added gap node and block improvements

app/node/block/block.h

@@ -23,6 +23,12 @@
 
 #include "node/node.h"
 
+/**
+ * @brief A Node that represents a block of time, also displayable on a Timeline
+ *
+ * This is an abstract function. Since different types of Block will provide their lengths in different ways, it's
+ * necessary to subclass and override the length() function for a Block to be usable.
+ */
 class Block : public Node
 {
   Q_OBJECT
@@ -31,10 +37,11 @@ public:
 
   virtual QString Category() override;
 
-  virtual rational in();
-  virtual rational out();
+  const rational& in();
+  const rational& out();
 
   virtual rational length() = 0;
+  virtual void set_length(const rational& length) = 0;
 
   virtual Block* previous();
   virtual Block* next();
@@ -44,6 +51,24 @@ public:
 public slots:
   virtual void Process(const rational &time) override;
 
+  /**
+   * @brief Refreshes internal cache of in/out points up to date
+   *
+   * A block can only know truly know its in point by adding all the lengths of the clips before it. Since this can
+   * become timeconsuming, blocks cache their in and out points for easy access, however this does mean their caches
+   * need to stay up to date to provide accurate results. Whenever this or any surrounding Block is changed, it's
+   * recommended to call Refresh().
+   *
+   * This function specifically sets the in point to the out point of the previous clip and sets its out point to the
+   * in point + this block's length. Therefore, before calling Refresh() on a Block, it's necessary that all the
+   * Blocks before it are accurate and up to date. You may need to traverse through the Block list (using previous())
+   * and run Refresh() on all Blocks sequentially.
+   */
+  void Refresh();
+
+protected:
+  void RefreshSurrounds();
+
 private:
   NodeInput* previous_input_;
   NodeInput* next_input_;
@@ -51,6 +76,9 @@ private:
   NodeOutput* next_output_;
 
   NodeOutput* texture_output_;
+
+  rational in_point_;
+  rational out_point_;
 };
 
 #endif // BLOCK_H