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C++ 在 Unreal 中为游戏增加实时音视频互动的教程详解

时间：2022-12-23 11:50:29 | 栏目：C代码 | 点击：次

我们已经上线了 Agora Unreal SDK，提供了支持 Blueprint 和 C++ 的两个版本 SDK。我们分享了如何基于 Blueprint 在游戏中创建实时音视频功能 。在本文中，我们来分享如何基于声网 Agora Unreal SDK C++版本，在游戏中实现实时音视频功能。

本篇教程较长，建议在 Web 浏览器端浏览，体验更好。

准备工作

需要的开发环境和需要准备的与 Blueprint 一样：

新建项目

如果你已经有 Unreal 项目了，可以跳过这一步。在 Unreal 中创建一个 C++类型的项目。

确保在 [your_project]/Source/[project_name]/[project_name].Build.cs文件的 PrivateDependencyModuleNames一行，去掉注释。Unreal 默认是将它注释掉的，这会导致在编译的时候报错。

// Uncomment if you are using Slate UI
 PrivateDependencyModuleNames.AddRange(new string[] { "UMG", "Slate", "SlateCore" });

接下来我们在项目中集成 Agora SDK

1.将 SDK 复制到这个路径下 [your_project]/Plugins

2.把插件依赖添加到[your_project]/Source/[project_name]/[project_name].Build.cs文件的私有依赖（Private Dependencies）部分 PrivateDependencyModuleNames.AddRange(new string[] { "AgoraPlugin", "AgoraBlueprintable" });

3.重启 Unreal

4.点击 Edit->Plugin，在分类中找到 Project->Other，确定插件已经生效

创建新的 Level

接下来我们将创建一个新的 Level，在那里建立我们的游戏环境。有几种不同的方法可以创建一个新的 Level，我们将使用文件菜单的方法，其中列出了关卡选择选项。

在虚幻编辑器里面，点击文件菜单选项，然后选择新建 Level......

然后会打开一个新的对话框 。

选择Empty Level ，然后指定一个存储的路径。

创建核心类

在这里我们要创建两个类：VideoFrameObserver 和VideoCall C++ Class。他们会负责与 Agora SDK 进行通信。

首先是 VideoFrameObserver。VideoFrameObserver 执行的是 agora::media::IVideoFrameObserver。这个方法在 VideoFrameObserver 类中负责管理视频帧的回调。它是用 registerVideoFrameObserver 在 agora::media::IMediaEngine 中注册的。

在 Unreal 编辑器中，选择 File->Add New C++ Class。

父类谁定为 None，然后点击下一步。

为 VideoFrameObserver明明，然后选择 Create Class。

创建 VideoFrameObserver 类接口。

打开 VideoFrameObserver.h 文件然后添加如下代码：

//VideoFrameObserver.h
#include "CoreMinimal.h"
#include <functional>
#include "AgoraMediaEngine.h"
class AGORAVIDEOCALL_API VideoFrameObserver : public agora::media::IVideoFrameObserver
{
public:
 virtual ~VideoFrameObserver() = default;
public:
 bool onCaptureVideoFrame(VideoFrame& videoFrame) override;
 bool onRenderVideoFrame(unsigned int uid, VideoFrame& videoFrame) override;
 void setOnCaptureVideoFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> callback);
 void setOnRenderVideoFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> callback);
 virtual VIDEO_FRAME_TYPE getVideoFormatPreference() override { return FRAME_TYPE_RGBA; }
private:
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnCaptureVideoFrame;
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnRenderVideoFrame;
};

AGORAVIDEOCALL_API 是项目依赖的定义，而不是由Unreal 生成的你自己的定义。

重写onCaptureVideoFrame/onRenderVideoFrame方法

onCaptureVideoFrame 会获取到摄像头捕获的画面，转换为 ARGB 格式并触发 OnCaptureVideoFrame 回调。

onRenderVideoFrame 讲收到的特定用户画面转换为 ARGB 格式，然后触发 onRenderVideoFrame 回调。

//VideoFrameObserver.cpp
bool VideoFrameObserver::onCaptureVideoFrame(VideoFrame& Frame)
{
 const auto BufferSize = Frame.yStride*Frame.height;
 if (OnCaptureVideoFrame)
 {
 OnCaptureVideoFrame( static_cast< uint8_t* >( Frame.yBuffer ), Frame.width, Frame.height, BufferSize );
 }
 return true;
}
bool VideoFrameObserver::onRenderVideoFrame(unsigned int uid, VideoFrame& Frame)
{
 const auto BufferSize = Frame.yStride*Frame.height;
 if (OnRenderVideoFrame)
 {
 OnRenderVideoFrame( static_cast<uint8_t*>(Frame.yBuffer), Frame.width, Frame.height, BufferSize );
 }
 return true;
}

增加setOnCaptureVideoFrameCallback/setOnRenderVideoFrameCallback方法。

设定回调，用来获取摄像头获取到的本地画面和远端的画面。

//VideoFrameObserver.cpp
void VideoFrameObserver::setOnCaptureVideoFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> Callback)
{
 OnCaptureVideoFrame = Callback;
}
void VideoFrameObserver::setOnRenderVideoFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> Callback)
{
 OnRenderVideoFrame = Callback;
}

创建视频通话C++类

VideoCall 类管理与 Agora SDK 的通信。需要创建多个方法和接口。

创建类接口

回到 Unreal 编辑器，再创建一个新的 C++类，命名为 VideoCall.h。然后进入VideoCall.h文件，添加一下接口：

//VideoCall.h
#pragma once
#include "CoreMinimal.h"
#include <functional>
#include <vector>
#include "AgoraRtcEngine.h"
#include "AgoraMediaEngine.h"
class VideoFrameObserver;
class AGORAVIDEOCALL_API VideoCall
{
public:
 VideoCall();
 ~VideoCall();
 FString GetVersion() const;
 void RegisterOnLocalFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnLocalFrameCallback);
 void RegisterOnRemoteFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnRemoteFrameCallback);
 void StartCall(
 const FString& ChannelName,
 const FString& EncryptionKey,
 const FString& EncryptionType);
 void StopCall();
 bool MuteLocalAudio(bool bMuted = true);
 bool IsLocalAudioMuted();
 bool MuteLocalVideo(bool bMuted = true);
 bool IsLocalVideoMuted();
 bool EnableVideo(bool bEnable = true);
private:
 void InitAgora();
private:
 TSharedPtr<agora::rtc::ue4::AgoraRtcEngine> RtcEnginePtr;
 TSharedPtr<agora::media::ue4::AgoraMediaEngine> MediaEnginePtr;
 TUniquePtr<VideoFrameObserver> VideoFrameObserverPtr;
 //callback
 //data, w, h, size
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnLocalFrameCallback;
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnRemoteFrameCallback;
 bool bLocalAudioMuted = false;
 bool bLocalVideoMuted = false;
};

创建初始化方法

进入 VideoCall.cpp 文件，添加以下代码：

//VideoCall.cpp
#include "AgoraVideoDeviceManager.h"
#include "AgoraAudioDeviceManager.h"
#include "MediaShaders.h"
#include "VideoFrameObserver.h"

用agora::rtc::ue4::AgoraRtcEngine::createAgoraRtcEngine()创建引擎，初始化 RtcEnginePtr 变量。创建一个RtcEngineContext对象，然后在ctx.eventHandler 和ctx.appId中设定 event handler 和 App ID 。初始化引擎，并创建AgoraMediaEngine对象，初始化 MediaEnginePtr。

