Add graph action to delete node and reconnect pins if possible (#192)

Author: MaksymKapelianovych

Source/FlowEditor/Private/Graph/FlowGraphEditor.cpp

@@ -67,6 +67,10 @@ void SFlowGraphEditor::BindGraphCommands()
 
 	CommandList->MapAction(GraphEditorCommands.StraightenConnections,
 	                               FExecuteAction::CreateSP(this, &SFlowGraphEditor::OnStraightenConnections));
+	
+	CommandList->MapAction(GraphEditorCommands.DeleteAndReconnectNodes,
+							   FExecuteAction::CreateSP(this, &SFlowGraphEditor::DeleteSelectedNodes),
+							   FCanExecuteAction::CreateSP(this, &SFlowGraphEditor::CanDeleteNodes));
 
 	// Generic Node commands
 	CommandList->MapAction(GenericCommands.Undo,
@@ -374,6 +378,76 @@ TSet<UFlowGraphNode*> SFlowGraphEditor::GetSelectedFlowNodes() const
 	return Result;
 }
 
+void SFlowGraphEditor::ReconnectExecPins(const UFlowGraphNode* Node)
+{
+	if(Node == nullptr)
+	{
+		return;
+	}
+
+	UEdGraphPin* InputPin = nullptr;
+	UEdGraphPin* OutputPin = nullptr;
+
+	for (UEdGraphPin* Pin : Node->InputPins)
+	{
+		if (Pin->HasAnyConnections())
+		{
+			if (InputPin)
+			{
+				// more that one connected input pins - do not reconnect anything
+				return;
+			}
+
+			if (Pin)
+			{
+				InputPin = Pin;
+			}
+		}
+		else if (InputPin == nullptr)
+		{
+			// first pin doesn't have any connections - do not reconnect anything, because we probably don't know expected result for user
+			return;
+		}
+	}
+
+	for (UEdGraphPin* Pin : Node->OutputPins)
+	{
+		if (Pin->HasAnyConnections())
+		{
+			if (OutputPin)
+			{
+				// more that one connected output pins - do not reconnect anything
+				return;
+			}
+
+			if (Pin)
+			{
+				OutputPin = Pin;
+			}
+		}
+		else if (OutputPin == nullptr)
+		{
+			// first pin doesn't have any connections - do not reconnect anything, because we probably don't know expected result for user
+			return;
+		}
+	}
+
+	if (InputPin && OutputPin)
+	{
+		// Make a connection from every incoming exec pin to every outgoing then pin
+		for (UEdGraphPin* const IncomingConnectionPin : InputPin->LinkedTo)
+		{
+			if (IncomingConnectionPin)
+			{
+				for (UEdGraphPin* const ConnectedCompletePin : OutputPin->LinkedTo)
+				{
+					IncomingConnectionPin->MakeLinkTo(ConnectedCompletePin);
+				}
+			}
+		}
+	}
+}
+
 void SFlowGraphEditor::DeleteSelectedNodes()
 {
 	const FScopedTransaction Transaction(LOCTEXT("DeleteSelectedNode", "Delete Selected Node"));
@@ -394,6 +468,12 @@ void SFlowGraphEditor::DeleteSelectedNodes()
 				{
 					const FGuid NodeGuid = FlowGraphNode->GetFlowNode()->GetGuid();
 
+					// If the user is pressing shift then try and reconnect the pins
+					if (FSlateApplication::Get().GetModifierKeys().IsShiftDown())
+					{
+						ReconnectExecPins(FlowGraphNode);
+					}
+
 					GetCurrentGraph()->GetSchema()->BreakNodeLinks(*Node);
 					Node->DestroyNode();
 

Source/FlowEditor/Public/Graph/FlowGraphEditor.h

@@ -65,6 +65,7 @@ class FLOWEDITOR_API SFlowGraphEditor : public SGraphEditor
 protected:
 	virtual bool CanSelectAllNodes() const { return true; }
 
+	void ReconnectExecPins(const UFlowGraphNode* Node);
 	virtual void DeleteSelectedNodes();
 	virtual void DeleteSelectedDuplicableNodes();
 	virtual bool CanDeleteNodes() const;