implemented new block system

Fixes recurring design issue that the Blocks were a frequent exception to the
DAG concept. The Blocks connecting to each others inputs/outputs while not
necessarily being "dependent" on each other to produce an image continually
causes issues while trying to create a rendering code path. This redesign
should provide a more "directed" approach to the directed acyclic graph.

app/widget/timelinewidget/timelinewidget.cpp

@@ -276,7 +276,7 @@ void TimelineWidget::GoToNextCut()
   int64_t closest_cut = INT64_MAX;
 
   foreach (TrackOutput* track, timeline_node_->Tracks()) {
-    int64_t this_track_closest_cut = olive::time_to_timestamp(track->in(), timebase());
+    int64_t this_track_closest_cut = olive::time_to_timestamp(track->track_length(), timebase());
 
     if (this_track_closest_cut <= playhead_) {
       this_track_closest_cut = INT64_MAX;
@@ -592,7 +592,7 @@ void TimelineWidget::AddBlock(Block *block, TrackReference track)
     connect(block, SIGNAL(Refreshed()), this, SLOT(BlockChanged()));
     break;
   }
-  case Block::kEnd:
+  case Block::kTrack:
     // Do nothing
     break;
   }

app/widget/timelinewidget/tool/pointer.cpp

@@ -513,7 +513,7 @@ rational TimelineWidget::PointerTool::ValidateOutTrimming(rational movement,
     if (prevent_overwriting) {
       // Determine if there's a block in the way
       Block* next = block->next();
-      while (next != nullptr && next->type() != Block::kEnd) {
+      while (next != nullptr) {
         if (next->type() == Block::kClip) {
           latest_out = qMin(latest_out, next->in());
           break;

app/widget/timelinewidget/tool/ripple.cpp

@@ -129,9 +129,7 @@ void TimelineWidget::RippleTool::InitiateGhosts(TimelineViewBlockItem *clicked_i
       Block* block_before_ripple = track->NearestBlockBefore(earliest_ripple);
 
       // If block is null, there will be no blocks after to ripple
-      if (block_before_ripple != nullptr
-          && block_before_ripple->type() != Block::kEnd
-          && block_before_ripple->next()->type() != Block::kEnd) {
+      if (block_before_ripple != nullptr) {
         TimelineViewGhostItem* ghost;
 
         TrackReference track_ref(track->track_type(), track->Index());

app/widget/timelinewidget/tool/rolling.cpp

@@ -90,7 +90,7 @@ void TimelineWidget::RollingTool::InitiateGhosts(TimelineViewBlockItem *clicked_
     if (ghost->mode() == olive::timeline::kTrimIn && ghost_block->previous() != nullptr) {
       // Add an extra Ghost for the previous block
       AddGhostFromBlock(ghost_block->previous(), ghost->Track(), olive::timeline::kTrimOut);
-    } else if (ghost->mode() == olive::timeline::kTrimOut && ghost_block->next() != nullptr && ghost_block->next()->type() != Block::kEnd) {
+    } else if (ghost->mode() == olive::timeline::kTrimOut && ghost_block->next() != nullptr) {
       AddGhostFromBlock(ghost_block->next(), ghost->Track(), olive::timeline::kTrimIn);
     }
   }

app/widget/timelinewidget/tool/slide.cpp

@@ -81,7 +81,7 @@ void TimelineWidget::SlideTool::InitiateGhosts(TimelineViewBlockItem *clicked_it
       AddGhostFromBlock(ghost_block->previous(), ghost->Track(), olive::timeline::kTrimOut);
     }
 
-    if (ghost_block->next() != nullptr && ghost_block->next()->type() != Block::kEnd) {
+    if (ghost_block->next() != nullptr) {
       AddGhostFromBlock(ghost_block->next(), ghost->Track(), olive::timeline::kTrimIn);
     }
   }

app/widget/timelinewidget/undo/undo.cpp

@@ -38,18 +38,6 @@ Node* TakeNodeFromParentGraph(Node* n, QObject* new_parent = nullptr)
   return n;
 }
 
