Unreal Engine 4：如何处理触屏事件

忘是亡心i 2022-04-05 05:11 862阅读 0赞

**目录**

一、处理屏幕点击事件

二、处理屏幕双击事件

三、处理屏幕长按事件

四、获取touch在World中的点击位置

--------------------

对于触控屏幕，如何处理触屏事件，下面给出了一些常用的C++实现：

### 一、处理屏幕点击事件 ###

void AModel::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
    {
      Super::SetupPlayerInputComponent(PlayerInputComponent);
    
      PlayerInputComponent->BindTouch(EInputEvent::IE_Pressed, this, &AModel::DoTouchPressed);
      PlayerInputComponent->BindTouch(EInputEvent::IE_Released, this, &AModel::DoTouchReleased);
    };
    void AModel::DoTouchPressed(ETouchIndex::Type type, FVector v)
    {
    };
    void AModel::DoTouchReleased(ETouchIndex::Type type, FVector v)
    {
    };

### 二、处理屏幕双击事件 ###

void AModel::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
    {
      Super::SetupPlayerInputComponent(PlayerInputComponent);
    
      PlayerInputComponent->BindTouch(EInputEvent::IE_DoubleClick, this, &AModel::DoTouchDoubleClick);
    };
    void AModel::DoTouchDoubleClick(ETouchIndex::Type type, FVector v)
    {
    };

### 三、处理屏幕长按事件 ###

// 需要长按多长时间。单位（毫秒）
    int32 AModel::pressTimeSpan = 400;
    int64 AModel::TouchPressedTime = 0;
    
    void AModel::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
    {
      Super::SetupPlayerInputComponent(PlayerInputComponent);
    
      PlayerInputComponent->BindTouch(EInputEvent::IE_Pressed, this, &AModel::DoTouchPressed);
      PlayerInputComponent->BindTouch(EInputEvent::IE_Released, this, &AModel::DoTouchReleased);
      PlayerInputComponent->BindTouch(EInputEvent::IE_Repeat, this, &AModel::DoTouchRepeat);
    };
    void AModel::DoTouchPressed(ETouchIndex::Type type, FVector v)
    {
      TouchPressedTime = FDateTime::Now().GetTicks();
    };
    void AModel::DoTouchReleased(ETouchIndex::Type type, FVector v)
    {
      TouchPressedTime = 0;
    };
    void AModel::DoTouchRepeat(ETouchIndex::Type type, FVector v)
    {
      if (TouchPressedTime == 0) {
        return;
      }
      int64 TouchReleasedTime = FDateTime::Now().GetTicks();
    
      int64 timeUsed = (TouchReleasedTime - TouchPressedTime) / 10000;
      if (timeUsed >= pressTimeSpan) {
        // do something you like
      }
      TouchPressedTime = 0;
    };

### 四、获取touch在World中的点击位置 ###

void AAndroidProjectCharacter::SetupPlayerInputComponent(class UInputComponent* PlayerInputComponent)
    {
    	// handle touch devices
    	PlayerInputComponent->BindTouch(IE_Pressed, this, &AAndroidProjectCharacter::TouchStarted);
    	PlayerInputComponent->BindTouch(IE_Released, this, &AAndroidProjectCharacter::TouchStopped);
    };
    
    
    void AAndroidProjectCharacter::TouchStarted(ETouchIndex::Type FingerIndex, FVector Location)
    {
    	APlayerController* PlayerController = Cast<APlayerController>(GetController());
    
    	FHitResult HitResult;
    	PlayerController->GetHitResultUnderCursorByChannel(ETraceTypeQuery::TraceTypeQuery1, true, HitResult);
    
    	// 在Windows和Android下都可取到正常的PositionLocation
    	FVector PositionLocation = HitResult.Location;
    	GEngine->AddOnScreenDebugMessage(-1, 60.f, FColor::Green, FString::Printf(TEXT("TouchStarted: PositionLocation=%s"), *PositionLocation.ToString()));
    };
    
    void AAndroidProjectCharacter::TouchStopped(ETouchIndex::Type FingerIndex, FVector Location)
    {
    	APlayerController* PlayerController = Cast<APlayerController>(GetController());
    
    	FHitResult HitResult;
    	PlayerController->GetHitResultUnderCursorByChannel(ETraceTypeQuery::TraceTypeQuery1, true, HitResult);
    
    	// 在Windows下都可取到正常的PositionLocation，但在Android下取不到正常的PositionLocation
    	FVector PositionLocation = HitResult.Location;
    	GEngine->AddOnScreenDebugMessage(-1, 60.f, FColor::Green, FString::Printf(TEXT("TouchStopped: PositionLocation=%s"), *PositionLocation.ToString()));
    };

需要注意IE\_Released时，在Windows可以正常取到touch在World中的点击位置，而在Android上却不行。