Run undo/redo commands only if there is something to undo/redo.

Author: kovacsv

Sources/NodeUIEngine/NUIE_InteractionHandler.cpp

@@ -624,13 +624,6 @@ void InteractionHandler::ExecuteCommand (NodeUIEnvironment& uiEnvironment, NUIE:
 	MenuCommandPtr menuCommand = nullptr;
 
 	switch (command) {
-		case CommandCode::Delete:
-			{
-				if (!selectedNodes.IsEmpty ()) {
-					menuCommand.reset (new DeleteNodesMenuCommand (uiManager, uiEnvironment, selectedNodes));
-				}
-			}
-			break;
 		case CommandCode::SelectAll:
 			{
 				NE::NodeCollection allSelectedNodes;
@@ -650,6 +643,13 @@ void InteractionHandler::ExecuteCommand (NodeUIEnvironment& uiEnvironment, NUIE:
 				}
 			}
 			break;
+		case CommandCode::Delete:
+			{
+				if (!selectedNodes.IsEmpty ()) {
+					menuCommand.reset (new DeleteNodesMenuCommand (uiManager, uiEnvironment, selectedNodes));
+				}
+			}
+			break;
 		case CommandCode::Copy:
 			{
 				if (!selectedNodes.IsEmpty ()) {
@@ -681,12 +681,16 @@ void InteractionHandler::ExecuteCommand (NodeUIEnvironment& uiEnvironment, NUIE:
 			break;
 		case CommandCode::Undo:
 			{
-				menuCommand.reset (new UndoMenuCommand (uiManager, uiEnvironment));
+				if (uiManager.CanUndo ()) {
+					menuCommand.reset (new UndoMenuCommand (uiManager, uiEnvironment));
+				}
 			}
 			break;
 		case CommandCode::Redo:
 			{
-				menuCommand.reset (new RedoMenuCommand (uiManager, uiEnvironment));
+				if (uiManager.CanRedo ()) {
+					menuCommand.reset (new RedoMenuCommand (uiManager, uiEnvironment));
+				}
 			}
 			break;
 		case CommandCode::Escape:

Sources/NodeUIEngine/NUIE_InteractionHandler.hpp

@@ -17,9 +17,9 @@ enum class CommandCode
 {
 	Undefined,
 	Escape,
-	Delete,
 	SelectAll,
 	SetParameters,
+	Delete,
 	Copy,
 	Paste,
 	Group,

Sources/NodeUIEngine/NUIE_NodeUIManager.cpp

@@ -625,6 +625,16 @@ void NodeUIManager::SaveUndoState ()
 	undoHandler.SaveUndoState (nodeManager);
 }
 
+bool NodeUIManager::CanUndo () const
+{
+	return undoHandler.CanUndo ();
+}
+
+bool NodeUIManager::CanRedo () const
+{
+	return undoHandler.CanRedo ();
+}
+
 bool NodeUIManager::Undo (NE::EvaluationEnv& env)
 {
 	NodeUIManagerUpdateEventHandler eventHandler (*this, env);

Sources/NodeUIEngine/NUIE_NodeUIManager.hpp

@@ -153,6 +153,8 @@ class NodeUIManager
 	NE::NodeCollection			Duplicate (const NE::NodeCollection& nodeCollection);
 
 	void						SaveUndoState ();
+	bool						CanUndo () const;
+	bool						CanRedo () const;
 	bool						Undo (NE::EvaluationEnv& env);
 	bool						Redo (NE::EvaluationEnv& env);
 

Sources/NodeUIEngine/NUIE_UndoHandler.cpp

@@ -22,9 +22,19 @@ void UndoHandler::SaveUndoState (const NE::NodeManager& nodeManager)
 	SaveAndAddState (nodeManager, undoStack);
 }
 
+bool UndoHandler::CanUndo () const
+{
+	return !undoStack.empty ();
+}
+
+bool UndoHandler::CanRedo () const
+{
+	return !redoStack.empty ();
+}
+
 bool UndoHandler::Undo (NE::NodeManager& targetNodeManager, NE::UpdateEventHandler& eventHandler)
 {
-	if (undoStack.empty ()) {
+	if (!CanUndo ()) {
 		return false;
 	}
 
@@ -38,7 +48,7 @@ bool UndoHandler::Undo (NE::NodeManager& targetNodeManager, NE::UpdateEventHandl
 
 bool UndoHandler::Redo (NE::NodeManager& targetNodeManager, NE::UpdateEventHandler& eventHandler)
 {
-	if (redoStack.empty ()) {
+	if (!CanRedo ()) {
 		return false;
 	}
 

Sources/NodeUIEngine/NUIE_UndoHandler.hpp

@@ -15,8 +15,13 @@ class UndoHandler
 	UndoHandler ();
 
 	void	SaveUndoState (const NE::NodeManager& nodeManager);
+
+	bool	CanUndo () const;
+	bool	CanRedo () const;
+
 	bool	Undo (NE::NodeManager& targetNodeManager, NE::UpdateEventHandler& eventHandler);
 	bool	Redo (NE::NodeManager& targetNodeManager, NE::UpdateEventHandler& eventHandler);
+
 	void	Clear ();
 
 private: