c# - PointerWheelChanged 事件 UWP

Question

我有一个启用了 VerticalScroll 的 GridView。在 MainPage.xaml.cs 中，我拦截了 ScrollView 的 PointerWheelChanged 事件。

在这个PointerWheelChanged事件中，你能知道滚轮是向上滚动还是向下滚动吗？

代码。

主页.xaml:

<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    <TextBlock x:Name="txbNumber" HorizontalAlignment="Center" Margin="0,-230,0,0" TextWrapping="Wrap" VerticalAlignment="Center"/>
    <GridView x:Name="TestGrid" HorizontalAlignment="Center" Height="200" Margin="0" VerticalAlignment="Center" Width="200" Background="#FF44AF0D">
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
        <GridViewItem Content="item"/>
    </GridView>
</Grid>

MainPage.xaml.cs:

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();
        TestGrid.AddHandler(UIElement.PointerWheelChangedEvent, new PointerEventHandler(OnPointerWheelChanged), true);
    }
    int number = 0;
    private void OnPointerWheelChanged(object sender, PointerRoutedEventArgs e)
    {
        txbNumber.Text = number.ToString();
        number += 1;
    }
}

提前谢谢你。

Answer 1

检查 MouseWheelDelta PointerRoutedEventArgs 的属性如下:

private void WindowsPage_PointerWheelChanged(object sender, PointerRoutedEventArgs e)
{
  var delta = e.GetCurrentPoint((UIElement)sender).Properties.MouseWheelDelta;
}

它的值(int)表示轮子移动的方向。

来自文档:

A positive value indicates that the wheel was rotated forward (away from the user) or tilted to the right; a negative value indicates that the wheel was rotated backward (toward the user) or tilted to the