//VideoCall.cpp
VideoCall::VideoCall()
{
 InitAgora();
}
VideoCall::~VideoCall()
{
 StopCall();
}
void VideoCall::InitAgora()
{
 RtcEnginePtr = TSharedPtr<agora::rtc::ue4::AgoraRtcEngine>(agora::rtc::ue4::AgoraRtcEngine::createAgoraRtcEngine());
 static agora::rtc::RtcEngineContext ctx;
 ctx.appId = "aab8b8f5a8cd4469a63042fcfafe7063";
 ctx.eventHandler = new agora::rtc::IRtcEngineEventHandler();
 int ret = RtcEnginePtr->initialize(ctx);
 if (ret < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("RtcEngine initialize ret: %d"), ret);
 }
 MediaEnginePtr = TSharedPtr<agora::media::ue4::AgoraMediaEngine>(agora::media::ue4::AgoraMediaEngine::Create(RtcEnginePtr.Get()));
}
FString VideoCall::GetVersion() const
{
 if (!RtcEnginePtr)
 {
 return "";
 }
 int build = 0;
 const char* version = RtcEnginePtr->getVersion(&build);
 return FString(ANSI_TO_TCHAR(version));
}

创建回调方法

接下来创建回调方法，返回本地和远端的视频帧

//VideoCall.cpp
void VideoCall::RegisterOnLocalFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnFrameCallback)
{
 OnLocalFrameCallback = std::move(OnFrameCallback);
}
void VideoCall::RegisterOnRemoteFrameCallback(
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnFrameCallback)
{
 OnRemoteFrameCallback = std::move(OnFrameCallback);
}

创建呼叫方法

我们需要利用这个方法来实现“加入频道”和“离开频道”。

增加 StartCall

首先创建 VideoFrameObserver 对象，然后根据你的场景来设置以下回调。

在 InitAgora 的 MediaEngine 对象中通过 registerVideoFrameObserver 方法注册 VideoFrameObserver。为了保证 EncryptionType 和 EncryptionKey 不为空，需要先设置 EncryptionMode 和 EncryptionSecret。然后按照你的需要来设置频道参数，并调用 joinChannel。

//VideoCall.cpp
void VideoCall::StartCall(
 const FString& ChannelName,
 const FString& EncryptionKey,
 const FString& EncryptionType)
{
 if (!RtcEnginePtr)
 {
 return;
 }
 if (MediaEnginePtr)
 {
 if (!VideoFrameObserverPtr)
 {
 VideoFrameObserverPtr = MakeUnique<VideoFrameObserver>();
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnCaptureVideoFrameCallback
 = [this](std::uint8_t* buffer, std::uint32_t width, std::uint32_t height, std::uint32_t size)
 {
 if (OnLocalFrameCallback)
 {
 OnLocalFrameCallback(buffer, width, height, size);
 }
 else { UE_LOG(LogTemp, Warning, TEXT("VideoCall OnLocalFrameCallback isn't set")); }
 };
 VideoFrameObserverPtr->setOnCaptureVideoFrameCallback(std::move(OnCaptureVideoFrameCallback));
 std::function<void(std::uint8_t*, std::uint32_t, std::uint32_t, std::uint32_t)> OnRenderVideoFrameCallback
 = [this](std::uint8_t* buffer, std::uint32_t width, std::uint32_t height, std::uint32_t size)
 {
 if (OnRemoteFrameCallback)
 {
 OnRemoteFrameCallback(buffer, width, height, size);
 }
 else { UE_LOG(LogTemp, Warning, TEXT("VideoCall OnRemoteFrameCallback isn't set")); }
 };
 VideoFrameObserverPtr->setOnRenderVideoFrameCallback(std::move(OnRenderVideoFrameCallback));
 }
 MediaEnginePtr->registerVideoFrameObserver(VideoFrameObserverPtr.Get());
 }
 int nRet = RtcEnginePtr->enableVideo();
 if (nRet < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("enableVideo : %d"), nRet)
 }
 if (!EncryptionType.IsEmpty() && !EncryptionKey.IsEmpty())
 {
 if (EncryptionType == "aes-256")
 {
 RtcEnginePtr->setEncryptionMode("aes-256-xts");
 }
 else
 {
 RtcEnginePtr->setEncryptionMode("aes-128-xts");
 }
 nRet = RtcEnginePtr->setEncryptionSecret(TCHAR_TO_ANSI(*EncryptionKey));
 if (nRet < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("setEncryptionSecret : %d"), nRet)
 }
 }
 nRet = RtcEnginePtr->setChannelProfile(agora::rtc::CHANNEL_PROFILE_COMMUNICATION);
 if (nRet < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("setChannelProfile : %d"), nRet)
 }
 //"demoChannel1";
 std::uint32_t nUID = 0;
 nRet = RtcEnginePtr->joinChannel(NULL, TCHAR_TO_ANSI(*ChannelName), NULL, nUID);
 if (nRet < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("joinChannel ret: %d"), nRet);
 }
}

增加 StopCall 功能

根据你的场景需要，通过调用 leaveChannel 方法来结束通话，比如当要结束通话的时候，当你需要关闭应用的时候，或是当你的应用运行于后台的时候。调用 nullptr 作为实参的 registerVideoFrameObserver，用来取消 VideoFrameObserver的注册。

//VideoCall.cpp
void VideoCall::StopCall()
{
 if (!RtcEnginePtr)
 {
 return;
 }
 auto ConnectionState = RtcEnginePtr->getConnectionState();
 if (agora::rtc::CONNECTION_STATE_DISCONNECTED != ConnectionState)
 {
 int nRet = RtcEnginePtr->leaveChannel();
 if (nRet < 0)
 {
 UE_LOG(LogTemp, Warning, TEXT("leaveChannel ret: %d"), nRet);
 }
 if (MediaEnginePtr)
 {
 MediaEnginePtr->registerVideoFrameObserver(nullptr);
 }
 }
}

创建 Video 方法

这些方法是用来管理视频的。

加 EnableVideo() 方法

EnableVideo() 会启用本示例中的视频。初始化 nRet，值为 0。如果 bEnable 为 true，则通过 RtcEnginePtr->enableVideo() 启用视频。否则，通过 RtcEnginePtr->disableVideo() 关闭视频。

//VideoCall.cpp
bool VideoCall::EnableVideo(bool bEnable)
{
 if (!RtcEnginePtr)
 {
 return false;
 }
 int nRet = 0;
 if (bEnable)
 nRet = RtcEnginePtr->enableVideo();
 else
 nRet = RtcEnginePtr->disableVideo();
 return nRet == 0 ? true : false;
}

增加 MuteLocalVideo() 方法

MuteLocalVideo() 方法负责开启或关闭本地视频。在其余方法完成运行之前，需要保证 RtcEnginePtr 不为 nullptr。如果可以成功mute 或 unmute 本地视频，那么把 bLocalVideoMuted 设置为 bMuted。

//VideoCall.cpp
bool VideoCall::MuteLocalVideo(bool bMuted)
{
 if (!RtcEnginePtr)
 {
 return false;
 }
 int ret = RtcEnginePtr->muteLocalVideoStream(bMuted);
 if (ret == 0)
 bLocalVideoMuted = bMuted;
 return ret == 0 ? true : false;
}

增加 IsLocalVideoMuted() 方法

IsLocalVideoMuted() 方法的作用是，当本地视频开启或关闭的时候，返回 bLocalVideoMuted。

//VideoCall.cpp
bool VideoCall::IsLocalVideoMuted()
{
 return bLocalVideoMuted;
}

创建音频相关的方法

这些方法是用来管理音频的。

添加 MuteLocalAudio() 方法

MuteLocalAudio()用于 mute 或 unmute 本地音频：

//VideoCall.cpp
bool VideoCall::MuteLocalAudio(bool bMuted)
{
 if (!RtcEnginePtr)
 {
 return false;
 }
 int ret = RtcEnginePtr->muteLocalAudioStream(bMuted);
 if (ret == 0)
 bLocalAudioMuted = bMuted;
 return ret == 0 ? true : false;
}

增加 IsLocalAudioMuted() 方法

IsLocalAudioMuted()方法的作用是，当 mute 或 unmute 本地音频的时候，返回 bLocalAudioMuted。

//VideoCall.cpp
bool VideoCall::IsLocalAudioMuted()
{
 return bLocalAudioMuted;
}

创建 GUI

接下来就是要为一对一对话创建用户交互界面了，包括：

创建 VideoCallPlayerController

为了能够将我们的Widget Blueprints添加到Viewport中，我们创建我们的自定义播放器控制器类。

在 "内容浏览器 "中，按 "Add New "按钮，选择 "新建C++类"。在 "添加C++类 "窗口中，勾选 "显示所有类 "按钮，并输入PlayerController。按 "下一步 "按钮，给类命名为 VideoCallPlayerController。按Create Class按钮。

//VideoCallPlayerController.h
#include "CoreMinimal.h"
#include "GameFramework/PlayerController.h"
#include "VideoCallPlayerController.generated.h"
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
};

这个类是 BP_VideoCallPlayerController 的 Blueprint Asset 的基类，我们将在最后创建。

增加需要的 Include

在 VideoCallPlayerController.h 文件的头部包括了所需的头文件。

//VideoCallPlayerController.h
#include "CoreMinimal.h"
#include "GameFramework/PlayerController.h"
#include "Templates/UniquePtr.h"
#include "VideoCall.h"
#include "VideoCallPlayerController.generated.h"
//VideoCallPlayerController.cpp
#include "Blueprint/UserWidget.h"
#include "EnterChannelWidget.h"
#include "VideoCallWidget.h"

类声明

为下一个类添加转发声明：

//VideoCallPlayerController.h
class UEnterChannelWidget;
class UVideoCallWidget;

稍后我们将跟进其中的两个创建，即 UEnterChannelWidget 和 UVideoCallWidget。

添加成员变量

现在，在编辑器中添加成员引用到 UMG Asset 中。

//VideoCallPlayerController.h
...
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
 UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Widgets")
 TSubclassOf<class UUserWidget> wEnterChannelWidget;
 UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Widgets")
 TSubclassOf<class UUserWidget> wVideoCallWidget;
 ...
};

变量来保持创建后的小部件，以及一个指向VideoCall的指针。

//VideoCallPlayerController.h
...
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
 ...
 UEnterChannelWidget* EnterChannelWidget = nullptr;
 UVideoCallWidget* VideoCallWidget = nullptr;
 TUniquePtr<VideoCall> VideoCallPtr;
 ...
};

覆盖 BeginPlay/EndPlay

//VideoCallPlayerController.h
...
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
 ...
 void BeginPlay() override;
 void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
 ...
};
//VideoCallPlayerController.cpp
void AVideoCallPlayerController::BeginPlay()
{
 Super::BeginPlay();
 //initialize wigets
 if (wEnterChannelWidget) // Check if the Asset is assigned in the blueprint.
 {
 // Create the widget and store it.
 if (!EnterChannelWidget)
 {
 EnterChannelWidget = CreateWidget<UEnterChannelWidget>(this, wEnterChannelWidget);
 EnterChannelWidget->SetVideoCallPlayerController(this);
 }
 // now you can use the widget directly since you have a referance for it.
 // Extra check to make sure the pointer holds the widget.
 if (EnterChannelWidget)
 {
 //let add it to the view port
 EnterChannelWidget->AddToViewport();
 }
 //Show the Cursor.
 bShowMouseCursor = true;
 }
 if (wVideoCallWidget)
 {
 if (!VideoCallWidget)
 {
 VideoCallWidget = CreateWidget<UVideoCallWidget>(this, wVideoCallWidget);
 VideoCallWidget->SetVideoCallPlayerController(this);
 }
 if (VideoCallWidget)
 {
 VideoCallWidget->AddToViewport();
 }
 VideoCallWidget->SetVisibility(ESlateVisibility::Collapsed);
 }
 //create video call and switch on the EnterChannelWidget
 VideoCallPtr = MakeUnique<VideoCall>();
 FString Version = VideoCallPtr->GetVersion();
 Version = "Agora version: " + Version;
 EnterChannelWidget->UpdateVersionText(Version);
 SwitchOnEnterChannelWidget(std::move(VideoCallPtr));
}
void AVideoCallPlayerController::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
 Super::EndPlay(EndPlayReason);
}

这时你可能注意到EnterChannelWidget和VideoCallWidget方法被标记为错误，那是因为它们还没有实现。我们将在接下来的步骤中实现它们。

增加 StartCall/EndCall

//VideoCallPlayerController.h
...
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
 ...
 void StartCall(
 TUniquePtr<VideoCall> PassedVideoCallPtr,
 const FString& ChannelName,
 const FString& EncryptionKey,
 const FString& EncryptionType
 );
 void EndCall(TUniquePtr<VideoCall> PassedVideoCallPtr);
 ...
};
//VideoCallPlayerController.cpp
void AVideoCallPlayerController::StartCall(
 TUniquePtr<VideoCall> PassedVideoCallPtr,
 const FString& ChannelName,
 const FString& EncryptionKey,
 const FString& EncryptionType)
{
 SwitchOnVideoCallWidget(std::move(PassedVideoCallPtr));
 VideoCallWidget->OnStartCall(
 ChannelName,
 EncryptionKey,
 EncryptionType);
}
void AVideoCallPlayerController::EndCall(TUniquePtr<VideoCall> PassedVideoCallPtr)
{
 SwitchOnEnterChannelWidget(std::move(PassedVideoCallPtr));
}

增加打开另一个小工具的方法

//VideoCallPlayerController.h
...
UCLASS()
class AGORAVIDEOCALL_API AVideoCallPlayerController : public APlayerController
{
 GENERATED_BODY()
public:
 ...
 void SwitchOnEnterChannelWidget(TUniquePtr<VideoCall> PassedVideoCallPtr);
 void SwitchOnVideoCallWidget(TUniquePtr<VideoCall> PassedVideoCallPtr);
 ...
};
//VideoCallPlayerController.cpp
void AVideoCallPlayerController::SwitchOnEnterChannelWidget(TUniquePtr<VideoCall> PassedVideoCallPtr)
{
 if (!EnterChannelWidget)
 {
 return;
 }
 EnterChannelWidget->SetVideoCall(std::move(PassedVideoCallPtr));
 EnterChannelWidget->SetVisibility(ESlateVisibility::Visible);
}
void AVideoCallPlayerController::SwitchOnVideoCallWidget(TUniquePtr<VideoCall> PassedVideoCallPtr)
{
 if (!VideoCallWidget)
 {
 return;
 }
 VideoCallWidget->SetVideoCall(std::move(PassedVideoCallPtr));
 VideoCallWidget->SetVisibility(ESlateVisibility::Visible);
}

