improved transition behavior

This is still not complete, but definitely should help a lot

app/widget/timelinewidget/tool/pointer.cpp

@@ -264,10 +264,30 @@ void PointerTool::InitiateDragInternal(Block *clicked_item,
       return;
     }
 
-    // Determine if this move is a slide, which is determined by either
+    bool sliding_due_to_transition = false;
-    bool clips_are_sliding = (slide_instead_of_moving || dynamic_cast<TransitionBlock*>(clicked_item));
 
-    if (clips_are_sliding) {
+    if (!slide_instead_of_moving) {
+      // If the user tries to move a transition without moving the clip it belongs to, we turn
+      // this into a slide
+      foreach (Block* block, clips) {
+        if (TransitionBlock* transit = dynamic_cast<TransitionBlock*>(block)) {
+          if (!CanTransitionMove(transit, clips)) {
+            slide_instead_of_moving = true;
+            break;
+          }
+        } else if (ClipBlock *clip = dynamic_cast<ClipBlock*>(block)) {
+          if ((clip->in_transition() && !CanTransitionMove(clip->in_transition(), clips))
+              || (clip->out_transition() && !CanTransitionMove(clip->out_transition(), clips))) {
+            slide_instead_of_moving = true;
+            break;
+          }
+        }
+      }
+
+      sliding_due_to_transition = slide_instead_of_moving;
+    }
+
+    if (slide_instead_of_moving) {
       // This is a slide. What we do here is move clips within their own track, between the clips
       // that they're already next to. We don't allow changing tracks or changing the order of
       // blocks.
@@ -297,17 +317,51 @@ void PointerTool::InitiateDragInternal(Block *clicked_item,
         Block* latest = latest_block_on_track.value(i.key());
 
         // First we add the block that's out trimming, the one prior to the earliest
-        TimelineViewGhostItem* earliest_ghost;
+        {
-        if (earliest->previous()) {
+          TimelineViewGhostItem* earliest_ghost;
-          earliest_ghost = AddGhostFromBlock(earliest->previous(), Timeline::kTrimOut);
+          bool slide_with_earliest_previous = true;
-        } else {
+          if (sliding_due_to_transition && earliest->previous()) {
-          earliest_ghost = AddGhostFromNull(earliest->in(), earliest->in(), track->ToReference(), Timeline::kTrimOut);
+            if (TransitionBlock *transit = dynamic_cast<TransitionBlock *>(earliest)) {
+              if (earliest->previous() != transit->connected_out_block()) {
+                slide_with_earliest_previous = false;
+              }
+            } else if (ClipBlock *clip = dynamic_cast<ClipBlock*>(earliest)) {
+              if (earliest->previous() != clip->in_transition()) {
+                slide_with_earliest_previous = false;
+              }
+            }
+          }
+
+          if (earliest->previous() && slide_with_earliest_previous) {
+            earliest_ghost = AddGhostFromBlock(earliest->previous(), Timeline::kTrimOut);
+          } else {
+            earliest_ghost = AddGhostFromNull(earliest->in(), earliest->in(), track->ToReference(), Timeline::kTrimOut);
+          }
+          SetGhostToSlideMode(earliest_ghost);
         }
-        SetGhostToSlideMode(earliest_ghost);
 
         // Then we add the block that's in trimming, the one after the latest
         if (latest->next()) {
-          TimelineViewGhostItem* latest_ghost = AddGhostFromBlock(latest->next(), Timeline::kTrimIn);
+          TimelineViewGhostItem* latest_ghost;
+
+          bool slide_with_latest_next = true;
+          if (sliding_due_to_transition) {
+            if (TransitionBlock *transit = dynamic_cast<TransitionBlock *>(latest)) {
+              if (latest->next() != transit->connected_in_block()) {
+                slide_with_latest_next = false;
+              }
+            } else if (ClipBlock *clip = dynamic_cast<ClipBlock*>(latest)) {
+              if (latest->next() != clip->out_transition()) {
+                slide_with_latest_next = false;
+              }
+            }
+          }
+
+          if (slide_with_latest_next) {
+            latest_ghost = AddGhostFromBlock(latest->next(), Timeline::kTrimIn);
+          } else {
+            latest_ghost = AddGhostFromNull(latest->out(), latest->out(), track->ToReference(), Timeline::kTrimIn);
+          }
           SetGhostToSlideMode(latest_ghost);
         }
 
@@ -329,13 +383,18 @@ void PointerTool::InitiateDragInternal(Block *clicked_item,
     } else {
       // Prepare for a standard pointer move by creating ghosts for them and any related blocks
       foreach (Block* block, clips) {
-        if (dynamic_cast<GapBlock*>(block) || dynamic_cast<TransitionBlock*>(block)) {
-          // Gaps cannot move, and we handle transitions further down
-          continue;
-        }
-
         // Create ghost for this block
-        AddGhostFromBlock(block, trim_mode, true);
+        auto ghost = AddGhostFromBlock(block, trim_mode, true);
+        Q_UNUSED(ghost)
+
+        if (ClipBlock *clip = dynamic_cast<ClipBlock*>(block)) {
+          if (clip->out_transition()) {
+            AddGhostFromBlock(clip->out_transition(), trim_mode, true);
+          }
+          if (clip->in_transition()) {
+            AddGhostFromBlock(clip->in_transition(), trim_mode, true);
+          }
+        }
       }
     }
 
