一、插件分类
插件分为七大类
Blank：空白插件，可以从头开始自己定义想要的插件风格和内容，用此模板创建的插件不会有注册或者菜单输入。BlueprintLibrary：创建一个含有蓝图函数库的插件，此模板函数都是静态全局函数，可以在蓝图中直接调用。ContentOnly：创建一个只包含内容的空白文件Editor Toolbar Button：创建关卡编辑器的工具栏中的按钮插件，首先在创建的点击事件中实现一些内容Editor Standalone Window：创建关卡编辑器的工具栏中的按钮插件，点击按钮可调出一个空白选项独立卡窗口Editor Mode：创建一个含有编辑器模式的插件Third Party Library：创建一个已包含第三方库的插件二、插件模块
插件可含有任意数量的模块源目录。多数插件仅有一个模块（但可创建多个模块，例如插件包含纯编辑器功能时），及游戏期间要运行的其他代码。
插件源文件的大部分布局与引擎中其他C++模块相同。
在模块的Source目录（或其子目录）内，插件可在标头文件中声明新反映的类型（UCLASS、USTRUCT等）。引擎的构建系统将检测此类文件，并按需要生成代码支持新类型。需遵守C++模块中使用Uobjects时的一般规则，例如在模块的源文件中包含生成的标头文件和模块generated.inl文件。
UE4支持共生模块和插件。通过在自身.uproject文件中启用插件，项目模块可依赖插件。类似地，通过在自身.uplugin文件中启用其他插件，插件可表明依赖性。但其中有一项重要限制：插件和模块将拆分为若干层级，仅能依赖同一级或更高级的其他插件或模块。例如，项目模块可依赖引擎模块，但引擎模块无法依赖项目模块。这是因为引擎（及其所有插件和模块）的级别高于项目，须能在无项目的情况下编译。
三、引擎插件和项目插件
虚幻引擎4的Engine目录下包含部分内置插件。引擎插件和项目插件类似，但可用于所有项目。此类插件通常由引擎和工具程序员创建，目的在于提供可在多个项目中使用并能在单一位置维护的基线功能。利用此功能，用户可直接添加或覆盖引擎功能，而无需修改引擎代码。
项目插件位于项目目录的Plugins子文件夹下，将在引擎或编辑器启动时被探测和加载。如插件包含具有Source文件夹（和.Build.cs文件）的模块，插件代码将被自动添加到生成的C++项目文件，以便在开发项目时开发插件。编译项目时，有可用源的插件都被作为游戏依赖项进行编译。项目生成器将忽略无Source文件夹的插件，其不会出现在C++项目文件中，但若存在二进制文件，启动时仍将加载此类插件。
插件的描述，描述的文件是Json格式，以官方案例为准
{"FileVersion" :3,"Version" :1,"VersionName" :"1.0","FriendlyName" :"UObject Example Plugin","Description" :"An example of a plugin which declares its own UObject type.This can be used as a starting point when creating your own plugin.","Category" :"Examples","CreatedBy" :"Epic Games, Inc.","CreatedByURL" :"","DocsURL" :"","MarketplaceURL" :"","SupportURL" :"","EnabledByDefault" : true,"CanContainContent" : false,"IsBetaVersion" : false,"Installed" : false,"Modules" :[{"Name" :"UObjectPlugin","Type" :"Developer","LoadingPhase" :"Default"}]}
四、案例分析Editor Standalone Window
创建一个Editor Standalone Window插件，命名为：MyEditorStandaloneWindow
创建成功之后VS会出现Plugins
出现三个cpp文件
MyEditorStandaloneWindow：主函数所有的主要逻辑都是写在这里，包含了注册命令，布局分布，按钮点击事件等。
MyEditorStandaloneWindowCommand：声明一些命令变量，注册函数等。
MyEditorStandaloneWindowStyle：插件的样式风格。
创建好之后我们会在编辑器工具栏中看到我们的插件
点击这个按钮触发的事件通过MapAction创建代理函数绑定，执行
创建独立窗口
void FMyEditorStandaloneWindowModule::PluginButtonClicked(){FGlobalTabmanager::Get()->TryInvokeTab(MyEditorStandaloneWindowTabName);}
内容的注册通过FGlobalTabmanager::Get()->RegisterNomadTabSpawner
FGlobalTabmanager::Get()->RegisterNomadTabSpawner(MyEditorStandaloneWindowTabName, FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::OnSpawnPluginTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyEditorStandaloneWindow")).SetMenuType(ETabSpawnerMenuType::Hidden);
他本质上就是一个SDockTab,返回的是一个TSharedRef<SDockTab>的引用，
TSharedRef<SDockTab> FMyEditorStandaloneWindowModule::OnSpawnPluginTab(const FSpawnTabArgs& SpawnTabArgs){FText WidgetText = FText::Format(LOCTEXT("WindowWidgetText", "Add code to {0} in {1} to override this window's contents"),FText::FromString(TEXT("FMyEditorStandaloneWindowModule::OnSpawnPluginTab")),FText::FromString(TEXT("MyEditorStandaloneWindow.cpp")));return SNew(SDockTab).TabRole(ETabRole::NomadTab)[// Put your tab content here!SNew(SBox).HAlign(HAlign_Center).VAlign(VAlign_Center)[SNew(STextBlock).Text(WidgetText)]];}
五、自定义插件内容
