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Merged
ChiR24 merged 2 commits into from
Jul 7, 2026
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fix(umg): bind_on_hovered and bind_on_value_changed author real bound-event nodes #482

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3cae682
fix(umg): bind_on_hovered and bind_on_value_changed author real bound…
SoloGorilla Jun 17, 2026
46b79fb
refactor(umg): route bind_on_clicked through the shared bound-event h…
SoloGorilla Jul 6, 2026
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227 changes: 121 additions & 106 deletions ...ate/Domains/WidgetAuthoring/Bindings/McpAutomationBridge_WidgetAuthoringEventBindings.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,105 @@ namespace WidgetAuthoringHandlers
{
using namespace WidgetAuthoringHelpers;

// Create a real UK2Node_ComponentBoundEvent for an arbitrary multicast delegate on a
// widget component — the same path the Designer's "+ <Event>" button uses. Shared by
// bind_on_clicked / bind_on_hovered / bind_on_value_changed so all three author genuine
// nodes (nodeId + compileSucceeded) through one code path. Idempotent: a repeat call
// reuses the existing bound event and leaves the asset untouched (no dirty / recompile).
// Response contract: functionName echoes the request input; the real handler is
// engine-generated and returned as eventFunctionName (CustomFunctionName).
// Sends the response itself and always returns true (request handled).
static bool BindComponentDelegateEvent(
UMcpAutomationBridgeSubsystem& Subsystem,
const FString& RequestId,
TSharedPtr<FMcpBridgeWebSocket> RequestingSocket,
TSharedPtr<FJsonObject> ResultJson,
UWidgetBlueprint* WidgetBP,
UWidget* TargetWidget,
const FString& SlotName,
UClass* DelegateOwnerClass,
const FName DelegateName,
const FString& EventTypeLabel,
const FString& FunctionName)
{
bool bBlueprintChanged = false;
if (!TargetWidget->bIsVariable)
{
TargetWidget->Modify();
TargetWidget->bIsVariable = true;
FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(WidgetBP);
bBlueprintChanged = true;
}

FMulticastDelegateProperty* DelegateProp =
FindFProperty<FMulticastDelegateProperty>(DelegateOwnerClass, DelegateName);
if (!DelegateProp)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId,
FString::Printf(TEXT("%s delegate not found on %s"), *DelegateName.ToString(), *DelegateOwnerClass->GetName()),
TEXT("DELEGATE_NOT_FOUND"));
return true;
}

FObjectProperty* CompProp =
FindFProperty<FObjectProperty>(WidgetBP->SkeletonGeneratedClass, FName(*SlotName));
if (!CompProp)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId,
FString::Printf(TEXT("Component variable '%s' not found on widget skeleton class"), *SlotName),
TEXT("COMPONENT_PROPERTY_NOT_FOUND"));
return true;
}

UEdGraph* EventGraph = FBlueprintEditorUtils::FindEventGraph(WidgetBP);
if (!EventGraph)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId, TEXT("Event graph not found on widget blueprint"), TEXT("EVENT_GRAPH_NOT_FOUND"));
return true;
}

// Idempotent: reuse an existing bound event for this delegate+component.
const UK2Node_ComponentBoundEvent* Existing =
FKismetEditorUtilities::FindBoundEventForComponent(WidgetBP, DelegateProp->GetFName(), CompProp->GetFName());

UK2Node_ComponentBoundEvent* BoundNode = const_cast<UK2Node_ComponentBoundEvent*>(Existing);
bool bCreatedNew = false;
if (!BoundNode)
{
EventGraph->Modify();
FGraphNodeCreator<UK2Node_ComponentBoundEvent> Creator(*EventGraph);
BoundNode = Creator.CreateNode(false);
BoundNode->InitializeComponentBoundEventParams(CompProp, DelegateProp);
Creator.Finalize();
// Adding a bound-event node is a structural change (new function entry on the class) — same call the
// Designer's FKismetEditorUtilities::CreateNewBoundEventForComponent path makes after node creation.
FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(WidgetBP);
bCreatedNew = true;
bBlueprintChanged = true;
}

bool bCompiled = true;
if (bBlueprintChanged)
{
FBlueprintEditorUtils::MarkBlueprintAsModified(WidgetBP);
bCompiled = McpSafeCompileBlueprint(WidgetBP);
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}

