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,你能知道轮子是向上还是向下滚动？

代码.

MainPage.xaml中:

<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中:

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;
    }
}

先感谢您.

Answer 1

检查如下MouseWheelDelta属性PointerRoutedEventArgs:

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

其值(int)表示车轮移动的方向.

来自文档:

正值表示车轮向前旋转(远离用户)或向右倾斜; 负值表示车轮向后旋转(朝向用户)或倾斜到