EM_Task/UnrealEd/Private/DragAndDrop/AssetDragDropOp.cpp

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

#include "DragAndDrop/AssetDragDropOp.h"
#include "Engine/Level.h"
#include "ActorFactories/ActorFactory.h"
#include "GameFramework/Actor.h"
#include "Widgets/SOverlay.h"
#include "Widgets/Layout/SBox.h"
#include "AssetThumbnail.h"
#include "ClassIconFinder.h"

TSharedRef<FAssetDragDropOp> FAssetDragDropOp::New(const FAssetData& InAssetData, UActorFactory* ActorFactory)
{
    TArray<FAssetData> AssetDataArray;
    AssetDataArray.Emplace(InAssetData);
    return New(MoveTemp(AssetDataArray), TArray<FString>(), ActorFactory);
}

TSharedRef<FAssetDragDropOp> FAssetDragDropOp::New(TArray<FAssetData> InAssetData, UActorFactory* ActorFactory)
{
    return New(MoveTemp(InAssetData), TArray<FString>(), ActorFactory);
}

TSharedRef<FAssetDragDropOp> FAssetDragDropOp::New(FString InAssetPath)
{
    TArray<FString> AssetPathsArray;
    AssetPathsArray.Emplace(MoveTemp(InAssetPath));
    return New(TArray<FAssetData>(), MoveTemp(AssetPathsArray), nullptr);
}

TSharedRef<FAssetDragDropOp> FAssetDragDropOp::New(TArray<FString> InAssetPaths)
{
    return New(TArray<FAssetData>(), MoveTemp(InAssetPaths), nullptr);
}

TSharedRef<FAssetDragDropOp> FAssetDragDropOp::New(TArray<FAssetData> InAssetData, TArray<FString> InAssetPaths, UActorFactory* ActorFactory)
{
    TSharedRef<FAssetDragDropOp> Operation = MakeShared<FAssetDragDropOp>();

    Operation->Init(MoveTemp(InAssetData), MoveTemp(InAssetPaths), ActorFactory);

    Operation->Construct();
    return Operation;
}

FAssetDragDropOp::~FAssetDragDropOp()
{
    ThumbnailPool.Reset();
}

TSharedPtr<SWidget> FAssetDragDropOp::GetDefaultDecorator() const
{
    const int32 TotalCount = GetTotalCount();

    TSharedPtr<SWidget> ThumbnailWidget;
    if (AssetThumbnail.IsValid())
    {
        ThumbnailWidget = AssetThumbnail->MakeThumbnailWidget();
    }
    else if (HasFolders())
    {
        ThumbnailWidget =
            SNew(SOverlay)

            + SOverlay::Slot()
                  [SNew(SImage)
                       .Image(FEditorStyle::GetBrush("ContentBrowser.ListViewFolderIcon.Base"))
                       .ColorAndOpacity(FLinearColor::Gray)]

            + SOverlay::Slot()
                  [SNew(SImage)
                       .Image(FEditorStyle::GetBrush("ContentBrowser.ListViewFolderIcon.Mask"))];
    }
    else
    {
        ThumbnailWidget =
            SNew(SImage)
                .Image(FEditorStyle::GetDefaultBrush());
    }

    const FSlateBrush* SubTypeBrush = FEditorStyle::GetDefaultBrush();
    FLinearColor SubTypeColor       = FLinearColor::White;
    if (AssetThumbnail.IsValid() && HasFolders())
    {
        SubTypeBrush = FEditorStyle::GetBrush("ContentBrowser.AssetTreeFolderClosed");
        SubTypeColor = FLinearColor::Gray;
    }
    else if (ActorFactory.IsValid() && HasFiles())
    {
        AActor* DefaultActor = ActorFactory->GetDefaultActor(AssetData[0]);
        SubTypeBrush         = FClassIconFinder::FindIconForActor(DefaultActor);
    }

    return SNew(SBorder)
        .BorderImage(FEditorStyle::GetBrush("ContentBrowser.AssetDragDropTooltipBackground"))
        .Content()
            [SNew(SHorizontalBox)

             // Left slot is for the thumbnail
             + SHorizontalBox::Slot()
                   .AutoWidth()
                   .HAlign(HAlign_Left)
                       [SNew(SBox)
                            .WidthOverride(ThumbnailSize)
                            .HeightOverride(ThumbnailSize)
                            .Content()
                                [SNew(SOverlay)

                                 + SOverlay::Slot()
                                       [ThumbnailWidget.ToSharedRef()]