创建 EnterChannelWidget C++类

EnterChannelWidget是负责管理 UI 元素交互的。我们要创建一个新的 UserWidget 类型的类。在内容浏览器中，按Add New按钮，选择New C++类，然后勾选Show All Classes按钮，输入UserWidget。按下 "下一步 "按钮，为类设置一个名称，EnterChannelWidget。

我们会得到如下代码：

//EnterChannelWidget.h
#include "CoreMinimal.h"
#include "Blueprint/UserWidget.h"
#include "EnterChannelWidget.generated.h"
UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()
};

在EnterChannelWidget.h文件中增加一些必要的 include：

//EnterCahnnelWidget.h
#include "CoreMinimal.h"
#include "Blueprint/UserWidget.h"
#include "Components/TextBlock.h"
#include "Components/RichTextBlock.h"
#include "Components/EditableTextBox.h"
#include "Components/ComboBoxString.h"
#include "Components/Button.h"
#include "Components/Image.h"
#include "VideoCall.h"
#include "EnterChannelWidget.generated.h"
class AVideoCallPlayerController;
//EnterCahnnelWidget.cpp
#include "Blueprint/WidgetTree.h"
#include "VideoCallPlayerController.h"

然后我们需要增加如下变量：

//EnterChannelWidget.h
...
UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()
public:
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UTextBlock* HeaderTextBlock = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UTextBlock* DescriptionTextBlock = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UEditableTextBox* ChannelNameTextBox = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UEditableTextBox* EncriptionKeyTextBox = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UTextBlock* EncriptionTypeTextBlock = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UComboBoxString* EncriptionTypeComboBox = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UButton* JoinButton = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UButton* TestButton = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UButton* VideoSettingsButton = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UTextBlock* ContactsTextBlock = nullptr;
 UPROPERTY(VisibleAnywhere, BlueprintReadOnly, meta = (BindWidget))
 UTextBlock* BuildInfoTextBlock = nullptr;
 ...
};

这些变量用来公职 blueprint asset 中相关的 UI 元素。这里最重要的是 BindWidget 元属性。通过将指向小部件的指针标记为 BindWidget，你可以在你的 C++类的 Blueprint 子类中创建一个同名的小部件，并在运行时从 C++中访问它。

同时，还要添加如下成员：

//EnterChannelWidget.h
...
UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()
 ...
public:
 AVideoCallPlayerController* PlayerController = nullptr;
 TUniquePtr<VideoCall> VideoCallPtr;
 ...
};

添加 Constructor 和 Construct/Destruct 方法

//EnterChannelWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 UEnterChannelWidget(const FObjectInitializer& objectInitializer);


 void NativeConstruct() override;


 ...
};
//EnterChannelWidget.cpp


UEnterChannelWidget::UEnterChannelWidget(const FObjectInitializer& objectInitializer)
 : Super(objectInitializer)
{
}


void UEnterChannelWidget::NativeConstruct()
{
 Super::NativeConstruct();


 if (HeaderTextBlock)
 HeaderTextBlock->SetText(FText::FromString("Enter a conference room name"));


 if (DescriptionTextBlock)
 DescriptionTextBlock->SetText(FText::FromString("If you are the first person to specify this name, \
the room will be created and you will\nbe placed in it. \
If it has already been created you will join the conference in progress"));


 if (ChannelNameTextBox)
 ChannelNameTextBox->SetHintText(FText::FromString("Channel Name"));


 if (EncriptionKeyTextBox)
 EncriptionKeyTextBox->SetHintText(FText::FromString("Encription Key"));


 if (EncriptionTypeTextBlock)
 EncriptionTypeTextBlock->SetText(FText::FromString("Enc Type:"));


 if (EncriptionTypeComboBox)
 {
 EncriptionTypeComboBox->AddOption("aes-128");
 EncriptionTypeComboBox->AddOption("aes-256");
 EncriptionTypeComboBox->SetSelectedIndex(0);
 }


 if (JoinButton)
 {
 UTextBlock* JoinTextBlock = WidgetTree->ConstructWidget<UTextBlock>(UTextBlock::StaticClass());
 JoinTextBlock->SetText(FText::FromString("Join"));
 JoinButton->AddChild(JoinTextBlock);
 JoinButton->OnClicked.AddDynamic(this, &UEnterChannelWidget::OnJoin);
 }


 if (ContactsTextBlock)
 ContactsTextBlock->SetText(FText::FromString("agora.io Contact support: 400 632 6626"));


 if (BuildInfoTextBlock)
 BuildInfoTextBlock->SetText(FText::FromString(" "));
}

增加 Setter 方法

初始化 PlayerController 和 VideoCallPtr 变量

//EnterChannelWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 void SetVideoCallPlayerController(AVideoCallPlayerController* VideoCallPlayerController);


 void SetVideoCall(TUniquePtr<VideoCall> PassedVideoCallPtr);


 ...
};
//EnterChannelWidget.cpp


void UEnterChannelWidget::SetVideoCallPlayerController(AVideoCallPlayerController* VideoCallPlayerController)
{
 PlayerController = VideoCallPlayerController;
}


void UEnterChannelWidget::SetVideoCall(TUniquePtr<VideoCall> PassedVideoCallPtr)
{
 VideoCallPtr = std::move(PassedVideoCallPtr);
}

增加 BlueprintCallable方法

要对相应的按钮 "onButtonClick "事件做出反应。

//EnterChannelWidget.h
..

UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 UFUNCTION(BlueprintCallable)
 void OnJoin();

 ...
};
//EnterChannelWidget.cpp


void UEnterChannelWidget::OnJoin()
{
 if (!PlayerController || !VideoCallPtr)
 {
 return;
 }

 FString ChannelName = ChannelNameTextBox->GetText().ToString();

 FString EncryptionKey = EncriptionKeyTextBox->GetText().ToString();
 FString EncryptionType = EncriptionTypeComboBox->GetSelectedOption();

 SetVisibility(ESlateVisibility::Collapsed);

 PlayerController->StartCall(
 std::move(VideoCallPtr),
 ChannelName,
 EncryptionKey,
 EncryptionType);
}

增加 update 方法

//EnterChannelWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UEnterChannelWidget : public UUserWidget
{
 GENERATED_BODY()

public:
 ...

 void UpdateVersionText(FString newValue);

 ...
};
//EnterChannelWidget.cpp

void UEnterChannelWidget::UpdateVersionText(FString newValue)
{
 if (BuildInfoTextBlock)
 BuildInfoTextBlock->SetText(FText::FromString(newValue));
}

创建 VideoViewWidget C++ 类

VideoViewWidget是一个存储动态纹理并使用RGBA buffer 更新动态纹理的类，该类是从VideoCall OnLocalFrameCallback/OnRemoteFrameCallback函数中接收到的。

创建类和添加所需的 include

//VideoViewWidget.h

#include "CoreMinimal.h"
#include "Blueprint/UserWidget.h"

#include "Components/Image.h"

#include "VideoViewWidget.generated.h"
//VideoViewWidget.cpp

#include "EngineUtils.h"
#include "Engine/Texture2D.h"

#include <algorithm>

添加成员变量

FUpdateTextureRegion2D：指定一个纹理的更新区域 刷子 - 一个包含如何绘制Slate元素的笔刷。我们将用它来绘制RenderTargetImage上的RenderTargetTexture。

//VideoViewWidget.h

...

