如何在WPF窗口中触发Usercontrol的Unload事件

Question

我在WPF中有一个UserControl:

<UserControl x:Class="XLogin.DBLogin"
             x:Name="DBLoginUserFrame"
             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"
             mc:Ignorable="d"
             Height="263"
             Width="353"
             Loaded="DBLoginUserFrame_Loaded"
             Unloaded="DBLoginUserFrame_Unloaded">
  <Grid>
    <GroupBox Header="Database Connection"
              HorizontalAlignment="Left"
              Height="243"
              Margin="10,10,0,0"
              VerticalAlignment="Top"
              Width="333">
      <Grid>
        <TextBox x:Name="TextUserDB"
                 HorizontalAlignment="Left"
                 Height="20"
                 Margin="101,60,0,0"
                 TextWrapping="Wrap"
                 VerticalAlignment="Top"
                 Width="173" />
        <Label Content="Password:"
               HorizontalAlignment="Left"
               Height="24"
               VerticalAlignment="Top"
               Width="70"
               HorizontalContentAlignment="Right"
               Margin="10,85,0,0" />
        <PasswordBox x:Name="TextPasswordDB"
                     HorizontalAlignment="Left"
                     Height="20"
                     Margin="101,89,0,0"
                     VerticalAlignment="Top"
                     Width="173" />
        <Button x:Name="BtnConnect"
                Content="Connetti"
                Height="29"
                Width="123"
                Margin="101,152,97,24"
                Click="BtnConnect_Click" />
      </Grid>
    </GroupBox>

  </Grid>
</UserControl>

当我卸载此控件时,WPF引发事件DBLoginUserFrame_Unloaded,保存我的设置,它完成一项工作.

我在WPF中的MainWindow加载了这个用户控件但是当窗口关闭时,我的usercontrol UNLOAD不会触发:

<Window x:Class="XLogin.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525"
    xmlns:local="clr-namespace:XLogin" Unloaded="Window_Unloaded_1">
<Grid>
    <local:DBLogin/>
</Grid></Window>

如何将UserControl Unload事件添加到MainWindow事件处理程序？

Answer 1

从文档:

"请注意,应用程序开始关闭后不会引发Unloaded事件.当ShutdownMode属性定义的条件发生时,将发生应用程序关闭.如果将清理代码放在Unloaded事件的处理程序中,例如Window或UserControl ,它可能没有按预期调用."

如果关闭Window会触发应用程序的关闭,那可能就是原因.在这种情况下,甚至可能也不会调用Window的Unload事件,所以我认为最好依赖Window.Closing事件.

处理卸载时UserControl执行的任务的一种方法是公开控件的卸载处理程序方法("DBLoginUserFrame_Unloaded"),在MainWindow中命名UserControl实例并从Window.Closing事件中调用它.

public MainWindow()
{
    // Add this
    this.Closing += MainWindow_Closing;
}

void MainWindow_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
    this.MyUserControl.MethodToBeCalledWhenUnloaded().
}

另一种选择是让你实现到目前为止也可加在你的用户控件的Dispatcher.ShutdownStarted事件的处理程序,如所描述这里.

public MyUserControl()
{
    this.Dispatcher.ShutdownStarted += Dispatcher_ShutdownStarted;
}

Answer 2

您还可以将逻辑放入用户控件本身以使其更加独立。

public UserControl1()
{
  InitializeComponent();
  this.Loaded += UserControl1_Loaded;
}

void UserControl1_Loaded(object sender, RoutedEventArgs e)
{
  Window window = Window.GetWindow(this);
  window.Closing += window_Closing;
}

void window_Closing(object sender, global::System.ComponentModel.CancelEventArgs e)
{
 //Save your settings here
}

在这里看到：https : //social.msdn.microsoft.com/Forums/vstudio/en-US/477e7e74-ccbf-4498-8ab9-ca2f3b836597/how-to-know-when-a-wpf-usercontrol-is-关闭？论坛=wpf