@@ -454,6 +513,18 @@ void PointerTool::InitiateDragInternal(Block *clicked_item,
   }
 }
 
+bool PointerTool::CanTransitionMove(TransitionBlock *transit, const QVector<Block *> &clips)
+{
+  Block *out = transit->connected_out_block();
+  Block *in = transit->connected_in_block();
+
+  if ((out && !clips.contains(out)) || (in && !clips.contains(in))) {
+    return false;
+  }
+
+  return true;
+}
+
 void PointerTool::ProcessDrag(const TimelineCoordinate &mouse_pos)
 {
   // Calculate track movement
@@ -691,8 +762,7 @@ void PointerTool::FinishDrag(TimelineViewMouseEvent *event)
     }
 
     if (!movement.isNull()) {
-      QHash<Track::Reference, QList<Block*> >::const_iterator i;
+      for (auto i=slide_info.constBegin(); i!=slide_info.constEnd(); i++) {
-      for (i=slide_info.constBegin(); i!=slide_info.constEnd(); i++) {
         command->add_child(new TrackSlideCommand(parent()->GetTrackFromReference(i.key()),
                                                  i.value(),
                                                  in_adjacents.value(i.key()),
@@ -737,6 +807,17 @@ void PointerTool::InitiateDrag(Block *clicked_item, Timeline::MovementMode trim_
   InitiateDragInternal(clicked_item, trim_mode, modifiers, false, false, false);
 }
 
+TimelineViewGhostItem *PointerTool::GetExistingGhostFromBlock(Block *block)
+{
+  foreach (TimelineViewGhostItem* ghost, parent()->GetGhostItems()) {
+    if (Node::ValueToPtr<Block>(ghost->GetData(TimelineViewGhostItem::kAttachedBlock)) == block) {
+      return ghost;
+    }
+  }
+
+  return nullptr;
+}
+
 //#define HIDE_GAP_GHOSTS
 
 TimelineViewGhostItem* PointerTool::AddGhostFromBlock(Block* block, Timeline::MovementMode mode, bool check_if_exists)
@@ -747,17 +828,17 @@ TimelineViewGhostItem* PointerTool::AddGhostFromBlock(Block* block, Timeline::Mo
     return nullptr;
   }
 
+  TimelineViewGhostItem* ghost;
+
   // Check if we've already made a ghost for this block
   if (check_if_exists) {
-    foreach (TimelineViewGhostItem* ghost, parent()->GetGhostItems()) {
+    if ((ghost = GetExistingGhostFromBlock(block))) {
-      if (Node::ValueToPtr<Block>(ghost->GetData(TimelineViewGhostItem::kAttachedBlock)) == block) {
+      return ghost;
-        return ghost;
-      }
     }
   }
 
   // Otherwise, it's time to make a ghost for this block
-  TimelineViewGhostItem* ghost = TimelineViewGhostItem::FromBlock(block);
+  ghost = TimelineViewGhostItem::FromBlock(block);
 
 #ifdef HIDE_GAP_GHOSTS
   if (block->type() == Block::kGap) {

app/widget/timelinewidget/tool/pointer.h

@@ -41,6 +41,8 @@ protected:
 
   virtual void InitiateDrag(Block* clicked_item, Timeline::MovementMode trim_mode, Qt::KeyboardModifiers modifiers);
 
+  TimelineViewGhostItem *GetExistingGhostFromBlock(Block *block);
+
   TimelineViewGhostItem* AddGhostFromBlock(Block *block, Timeline::MovementMode mode, bool check_if_exists = false);
 
   TimelineViewGhostItem* AddGhostFromNull(const rational& in, const rational& out, const Track::Reference& track, Timeline::MovementMode mode);
@@ -72,6 +74,8 @@ protected:
   const Timeline::MovementMode& drag_movement_mode() const { return drag_movement_mode_; }
   void set_drag_movement_mode(const Timeline::MovementMode &d) { drag_movement_mode_ = d; }
 
+  static bool CanTransitionMove(TransitionBlock *transit, const QVector<Block*> &clips);
+
   void SetMovementAllowed(bool e)
   {
     movement_allowed_ = e;

app/widget/timelinewidget/view/timelineviewghostitem.h

@@ -75,7 +75,6 @@ public:
       ghost->can_have_zero_length_ = false;
     } else if (dynamic_cast<TransitionBlock*>(block)) {
       ghost->can_have_zero_length_ = false;
-      ghost->SetCanMoveTracks(false);
     }
 
     return ghost;