UCLASS()
class AGORAVIDEOCALL_API UVideoViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:
 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UImage* RenderTargetImage = nullptr;

 UPROPERTY(EditDefaultsOnly)
 UTexture2D* RenderTargetTexture = nullptr;

 UTexture2D* CameraoffTexture = nullptr;

 uint8* Buffer = nullptr;
 uint32_t Width = 0;
 uint32_t Height = 0;
 uint32 BufferSize = 0;
 FUpdateTextureRegion2D* UpdateTextureRegion = nullptr;

 FSlateBrush Brush;

 FCriticalSection Mutex;

 ...
};

覆盖 NativeConstruct() 方法

在NativeConstruct中，我们将用默认颜色初始化我们的图像。为了初始化我们的RenderTargetTexture，我们需要使用CreateTransient调用创建动态纹理（Texture2D）。然后分配BufferSize为Width * Height * 4的BufferSize（用于存储RGBA格式，每个像素可以用4个字节表示）。为了更新我们的纹理，我们可以使用UpdateTextureRegions函数。这个函数的输入参数之一是我们的像素数据缓冲区。这样，每当我们修改像素数据缓冲区时，我们就需要调用这个函数来使变化在纹理中可见。现在用我们的RenderTargetTexture初始化Brush变量，然后在RenderTargetImage widget中设置这个Brush。

//VideoViewWidget.h
...

UCLASS()
class AGORAVIDEOCALL_API UVideoViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

...

 void NativeConstruct() override;

 ...
};
//VideoViewWidget.cpp

void UVideoViewWidget::NativeConstruct()
{
 Super::NativeConstruct();

 Width = 640;
 Height = 360;

 RenderTargetTexture = UTexture2D::CreateTransient(Width, Height, PF_R8G8B8A8);
 RenderTargetTexture->UpdateResource();

 BufferSize = Width * Height * 4;
 Buffer = new uint8[BufferSize];
 for (uint32 i = 0; i < Width * Height; ++i)
 {
 Buffer[i * 4 + 0] = 0x32;
 Buffer[i * 4 + 1] = 0x32;
 Buffer[i * 4 + 2] = 0x32;
 Buffer[i * 4 + 3] = 0xFF;
 }
 UpdateTextureRegion = new FUpdateTextureRegion2D(0, 0, 0, 0, Width, Height);
 RenderTargetTexture->UpdateTextureRegions(0, 1, UpdateTextureRegion, Width * 4, (uint32)4, Buffer);

 Brush.SetResourceObject(RenderTargetTexture);
 RenderTargetImage->SetBrush(Brush);
}

覆盖 NativeDestruct() 方法

//VideoViewWidget.h
...

UCLASS()
class AGORAVIDEOCALL_API UVideoViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 void NativeDestruct() override;

 ...
};
//VideoViewWidget.cpp

void UVideoViewWidget::NativeDestruct()
{
 Super::NativeDestruct();

 delete[] Buffer;
 delete UpdateTextureRegion;
}

覆盖 NativeTick() 方法

如果UpdateTextureRegion Width或Height不等于memember的Width Height值，我们需要重新创建RenderTargetTexture以支持更新的值，并像Native Construct成员一样重复初始化。否则只需用Buffer调用UpdateTextureRegions。

//VideoViewWidget.h

...

UCLASS()
class AGORAVIDEOCALL_API UVideoViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 void NativeTick(const FGeometry& MyGeometry, float DeltaTime) override;

 ...
};
//VideoViewWidget.cpp

void UVideoViewWidget::NativeTick(const FGeometry& MyGeometry, float DeltaTime)
{
 Super::NativeTick(MyGeometry, DeltaTime);

 FScopeLock lock(&Mutex);

 if (UpdateTextureRegion->Width != Width ||
 UpdateTextureRegion->Height != Height)
 {
 auto NewUpdateTextureRegion = new FUpdateTextureRegion2D(0, 0, 0, 0, Width, Height);

 auto NewRenderTargetTexture = UTexture2D::CreateTransient(Width, Height, PF_R8G8B8A8);
 NewRenderTargetTexture->UpdateResource();
 NewRenderTargetTexture->UpdateTextureRegions(0, 1, NewUpdateTextureRegion, Width * 4, (uint32)4, Buffer);

 Brush.SetResourceObject(NewRenderTargetTexture);
 RenderTargetImage->SetBrush(Brush);

 //UClass's such as UTexture2D are automatically garbage collected when there is no hard pointer references made to that object.
 //So if you just leave it and don't reference it elsewhere then it will be destroyed automatically.

 FUpdateTextureRegion2D* TmpUpdateTextureRegion = UpdateTextureRegion;

 RenderTargetTexture = NewRenderTargetTexture;
 UpdateTextureRegion = NewUpdateTextureRegion;

 delete TmpUpdateTextureRegion;
 return;
 }
 RenderTargetTexture->UpdateTextureRegions(0, 1, UpdateTextureRegion, Width * 4, (uint32)4, Buffer);
}

增加 UpdateBuffer() 方法

通过调用来更新 Buffer 值。我们希望从 Agora SDK 线程接收到新的值。由于 UE4 的限制，我们将值保存到变量 Buffer 中，并在 NativeTick 方法中更新纹理，所以这里不调用UpdateTextureRegions。

//VideoViewWidget.h
...

UCLASS()
class AGORAVIDEOCALL_API UVideoViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 void UpdateBuffer( uint8* RGBBuffer, uint32_t Width, uint32_t Height, uint32_t Size );
 void ResetBuffer();
 ...
};
//VideoViewWidget.cpp 

void UVideoViewWidget::UpdateBuffer(
 uint8* RGBBuffer,
 uint32_t NewWidth,
 uint32_t NewHeight,
 uint32_t NewSize)
{
 FScopeLock lock(&Mutex);

 if (!RGBBuffer)
 {
 return;
 }

 if (BufferSize == NewSize)
 {
 std::copy(RGBBuffer, RGBBuffer + NewSize, Buffer);
 }
 else
 {
 delete[] Buffer;
 BufferSize = NewSize;
 Width = NewWidth;
 Height = NewHeight;
 Buffer = new uint8[BufferSize];
 std::copy(RGBBuffer, RGBBuffer + NewSize, Buffer);
 }
}

void UVideoViewWidget::ResetBuffer()
{
 for (uint32 i = 0; i < Width * Height; ++i)
 {
 Buffer[i * 4 + 0] = 0x32;
 Buffer[i * 4 + 1] = 0x32;
 Buffer[i * 4 + 2] = 0x32;
 Buffer[i * 4 + 3] = 0xFF;
 }
}

创建 VideoCallViewWidget C++类

VideoCallViewWidget 类的作用是显示本地和远程用户的视频。我们需要两个 VideoViewWidget 小部件，一个用来显示来自本地摄像头的视频，另一个用来显示从远程用户收到的视频（假设我们只支持一个远程用户）。

创建类和添加所需的 include

像之前那样创建Widget C++类，添加所需的include。

//VideoCallViewWidget.h 

#include "CoreMinimal.h"
#include "Blueprint/UserWidget.h"
#include "Components/SizeBox.h"