首先打开UI扩展点
这些绿色的扩展点主要是用于菜单按钮和工具按钮的排序的，添加一个绿色的扩展点统管N个菜单按钮，如果你可以自定义自己的UI扩展点，并将自己的扩展点下的菜单按钮安插在某个扩展点之后。也就是UI扩展点是用于布局菜单栏和工具栏的顺序的。
第一步：首先加载模块
//首先加载模块FExtend最后都在FLevelEditorModule中管理FLevelEditorModule& LevelEditorModule = FModuleManager::LoadModuleChecked<FLevelEditorModule>("LevelEditor");
第二步：创建对象
{TSharedPtr<FExtender> MenuExtender = MakeShareable(new FExtender());MenuExtender->AddMenuExtension("WindowLayout", EExtensionHook::After, PluginCommands, FMenuExtensionDelegate::CreateRaw(this, &FMyEditorStandaloneWindowModule::AddMenuExtension));LevelEditorModule.GetMenuExtensibilityManager()->AddExtender(MenuExtender);}{TSharedPtr<FExtender> ToolbarExtender = MakeShareable(new FExtender);ToolbarExtender->AddToolBarExtension("Settings", EExtensionHook::After, PluginCommands, FToolBarExtensionDelegate::CreateRaw(this, &FMyEditorStandaloneWindowModule::AddToolbarExtension));LevelEditorModule.GetToolBarExtensibilityManager()->AddExtender(ToolbarExtender);}
第三步：注册绑定对象事件
FGlobalTabmanager::Get()->RegisterNomadTabSpawner(MyEditorStandaloneWindowTabName, FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::OnSpawnPluginTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyTestWindow")).SetMenuType(ETabSpawnerMenuType::Hidden);FGlobalTabmanager::Get()->RegisterNomadTabSpawner("MyWindow1", FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::SpawnCustomTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyWindow1")).SetMenuType(ETabSpawnerMenuType::Hidden);FGlobalTabmanager::Get()->RegisterNomadTabSpawner("MyWindow2", FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::SpawnCustomTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyWindow2")).SetMenuType(ETabSpawnerMenuType::Hidden);
第四步：FTabManager重新布局
const TSharedRef<SDockTab> NomadTab = SNew(SDockTab).TabRole(ETabRole::NomadTab);if (!MyWindowTabManager.IsValid()){MyWindowTabManager = FGlobalTabmanager::Get()->NewTabManager(NomadTab);}if (!MyWindowLayout.IsValid()){MyWindowLayout = FTabManager::NewLayout("TestLayoutWindow")->AddArea(FTabManager::NewPrimaryArea()->SetOrientation(Orient_Vertical)->Split(FTabManager::NewStack()->SetSizeCoefficient(.5f)->AddTab("MyWindow1", ETabState::OpenedTab))->Split(FTabManager::NewStack()->SetSizeCoefficient(.5f)->AddTab("MyWindow2", ETabState::OpenedTab)));}TSharedRef<SWidget> TabContents = MyWindowTabManager->RestoreFrom(MyWindowLayout.ToSharedRef(), TSharedPtr<SWindow>()).ToSharedRef();NomadTab->SetContent(TabContents);
效果如下：
完整代码附上：
MyEditorStandaloneWindow.h文件
// Copyright Epic Games, Inc. All Rights Reserved.#pragma once#include "CoreMinimal.h"#include "Modules/ModuleManager.h"class FToolBarBuilder;class FMenuBuilder;class FMyEditorStandaloneWindowModule : public IModuleInterface{public:/** IModuleInterface implementation */virtual void StartupModule() override;virtual void ShutdownModule() override;/** This function will be bound to Command (by default it will bring up plugin window) */void PluginButtonClicked();private:void RegisterMenus();TSharedRef<class SDockTab> OnSpawnPluginTab(const class FSpawnTabArgs& SpawnTabArgs);private:TSharedPtr<class FUICommandList> PluginCommands;void AddMenuExtension(FMenuBuilder& Builder);void AddToolbarExtension(FToolBarBuilder& Builder);TSharedRef<SDockTab> SpawnCustomTab(const FSpawnTabArgs& Arg);TSharedPtr<FTabManager> MyWindowTabManager;TSharedPtr<FTabManager::FLayout> MyWindowLayout;};
