Fix various spacer issues.

Fixes #1093

src/bin/model/subtitlemodel.cpp

@@ -1225,3 +1225,18 @@ int SubtitleModel::getBlankSizeAtPos(int pos) const
     }
     return max.frames(pCore->getCurrentFps()) - min.frames(pCore->getCurrentFps());
 }
+
+int SubtitleModel::getBlankStart(int pos) const
+{
+    GenTime matchPos(pos, pCore->getCurrentFps());
+    std::unordered_set<int> matching;
+    bool found = false;
+    GenTime min;
+    for (const auto &subtitles : m_subtitleList) {
+        if (subtitles.second.second < matchPos && (min == GenTime() ||  subtitles.second.second > min)) {
+            min = subtitles.second.second;
+            found = true;
+        }
+    }
+    return found ? min.frames(pCore->getCurrentFps()) + 1 : 0;
+}

src/bin/model/subtitlemodel.hpp

@@ -144,6 +144,8 @@ public:
     QDomElement toXml(int sid, QDomDocument &document);
     /** @brief Returns the size of the space between subtitles */
     int getBlankSizeAtPos(int pos) const;
+    /** @brief Returns the position of the first blank frame before a position */
+    int getBlankStart(int pos) const;
     /** @brief Switch a subtitle's grab state */
     void switchGrab(int sid);
     /** @brief Ungrab all items */

src/timeline2/model/timelinefunctions.cpp

@@ -1925,14 +1925,31 @@ bool TimelineFunctions::pasteTimelineClips(const std::shared_ptr<TimelineItemMod
 bool TimelineFunctions::requestDeleteBlankAt(const std::shared_ptr<TimelineItemModel> &timeline, int trackId, int position, bool affectAllTracks)
 {
     // find blank duration
-    int spaceDuration;
-    if (trackId == -2) {
-        // Subtitle track
-        spaceDuration = timeline->getSubtitleModel()->getBlankSizeAtPos(position);
+    int spaceStart = 0;
+    if (affectAllTracks) {
+        int lastFrame = 0;
+        for (const auto &track: timeline->m_allTracks) {
+            lastFrame = track->getBlankStart(position);
+            if (lastFrame > spaceStart) {
+                spaceStart = lastFrame;
+            }
+        }
+        // check subtitle track
+        if (timeline->getSubtitleModel()) {
+            lastFrame = timeline->getSubtitleModel()->getBlankStart(position);
+            if (lastFrame > spaceStart) {
+                spaceStart = lastFrame;
+            }
+        }
     } else {
-        spaceDuration = timeline->getTrackById_const(trackId)->getBlankSizeAtPos(position);
+        if (trackId == -2) {
+            // Subtitle track
+            spaceStart = timeline->getSubtitleModel()->getBlankStart(position);
+        } else {
+            spaceStart = timeline->getTrackById_const(trackId)->getBlankStart(position);
+        }
     }
-    if (spaceDuration <= 0) {
+    if (spaceStart == position) {
         return false;
     }
     int cid = requestSpacerStartOperation(timeline, affectAllTracks ? -1 : trackId, position);
@@ -1943,7 +1960,7 @@ bool TimelineFunctions::requestDeleteBlankAt(const std::shared_ptr<TimelineItemM
     // Start undoable command
     std::function<bool(void)> undo = []() { return true; };
     std::function<bool(void)> redo = []() { return true; };
-    requestSpacerEndOperation(timeline, cid, start, start - spaceDuration, affectAllTracks ? -1 : trackId, !KdenliveSettings::lockedGuides(), undo, redo);
+    requestSpacerEndOperation(timeline, cid, start, spaceStart, affectAllTracks ? -1 : trackId, !KdenliveSettings::lockedGuides(), undo, redo);
     return true;
 }
 

src/timeline2/model/trackmodel.cpp

@@ -459,8 +459,9 @@ int TrackModel::getBlankSizeAtPos(int frame)
     int min_length = 0;
     int blank_length = 0;
     for (auto &m_playlist : m_playlists) {
-        if (frame >= m_playlist.get_length()) {
-            blank_length = frame - m_playlist.get_length() + 1;
+        int playlistLength = m_playlist.get_length();
+        if (frame >= playlistLength) {
+            continue;
         } else {
             int ix = m_playlist.get_clip_index_at(frame);
             if (m_playlist.is_blank(ix)) {
@@ -474,6 +475,10 @@ int TrackModel::getBlankSizeAtPos(int frame)
             min_length = blank_length;
         }
     }
+    if (blank_length == 0) {
+        // playlists are shorter than frame
+        return -1;
+    }
     return min_length;
 }