UFUNCTION()
        void LearnImage();
实现是：
void AWidgetMng::LearnImage()
{
    UImage* MyImage = Cast<UImage>(SlaveWidget->GetWidgetFromName(TEXT("MyImage")));
    if (MyImage)
    {
        UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Learning How 2 Use C++ to Change UI"));
        MyImage->SetColorAndOpacity(FLinearColor(1, 0, 0, 0.5));//【本迷你教程的要点】设置image的ColorandOpacity
/*
笔者也尝试过
MyImage->ColorAndOpacity = FLinearColor(1, 0, 0, 0.5);这种方式没有效果；
*/
    }
}

void ALearnWidgetsCharacter::Action1()
{
    UE_LOG(LogTemp, Warning, TEXT("%s"), *FString("Action1 ing"));
    ALearnWidgetsHUD*  HUD = Cast<ALearnWidgetsHUD>(UGameplayStatics::GetPlayerController(this, 0)->GetHUD());
    if (HUD->WidgetMngs.Num())
    {
        //HUD->WidgetMngs[0]->ChangeImage(HUD->WidgetMngs[0]->T2D);
        HUD->WidgetMngs[0]->LearnImage();
    }
}