我有一个包含菜单项的ListBox。
<ListBox x:Name="ListBoxMenu" SelectionChanged="ListBoxMenu_SelectionChanged"
Grid.Column="0" Margin="0" Padding="0" Grid.Row="1" Width="{StaticResource LeftMenuWidth}"
ItemsSource="{Binding MenuItems}"
Background="{StaticResource ListBoxColor}"
BorderThickness="0"
SelectedIndex="0" VerticalAlignment="Stretch" >
<ListBox.ItemTemplate>
<DataTemplate>
<DockPanel>
<Image Source="{Binding MenuImage}" Height="20" Width="20" DockPanel.Dock="Left" Margin="5" />
<TextBlock Text="{Binding MenuName}" FontSize="{StaticResource MenuFontSize}" FontWeight="Bold" DockPanel.Dock="Left" Width="Auto" VerticalAlignment="Center" HorizontalAlignment="Left"/>
</DockPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
我切断了代码，希望它仍然可以制作。
然后我有一个加载每个用户控件的控件模板。
<ContentControl Content="{Binding ElementName=ListBoxMenu, Path=SelectedItem}" Grid.Column="1" Grid.Row="1"/>
问题：
我的问题是，我想测试用户何时离开用户控件，如果他们进行了任何更改以要求他们保存更改。我已经有NotifyPropertyChange工作，所以这不是问题所在。我需要弄清楚如何查看用户何时离开控件/页面。
我尝试了什么
正如您所看到的，我已将selectionchanged添加到列表框中，但在技术上确实有效，但由于用户控件在视觉上发生了变化，因此提示用户保存所有更改。我想在他们离开用户控件之前提示他们。
SelectionChanged="ListBoxMenu_SelectionChanged"
答案 0 :(得分：0)
更新＃1
有一个以上可能有用的建议来处理＆＃34;从视图导航＆＃34;，这里有几个简单的例子：
以下是IsHitTest visibilty（from this link）
的示例 /// <summary>
/// helps to indicate the partial IsVisible state
/// </summary>
/// <param name="element">elemnt under the test</param>
/// <param name="container">parent window or control</param>
/// <returns></returns>
private bool IsUserVisible(FrameworkElement element, FrameworkElement container)
{
if (!element.IsVisible)
return false;
Rect bounds = element.TransformToAncestor(container).TransformBounds(new Rect(0.0, 0.0, element.ActualWidth, element.ActualHeight));
Rect rect = new Rect(0.0, 0.0, container.ActualWidth, container.ActualHeight);
return rect.Contains(bounds.TopLeft) || rect.Contains(bounds.BottomRight);
}
此外，您应该在ViewModel上实现IsDirty。以下是如何执行此操作的几个示例：
以下是IsDirty实施的一些代码示例（Almost-automatic INotifyPropertyChanged, automatic IsDirty, and automatic ChangeTracking）
/// <summary>
/// Provides a base class for objects that support property change notification
/// and querying for changes and resetting of the changed status.
/// </summary>
public abstract class ViewModelBase : IChangeTracking, INotifyPropertyChanged
{
//========================================================
// Constructors
//========================================================
#region ViewModelBase()
/// <summary>
/// Initializes a new instance of the <see cref="ViewModelBase"/> class.
/// </summary>
protected ViewModelBase()
{
this.PropertyChanged += new PropertyChangedEventHandler(OnNotifiedOfPropertyChanged);
}
#endregion
//========================================================
// Private Methods
//========================================================
#region OnNotifiedOfPropertyChanged(object sender, PropertyChangedEventArgs e)
/// <summary>
/// Handles the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for this object.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">A <see cref="PropertyChangedEventArgs"/> that contains the event data.</param>
private void OnNotifiedOfPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e != null && !String.Equals(e.PropertyName, "IsChanged", StringComparison.Ordinal))
{
this.IsChanged = true;
}
}
#endregion
//========================================================
// IChangeTracking Implementation
//========================================================
#region IsChanged
/// <summary>
/// Gets the object's changed status.
/// </summary>
/// <value>
/// <see langword="true"/> if the object’s content has changed since the last call to <see cref="AcceptChanges()"/>; otherwise, <see langword="false"/>.
/// The initial value is <see langword="false"/>.
/// </value>
public bool IsChanged
{
get
{
lock (_notifyingObjectIsChangedSyncRoot)
{
return _notifyingObjectIsChanged;
}
}
protected set
{
lock (_notifyingObjectIsChangedSyncRoot)
{
if (!Boolean.Equals(_notifyingObjectIsChanged, value))
{
_notifyingObjectIsChanged = value;
this.OnPropertyChanged("IsChanged");
}
}
}
}
private bool _notifyingObjectIsChanged;
private readonly object _notifyingObjectIsChangedSyncRoot = new Object();
#endregion
#region AcceptChanges()
/// <summary>
/// Resets the object’s state to unchanged by accepting the modifications.
/// </summary>
public void AcceptChanges()
{
this.IsChanged = false;
}
#endregion
//========================================================
// INotifyPropertyChanged Implementation
//========================================================
#region PropertyChanged
/// <summary>
/// Occurs when a property value changes.
/// </summary>
public event PropertyChangedEventHandler PropertyChanged;
#endregion
#region OnPropertyChanged(PropertyChangedEventArgs e)
/// <summary>
/// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event.
/// </summary>
/// <param name="e">A <see cref="PropertyChangedEventArgs"/> that provides data for the event.</param>
protected void OnPropertyChanged(PropertyChangedEventArgs e)
{
var handler = this.PropertyChanged;
if (handler != null)
{
handler(this, e);
}
}
#endregion
#region OnPropertyChanged(string propertyName)
/// <summary>
/// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for the specified <paramref name="propertyName"/>.
/// </summary>
/// <param name="propertyName">The <see cref="MemberInfo.Name"/> of the property whose value has changed.</param>
protected void OnPropertyChanged(string propertyName)
{
this.OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
}
#endregion
#region OnPropertyChanged(params string[] propertyNames)
/// <summary>
/// Raises the <see cref="INotifyPropertyChanged.PropertyChanged"/> event for the specified <paramref name="propertyNames"/>.
/// </summary>
/// <param name="propertyNames">An <see cref="Array"/> of <see cref="String"/> objects that contains the names of the properties whose values have changed.</param>
/// <exception cref="ArgumentNullException">The <paramref name="propertyNames"/> is a <see langword="null"/> reference (Nothing in Visual Basic).</exception>
protected void OnPropertyChanged(params string[] propertyNames)
{
if (propertyNames == null)
{
throw new ArgumentNullException("propertyNames");
}
foreach (var propertyName in propertyNames)
{
this.OnPropertyChanged(propertyName);
}
}
#endregion
}
如果您想要更多示例或代码，请与我们联系。