDO(operation, reverse, undo, redo);
         return true;
     }
-    undo();
     return false;
 }
 
@@ -2881,10 +2880,15 @@ int TimelineModel::requestItemResize(int itemId, int size, bool right, bool logU
         TRACE_RES(-1)
         return -1;
     }
-    int in = getItemPosition(itemId);
+    int in = 0;
     int offset = getItemPlaytime(itemId);
-    int out = in + offset;
-    size = requestItemResizeInfo(itemId, in, out, size, right, snapDistance);
+    int tid = getItemTrackId(itemId);
+    int out = offset;
+    if (tid != -1) {
+        in = getItemPosition(itemId);
+        out += in;
+        size = requestItemResizeInfo(itemId, in, out, size, right, snapDistance);
+    }
     offset -= size;
     Fun undo = []() { return true; };
     Fun redo = []() { return true; };
@@ -2896,8 +2900,7 @@ int TimelineModel::requestItemResize(int itemId, int size, bool right, bool logU
     std::unordered_set<int> all_items;
     QList <int> tracksWithMixes;
     all_items.insert(itemId);
-    if (logUndo && isClip(itemId)) {
-        int tid = getItemTrackId(itemId);
+    if (logUndo && isClip(itemId)) { 
         if (tid > -1) {
             if (right) {
                 if (getTrackById_const(tid)->hasEndMix(itemId)) {
@@ -3078,6 +3081,9 @@ int TimelineModel::requestItemResize(int itemId, int size, bool right, bool logU
         if (tid > -1 && getTrackById_const(tid)->isLocked()) {
             continue;
         }
+        if (tid == -2 && m_subtitleModel && m_subtitleModel->isLocked()) {
+            continue;
+        }
         if (right) {
             finalSize = finalPos - getItemPosition(id);
         } else {
@@ -3871,7 +3877,8 @@ int TimelineModel::getNextSnapPos(int pos, std::vector<int> &snaps)
         }
         ++it;
     }
-    if (tracks.isEmpty() || tracks.count() == (int) m_allTracks.size()) {
+    bool hasSubtitles = m_subtitleModel && !m_allSubtitles.empty();
+    if ((tracks.isEmpty() || tracks.count() == (int) m_allTracks.size()) && (!hasSubtitles || !m_subtitleModel->isLocked())) {
         // No active track, use all possible snap points
         return m_snaps->getNextPoint((int)pos);
     }
@@ -3883,6 +3890,11 @@ int TimelineModel::getNextSnapPos(int pos, std::vector<int> &snaps)
             clip->allSnaps(snaps);
         }
     }
+    // Subtitle snaps
+    if (hasSubtitles && !m_subtitleModel->isLocked()) {
+        // Add subtitle snaps
+        m_subtitleModel->allSnaps(snaps);
+    }
     // sort snaps
     std::sort(snaps.begin(), snaps.end());
     for (auto i : snaps) {
@@ -3904,7 +3916,8 @@ int TimelineModel::getPreviousSnapPos(int pos, std::vector<int> &snaps)
         }
         ++it;
     }
-    if (tracks.isEmpty() || tracks.count() == (int) m_allTracks.size()) {
+    bool hasSubtitles = m_subtitleModel && !m_allSubtitles.empty();
+    if ((tracks.isEmpty() || tracks.count() == (int) m_allTracks.size()) && (!hasSubtitles || !m_subtitleModel->isLocked())) {
         // No active track, use all possible snap points
         return m_snaps->getPreviousPoint((int)pos);
     }
@@ -3916,6 +3929,11 @@ int TimelineModel::getPreviousSnapPos(int pos, std::vector<int> &snaps)
             clip->allSnaps(snaps);
         }
     }
+    // Subtitle snaps
+    if (hasSubtitles && !m_subtitleModel->isLocked()) {
+        // Add subtitle snaps
+        m_subtitleModel->allSnaps(snaps);
+    }
     // sort snaps
     std::sort(snaps.begin(), snaps.end());
     // sort descending