#include "VideoViewWidget.h"

#include "VideoCallViewWidget.generated.h"
//VideoCallViewWidget.cpp

#include "Components/CanvasPanelSlot.h"

添加成员变量

//VideoCallViewWidget.h 

...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UVideoViewWidget* MainVideoViewWidget = nullptr;

 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 USizeBox* MainVideoSizeBox = nullptr;

 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UVideoViewWidget* AdditionalVideoViewWidget = nullptr;

 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 USizeBox* AdditionalVideoSizeBox = nullptr;

public:
 int32 MainVideoWidth = 0;
 int32 MainVideoHeight = 0;

 ...
};

覆盖 NativeTick() 方法

``
//VideoCallViewWidget.h 

...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 void NativeTick(const FGeometry& MyGeometry, float DeltaTime) override;

 ...
};
//VideoCallViewWidget.cpp

void UVideoCallViewWidget::NativeTick(const FGeometry& MyGeometry, float DeltaTime)
{
 Super::NativeTick(MyGeometry, DeltaTime);

 auto ScreenSize = MyGeometry.GetLocalSize();

 if (MainVideoHeight != 0)
 {
 float AspectRatio = 0;
 AspectRatio = MainVideoWidth / (float)MainVideoHeight;

 auto MainVideoGeometry = MainVideoViewWidget->GetCachedGeometry();
 auto MainVideoScreenSize = MainVideoGeometry.GetLocalSize();
 if (MainVideoScreenSize.X == 0)
 {
 return;
 }

 auto NewMainVideoHeight = MainVideoScreenSize.Y;
 auto NewMainVideoWidth = AspectRatio * NewMainVideoHeight;

 MainVideoSizeBox->SetMinDesiredWidth(NewMainVideoWidth);
 MainVideoSizeBox->SetMinDesiredHeight(NewMainVideoHeight);

 UCanvasPanelSlot* CanvasSlot = Cast<UCanvasPanelSlot>(MainVideoSizeBox->Slot);
 CanvasSlot->SetAutoSize(true);

 FVector2D NewPosition;
 NewPosition.X = -NewMainVideoWidth / 2;
 NewPosition.Y = -NewMainVideoHeight / 2;
 CanvasSlot->SetPosition(NewPosition);
 }
}

更新 UpdateMainVideoBuffer/UpdateAdditionalVideoBuffe

//VideoCallViewWidget.h 


...


UCLASS()
class AGORAVIDEOCALL_API UVideoCallViewWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ...

 void UpdateMainVideoBuffer( uint8* RGBBuffer, uint32_t Width, uint32_t Height, uint32_t Size);
 void UpdateAdditionalVideoBuffer( uint8* RGBBuffer, uint32_t Width, uint32_t Height, uint32_t Size);

 void ResetBuffers();
 ...
};
//VideoCallViewWidget.cpp

void UVideoCallViewWidget::UpdateMainVideoBuffer(
 uint8* RGBBuffer,
 uint32_t Width,
 uint32_t Height,
 uint32_t Size)
{
 if (!MainVideoViewWidget)
 {
 return;
 }
 MainVideoWidth = Width;
 MainVideoHeight = Height;
 MainVideoViewWidget->UpdateBuffer(RGBBuffer, Width, Height, Size);
}

void UVideoCallViewWidget::UpdateAdditionalVideoBuffer(
 uint8* RGBBuffer,
 uint32_t Width,
 uint32_t Height,
 uint32_t Size)
{
 if (!AdditionalVideoViewWidget)
 {
 return;
 }
 AdditionalVideoViewWidget->UpdateBuffer(RGBBuffer, Width, Height, Size);
}

void UVideoCallViewWidget::ResetBuffers()
{
 if (!MainVideoViewWidget || !AdditionalVideoViewWidget)
 {
 return;
 }
 MainVideoViewWidget->ResetBuffer();
 AdditionalVideoViewWidget->ResetBuffer();
}

创建 VideoCallWidget C++ 类

VideoCallWidget 类作为示例应用程序的音频/视频调用小部件。它包含以下控件，与蓝图资产中的UI元素绑定。

创建类和添加所需的include

像之前那样创建Widget C++类，添加必要的include和转发声明。

//VideoCallWidget.h
#include "CoreMinimal.h"
#include "Blueprint/UserWidget.h"

#include "Templates/UniquePtr.h"
#include "Components/Image.h"
#include "Components/Button.h"
#include "Engine/Texture2D.h"

#include "VideoCall.h"

#include "VideoCallViewWidget.h"

#include "VideoCallWidget.generated.h"

class AVideoCallPlayerController;
class UVideoViewWidget;
//VideoCallWidget.cpp

#include "Kismet/GameplayStatics.h"
#include "UObject/ConstructorHelpers.h"
#include "Components/CanvasPanelSlot.h"

#include "VideoViewWidget.h"

#include "VideoCallPlayerController.h"

增加成员变量

//VideoCallWidget.h
...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()

public:
 AVideoCallPlayerController* PlayerController = nullptr;

public:
 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UVideoCallViewWidget* VideoCallViewWidget = nullptr;

 //Buttons
 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UButton* EndCallButton = nullptr;
 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UButton* MuteLocalAudioButton = nullptr;
 UPROPERTY(BlueprintReadOnly, meta = (BindWidget))
 UButton* VideoModeButton = nullptr;

 //Button textures
 int32 ButtonSizeX = 96;
 int32 ButtonSizeY = 96;
 UTexture2D* EndCallButtonTexture = nullptr;
 UTexture2D* AudioButtonMuteTexture = nullptr;
 UTexture2D* AudioButtonUnmuteTexture = nullptr;
 UTexture2D* VideomodeButtonCameraoffTexture = nullptr;
 UTexture2D* VideomodeButtonCameraonTexture = nullptr;

 TUniquePtr<VideoCall> VideoCallPtr;

 ...
};

初始化VideoCallWidget

为每个按钮找到asset图像，并将其分配到相应的纹理。然后用纹理初始化每个按钮。

//VideoCallWidget.h

...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()

public:

 ..

 UVideoCallWidget(const FObjectInitializer& ObjectInitializer);

 void NativeConstruct() override;
 void NativeDestruct() override;

private:
 void InitButtons();

 ...
};
//VideoCallWidget.cpp 


void UVideoCallWidget::NativeConstruct()
{
 Super::NativeConstruct();

