timeline: auto-unlink blocks when they're deleted

app/node/block/block.cpp

@@ -204,11 +204,12 @@ void Block::LengthInputChanged()
 
 void Block::Link(Block *a, Block *b)
 {
-  if (a == b || a == nullptr || b == nullptr) {
+  if (a == b || !a || !b) {
     return;
   }
 
-  // Assume both clips are already linked since Link() and Unlink() should be the only entry points to this array
+  // Prevent duplicate link entries (assume that we only need to check one clip since this should be the only function
+  // that adds to the linked array)
   if (a->linked_clips_.contains(b)) {
     return;
   }
@@ -217,7 +218,7 @@ void Block::Link(Block *a, Block *b)
   b->linked_clips_.append(a);
 }
 
-void Block::Link(QList<Block *> blocks)
+void Block::Link(const QList<Block*>& blocks)
 {
   foreach (Block* a, blocks) {
     foreach (Block* b, blocks) {
@@ -228,10 +229,23 @@ void Block::Link(QList<Block *> blocks)
 
 void Block::Unlink(Block *a, Block *b)
 {
+  if (a == b || !a || !b) {
+    return;
+  }
+
   a->linked_clips_.removeOne(b);
   b->linked_clips_.removeOne(a);
 }
 
+void Block::Unlink(const QList<Block *> &blocks)
+{
+  foreach (Block* a, blocks) {
+    foreach (Block* b, blocks) {
+      Unlink(a, b);
+    }
+  }
+}
+
 bool Block::AreLinked(Block *a, Block *b)
 {
   return a->linked_clips_.contains(b);

app/node/block/block.h

@@ -77,8 +77,9 @@ public:
   void set_block_name(const QString& name);
 
   static void Link(Block* a, Block* b);
-  static void Link(QList<Block*> blocks);
+  static void Link(const QList<Block*>& blocks);
   static void Unlink(Block* a, Block* b);
+  static void Unlink(const QList<Block*>& blocks);
   static bool AreLinked(Block* a, Block* b);
   const QVector<Block*>& linked_clips();
   bool HasLinks();

app/widget/timelinewidget/timelinewidget.cpp

@@ -380,6 +380,8 @@ void TimelineWidget::DeleteSelectedInternal(const QList<Block *> &blocks,
     }
 
     if (remove_from_graph) {
+      new BlockUnlinkAllCommand(b, command);
+
       new NodeRemoveWithExclusiveDeps(static_cast<NodeGraph*>(b->parent()), b, command);
     }
   }

app/widget/timelinewidget/undo/undo.cpp

@@ -715,3 +715,52 @@ void WorkareaSetRangeCommand::undo_internal()
 {
   points_->workarea()->set_range(old_range_);
 }
+
+BlockLinkCommand::BlockLinkCommand(const QList<Block *> &blocks, bool link, QUndoCommand *parent) :
+  UndoCommand(parent),
+  blocks_(blocks),
+  link_(link)
+{
+}
+
+void BlockLinkCommand::redo_internal()
+{
+  if (link_) {
+    Block::Link(blocks_);
+  } else {
+    Block::Unlink(blocks_);
+  }
+}
+
+void BlockLinkCommand::undo_internal()
+{
+  if (link_) {
+    Block::Unlink(blocks_);
+  } else {
+    Block::Link(blocks_);
+  }
+}
+
+BlockUnlinkAllCommand::BlockUnlinkAllCommand(Block *block, QUndoCommand *parent) :
+  UndoCommand(parent),
+  block_(block)
+{
+}
+
+void BlockUnlinkAllCommand::redo_internal()
+{
+  unlinked_ = block_->linked_clips();
+
+  foreach (Block* link, unlinked_) {
+    Block::Unlink(block_, link);
+  }
+}
+
+void BlockUnlinkAllCommand::undo_internal()
+{
+  foreach (Block* link, unlinked_) {
+    Block::Link(block_, link);
+  }
+
+  unlinked_.clear();
+}

app/widget/timelinewidget/undo/undo.h

@@ -331,4 +331,34 @@ private:
 
 };
 
+class BlockLinkCommand : public UndoCommand {
+public:
+  BlockLinkCommand(const QList<Block*>& blocks, bool link, QUndoCommand* parent = nullptr);
+
+protected:
+  virtual void redo_internal() override;
+  virtual void undo_internal() override;
+
+private:
+  QList<Block*> blocks_;
+
+  bool link_;
+
+};
+
+class BlockUnlinkAllCommand : public UndoCommand {
+public:
+  BlockUnlinkAllCommand(Block* block, QUndoCommand* parent = nullptr);
+
+protected:
+  virtual void redo_internal() override;
+  virtual void undo_internal() override;
+
+private:
+  Block* block_;
+
+  QVector<Block*> unlinked_;
+
+};
+
 #endif // TIMELINEUNDOABLE_H