MyEditorStandaloneWindow.cpp文件
// Copyright Epic Games, Inc. All Rights Reserved.#include "MyEditorStandaloneWindow.h"#include "MyEditorStandaloneWindowStyle.h"#include "MyEditorStandaloneWindowCommands.h"#include "LevelEditor.h"#include "Widgets/Docking/SDockTab.h"#include "Widgets/Layout/SBox.h"#include "Widgets/Text/STextBlock.h"#include "ToolMenus.h"static const FName MyEditorStandaloneWindowTabName("MyEditorStandaloneWindow");#define LOCTEXT_NAMESPACE "FMyEditorStandaloneWindowModule"void FMyEditorStandaloneWindowModule::StartupModule(){// This code will execute after your module is loaded into memory; the exact timing is specified in the .uplugin file per-moduleFMyEditorStandaloneWindowStyle::Initialize();FMyEditorStandaloneWindowStyle::ReloadTextures();FMyEditorStandaloneWindowCommands::Register();PluginCommands = MakeShareable(new FUICommandList);PluginCommands->MapAction(FMyEditorStandaloneWindowCommands::Get().OpenPluginWindow,FExecuteAction::CreateRaw(this, &FMyEditorStandaloneWindowModule::PluginButtonClicked),FCanExecuteAction());//UToolMenus::RegisterStartupCallback(FSimpleMulticastDelegate::FDelegate::CreateRaw(this, &FMyEditorStandaloneWindowModule::RegisterMenus));//首先加载模块FExtend最后都在FLevelEditorModule中管理FLevelEditorModule& LevelEditorModule = FModuleManager::LoadModuleChecked<FLevelEditorModule>("LevelEditor");{TSharedPtr<FExtender> MenuExtender = MakeShareable(new FExtender());MenuExtender->AddMenuExtension("WindowLayout", EExtensionHook::After, PluginCommands, FMenuExtensionDelegate::CreateRaw(this, &FMyEditorStandaloneWindowModule::AddMenuExtension));LevelEditorModule.GetMenuExtensibilityManager()->AddExtender(MenuExtender);}{TSharedPtr<FExtender> ToolbarExtender = MakeShareable(new FExtender);ToolbarExtender->AddToolBarExtension("Settings", EExtensionHook::After, PluginCommands, FToolBarExtensionDelegate::CreateRaw(this, &FMyEditorStandaloneWindowModule::AddToolbarExtension));LevelEditorModule.GetToolBarExtensibilityManager()->AddExtender(ToolbarExtender);}FGlobalTabmanager::Get()->RegisterNomadTabSpawner(MyEditorStandaloneWindowTabName, FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::OnSpawnPluginTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyTestWindow")).SetMenuType(ETabSpawnerMenuType::Hidden);FGlobalTabmanager::Get()->RegisterNomadTabSpawner("MyWindow1", FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::SpawnCustomTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyWindow1")).SetMenuType(ETabSpawnerMenuType::Hidden);FGlobalTabmanager::Get()->RegisterNomadTabSpawner("MyWindow2", FOnSpawnTab::CreateRaw(this, &FMyEditorStandaloneWindowModule::SpawnCustomTab)).SetDisplayName(LOCTEXT("FMyEditorStandaloneWindowTabTitle", "MyWindow2")).SetMenuType(ETabSpawnerMenuType::Hidden);}void