Custom property customization

Resources

• Zomg’s post
• Docs

Difference between CustomizeHeader and CustomizeChildren

Widget Classes

• SPropertyNameWidget: Made by FPropertyHandleBase::CreatePropertyNameWidget
  • SPropertyEditorTitle
• SPropertyValueWidget: Made by FPropertyHandleBase::CreatePropertyValueWidget
• Pick in order:
  • SPropertyEditorArray
  • SPropertyEditorSet
  • SPropertyEditorMap
  • SPropertyEditorOptional
  • SPropertyEditorClass
  • SPropertyEditorStruct
  • SPropertyEditorAsset
  • SPropertyEditorNumeric
  • SPropertyEditorCombo
  • SPropertyEditorEditInline
  • SPropertyEditorText
  • SPropertyEditorBool
  • SPropertyEditorArrayItem
  • SPropertyEditorDateTime
  • SPropertyEditor uses FPropertyEditor::GetValueAsText → FPropertyHandleBase::GetValueAsFormattedText → FPropertyNode::GetPropertyValueText → FPropertyTextUtilities::PropertyToTextHelper → FProperty::ExportText_Direct

Miscs

PropertyHandle

PropertyHandle in CustomizeHeader and CustomizeChildren is always the root property (for example, your struct).

Get/Set property

This works if the property has a Edit specifier

TSharedPtr<IPropertyHandle> SelectedSocketProp = PropertyHandle->GetChildHandle(GET_MEMBER_NAME_CHECKED(FFUPickerSockets, SelectedSocket));  
 
// Get
FName SelectedSocket;  
SelectedSocketProp->GetValue(SelectedSocket);
 
// Set 
SelectedSocketProp->SetValue(FName("NewValue"));

CustomizeChildren

This will construct default child members for the member props of your type details customization.

// Thanks to aquanox for the snippet
void FCustomization::CustomizeChildren(TSharedRef<IPropertyHandle> PropertyHandle, IDetailChildrenBuilder& ChildBuilder, IPropertyTypeCustomizationUtils& CustomizationUtils)  
{  
    uint32 NumberOfChild = 0;  
    if (PropertyHandle->GetNumChildren(NumberOfChild) == FPropertyAccess::Success)
    {
	    for (uint32 Index = 0; Index < NumberOfChild; ++Index)  
       {
	       TSharedRef<IPropertyHandle> ChildPropertyHandle = PropertyHandle->GetChildHandle(Index).ToSharedRef();  
          ChildBuilder.AddProperty(ChildPropertyHandle);  
       }
    }
}

Custom ReadOnly/Editable override

Taking the same base snippet as above but we set some specific properties to be readonly (while having EditAnywhere metadata)

uint32 NumberOfChild = 0;  
		if (PropertyHandle->GetNumChildren(NumberOfChild) == FPropertyAccess::Success)
		{
			TArray<FProperty*> MakeConst = {
				CachedStructRowCountPropertyHandle->GetProperty(),
				CachedStructColumnCountPropertyHandle->GetProperty(),
				CachedStructCellsDataPropertyHandle->GetProperty()
			};
			
			for (uint32 Index = 0; Index < NumberOfChild; ++Index)  
			{
				TSharedPtr<IPropertyHandle> ChildPropertyHandle = PropertyHandle->GetChildHandle(Index);
				auto& DetailRow = FragmentGroupBuilder.AddPropertyRow(ChildPropertyHandle.ToSharedRef());
				
				if (MakeConst.Contains(ChildPropertyHandle->GetProperty()))
				{
					DetailRow.IsEnabled(false);
				}
			}
		}

Get context

You may want to know in what BP/Actor this property is being rendered Here is how aquanox does for his BlueprintComponentReference plugin

Add new rows

See ChildBuilder.AddCustomRow

Containers

With TMap you can use AsMap on IPropertyHandle. Then GetElement to get a “Pair”. You can then get they key with GetKeyHandle

Use GetValueData do get the value data.

Example on how to find back a property handle from a key.

uint32 NumChilds;
	CachedStructCellsDataPropertyHandle->GetNumChildren(NumChilds);
	for (uint32 ChildIndex = 0; ChildIndex < NumChilds; ++ChildIndex)
	{
		TSharedRef<IPropertyHandle> EntryHandle = CachedStructCellsDataPropertyHandle->AsMap()->GetElement(ChildIndex);
		TSharedPtr<IPropertyHandle> KeyHandle = EntryHandle->GetKeyHandle();
		
		void* KeyRawData;
		KeyHandle->GetValueData(KeyRawData);
		FIntVector3* KeyPtr = static_cast<FIntVector3*>(KeyRawData);
		
		if (*KeyPtr == Coords)
		{
			return EntryHandle;
		}
	}