 InitButtons();
}

void UVideoCallWidget::NativeDestruct()
{
 Super::NativeDestruct();


 if (VideoCallPtr)
 {
 VideoCallPtr->StopCall();
 }
}

UVideoCallWidget::UVideoCallWidget(const FObjectInitializer& ObjectInitializer)
 : Super(ObjectInitializer)
{
 static ConstructorHelpers::FObjectFinder<UTexture2D>
 EndCallButtonTextureFinder(TEXT("Texture'/Game/ButtonTextures/hangup.hangup'"));
 if (EndCallButtonTextureFinder.Succeeded())
 {
 EndCallButtonTexture = EndCallButtonTextureFinder.Object;
 }
 static ConstructorHelpers::FObjectFinder<UTexture2D>
 AudioButtonMuteTextureFinder(TEXT("Texture'/Game/ButtonTextures/mute.mute'"));
 if (AudioButtonMuteTextureFinder.Succeeded())
 {
 AudioButtonMuteTexture = AudioButtonMuteTextureFinder.Object;
 }
 static ConstructorHelpers::FObjectFinder<UTexture2D>
 AudioButtonUnmuteTextureFinder(TEXT("Texture'/Game/ButtonTextures/unmute.unmute'"));
 if (AudioButtonUnmuteTextureFinder.Succeeded())
 {
 AudioButtonUnmuteTexture = AudioButtonUnmuteTextureFinder.Object;
 }
 static ConstructorHelpers::FObjectFinder<UTexture2D>
 VideomodeButtonCameraonTextureFinder(TEXT("Texture'/Game/ButtonTextures/cameraon.cameraon'"));
 if (VideomodeButtonCameraonTextureFinder.Succeeded())
 {
 VideomodeButtonCameraonTexture = VideomodeButtonCameraonTextureFinder.Object;
 }
 static ConstructorHelpers::FObjectFinder<UTexture2D>
 VideomodeButtonCameraoffTextureFinder(TEXT("Texture'/Game/ButtonTextures/cameraoff.cameraoff'"));
 if (VideomodeButtonCameraoffTextureFinder.Succeeded())
 {
 VideomodeButtonCameraoffTexture = VideomodeButtonCameraoffTextureFinder.Object;
 }
}

void UVideoCallWidget::InitButtons()
{
 if (EndCallButtonTexture)
 {
 EndCallButton->WidgetStyle.Normal.SetResourceObject(EndCallButtonTexture);
 EndCallButton->WidgetStyle.Normal.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 EndCallButton->WidgetStyle.Normal.DrawAs = ESlateBrushDrawType::Type::Image;

 EndCallButton->WidgetStyle.Hovered.SetResourceObject(EndCallButtonTexture);
 EndCallButton->WidgetStyle.Hovered.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 EndCallButton->WidgetStyle.Hovered.DrawAs = ESlateBrushDrawType::Type::Image;

 EndCallButton->WidgetStyle.Pressed.SetResourceObject(EndCallButtonTexture);
 EndCallButton->WidgetStyle.Pressed.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 EndCallButton->WidgetStyle.Pressed.DrawAs = ESlateBrushDrawType::Type::Image;
 }
 EndCallButton->OnClicked.AddDynamic(this, &UVideoCallWidget::OnEndCall);

 SetAudioButtonToMute();
 MuteLocalAudioButton->OnClicked.AddDynamic(this, &UVideoCallWidget::OnMuteLocalAudio);

 SetVideoModeButtonToCameraOff();
 VideoModeButton->OnClicked.AddDynamic(this, &UVideoCallWidget::OnChangeVideoMode);

}

添加按钮纹理

在演示程序中找到目录Content/ButtonTextures（你不必打开项目，只需在文件系统中找到这个文件夹即可）。所有的按钮纹理都存储在那里。在你的项目内容中创建一个名为ButtonTextures的新目录，将所有的按钮图片拖放到那里，让它们在你的项目中可用。

添加Setters

//VideoCallWidget.h

...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()

 ...

public:
 void SetVideoCallPlayerController(AVideoCallPlayerController* VideoCallPlayerController);
 void SetVideoCall(TUniquePtr<VideoCall> PassedVideoCallPtr);

 ...
};
//VideoCallWidget.cpp

void UVideoCallWidget::SetVideoCallPlayerController(AVideoCallPlayerController* VideoCallPlayerController)
{
 PlayerController = VideoCallPlayerController;
}

void UVideoCallWidget::SetVideoCall(TUniquePtr<VideoCall> PassedVideoCallPtr)
{
 VideoCallPtr = std::move(PassedVideoCallPtr);
}

增加用来更新 view 的方法

//VideoCallWidget.h

...

UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()

 ...

private:


 void SetVideoModeButtonToCameraOff();
 void SetVideoModeButtonToCameraOn();

 void SetAudioButtonToMute();
 void SetAudioButtonToUnMute();

 ...
};
//VideoCallWidget.cpp


void UVideoCallWidget::SetVideoModeButtonToCameraOff()
{
 if (VideomodeButtonCameraoffTexture)
 {
 VideoModeButton->WidgetStyle.Normal.SetResourceObject(VideomodeButtonCameraoffTexture);
 VideoModeButton->WidgetStyle.Normal.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Normal.DrawAs = ESlateBrushDrawType::Type::Image;


 VideoModeButton->WidgetStyle.Hovered.SetResourceObject(VideomodeButtonCameraoffTexture);
 VideoModeButton->WidgetStyle.Hovered.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Hovered.DrawAs = ESlateBrushDrawType::Type::Image;


 VideoModeButton->WidgetStyle.Pressed.SetResourceObject(VideomodeButtonCameraoffTexture);
 VideoModeButton->WidgetStyle.Pressed.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Pressed.DrawAs = ESlateBrushDrawType::Type::Image;
 }
}

void UVideoCallWidget::SetVideoModeButtonToCameraOn()
{
 if (VideomodeButtonCameraonTexture)
 {
 VideoModeButton->WidgetStyle.Normal.SetResourceObject(VideomodeButtonCameraonTexture);
 VideoModeButton->WidgetStyle.Normal.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Normal.DrawAs = ESlateBrushDrawType::Type::Image;

 VideoModeButton->WidgetStyle.Hovered.SetResourceObject(VideomodeButtonCameraonTexture);
 VideoModeButton->WidgetStyle.Hovered.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Hovered.DrawAs = ESlateBrushDrawType::Type::Image;

 VideoModeButton->WidgetStyle.Pressed.SetResourceObject(VideomodeButtonCameraonTexture);
 VideoModeButton->WidgetStyle.Pressed.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 VideoModeButton->WidgetStyle.Pressed.DrawAs = ESlateBrushDrawType::Type::Image;
 }
}

void UVideoCallWidget::SetAudioButtonToMute()
{
 if (AudioButtonMuteTexture)
 {
 MuteLocalAudioButton->WidgetStyle.Normal.SetResourceObject(AudioButtonMuteTexture);
 MuteLocalAudioButton->WidgetStyle.Normal.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Normal.DrawAs = ESlateBrushDrawType::Type::Image;

 MuteLocalAudioButton->WidgetStyle.Hovered.SetResourceObject(AudioButtonMuteTexture);
 MuteLocalAudioButton->WidgetStyle.Hovered.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Hovered.DrawAs = ESlateBrushDrawType::Type::Image;

 MuteLocalAudioButton->WidgetStyle.Pressed.SetResourceObject(AudioButtonMuteTexture);
 MuteLocalAudioButton->WidgetStyle.Pressed.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Pressed.DrawAs = ESlateBrushDrawType::Type::Image;
 }
}

void UVideoCallWidget::SetAudioButtonToUnMute()
{
 if (AudioButtonUnmuteTexture)
 {
 MuteLocalAudioButton->WidgetStyle.Normal.SetResourceObject(AudioButtonUnmuteTexture);
 MuteLocalAudioButton->WidgetStyle.Normal.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Normal.DrawAs = ESlateBrushDrawType::Type::Image;

 MuteLocalAudioButton->WidgetStyle.Hovered.SetResourceObject(AudioButtonUnmuteTexture);
 MuteLocalAudioButton->WidgetStyle.Hovered.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Hovered.DrawAs = ESlateBrushDrawType::Type::Image;

