UE5: Content browser工具编写02

DebugHeader.h 中的全局变量，已经在一个cpp file中被include了，如果在另一个cpp file中再include它，就会有一些conflicts。先全部给加一个static

Add static keyword to debug functions
Wrap all the functions inside of a namespace
print message to the screen when pressing delete unused assets

#pragma once
#include "Misc/MessageDialog.h"
#include "Widgets/Notifications/SNotificationList.h"
#include "Framework/Notifications/NotificationManager.h"

static void Print(const FString& Message, const FColor& Color)
{
	if (GEngine)
	{
		GEngine->AddOnScreenDebugMessage(-1, 8.f, Color, Message);
	}
}

static void PrintLog(const FString& Message)
{
	UE_LOG(LogTemp, Warning, TEXT("%s"),*Message);
}

static EAppReturnType::Type ShowMsgDialog(EAppMsgType::Type MsgType, const FString& Message,
bool bShowMsgAsWarning = true) 
{
	if (bShowMsgAsWarning == true) 
	{
		FText MsgTitle = FText::FromString(TEXT("Warning"));

		return FMessageDialog::Open(MsgType, FText::FromString(Message), &MsgTitle);
	//return FMessageDialog::Open(MsgType, FText::FromString(TEXT("Warning: ") + Message));
	}

	else
	{
		return FMessageDialog::Open(MsgType, FText::FromString(Message));
	}
}

static void ShowNotifyInfo(const FString& Message)
{
	FNotificationInfo NotifyInfo(FText::FromString(Message));
	NotifyInfo.bUseLargeFont = true;
	NotifyInfo.FadeOutDuration = 7.f;

	FSlateNotificationManager::Get().AddNotification(NotifyInfo);
}

EditorAssetLibrary.h里面，ListAssets的功能

UFUNCTION(BlueprintCallable, Category = "Editor Scripting | Asset")
static TArray<FString> ListAssets(const FString& DirectoryPath, bool bRecursive = true, bool bIncludeFolder = false);

在 ListAssets 函数中，bRecursive 是一个布尔变量，通常用来控制函数是否以递归方式列出某个目录下的所有资产（Assets）。（if we go inside of the subfolder)

当 bRecursive 为 true 时，函数会递归遍历指定目录以及其所有子目录，并列出其中的所有资产。
当 bRecursive 为 false 时，函数只会列出指定目录中的资产，而不会深入子目录。

bool bIncludeFolder

假设你的资产结构目录如下

/Assets
├── File1.uasset
├── Folder1
│   └── File2.uasset
└── Folder2

bIncludeFolder = true:
输出可能是：File1.uasset, Folder1/, Folder1/File2.uasset, Folder2/
bIncludeFolder = false:
输出可能是：File1.uasset, Folder1/File2.uasset

在content folder里面，不要碰collections和developers目录。DO NOT TOUCH ROOT FOLDER (COLLECTIONS/DEVELOPERS)

示例代码

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

#include "SuperManager.h"
#include "ContentBrowserModule.h"
#include "DebugHeader.h"
#include "EditorAssetLibrary.h"
#include "ObjectTools.h"//DeleteAssets()

#define LOCTEXT_NAMESPACE "FSuperManagerModule"

void FSuperManagerModule::StartupModule()
{
	InitContentBrowserExtension();
}


void FSuperManagerModule::ShutdownModule()
{
	 //This function may be called during shutdown to clean up your module.  For modules that support dynamic reloading,
	 //we call this function before unloading the module.
}

#pragma region ContentBrowserMenuExtension
void FSuperManagerModule::InitContentBrowserExtension()
{
	FContentBrowserModule& ContentBrowserModule = 
	FModuleManager::LoadModuleChecked<FContentBrowserModule>(TEXT("ContentBrowser"));

	TArray<FContentBrowserMenuExtender_SelectedPaths>& ContentBrowserModuleMenuExtenders = 
	ContentBrowserModule.GetAllPathViewContextMenuExtenders();

	//FContentBrowserMenuExtender_SelectedPaths CustomContentBrowserMenuDelegate;
	//CustomContentBrowserMenuDelegate.BindRaw(this, &FSuperManagerModule::CustomContentBrowserMenuExtender);
	
	//ContentBrowserModuleMenuExtenders.Add(CustomContentBrowserMenuDelegate);
	//***same with the two lines below

	ContentBrowserModuleMenuExtenders.Add(FContentBrowserMenuExtender_SelectedPaths::
		CreateRaw(this, &FSuperManagerModule::CustomContentBrowserMenuExtender));
	
}

TSharedRef<FExtender> FSuperManagerModule::CustomContentBrowserMenuExtender(const TArray<FString>& SelectedPaths)
{
	TSharedRef<FExtender> MenuExtender(new FExtender());

	if (SelectedPaths.Num() > 0) {
		//define the position
		//-> 是一个运算符，用于访问指针所指向对象的成员。

		MenuExtender->AddMenuExtension(FName("Delete"),//name of extension hook
			//we want to insert after DELETE(extension hook)
			EExtensionHook::After,
			TSharedPtr<FUICommandList>(),//no hotkey
			//first binding
            FMenuExtensionDelegate::CreateRaw(this, &FSuperManagerModule::AddContentBrowserMenuEntry));
		    //second binding

