Spacer tool should not allow moving items before another clip

src/timeline2/model/timelinefunctions.cpp

@@ -71,6 +71,7 @@ QStringList waitingBinIds;
 QMap<QString, QString> mappedIds;
 QMap<int, int> tracksMap;
 QMap<int, int> spacerUngroupedItems;
+int spacerMinPosition;
 QSemaphore semaphore(1);
 
 bool TimelineFunctions::cloneClip(const std::shared_ptr<TimelineItemModel> &timeline, int clipId, int &newId, PlaylistState::ClipState state, Fun &undo,
@@ -327,6 +328,7 @@ int TimelineFunctions::requestSpacerStartOperation(const std::shared_ptr<Timelin
 {
     std::unordered_set<int> clips = timeline->getItemsInRange(trackId, position, -1);
     timeline->requestClearSelection();
+    spacerMinPosition = -1;
     if (!clips.empty()) {
         // Remove grouped items that are before the click position
         // First get top groups ids
@@ -386,6 +388,30 @@ int TimelineFunctions::requestSpacerStartOperation(const std::shared_ptr<Timelin
             timeline->m_groups->ungroupItem(i.key(), undo, redo);
         }
         timeline->requestSetSelection(roots);
+        if (firstPosition > 0) {
+            // Find minimum position, parse all tracks
+            if (trackId > -1) {
+                // Easy, check blank size
+                int spaceDuration = timeline->getTrackById_const(trackId)->getBlankSizeAtPos(firstPosition - 1);
+                if (spaceDuration > 0 ) {
+                    spacerMinPosition = firstPosition - spaceDuration;
+                }
+            } else {
+                // Check space in all tracks
+                auto it = timeline->m_allTracks.cbegin();
+                int space = -1;
+                while (it != timeline->m_allTracks.cend()) {
+                    int spaceDuration = timeline->getTrackById_const((*it)->getId())->getBlankSizeAtPos(firstPosition - 1);
+                    if (space == -1 || spaceDuration < space) {
+                        space = spaceDuration;
+                    }
+                    ++it;
+                }
+                if (space > -1) {
+                    spacerMinPosition = firstPosition - space;
+                }
+            }
+        }
         return (firstCid);
     }
     return -1;
@@ -394,6 +420,7 @@ int TimelineFunctions::requestSpacerStartOperation(const std::shared_ptr<Timelin
 bool TimelineFunctions::requestSpacerEndOperation(const std::shared_ptr<TimelineItemModel> &timeline, int itemId, int startPosition, int endPosition, int affectedTrack, bool moveGuides, Fun &undo, Fun &redo)
 {
     // Move group back to original position
+    spacerMinPosition = -1;
     int track = timeline->getItemTrackId(itemId);
     bool isClip = timeline->isClip(itemId);
     if (isClip) {
@@ -1905,6 +1932,9 @@ bool TimelineFunctions::requestDeleteBlankAt(const std::shared_ptr<TimelineItemM
     } else {
         spaceDuration = timeline->getTrackById_const(trackId)->getBlankSizeAtPos(position);
     }
+    if (spaceDuration <= 0) {
+        return false;
+    }
     int cid = requestSpacerStartOperation(timeline, affectAllTracks ? -1 : trackId, position);
     if (cid == -1) {
         return false;
@@ -2133,3 +2163,7 @@ QDomDocument TimelineFunctions::extractClip(const std::shared_ptr<TimelineItemMo
     return destDoc;
 }
 
+int TimelineFunctions::spacerMinPos()
+{
+    return spacerMinPosition;
+}

src/timeline2/model/timelinefunctions.hpp

@@ -135,6 +135,8 @@ struct TimelineFunctions
     /** @brief This function extracts the content of an xml playlist file and converts it to json paste format
      */
     static QDomDocument extractClip(const std::shared_ptr<TimelineItemModel> &timeline, int cid, const QString &binId);
+
+    static int spacerMinPos();
 };
 