 MuteLocalAudioButton->WidgetStyle.Pressed.SetResourceObject(AudioButtonUnmuteTexture);
 MuteLocalAudioButton->WidgetStyle.Pressed.ImageSize = FVector2D(ButtonSizeX, ButtonSizeY);
 MuteLocalAudioButton->WidgetStyle.Pressed.DrawAs = ESlateBrushDrawType::Type::Image;
 }
}

增加 OnStartCall 方法

//VideoCallWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 void OnStartCall( const FString& ChannelName, const FString& EncryptionKey, const FString& EncryptionType );


 ...
};
//VideoCallWidget.cpp


void UVideoCallWidget::OnStartCall(
 const FString& ChannelName,
 const FString& EncryptionKey,
 const FString& EncryptionType)
{
 if (!VideoCallPtr)
 {
 return;
 }


 auto OnLocalFrameCallback = [this](
 std::uint8_t* Buffer,
 std::uint32_t Width,
 std::uint32_t Height,
 std::uint32_t Size)
 {
 VideoCallViewWidget->UpdateAdditionalVideoBuffer(Buffer, Width, Height, Size);
 };
 VideoCallPtr->RegisterOnLocalFrameCallback(OnLocalFrameCallback);


 auto OnRemoteFrameCallback = [this](
 std::uint8_t* Buffer,
 std::uint32_t Width,
 std::uint32_t Height,
 std::uint32_t Size)
 {
 VideoCallViewWidget->UpdateMainVideoBuffer(Buffer, Width, Height, Size);
 };
 VideoCallPtr->RegisterOnRemoteFrameCallback(OnRemoteFrameCallback);


 VideoCallPtr->StartCall(ChannelName, EncryptionKey, EncryptionType);
}

增加 OnEndCall方法

//VideoCallWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 UFUNCTION(BlueprintCallable)
 void OnEndCall();


 ...
};
//VideoCallWidget.cpp 


void UVideoCallWidget::OnEndCall()
{
 if (VideoCallPtr)
 {
 VideoCallPtr->StopCall();
 }


 if (VideoCallViewWidget)
 {
 VideoCallViewWidget->ResetBuffers();
 }


 if (PlayerController)
 {
 SetVisibility(ESlateVisibility::Collapsed);
 PlayerController->EndCall(std::move(VideoCallPtr));
 }
}

增加 OnMuteLocalAudio 方法

//VideoCallWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 UFUNCTION(BlueprintCallable)
 void OnMuteLocalAudio();


 ...
};
//VideoCallWidget.cpp


void UVideoCallWidget::OnMuteLocalAudio()
{
 if (!VideoCallPtr)
 {
 return;
 }
 if (VideoCallPtr->IsLocalAudioMuted())
 {
 VideoCallPtr->MuteLocalAudio(false);
 SetAudioButtonToMute();
 }
 else
 {
 VideoCallPtr->MuteLocalAudio(true);
 SetAudioButtonToUnMute();
 }
}

增加 OnChangeVideoMode方法

//VideoCallWidget.h


...


UCLASS()
class AGORAVIDEOCALL_API UVideoCallWidget : public UUserWidget
{
 GENERATED_BODY()


public:


 ...


 UFUNCTION(BlueprintCallable)
 void OnChangeVideoMode();


 ...
};
//VideoCallWidget.cpp


void UVideoCallWidget::OnChangeVideoMode()
{
 if (!VideoCallPtr)
 {
 return;
 }
 if (!VideoCallPtr->IsLocalVideoMuted())
 {
 VideoCallPtr->MuteLocalVideo(true);


 SetVideoModeButtonToCameraOn();
 }
 else
 {
 VideoCallPtr->EnableVideo(true);
 VideoCallPtr->MuteLocalVideo(false);


 SetVideoModeButtonToCameraOff();
 }
}

增加 Blueprint 类

确保C++代码正确编译。没有成功编译的项目，你将无法进行下一步的操作。如果你已经成功地编译了C++代码，但在虚幻编辑器中仍然没有看到所需的类，请尝试重新打开项目。

创建 BP_EnterChannelWidget Blueprint Asset。

创建一个 UEnterChannelWidget 的 Blueprint，右键点击内容，选择用户界面菜单并选择 Widget Blueprint。

更改这个新的用户小工具的类的父类。打开 Blueprint，会出现 UMG 编辑器界面，默认情况下 Designer 选项卡是打开的。点击图形按钮（右上角按钮），选择 "类设置"。在面板 "Details "中，点击下拉列表 "父类"，选择之前创建的C++ 类 UEnterChannelWidget。现在返回到设计页面。调色板窗口包含几种不同类型的小部件，你可以用它们来构造你的 UI 元素。找到 Text、Editable Text、Button 和 ComboBox（String）元素，然后将它们拖到工作区，如图中所示。然后进入 "EnterChannelWidget.h "文件中的 UEnterChannelWidget 的定义，查看成员变量的名称和对应的类型（UTextBlock、EditableTextBox、UButton和UComboBoxString）。返回到 BP_VideoCallWiewVidget 编辑器中，给你拖动的UI元素设置相同的名称。你可以通过点击元素并在 "详细信息 "面板中更改名称来完成。尝试编译蓝图。如果你忘了添加什么东西，或者在你的UserWidget类中出现了widget名称/类型不匹配的情况，你会出现一个错误。

保存到文件夹中，例如 /Content/Widgets/BP_EnterChannelWidget.uasset。

创建 BP_VideoViewWidget Asset。

设定图片的锚点

创建 BP_VideoCallViewWidget Asset

创建 BP VideoCallViewWidget Asset ，将父类设置为 UVideoCallViewWidget，并添加 BP VideoViewWidget 类型的 UI 元素MainVideoViewWidget 和ExtendedVideoViewWidget。同时添加 SizeBox 类型的 MainVideoSizeBox 和 AdditionalVideoSizeBox UI 元素。

创建 BP_VideoCallWidget Asset

创建BPVideoCallWidget Asset，将父类设置为UVideoCallWidget，在 Palette UI 元素BPVideoCallViewWidget 中找到并添加名称为VideoCallViewWidget，添加 EndCallButton、MuteLocalAudioButton 和 VideoModeButton 按钮。

创建 BP_VideoCallPlayerController blueprint asset

现在是创建 BPVideoCallPlayerPlayerController blueprint asset 的时候了，基于我们前面描述的 AVideoCallPlayerPlayerController 类，创建 BPVideoCallPlayerController 蓝图资产。

创建一个AVideoCallPlayerPlayerController的bluepringt。右键点击内容，按Add New按钮，选择Blueprint类，在窗口中选择父类，在Pick parent类进入All classes部分，找到VideoCallPlayerController类。

现在将我们之前创建的小部件分配给PlayerController，如下图所示。

将其保存到文件夹，例如 /Content/Widgets/BP_VideoCallPlayerController.uasset。

创建 BP_AgoraVideoCallGameModeBase Asset

创建一个 AVideoCallPlayerController 的 Blueprint，右键点击内容，按 Add New 按钮，选择 Blueprint 类，在 Pick parent class 窗口中选择 Game Mode Base Class。这是所有游戏模式的父类。

修改 GameMode

现在你需要设置你的自定义 GameMode 类和玩家控制器。到世界设置中，设置指定的变量：

指定项目的设置

进入 Edit->Project settings，打开 Maps & Modes。设定默认参数：

总结

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