		FolderPathsSelected = SelectedPaths;//then we have access to the folders that the user has currently selected
	};

	return MenuExtender;
}

void FSuperManagerModule::AddContentBrowserMenuEntry(FMenuBuilder& MenuBuilder)
{//in this function we can define all the details for our menu entry //and we can use the menu builder to do so
	MenuBuilder.AddMenuEntry
	(
		FText::FromString(TEXT("Delete Unused Assets")),
		FText::FromString(TEXT("Safely delete all unused assets under folder")),
		FSlateIcon(),//empty placeholder
		//SECOND BINDING
		FExecuteAction::CreateRaw(this, &FSuperManagerModule::OnDeleteUnusedAssetButtonClicked)
	);
}

void FSuperManagerModule::OnDeleteUnusedAssetButtonClicked()
{
	if (FolderPathsSelected.Num() > 1)//delete stuff in multiple folders will cause some unexpected behaviors
	{
		DebugHeader::ShowMsgDialog(EAppMsgType::Ok, TEXT("Please select ONE folder"));
		return;
	}

	//DebugHeader::Print(TEXT("Currently selected folder: ")+ FolderPathsSelected[0], FColor::Green);
	//pure debug, can be deleted later

	TArray<FString> AssetsPathName = UEditorAssetLibrary::ListAssets(FolderPathsSelected[0]);

	if (AssetsPathName.Num() == 0)
	{
		DebugHeader::ShowMsgDialog(EAppMsgType::Ok, TEXT("No Asset found under selected folder"));
		return;
	}

	//not finished yet
	//DebugHeader::ShowMsgDialog(EAppMsgType::Ok, TEXT("Delete Unused Assets"));
	//DebugHeader::Print(TEXT("Unused Assets Deleted"), FColor::Red);

	FString Message = FString::Printf(TEXT("A total of %d found.\nConfirm deletion?"), AssetsPathName.Num());
	//%d 是一个格式说明符，用于表示一个整数（int 类型）
	EAppReturnType::Type ConfirmResult =
	DebugHeader::ShowMsgDialog(EAppMsgType::OkCancel, Message);

	//error   error   //EAppReturnType::Type ConfirmResult = DebugHeader::ShowMsgDialog(EAppMsgType::OkCancel, TEXT("A total of ") + FString::Printf(AssetsPathName.Num()) + TEXT(" found.\nConfirm deletion?"));

	if (ConfirmResult == EAppReturnType::Cancel)return;

	TArray<FAssetData>UnusedAssetsDataArray;

	for (const FString& AssetPathNameWWWWW : AssetsPathName)
	{
		if (AssetPathNameWWWWW.Contains(TEXT("Collections")) || AssetPathNameWWWWW.Contains(TEXT("Developers")))
		{
			continue;//不执行操作，继续循环
		}
		//DO NOT TOUCH ROOT FOLDER (COLLECTIONS/DEVELOPERS)

		if (!UEditorAssetLibrary::DoesAssetExist(AssetPathNameWWWWW)) continue;
		//if we don't do this, sometimes we will get some error message saying that Assets does not exist

		TArray<FString> AssetReferencers = 
		UEditorAssetLibrary::FindPackageReferencersForAsset(AssetPathNameWWWWW);
		//it is same with(delete asset from selection)

		if (AssetReferencers.Num() == 0)//this asset is unused
			//error   error   E0137	expression must be a modifiable lvalue
			//报错的中文意思是：“表达式必须是可修改的左值。”
			//这是因为在这段代码里，你错误地使用了单等号 = ，而不是双等号 == ，在比较语句中使用了赋值运算符。
		{
			const FAssetData UnusedAssetData = UEditorAssetLibrary::FindAssetData(AssetPathNameWWWWW);
			UnusedAssetsDataArray.Add(UnusedAssetData);
		}
		//塞入“无用资产”动态数组

		if (UnusedAssetsDataArray.Num() > 0)
		{
			ObjectTools::DeleteAssets(UnusedAssetsDataArray);
		}

		else
		{
			DebugHeader::ShowMsgDialog(EAppMsgType::Ok, TEXT("No Unused Asset found under selected folder"));
		}
	}

}

#pragma endregion



#undef LOCTEXT_NAMESPACE
	
IMPLEMENT_MODULE(FSuperManagerModule, SuperManager)

可以将 C++ 中的 delegate 比作一个 “邮递员”。

比喻解释：

邮递员：邮递员负责将信件从一个地方送到另一个地方。你把信件（消息、请求等）交给邮递员，告诉他该去哪个地址送达。
委托的角色：
- 发送者：在你的代码中，发送者（或发布者）就像是给邮递员信件的人。发送者生成一个事件（例如某个操作完成）并把它交给邮递员（委托）。
- 邮递员（委托）：邮递员不处理信件的内容，只负责把信件送到指定的地址。在委托的情况下，它会将事件传递给事先注册好的接收者（或订阅者）。
- 接收者：接收者就像是收件人，当邮递员把信件送到他们那里时，他们会根据信件的内容采取相应的行动。