EM_Task/UnrealEd/Private/Subsystems/PanelExtensionSubsystem.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

#include "Subsystems/PanelExtensionSubsystem.h"

#include "Editor.h"
#include "AssetToolsModule.h"
#include "ObjectTools.h"
#include "FileHelpers.h"
#include "EditorReimportHandler.h"

SExtensionPanel::~SExtensionPanel()
{
    if (GEditor && ExtensionPanelID != NAME_None)
    {
        if (UPanelExtensionSubsystem* PanelExtensionSubsystem = GEditor->GetEditorSubsystem<UPanelExtensionSubsystem>())
        {
            PanelExtensionSubsystem->OnPanelFactoryRegistryChanged(ExtensionPanelID).RemoveAll(this);
        }
    }
}

void SExtensionPanel::Construct(const FArguments& InArgs)
{
    ExtensionPanelID = InArgs._ExtensionPanelID.Get(NAME_None);
    DefaultWidget    = InArgs._DefaultWidget.Get(nullptr);
    ExtensionContext = InArgs._ExtensionContext.Get(nullptr);

    if (GEditor && ExtensionPanelID != NAME_None)
    {
        if (UPanelExtensionSubsystem* PanelExtensionSubsystem = GEditor->GetEditorSubsystem<UPanelExtensionSubsystem>())
        {
            PanelExtensionSubsystem->OnPanelFactoryRegistryChanged(ExtensionPanelID).AddRaw(this, &SExtensionPanel::RebuildWidget);
            RebuildWidget();
        }
    }
}

void SExtensionPanel::RebuildWidget()
{
    if (GEditor && ExtensionPanelID != NAME_None)
    {
        if (UPanelExtensionSubsystem* PanelExtensionSubsystem = GEditor->GetEditorSubsystem<UPanelExtensionSubsystem>())
        {
            TSharedRef<SWidget> Widget = PanelExtensionSubsystem->CreateWidget(ExtensionPanelID, ExtensionContext);
            if (Widget == SNullWidget::NullWidget && DefaultWidget.IsValid())
            {
                Widget = DefaultWidget.ToSharedRef();
            }

            ChildSlot
                [Widget];
        }
    }
}

UPanelExtensionSubsystem::UPanelExtensionSubsystem()
    : UEditorSubsystem()
{
}

void UPanelExtensionSubsystem::Initialize(FSubsystemCollectionBase& Collection)
{
}

void UPanelExtensionSubsystem::Deinitialize()
{
}

void UPanelExtensionSubsystem::RegisterPanelFactory(FName ExtensionPanelID, const FPanelExtensionFactory& InPanelExtensionFactory)
{
    TArray<FPanelExtensionFactory>& Factories = ExtensionPointMap.FindOrAdd(ExtensionPanelID);
    Factories.Add(InPanelExtensionFactory);

    UPanelExtensionSubsystem::FPanelFactoryRegistryChanged& PanelFactoryRegsitered = OnPanelFactoryRegistryChanged(ExtensionPanelID);
    PanelFactoryRegsitered.Broadcast();
}

void UPanelExtensionSubsystem::UnregisterPanelFactory(FName Identifier, FName ExtensionPanelID)
{
    for (auto& AssetPair: ExtensionPointMap)
    {
        if (ExtensionPanelID == NAME_None || AssetPair.Key == ExtensionPanelID)
        {
            int32 numRemoved = AssetPair.Value.RemoveAll([Identifier](const FPanelExtensionFactory& Factory)
                                                         {
                                                             return Factory.Identifier == Identifier;
                                                         });
            if (numRemoved > 0)
            {
                UPanelExtensionSubsystem::FPanelFactoryRegistryChanged& PanelFactoryRegsitered = OnPanelFactoryRegistryChanged(AssetPair.Key);
                PanelFactoryRegsitered.Broadcast();
            }
        }
    }
}

bool UPanelExtensionSubsystem::IsPanelFactoryRegistered(FName Identifier, FName ExtensionPanelID) const
{
    for (auto& AssetPair: ExtensionPointMap)
    {
        if (ExtensionPanelID == NAME_None || AssetPair.Key == ExtensionPanelID)
        {
            if (AssetPair.Value.FindByPredicate([Identifier](const FPanelExtensionFactory& Factory)
                                                {
                                                    return Factory.Identifier == Identifier;
                                                }))
            {
                return true;
            }
        }
    }
    return false;
}

TSharedRef<SWidget> UPanelExtensionSubsystem::CreateWidget(FName ExtensionPanelID, FWeakObjectPtr ExtensionContext)
{
    const TArray<FPanelExtensionFactory>* ExtensionArray = ExtensionPointMap.Find(ExtensionPanelID);
    if (ExtensionArray && ExtensionArray->Num() > 0)
    {
        const FPanelExtensionFactory& Extension = (*ExtensionArray)[0];  // TODO: We need to add support for multiple widgets
        if (Extension.CreateExtensionWidget.IsBound())
        {
            return Extension.CreateExtensionWidget.Execute(ExtensionContext);
        }
        PRAGMA_DISABLE_DEPRECATION_WARNINGS
        else if (Extension.CreateWidget.IsBound())
        {
            TArray<UObject*> Temp;
            return Extension.CreateWidget.Execute(Temp);
        }
        PRAGMA_ENABLE_DEPRECATION_WARNINGS
    }
    return SNullWidget::NullWidget;
}

UPanelExtensionSubsystem::FPanelFactoryRegistryChanged& UPanelExtensionSubsystem::OnPanelFactoryRegistryChanged(FName ExtensionPanelID)
{
    return PanelFactoryRegistryChangedCallbackMap.FindOrAdd(ExtensionPanelID);
}