ResultJson->SetBoolField(TEXT("success"), true);
ResultJson->SetStringField(TEXT("slotName"), SlotName);
ResultJson->SetStringField(TEXT("eventType"), EventTypeLabel);
ResultJson->SetStringField(TEXT("functionName"), FunctionName);
ResultJson->SetBoolField(TEXT("bound"), true);
ResultJson->SetBoolField(TEXT("createdNew"), bCreatedNew);
ResultJson->SetBoolField(TEXT("compileSucceeded"), bCompiled);
ResultJson->SetStringField(TEXT("nodeId"), BoundNode->NodeGuid.ToString());
ResultJson->SetStringField(TEXT("eventFunctionName"), BoundNode->CustomFunctionName.ToString());

Subsystem.SendAutomationResponse(RequestingSocket, RequestId, true,
FString::Printf(TEXT("%s event bound"), *EventTypeLabel), ResultJson);
return true;
}

bool HandleWidgetAuthoringEventBindings(
UMcpAutomationBridgeSubsystem& Subsystem,
const FString& RequestId,
Expand Down Expand Up @@ -63,85 +162,9 @@ bool HandleWidgetAuthoringEventBindings(
return true;
}

// Create a real UK2Node_ComponentBoundEvent bound to the button's OnClicked
// multicast delegate — the exact node the Designer's "+ OnClicked" adds.
// Track whether we actually mutate the blueprint so the reuse path stays
// side-effect free (no dirty / recompile when nothing changed).
bool bBlueprintChanged = false;
if (!ButtonWidget->bIsVariable)
{
ButtonWidget->Modify();
ButtonWidget->bIsVariable = true;
FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(WidgetBP);
bBlueprintChanged = true;
}

FMulticastDelegateProperty* DelegateProp =
FindFProperty<FMulticastDelegateProperty>(UButton::StaticClass(), FName(TEXT("OnClicked")));
if (!DelegateProp)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId, TEXT("OnClicked delegate not found on UButton"), TEXT("DELEGATE_NOT_FOUND"));
return true;
}

FObjectProperty* CompProp =
FindFProperty<FObjectProperty>(WidgetBP->SkeletonGeneratedClass, FName(*SlotName));
if (!CompProp)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId,
FString::Printf(TEXT("Component variable '%s' not found on widget skeleton class"), *SlotName),
TEXT("COMPONENT_PROPERTY_NOT_FOUND"));
return true;
}

UEdGraph* EventGraph = FBlueprintEditorUtils::FindEventGraph(WidgetBP);
if (!EventGraph)
{
Subsystem.SendAutomationError(RequestingSocket, RequestId, TEXT("Event graph not found on widget blueprint"), TEXT("EVENT_GRAPH_NOT_FOUND"));
return true;
}

// Idempotent: reuse an existing bound event for this delegate+component.
const UK2Node_ComponentBoundEvent* Existing =
FKismetEditorUtilities::FindBoundEventForComponent(WidgetBP, DelegateProp->GetFName(), CompProp->GetFName());

UK2Node_ComponentBoundEvent* BoundNode = const_cast<UK2Node_ComponentBoundEvent*>(Existing);
bool bCreatedNew = false;
if (!BoundNode)
{
EventGraph->Modify();
FGraphNodeCreator<UK2Node_ComponentBoundEvent> Creator(*EventGraph);
BoundNode = Creator.CreateNode(false);
BoundNode->InitializeComponentBoundEventParams(CompProp, DelegateProp);
Creator.Finalize();
bCreatedNew = true;
bBlueprintChanged = true;
}

// Only dirty + recompile when something actually changed — a repeat
// bind_on_clicked that reuses the existing node leaves the asset untouched.
bool bCompiled = true;
if (bBlueprintChanged)
{
FBlueprintEditorUtils::MarkBlueprintAsModified(WidgetBP);
bCompiled = McpSafeCompileBlueprint(WidgetBP);
}

ResultJson->SetBoolField(TEXT("success"), true);
ResultJson->SetStringField(TEXT("slotName"), SlotName);
ResultJson->SetStringField(TEXT("eventType"), TEXT("OnClicked"));
// Response contract: functionName echoes the request input (default "OnButtonClicked").
// The real handler is engine-generated -- returned as eventFunctionName
// (UK2Node_ComponentBoundEvent::CustomFunctionName). Reference the handler via that.
ResultJson->SetStringField(TEXT("functionName"), FunctionName);
ResultJson->SetBoolField(TEXT("bound"), true);
ResultJson->SetBoolField(TEXT("createdNew"), bCreatedNew);
ResultJson->SetBoolField(TEXT("compileSucceeded"), bCompiled);
ResultJson->SetStringField(TEXT("nodeId"), BoundNode->NodeGuid.ToString());
ResultJson->SetStringField(TEXT("eventFunctionName"), BoundNode->CustomFunctionName.ToString());

