在父控件中处理PreviewMouseDown-Event后，WPF切换按钮不切换

本文关键字：WPF 按钮 控件 处理 PreviewMouseDown-Event | 更新日期: 2023-09-27 18:17:57

如果您处理UserControl的PreviewMouseDown事件，并且UserControl内部是ToggleButton，则它不会触发内置的本机检查事件，也不会触发单击事件(蓝色突出显示)。如果你不处理预览事件，它可以正常工作。

我认为预览事件不会将事件标记为已处理，但即使使用

e.handled = false;

之后将没有click或checked事件。

如何启用切换按钮的点击和检查事件?

理解问题的代码:

WpfApplication1.cs 

namespace WpfApplication1
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        private void UserControl1_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            //working
            MessageBox.Show("Preview down");
            e.Handled = false; //this is what I tried
        }
        private void UserControl1_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            //working
            MessageBox.Show("preview up");
        }
    }
}

WpfApplication。Xaml 

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApplication1"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <local:UserControl1 PreviewMouseLeftButtonDown="UserControl1_PreviewMouseLeftButtonDown" PreviewMouseLeftButtonUp="UserControl1_PreviewMouseLeftButtonUp" ></local:UserControl1>
    </Grid>
</Window>

UserControl1.cs: 

namespace WpfApplication1
{
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
        }
        private void ToggleButton_Checked(object sender, RoutedEventArgs e)
        {
            //Not called
            MessageBox.Show("test");
        }
        private void ToggleButton_Click(object sender, RoutedEventArgs e)
        {
            //not called
            MessageBox.Show("test");
        }
    }
}

UserControl1.xaml 

<UserControl x:Class="WpfApplication1.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApplication1"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <ToggleButton Checked="ToggleButton_Checked" Click="ToggleButton_Click"></ToggleButton>  
    </Grid>
</UserControl>

在父控件中处理PreviewMouseDown-Event后，WPF切换按钮不切换

当用户控件中的事件被触发时，需要为用户控件引发事件处理程序。这将向上传递，并处理来自两者的偶数。

点击ToggleButton，触发ToggleButton_Click，触发UserControl1_PreviousMouseLeftButtonDown事件。

WpfApplication1 

UserControl1.ToggleButtonClick += new EventHandler(UserControl1_PreviewMouseLeftButtonDown);
private void UserControl1_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    MessageBox.Show("Preview down");
    // Handle the event
}

UserControl1 

public event EventHandler ToggleButtonClick;
private void ToggleButton_Click(object sender, RoutedEventArgs e)
{
    MessageBox.Show("test");
    // Handle the event
}
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