UE4如何调用打开系统消息对话窗口

游戏开发过程中，有时需要明显的提示游戏运行时出现的问题，比如配置错误等信息，不仅需要输出错误到日记文件，还需要明显的显示错误信息给到非程序人员看到。那么打开系统窗口提示就是一个非常好的选择。

案例1：

在UE4中，你可以使用 FMessageDialog::Open 函数来打开一个自定义的消息对话框。以下是一个简单的示例：

#include "Runtime/Engine/Public/Slate/Dialogs/MessageDialog.h"

void AMyTestActor::TestFMessageDialog()
{
	FText Title = FText::FromString("My Dialog");
	FText Message = FText::FromString("This is a message.The UE invokes the interface and displays the Windows window.Display this information.");
	EAppMsgType::Type Type = EAppMsgType::OkCancel;

	const EAppReturnType::Type Response = FMessageDialog::Open(Type, Message, &Title);

	if (Response == EAppReturnType::Ok)
	{
		UE_LOG(LogTemp, Log, TEXT("User clicked OK."));
		// 处理用户确认...
	}
	else if (Response == EAppReturnType::Cancel)
	{
		UE_LOG(LogTemp, Log, TEXT("User clicked Cancel."));
		// 处理用户取消...
	}
}

在这个示例中，我们使用了 FMessageDialog::Open 函数来打开一个自定义的消息对话框。Title 参数指定了对话框显示的标题文本，Message 参数指定了对话框显示的消息文本。Type 参数指定了对话框按钮类型。

如果用户单击了对话框上的“确定”按钮，则 FMessageDialog::Open 函数返回 EAppReturnType::Ok。否则，如果用户单击了“取消”按钮，则函数返回 EAppReturnType::Cancel。你可以使用这个返回值来处理用户的选择。

效果：

 

案例2：

在UE4中，你可以使用 FPlatformMisc::MessageBoxExt 函数来打开系统消息对话框。以下是一个简单的示例：

#include "Runtime/Core/Public/GenericPlatform/GenericPlatformMisc.h"

void AMyTestActor::TestMessageBoxExt()
{
	FText Message = FText::FromString("This is a message.");
	FText Title = FText::FromString("Message Box");
	EAppMsgType::Type Type = EAppMsgType::Ok;

	EAppReturnType::Type ret = FPlatformMisc::MessageBoxExt(Type, *Message.ToString(), *Title.ToString());

	switch (ret)
	{
	case EAppReturnType::Ok:
		UE_LOG(LogTemp, Log, TEXT("User clicked OK."));
		// 处理用户确认...
		break;
	case EAppReturnType::Cancel:
		UE_LOG(LogTemp, Log, TEXT("User clicked Cancel."));
		// 处理用户取消...
		break;
	}
}

在这个示例中，我们使用了 FPlatformMisc::MessageBoxExt 函数来打开一个简单的消息对话框。Message 参数指定了对话框显示的消息文本，Title 参数指定了对话框的标题。Type 参数指定了对话框按钮类型。

如果用户单击了对话框上的“确定”按钮，则 FPlatformMisc::MessageBoxExt 函数返回 true。否则，它将返回 false。你可以使用这个返回值来处理用户的选择。

效果：

 

参考：

UE引擎代码：ProjectManager.cpp

bool FProjectManager::LoadModulesForProject( const ELoadingPhase::Type LoadingPhase )
{
	DECLARE_SCOPE_CYCLE_COUNTER(TEXT("Loading Game Modules"), STAT_GameModule, STATGROUP_LoadTime);

	bool bSuccess = true;

	if ( CurrentProject.IsValid() )
	{
		TMap ModuleLoadFailures;
		FModuleDescriptor::LoadModulesForPhase(LoadingPhase, CurrentProject->Modules, ModuleLoadFailures);

		if ( ModuleLoadFailures.Num() > 0 )
		{
			FText FailureMessage;
			for ( auto FailureIt = ModuleLoadFailures.CreateConstIterator(); FailureIt; ++FailureIt )
			{
				const EModuleLoadResult FailureReason = FailureIt.Value();

				if( FailureReason != EModuleLoadResult::Success )
				{
					const FText TextModuleName = FText::FromName(FailureIt.Key());

					if ( FailureReason == EModuleLoadResult::FileNotFound )
					{
						FailureMessage = FText::Format( LOCTEXT("PrimaryGameModuleNotFound", "The game module '{0}' could not be found. Please ensure that this module exists and that it is compiled."), TextModuleName );
					}
					else if ( FailureReason == EModuleLoadResult::FileIncompatible )
					{
						FailureMessage = FText::Format( LOCTEXT("PrimaryGameModuleIncompatible", "The game module '{0}' does not appear to be up to date. This may happen after updating the engine. Please recompile this module and try again."), TextModuleName );
					}
					else if ( FailureReason == EModuleLoadResult::FailedToInitialize )
					{
						FailureMessage = FText::Format( LOCTEXT("PrimaryGameModuleFailedToInitialize", "The game module '{0}' could not be successfully initialized after it was loaded."), TextModuleName );
					}
					else if ( FailureReason == EModuleLoadResult::CouldNotBeLoadedByOS )
					{
						FailureMessage = FText::Format( LOCTEXT("PrimaryGameModuleCouldntBeLoaded", "The game module '{0}' could not be loaded. There may be an operating system error, the module may not be properly set up, or a plugin which has been included into the build has not been turned on."), TextModuleName );
					}
					else
					{
						ensure(0);	// If this goes off, the error handling code should be updated for the new enum values!
						FailureMessage = FText::Format( LOCTEXT("PrimaryGameModuleGenericLoadFailure", "The game module '{0}' failed to load for an unspecified reason.  Please report this error."), TextModuleName );
					}

					// Just report the first error
					break;
				}
			}

			FMessageDialog::Open(EAppMsgType::Ok, FailureMessage);
			bSuccess = false;
		}
	}

	OnLoadingPhaseCompleteEvent.Broadcast(LoadingPhase, bSuccess);
	return bSuccess;
} 

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