PointerWheelChanged事件UWP

Question

我有一個啟用了VerticalScroll的GridView。 在MainPage.xaml.cs中，我攔截了ScrollView的PointerWheelChanged事件。

在此PointerWheelChanged事件中，您可以知道方向盤是向上滾動還是向下滾動？

編碼。

MainPage.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;
    }
}

先感謝您。

Answer 1

檢查PointerRoutedEventArgs的MouseWheelDelta屬性，如下所示：

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

其值（int）指示車輪移動的方向。

從文檔：

正值表示輪子向前旋轉（遠離用戶）或向右傾斜； 負值表示滾輪向后旋轉（朝用戶方向）或向后傾斜