-TrackOutput* TrackFromBlock(Block* b)
-{
-  Block* next = b;
-
-  do {
-    next = next->next();
-  } while (next != nullptr && next->type() != Block::kEnd);
-
-  // A little hacky, but this should either be a TrackOutput* or nullptr
-  return static_cast<TrackOutput*>(next);
-}
-
 BlockResizeCommand::BlockResizeCommand(Block *block, rational new_length, QUndoCommand* parent) :
   QUndoCommand(parent),
   block_(block),
@@ -108,8 +96,7 @@ TrackRippleRemoveBlockCommand::TrackRippleRemoveBlockCommand(TrackOutput *track,
   QUndoCommand(parent),
   track_(track),
   block_(block),
-  before_(block->previous()),
-  after_(block->next())
+  before_(block->previous())
 {
 }
 
@@ -120,7 +107,7 @@ void TrackRippleRemoveBlockCommand::redo()
 
 void TrackRippleRemoveBlockCommand::undo()
 {
-  track_->InsertBlockBetweenBlocks(block_, before_, after_);
+  track_->InsertBlockAfter(block_, before_);
 }
 
 TrackInsertBlockBetweenBlocksCommand::TrackInsertBlockBetweenBlocksCommand(TrackOutput *track,
@@ -138,7 +125,7 @@ TrackInsertBlockBetweenBlocksCommand::TrackInsertBlockBetweenBlocksCommand(Track
 
 void TrackInsertBlockBetweenBlocksCommand::redo()
 {
-  track_->InsertBlockBetweenBlocks(block_, before_, after_);
+  track_->InsertBlockAfter(block_, before_);
 }
 
 void TrackInsertBlockBetweenBlocksCommand::undo()
@@ -245,7 +232,7 @@ void TrackRippleRemoveAreaCommand::redo()
       track_->AppendBlock(insert_);
     } else {
       // This is somewhere in the middle of the Sequence
-      track_->InsertBlockBetweenBlocks(insert_, trim_out_, trim_in_);
+      track_->InsertBlockAfter(insert_, trim_out_);
     }
   }
 
@@ -320,14 +307,14 @@ void TrackPlaceBlockCommand::redo()
 
   track_ = timeline_->TrackAt(track_index_);
 
-  append_ = (in_ >= track_->in());
+  append_ = (in_ >= track_->track_length());
 
   // Check if the placement location is past the end of the timeline
   if (append_) {
-    if (in_ > track_->in()) {
+    if (in_ > track_->track_length()) {
       // If so, insert a gap here
       gap_ = new GapBlock();
-      gap_->set_length(in_ - track_->in());
+      gap_->set_length(in_ - track_->track_length());
       track_->AppendBlock(gap_);
     }
 
@@ -471,7 +458,11 @@ BlockSplitPreservingLinksCommand::BlockSplitPreservingLinksCommand(const QVector
       Block* b = blocks.at(j);
 
       if (b->in() < time && b->out() > time) {
-        BlockSplitCommand* split_command = new BlockSplitCommand(TrackFromBlock(b), b, time, this);
+        TrackOutput* track = TrackOutput::TrackFromBlock(b);
+
+        Q_ASSERT(track);
+
+        BlockSplitCommand* split_command = new BlockSplitCommand(track, b, time, this);
         splits.replace(j, split_command->new_block());
       } else {
         splits.replace(j, nullptr);

app/widget/timelinewidget/undo/undo.h

@@ -80,7 +80,6 @@ private:
   Block* block_;
 
   Block* before_;
-  Block* after_;
 };
 
 class TrackPrependBlockCommand : public QUndoCommand {

app/widget/timelinewidget/view/timelineviewblockitem.cpp

@@ -118,7 +118,7 @@ void TimelineViewBlockItem::paint(QPainter *painter, const QStyleOptionGraphicsI
       painter->fillRect(rect(), Qt::white);
     }
     break;
-  case Block::kEnd:
+  case Block::kTrack:
     break;
   }
 }