implement right-to-left

engine/node.h

@@ -41,6 +41,7 @@ enum class kAttribute : uint16_t
     AspectRatio = const_hash("aspect-ratio"),
     ComboList = const_hash("combo-list"),
     Default = const_hash("default"),
+    RTL = const_hash("rtl"),
 };
 
 enum class kWidget : uint16_t
@@ -143,11 +144,13 @@ public:
     void SetAlign(YGAlign value);
     void SetPositioning(YGPositionType value);
     void SetAspectRatio(float ar);
+    void SetRTL(YGDirection dir);
 
     glm::vec2 GetPosition();
     float GetWidth();
     float GetHeight();
     glm::vec2 GetSize();
+    YGDirection GetRTL();
 
     virtual void restore_context();;
     virtual void clear_context();
@@ -162,7 +165,7 @@ public:
     virtual void clone_copy(Node* dest) const;
     virtual void clone_children(Node* dest) const;
     virtual void clone_finalize(Node* dest) const;;
-    void watch(std::function<void(Node*)> observer);
+    void watch(std::function<bool(Node*)> observer);
     void destroy();
     Node* root();