implemented base transition support

While very much incomplete, transitions can now be created and will render
correctly.

app/widget/timelinewidget/tool/transition.cpp

@@ -1,29 +1,104 @@
 #include "widget/timelinewidget/timelinewidget.h"
 
+#include "node/block/transition/crossdissolve/crossdissolve.h"
+#include "widget/nodeview/nodeviewundo.h"
+
 TimelineWidget::TransitionTool::TransitionTool(TimelineWidget *parent) :
-  Tool(parent)
+  AddTool(parent)
 {
 }
 
 void TimelineWidget::TransitionTool::MousePress(TimelineViewMouseEvent *event)
 {
-  TimelineViewBlockItem* item = GetItemAtScenePos(event->GetCoordinates());
+  const TrackReference& track = event->GetCoordinates().GetTrack();
+  TrackOutput* t = parent()->GetTrackFromReference(track);
+  rational cursor_frame = event->GetCoordinates().GetFrame();
 
-  bool selectable_item = (item != nullptr
-      && item->flags() & QGraphicsItem::ItemIsSelectable
-      && !parent()->GetTrackFromReference(item->Track())->IsLocked());
-
-  if (!selectable_item) {
+  if (!t || t->IsLocked()) {
     return;
   }
+
+  Block* block_at_time = t->BlockAtTime(event->GetCoordinates().GetFrame());
+  if (!block_at_time || block_at_time->type() != Block::kClip) {
+    return;
+  }
+
+  // Determine which side of the clip the transition belongs to
+  rational transition_start_point;
+  olive::timeline::MovementMode trim_mode;
+  rational halfway_point = block_at_time->in() + block_at_time->length() / 2;
+  if (cursor_frame < halfway_point) {
+    transition_start_point = block_at_time->in();
+    trim_mode = olive::timeline::kTrimIn;
+  } else {
+    transition_start_point = block_at_time->out();
+    trim_mode = olive::timeline::kTrimOut;
+  }
+
+  // Create ghost
+  ghost_ = new TimelineViewGhostItem();
+  ghost_->SetTrack(track);
+  ghost_->SetYCoords(parent()->GetTrackY(track), parent()->GetTrackHeight(track));
+  ghost_->SetIn(transition_start_point);
+  ghost_->SetOut(transition_start_point);
+  ghost_->SetMode(trim_mode);
+  ghost_->setData(TimelineViewGhostItem::kAttachedBlock, Node::PtrToValue(block_at_time));
+  parent()->AddGhost(ghost_);
+
+  snap_points_.append(transition_start_point);
+
+  // Set the drag start point
+  drag_start_point_ = cursor_frame;
 }
 
 void TimelineWidget::TransitionTool::MouseMove(TimelineViewMouseEvent *event)
 {
-  Q_UNUSED(event)
+  if (!ghost_) {
+    return;
+  }
+
+  MouseMoveInternal(event->GetCoordinates().GetFrame(), false);
 }
 
 void TimelineWidget::TransitionTool::MouseRelease(TimelineViewMouseEvent *event)
 {
-  Q_UNUSED(event)
+  MouseMove(event);
+
+  const TrackReference& track = ghost_->Track();
+
+  if (ghost_) {
+    if (!ghost_->AdjustedLength().isNull()) {
+      Block* block_to_transition = Node::ValueToPtr<Block>(ghost_->data(TimelineViewGhostItem::kAttachedBlock));
+      CrossDissolveTransition* transition = new CrossDissolveTransition();
+      NodeInput* transition_input_to_connect;
+
+      if (ghost_->mode() == olive::timeline::kTrimIn) {
+        transition->set_in_and_out_offset(ghost_->AdjustedLength(), 0);
+        transition_input_to_connect = transition->in_block_input();
+      } else {
+        transition->set_in_and_out_offset(0, ghost_->AdjustedLength());
+        transition_input_to_connect = transition->out_block_input();
+      }
+
+      QUndoCommand* command = new QUndoCommand();
+
+      // Place transition in place
+      new TrackPlaceBlockCommand(parent()->timeline_node_->track_list(track.type()),
+                                                              track.index(),
+                                                              transition,
+                                                              ghost_->GetAdjustedIn(),
+                                                              command);
+
+      // Connect block to transition
+      new NodeEdgeAddCommand(block_to_transition->output(),
+                             transition_input_to_connect,
+                             command);
+
+      olive::undo_stack.push(command);
+    }
+
+    parent()->ClearGhosts();
+    snap_points_.clear();
+    ghost_ = nullptr;
+  }
 }