                                 + SOverlay::Slot()
                                       .HAlign(HAlign_Center)
                                       .VAlign(VAlign_Top)
                                       .Padding(FMargin(0, 4, 0, 0))
                                           [SNew(SBorder)
                                                .BorderImage(FEditorStyle::GetBrush("Menu.Background"))
                                                .Visibility(TotalCount > 1 ? EVisibility::Visible : EVisibility::Collapsed)
                                                .Content()
                                                    [SNew(STextBlock)
                                                         .Text(FText::AsNumber(TotalCount))]]

                                 + SOverlay::Slot()
                                       .HAlign(HAlign_Right)
                                       .VAlign(VAlign_Bottom)
                                       .Padding(FMargin(4, 4))
                                           [SNew(SImage)
                                                .Image(SubTypeBrush)
                                                .Visibility(SubTypeBrush != FEditorStyle::GetDefaultBrush() ? EVisibility::Visible : EVisibility::Collapsed)
                                                .ColorAndOpacity(SubTypeColor)]]]

             // Right slot is for optional tooltip
             + SHorizontalBox::Slot()
                   .AutoWidth()
                   .VAlign(VAlign_Center)
                       [SNew(SBox)
                            .MinDesiredWidth(80)
                            .Content()
                                [SNew(SHorizontalBox)

                                 + SHorizontalBox::Slot()
                                       .AutoWidth()
                                       .Padding(3.0f)
                                       .VAlign(VAlign_Center)
                                           [SNew(SImage)
                                                .Image(this, &FAssetDragDropOp::GetIcon)]

                                 + SHorizontalBox::Slot()
                                       .AutoWidth()
                                       .Padding(0, 0, 3, 0)
                                       .VAlign(VAlign_Center)
                                           [SNew(STextBlock)
                                                .Text(this, &FAssetDragDropOp::GetDecoratorText)]]]];
}

FText FAssetDragDropOp::GetDecoratorText() const
{
    if (CurrentHoverText.IsEmpty())
    {
        const int32 TotalCount = GetTotalCount();
        if (TotalCount > 0)
        {
            const FText FirstItemText = GetFirstItemText();
            return (TotalCount == 1) ? FirstItemText : FText::Format(NSLOCTEXT("ContentBrowser", "AssetDragDropOpDescriptionMulti", "'{0}' and {1} {1}|plural(one=other,other=others)"), FirstItemText, TotalCount - 1);
        }
    }

    return CurrentHoverText;
}

void FAssetDragDropOp::Init(TArray<FAssetData> InAssetData, TArray<FString> InAssetPaths, UActorFactory* InActorFactory)
{
    MouseCursor   = EMouseCursor::GrabHandClosed;
    ThumbnailSize = 64;

    AssetData     = MoveTemp(InAssetData);
    AssetPaths    = MoveTemp(InAssetPaths);
    ActorFactory  = InActorFactory;

    // Load all assets first so that there is no loading going on while attempting to drag
    // Can cause unsafe frame reentry
    for (FAssetData& Data: AssetData)
    {
        Data.GetAsset();
    }

    InitThumbnail();
}

void FAssetDragDropOp::InitThumbnail()
{
    if (AssetData.Num() > 0 && ThumbnailSize > 0)
    {
        // Create a thumbnail pool to hold the single thumbnail rendered
        ThumbnailPool = MakeShared<FAssetThumbnailPool>(1, /*InAreRealTileThumbnailsAllowed=*/false);

        // Create the thumbnail handle
        AssetThumbnail = MakeShared<FAssetThumbnail>(AssetData[0], ThumbnailSize, ThumbnailSize, ThumbnailPool);

        // Request the texture then tick the pool once to render the thumbnail
        AssetThumbnail->GetViewportRenderTargetTexture();
        ThumbnailPool->Tick(0);
    }
}

bool FAssetDragDropOp::HasFiles() const
{
    return AssetData.Num() > 0;
}

bool FAssetDragDropOp::HasFolders() const
{
    return AssetPaths.Num() > 0;
}

int32 FAssetDragDropOp::GetTotalCount() const
{
    return AssetData.Num() + AssetPaths.Num();
}

FText FAssetDragDropOp::GetFirstItemText() const
{
    if (AssetData.Num() > 0)
    {
        return FText::FromName(AssetData[0].AssetName);
    }

    if (AssetPaths.Num() > 0)
    {
        return FText::FromString(AssetPaths[0]);
    }

    return FText::GetEmpty();
}