向上和向下滑动手势方向在 .NET MAUI 中不起作用

Question

我在 .NET MAUI 中使用滑动手势得到了一个非常奇怪的行为。方向 Up 和 Down 似乎不起作用，而方向 Right 和 Left 工作得很好。有人知道我做错了什么吗？

这里有一个简单的例子：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="SwipeTester.MainPage">

        <VerticalStackLayout Spacing="25" Padding="30,0" VerticalOptions="Center">
            <Label x:Name="SwipedCounter" FontSize="18" HorizontalOptions="Center"
                   BackgroundColor="Yellow" HeightRequest="100" WidthRequest="100"
                   HorizontalTextAlignment="Center" VerticalTextAlignment="Center"/>

            <Label HeightRequest="200"
                   WidthRequest="100"
                   BackgroundColor="Red">
                <Label.GestureRecognizers>
                    <SwipeGestureRecognizer
                        Direction="Down"
                        Swiped="SwipeGestureRecognizer_OnSwiped"
                        Threshold="20"/>
                    <SwipeGestureRecognizer
                        Direction="Up"
                        Swiped="SwipeGestureRecognizer_OnSwiped"
                        Threshold="20"/>
                    <SwipeGestureRecognizer
                        Direction="Left"
                        Swiped="SwipeGestureRecognizer_OnSwiped"
                        Threshold="20"/>
                    <SwipeGestureRecognizer
                        Direction="Right"
                        Swiped="SwipeGestureRecognizer_OnSwiped"
                        Threshold="20"/>
                </Label.GestureRecognizers>
            </Label>
        </VerticalStackLayout>
</ContentPage>

public partial class MainPage : ContentPage
{
    int count = 0;

    public MainPage()
    {
        InitializeComponent();
    }

    private void SwipeGestureRecognizer_OnSwiped(object sender, SwipedEventArgs e)
    {
        count++;

        SwipedCounter.Text = count.ToString();
    }
}

Answer 1

SwipeGestureRecognizer.Direction

属性可以设置为

SwipeDirection

枚举中的单个值，或多个值。

通过将 Direction 属性设置为

Left

和

Right

可以识别发生在水平轴上的滑动。同样，可以通过将 Direction 属性设置为

Up

和

Down

来识别在垂直轴上发生的滑动。

您可以参考下面的示例代码：

<VerticalStackLayout Spacing="25" Padding="30,0" VerticalOptions="Center"> 

    <Label x:Name="SwipedCounter" FontSize="18" HorizontalOptions="Center"
           BackgroundColor="Yellow" HeightRequest="100" WidthRequest="100"
           HorizontalTextAlignment="Center" VerticalTextAlignment="Center"/>

    <Label HeightRequest="200"
           WidthRequest="200"          
           BackgroundColor="Red">

        <Label.GestureRecognizers>

            <SwipeGestureRecognizer
                Direction="Down"
                Swiped="OnSwiped"
                Threshold="50" 
                />

            <SwipeGestureRecognizer
                Direction="Up"
                Swiped="OnSwiped"
                Threshold="50"
                />

            <SwipeGestureRecognizer
                Direction="Left"
                Swiped="OnSwiped"
                Threshold="50"
                />

            <SwipeGestureRecognizer
                Direction="Right"
                Swiped="OnSwiped"
                Threshold="50"
                />

        </Label.GestureRecognizers>

    </Label>

</VerticalStackLayout>

void OnSwiped(object sender, SwipedEventArgs e) 
{
    switch (e.Direction)
    {
        case SwipeDirection.Left:
            SwipedCounter.Text = "left";
            break;

        case SwipeDirection.Right:
            SwipedCounter.Text = "right";
            break;

        case SwipeDirection.Up:
            SwipedCounter.Text = "up";
            break;

        case SwipeDirection.Down:
            SwipedCounter.Text = "down";
            break;
    }
}