Extending Unreal Editor

Extending Content Browser.

Let's see how to extend Content Browser's context menu. We'd like to add custom commands that can be performed over selected folders. 

There is a lot of information about extending editor menu. A good point to start is to read this article:

http://www.danielmayor.com/ue4-simple-menus

As it is described in the article, we have our custom game module and started to extend editor from here:

	void FGameEditorMobule::StartupModule()
	{
	FContentBrowserModule& ContentBrowserModule = FModuleManager::LoadModuleChecked<FContentBrowserModule>(TEXT("ContentBrowser"));
	TArray<FContentBrowserMenuExtender_SelectedPaths>& MenuExtenderDelegates = ContentBrowserModule.GetAllPathViewContextMenuExtenders();
	// Create new delegate that will be called to provide our menu extener
	MenuExtenderDelegates.Add(FContentBrowserMenuExtender_SelectedPaths::CreateRaw(this, &FGameEditorMobule::MyExtender));
	}

view raw GameEditorModule.cpp hosted with ❤ by GitHub

You see that ContentBrowser doesn't provide methods to get MenuEsteder but has methods to get reference on array that contatin delegates that will be called when unreal builds context menu.

	TSharedRef<FExtender> FGameEditorMobule::MyExtender(const TArray<FString>&Path)
	{
	// Extension variable contains a copy of selected paths array
	// We must keep Extension somewhere to prevent it from being deleted
	Extension = MakeShareable(new FContentBrowserMenuExtension(Path));
	// Create extender that contains a delegate that will be called to get information about new context menu items
	TSharedPtr<FExtender> MenuExtender = MakeShareable(new FExtender());
	// Create a Shared-pointer delegate that keeps a weak reference to object
	// "NewFolder" is a hook name that is used by extender to identify externders that will extend path context menu
	MenuExtender->AddMenuExtension("NewFolder", EExtensionHook::After, TSharedPtr<FUICommandList>(),
	FMenuExtensionDelegate::CreateSP(Extension.ToSharedRef(),
	&FContentBrowserMenuExtension::AddMenuEntry));
	return MenuExtender.ToSharedRef();
	}

view raw GameEditor.cpp hosted with ❤ by GitHub

Note that we must pass "NewFolder" as hook name to extend path menu (See MultiBoxBuilder.cpp::ApplyHook) It is important to store information about selected path  that came from content browser to have a proper context for our extenstion. I've decide to keep Extension variable in FGameEditorModule instance. This solution is a little bit ugly, but works fine. 

	#define LOCTEXT_NAMESPACE "GameEditor"
	void FContentBrowserMenuExtension::AddMenuEntry(FMenuBuilder& MenuBuilder)
	{
	// Create Section
	MenuBuilder.BeginSection("CustomMenu", LOCTEXT("PathViewOptionsMenuHeading", "Bulk Edit"));
	{
	// Create a Submenu inside of the Section
	MenuBuilder.AddSubMenu(FText::FromString("Batch Folder"),
	FText::FromString("Batch opertaions"),
	FNewMenuDelegate::CreateSP(this,&FContentBrowserMenuExtension::FillSubmenu));
	}
	MenuBuilder.EndSection();
	}
	void FContentBrowserMenuExtension::FillSubmenu(FMenuBuilder& MenuBuilder)
	{
	// Create the Submenu Entries
	MenuBuilder.AddMenuEntry(
	FText::FromString("Regenerate LODS"),
	FText::FromString("Regenerate LODS"),
	FSlateIcon(),
	FUIAction(FExecuteAction::CreateSP(this, &FContentBrowserMenuExtension::OnRegenerateLODSClicked))
	);
	}
	void FContentBrowserMenuExtension::OnRegenerateLODSClicked()
	{
	// Get selected path: this->Paths
	// Do something
	}
	#undef LOCTEXT_NAMESPACE
	IMPLEMENT_GAME_MODULE(FGameEditorMobule, GameEditor);

view raw GameEditorModule.cpp hosted with ❤ by GitHub

Don't forget to add public dependencies to Slate, ContentBrowser and other modules in GameEditor.Build.cs