Subsystem.SendAutomationResponse(RequestingSocket, RequestId, true, TEXT("OnClicked event bound"), ResultJson);
return true;
return BindComponentDelegateEvent(Subsystem, RequestId, RequestingSocket, ResultJson,
WidgetBP, ButtonWidget, SlotName, UButton::StaticClass(), FName(TEXT("OnClicked")),
TEXT("OnClicked"), FunctionName);
}

if (SubAction.Equals(TEXT("bind_on_hovered"), ESearchCase::IgnoreCase))
Expand Down Expand Up @@ -177,16 +200,9 @@ bool HandleWidgetAuthoringEventBindings(
return true;
}

ResultJson->SetBoolField(TEXT("success"), true);
ResultJson->SetStringField(TEXT("slotName"), SlotName);
ResultJson->SetStringField(TEXT("eventType"), TEXT("OnHovered"));
ResultJson->SetStringField(TEXT("functionName"), FunctionName);
ResultJson->SetStringField(TEXT("instruction"), FString::Printf(TEXT("Bind '%s' to %s's OnHovered event."), *FunctionName, *SlotName));

FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(WidgetBP);

Subsystem.SendAutomationResponse(RequestingSocket, RequestId, true, TEXT("OnHovered binding info provided"), ResultJson);
return true;
return BindComponentDelegateEvent(Subsystem, RequestId, RequestingSocket, ResultJson,
WidgetBP, ButtonWidget, SlotName, UButton::StaticClass(), FName(TEXT("OnHovered")),
TEXT("OnHovered"), FunctionName);
}

if (SubAction.Equals(TEXT("bind_on_value_changed"), ESearchCase::IgnoreCase))
Expand Down Expand Up @@ -222,26 +238,25 @@ bool HandleWidgetAuthoringEventBindings(
return true;
}

// Determine widget type for appropriate binding info
FString WidgetType = TargetWidget->GetClass()->GetName();
FString EventName = TEXT("OnValueChanged");
// Resolve the value-changed multicast delegate per widget type.
const FString WidgetType = TargetWidget->GetClass()->GetName();
FName DelegateName = NAME_None;
if (Cast<USlider>(TargetWidget) || Cast<USpinBox>(TargetWidget)) DelegateName = FName(TEXT("OnValueChanged"));
else if (Cast<UCheckBox>(TargetWidget)) DelegateName = FName(TEXT("OnCheckStateChanged"));
else if (Cast<UComboBoxString>(TargetWidget)) DelegateName = FName(TEXT("OnSelectionChanged"));

if (Cast<USlider>(TargetWidget)) EventName = TEXT("OnValueChanged (float)");
else if (Cast<UCheckBox>(TargetWidget)) EventName = TEXT("OnCheckStateChanged (bool)");
else if (Cast<USpinBox>(TargetWidget)) EventName = TEXT("OnValueChanged (float)");
else if (Cast<UComboBoxString>(TargetWidget)) EventName = TEXT("OnSelectionChanged (FString)");
if (DelegateName.IsNone())
{
Subsystem.SendAutomationError(RequestingSocket, RequestId,
FString::Printf(TEXT("Widget '%s' (%s) has no supported value-changed delegate. Supported: Slider, SpinBox, CheckBox, ComboBoxString."), *SlotName, *WidgetType),
TEXT("UNSUPPORTED_WIDGET"));
return true;
}

ResultJson->SetBoolField(TEXT("success"), true);
ResultJson->SetStringField(TEXT("slotName"), SlotName);
ResultJson->SetStringField(TEXT("widgetType"), WidgetType);
ResultJson->SetStringField(TEXT("eventType"), EventName);
ResultJson->SetStringField(TEXT("functionName"), FunctionName);
ResultJson->SetStringField(TEXT("instruction"), FString::Printf(TEXT("Bind '%s' to %s's %s event."), *FunctionName, *SlotName, *EventName));

FBlueprintEditorUtils::MarkBlueprintAsStructurallyModified(WidgetBP);

Subsystem.SendAutomationResponse(RequestingSocket, RequestId, true, TEXT("OnValueChanged binding info provided"), ResultJson);
return true;
return BindComponentDelegateEvent(Subsystem, RequestId, RequestingSocket, ResultJson,
WidgetBP, TargetWidget, SlotName, TargetWidget->GetClass(), DelegateName,
DelegateName.ToString(), FunctionName);
}

if (SubAction.Equals(TEXT("create_property_binding"), ESearchCase::IgnoreCase))
Expand Down