 #endif

src/timeline2/model/trackmodel.cpp

@@ -457,14 +457,22 @@ int TrackModel::getBlankSizeAtPos(int frame)
 {
     READ_LOCK();
     int min_length = 0;
+    int blank_length = 0;
     for (auto &m_playlist : m_playlists) {
-        int ix = m_playlist.get_clip_index_at(frame);
-        if (m_playlist.is_blank(ix)) {
-            int blank_length = m_playlist.clip_length(ix);
-            if (min_length == 0 || (blank_length > 0 && blank_length < min_length)) {
-                min_length = blank_length;
+        if (frame >= m_playlist.get_length()) {
+            blank_length = frame - m_playlist.get_length() + 1;
+        } else {
+            int ix = m_playlist.get_clip_index_at(frame);
+            if (m_playlist.is_blank(ix)) {
+                blank_length = m_playlist.clip_length(ix);
+            } else {
+                // There is a clip at that position, abort
+                return 0;
             }
         }
+        if (min_length == 0 || blank_length < min_length) {
+            min_length = blank_length;
+        }
     }
     return min_length;
 }

src/timeline2/view/qml/timeline.qml

@@ -409,6 +409,7 @@ Rectangle {
     property bool subtitlesDisabled: timeline.subtitlesDisabled
     property int trackTagWidth: fontMetrics.boundingRect("M").width * ((getAudioTracksCount() > 9) || (trackHeaderRepeater.count - getAudioTracksCount() > 9)  ? 3 : 2)
     property bool scrollVertically: timeline.scrollVertically
+    property int spacerMinPos: 0
 
     onSeekingFinishedChanged : {
         playhead.opacity = seekingFinished ? 1 : 0.5
@@ -1155,6 +1156,7 @@ Rectangle {
                         }
 
                         spacerGroup = timeline.requestSpacerStartOperation(spacerTrack, frame)
+                        spacerMinPos = timeline.spacerMinPos()
                         if (spacerGroup > -1 || spacerGuides) {
                             drag.axis = Drag.XAxis
                             Drag.active = true
@@ -1256,6 +1258,7 @@ Rectangle {
                         // Spacer tool, move group
                         var track = controller.getItemTrackId(spacerGroup)
                         var frame = Math.round((mouse.x + scrollView.contentX) / timeline.scaleFactor) + spacerFrame - spacerClickFrame
+                        frame = Math.max(spacerMinPos, frame)
                         finalSpacerFrame = controller.suggestItemMove(spacerGroup, track, frame, root.consumerPosition, (mouse.modifiers & Qt.ShiftModifier) ? 0 : root.snapping)[0]
                         continuousScrolling(mouse.x + scrollView.contentX, mouse.y + scrollView.contentY)
                     } else if (spacerGuides) {

src/timeline2/view/timelinecontroller.cpp

@@ -1625,7 +1625,6 @@ void TimelineController::cutAllClipsUnderCursor(int position)
         position = pCore->getTimelinePosition();
     }
     QMutexLocker lk(&m_metaMutex);
-
     TimelineFunctions::requestClipCutAll(m_model, position);
 }
 
@@ -1636,6 +1635,11 @@ int TimelineController::requestSpacerStartOperation(int trackId, int position)
     return itemId;
 }
 
+int TimelineController::spacerMinPos() const
+{
+    return TimelineFunctions::spacerMinPos();
+}
+
 bool TimelineController::requestSpacerEndOperation(int clipId, int startPosition, int endPosition, int affectedTrack, int guideStart)
 {
     QMutexLocker lk(&m_metaMutex);

src/timeline2/view/timelinecontroller.h

@@ -396,6 +396,9 @@ public:
     /** @brief Request a spacer operation
      */
     Q_INVOKABLE int requestSpacerStartOperation(int trackId, int position);
+    /** @brief Returns the minimum available position for a spacer operation
+     */
+    Q_INVOKABLE int spacerMinPos() const;
     /** @brief Request a spacer operation
      */
     Q_INVOKABLE bool requestSpacerEndOperation(int clipId, int startPosition, int endPosition, int affectedTrack, int guideStart = -1);