Windows.UI.Xaml.Controls.TextBlock.DoubleTapped 事件未触发

Question

在适用于 Android 和 UWP 的 Xamarin.Forms 项目中，我想定义长按 (Android) 和双击（在 UWP 上）的效果。为此，我做了所有我能找到的事情，在 Android 和 UWP 通用代码中定义了一个适当的

RoutingEffect

类：

/// <summary>
/// Long press on a Control - Double Click in UWP
/// </summary>
public class LongPressedDblClickEffect : RoutingEffect
{
    public LongPressedDblClickEffect() : base("MyApp.LongPressedDblClickEffect")
    {
    }

    #region LongPressed

    public static readonly BindableProperty LongPressedCommandProperty = BindableProperty.CreateAttached("LongPressedCommand", typeof(ICommand),
        typeof(LongPressedEffect), null);

    public static ICommand GetLongPressedCommand(BindableObject view)
    {
        return (ICommand)view.GetValue(LongPressedCommandProperty);
    }

    public static void SetLongPressedCommand(BindableObject view, ICommand value, object parameter)
    {
        view.SetValue(LongPressedCommandProperty, value);
        SetLongPressedCommandParameter(view, parameter);
    }

    public static void SetLongPressedCommand(BindableObject view, ICommand value)
    {
        view.SetValue(LongPressedCommandProperty, value);
    }

    public static readonly BindableProperty LongPressedCommandParameterProperty =
        BindableProperty.CreateAttached("LongPressedCommandParameter", typeof(object), typeof(LongPressedEffect), null);

    public static object GetLongPressedCommandParameter(BindableObject view)
    {
        return view.GetValue(LongPressedCommandParameterProperty);
    }

    public static void SetLongPressedCommandParameter(BindableObject view, object value)
    {
        view.SetValue(LongPressedCommandParameterProperty, value);
    }

    #endregion

    #region Clicked

    public static readonly BindableProperty ClickCommandProperty = BindableProperty.CreateAttached("ClickCommand", typeof(ICommand),
        typeof(LongPressedEffect), null);


    public static ICommand GetClickCommand(BindableObject view)
    {
        return (ICommand)view.GetValue(ClickCommandProperty);
    }

    public static void SetClickCommand(BindableObject view, ICommand value, object parameter)
    {
        view.SetValue(ClickCommandProperty, value);
        SetClickCommandParameter(view, parameter);
    }

    public static void SetClickCommand(BindableObject view, ICommand value)
    {
        view.SetValue(ClickCommandProperty, value);
    }

    public static readonly BindableProperty ClickCommandParameterProperty =
        BindableProperty.CreateAttached("ClickCommandParameter", typeof(object), typeof(LongPressedEffect), null);

    public static object GetClickCommandParameter(BindableObject view)
    {
        return view.GetValue(ClickCommandParameterProperty);
    }

    public static void SetClickCommandParameter(BindableObject view, object value)
    {
        view.SetValue(ClickCommandParameterProperty, value);
    }

    #endregion
}

对于 UWP，我定义了以下类：

[assembly: ResolutionGroupName("MyApp")]
[assembly: ExportEffect(typeof(MyNamespace.UWP.DoubleClickEffect), "LongPressedDblClickEffect")]
namespace MyNamespace.UWP
{
    public class DoubleClickEffect : PlatformEffect
    {
        private bool _attached;
        public bool IsSingleTap { get; set; }

        public DoubleClickEffect()
        {

        }

        /// <summary>
        /// Attach handlers needed for this event
        /// </summary>
        protected override void OnAttached()
        {
            if (!_attached)
            {
                if (Control != null)
                {
                    Control.IsTapEnabled = true;
                    Control.IsDoubleTapEnabled = true;
                    Control.Tapped += Tapped;
                    Control.DoubleTapped += DoubleTapped;
                }
                else
                {
                    Container.IsTapEnabled = true;
                    Container.IsDoubleTapEnabled = true;
                    Container.Tapped += Tapped;
                    Container.DoubleTapped += DoubleTapped;
                }
                _attached = true;
            }
        }

        /// <summary>
        /// Remove handlers on detach
        /// </summary>
        protected override void OnDetached()
        {
            if (_attached)
            {
                if (Control != null)
                {
                    Control.Tapped -= Tapped;
                    Control.DoubleTapped -= DoubleTapped;
                }
                else
                {
                    Container.Tapped -= Tapped;
                    Container.DoubleTapped -= DoubleTapped;
                }
                _attached = false;
            }
        }

        private void DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
        {
            IsSingleTap = false;

            var command = LongPressedDblClickEffect.GetLongPressedCommand(Element);
            command?.Execute(LongPressedDblClickEffect.GetLongPressedCommandParameter(Element));
        }

        private async void Tapped(object sender, TappedRoutedEventArgs e)
        {
            IsSingleTap = true;
            await Task.Delay(200);
            if (IsSingleTap)
            {
                var command = LongPressedDblClickEffect.GetClickCommand(Element);
                command?.Execute(LongPressedDblClickEffect.GetClickCommandParameter(Element));
            }
        }
    }
}

在 XAML 中：

<Label Text="{Binding Name}" 
    ...
    mycode:LongPressedDblClickEffect.LongPressedCommand="{Binding LongPressCommand}"
    FontSize="16" >
<Label.GestureRecognizers>
    <TapGestureRecognizer Command="{Binding ShortPressCommand}" />
</Label.GestureRecognizers>
<Label.Effects>
    <code:LongPressedDblClickEffect />
</Label.Effects></Label>

正确调用UWP代码并注册事件。但是，

Tapped

事件仅在双击时触发一次，并且

DoubleTapped

永远不会被调用。我在网络上没有找到任何有关此问题的信息。所以我不认为这是一个错误，而是我这边的一个错误。

谁可以帮忙？

Answer 1

这个问题的原因是

TapGestureRecognizer

和我的

LongPressedDblClickEffect

的混合。

将 XAML 更改为

后

<Label Text="{Binding Name}" ...
    Style="{DynamicResource ListItemTextStyle}" 
    code:LongPressedDblClickEffect.LongPressedCommand="{Binding LongPressCommand}"
    code:LongPressedDblClickEffect.ClickCommand="{Binding ShortPressCommand}"
    FontSize="16" >
<Label.Effects>
    <code:LongPressedDblClickEffect />
</Label.Effects>

双击事件被正确触发。