FMyEditorStandaloneWindowModule::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.UToolMenus::UnRegisterStartupCallback(this);UToolMenus::UnregisterOwner(this);FMyEditorStandaloneWindowStyle::Shutdown();FMyEditorStandaloneWindowCommands::Unregister();FGlobalTabmanager::Get()->UnregisterNomadTabSpawner(MyEditorStandaloneWindowTabName);}TSharedRef<SDockTab> FMyEditorStandaloneWindowModule::OnSpawnPluginTab(const FSpawnTabArgs& SpawnTabArgs){/*FText WidgetText = FText::Format(LOCTEXT("WindowWidgetText", "Add code to {0} in {1} to override this window's contents"),FText::FromString(TEXT("FMyEditorStandaloneWindowModule::OnSpawnPluginTab")),FText::FromString(TEXT("MyEditorStandaloneWindow.cpp")));*///return SNew(SDockTab)//.TabRole(ETabRole::NomadTab)//[//// Put your tab content here!//SNew(SBox)//.HAlign(HAlign_Center)//.VAlign(VAlign_Center)//[//SNew(STextBlock)//.Text(WidgetText)//]//];const TSharedRef<SDockTab> NomadTab = SNew(SDockTab).TabRole(ETabRole::NomadTab);if (!MyWindowTabManager.IsValid()){MyWindowTabManager = FGlobalTabmanager::Get()->NewTabManager(NomadTab);}if (!MyWindowLayout.IsValid()){MyWindowLayout = FTabManager::NewLayout("TestLayoutWindow")->AddArea(FTabManager::NewPrimaryArea()->SetOrientation(Orient_Vertical)->Split(FTabManager::NewStack()->SetSizeCoefficient(.5f)->AddTab("MyWindow1", ETabState::OpenedTab))->Split(FTabManager::NewStack()->SetSizeCoefficient(.5f)->AddTab("MyWindow2", ETabState::OpenedTab)));}TSharedRef<SWidget> TabContents = MyWindowTabManager->RestoreFrom(MyWindowLayout.ToSharedRef(), TSharedPtr<SWindow>()).ToSharedRef();NomadTab->SetContent(TabContents);return NomadTab;}void FMyEditorStandaloneWindowModule::AddMenuExtension(FMenuBuilder& Builder){Builder.AddMenuEntry(FMyEditorStandaloneWindowCommands::Get().OpenPluginWindow);}void FMyEditorStandaloneWindowModule::AddToolbarExtension(FToolBarBuilder& Builder){Builder.AddToolBarButton(FMyEditorStandaloneWindowCommands::Get().OpenPluginWindow);}TSharedRef<SDockTab> FMyEditorStandaloneWindowModule::SpawnCustomTab(const FSpawnTabArgs& Arg){return SNew(SDockTab);}void FMyEditorStandaloneWindowModule::PluginButtonClicked(){FGlobalTabmanager::Get()->TryInvokeTab(MyEditorStandaloneWindowTabName);}void FMyEditorStandaloneWindowModule::RegisterMenus(){// Owner will be used for cleanup in call to UToolMenus::UnregisterOwnerFToolMenuOwnerScoped OwnerScoped(this);{UToolMenu* Menu = UToolMenus::Get()->ExtendMenu("LevelEditor.MainMenu.Window");{FToolMenuSection& Section = Menu->FindOrAddSection("WindowLayout");Section.AddMenuEntryWithCommandList(FMyEditorStandaloneWindowCommands::Get().OpenPluginWindow, PluginCommands);}}{UToolMenu* ToolbarMenu = UToolMenus::Get()->ExtendMenu("LevelEditor.LevelEditorToolBar");{FToolMenuSection& Section = ToolbarMenu->FindOrAddSection("Settings");{FToolMenuEntry& Entry = Section.AddEntry(FToolMenuEntry::InitToolBarButton(FMyEditorStandaloneWindowCommands::Get().OpenPluginWindow));Entry.SetCommandList(PluginCommands);}}}}#undef LOCTEXT_NAMESPACEIMPLEMENT_MODULE(FMyEditorStandaloneWindowModule, MyEditorStandaloneWindow)
