WPF区分编码-SelectionChanged和鼠标-SelectionChanged

Question

我有一个马基雅维利式的问题(对我来说)。在我的WPF应用程序中，我有一个在ItemTemplate中有一个组合框的ListBox。当用户选择一个ComboBoxItem时，我必须在作为ItemsSource的ListBox的ObservableCollection上执行一些复杂的操作，然后我必须使用更改后的数据显示ListBox。问题是，如果我处理ComboBox控件的事件"SelectionChanged“，每次修改我在处理该事件的方法中输入的comboboxItems的源类时，都会生成错误的结果。简而言之，我必须在某种程度上区分代码生成的SelectionChanged和用户使用鼠标手动生成的SelectionChanged。我试过很多方法，但都不管用：

我认为最好的方法是处理Combo的ItemContainerStyle的ContentPresenter的"GotFocus“或"MouseUp”事件，或者处理Combo的ItemsPanel的相同事件("GotFocus“和"MouseUp")，但我处理的方法没有捕获事件(在debug中，光标根本不会进入该方法)。

在“第一轮”完成之前，我不能使用布尔值来停止方法"SelectionChanged“，因为ComboBoxItems的源类的更改是在该方法全部执行之后发生的。

Combos的默认值并不总是第一个(这太容易了：-)，并且不总是相同的。每次用户选择其中一个组合的项目时，其他组合的默认值都必须更改。

你能帮帮我吗?皮莱基

' XAML
<Style x:Key="modComboCriteriEventParts" TargetType="{x:Type ComboBox}">
    <EventSetter Event="Selector.SelectionChanged" Handler="cb_SelectionChanged"/>
</Style>

<DataTemplate x:Key="modLBoxCriteriParts">
    <ComboBox Style = "{StaticResource modComboCriteriEventParts}"
        ItemsSource = "{Binding CriteriItemList}"
        ItemContainerStyle = "{DynamicResource modComboContainerParts}"
        SelectedIndex = "{Binding valueSelected}" ... />
</DataTemplate>

<ListBox x:Name="lbCriteri" IsSynchronizedWithCurrentItem="True"
    ItemsSource = "{Binding CriteriList, Source={StaticResource P_CriteriDataSource}}"
    ItemTemplate = "{DynamicResource modLBoxCriteriParts}"
    ... />


' Code Behind
Private Sub cb_SelectionChanged(ByVal sender As System.Object, ByVal e As SelectionChangedEventArgs)
    Dim ri as New RicambiCriteriList() As ObservableCollection(Of P_CriteriItem)

    ' some complex operations with ri ...

    be = BindingOperations.GetBindingExpression(Me.lbCriteri, ListBox.ItemsSourceProperty)
    Dim allCriteri As P_Criteri = DirectCast(be.DataItem, P_Criteri)
    allCriteri.AddData (ri)

    e.Handled = True
End Sub


' Source-Class
Public Class P_Criteri

    Private _CriteriList As New ObservableCollection(Of P_CriteriItem)

    Public ReadOnly Property CriteriList() As ObservableCollection(Of P_CriteriItem)
        Get
            CriteriList = _CriteriList
        End Get
    End Property

    Public Sub AddData(ByVal CriteriListPass As ObservableCollection(Of P_CriteriItem))
        _CriteriList.Clear()
        For Each a As P_CriteriItem In CriteriListPass
            _CriteriList.Add(a)
        Next
    End Sub
End Class

Public Class P_CriteriItem
    Implements INotifyPropertyChanged

    Public Sub New(ByVal criterioPass As String, ByVal CriteriItemListPass As ObservableCollection(Of P_CriteriItemValore), _
        ByVal widthCriteriValuesPass As Double)

        Me._criterio = criterioPass
        Me._CriteriItemList = CriteriItemListPass
        Me._widthCriteriValues = widthCriteriValuesPass
    End Sub

    Private _criterio As String = ""
    Private _CriteriItemList As New ObservableCollection(Of P_CriteriItemValore)

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Public Property criterio() As String
        Get
            Return Me._criterio
        End Get
        Set(ByVal value As String)
            If Not Object.Equals(Me._criterio, value) Then
                Me._criterio = value
                Me.OnPropertyChanged ("criterio")
            End If
        End Set
    End Property

    Public Property CriteriItemList() As ObservableCollection(Of P_CriteriItemValore)
        Get
            Return Me._CriteriItemList
        End Get
        Set(ByVal value As ObservableCollection(Of P_CriteriItemValore))
            If Not Object.Equals(Me._CriteriItemList, value) Then
                Me._CriteriItemList = value
                Me.OnPropertyChanged ("CriteriItemList")
            End If
        End Set
    End Property

    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        Dim handler As PropertyChangedEventHandler = Me.PropertyChangedEvent
        If handler IsNot Nothing Then
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
        End If
    End Sub
End Class

Public Class P_CriteriItemValore
    Implements INotifyPropertyChanged

    Public Sub New(ByVal criterioValorePass As String)
        Me._criterioValore = criterioValorePass
    End Sub

    Private _criterioValore As String = Nothing

    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Public Property criterioValore() As String
        Get
            Return Me._criterioValore
        End Get
        Set(ByVal value As String)
            If Not Object.Equals(Me._criterioValore, value) Then
                Me._criterioValore = value
                Me.OnPropertyChanged ("criterioValore")
            End If
        End Set
    End Property

    Protected Overridable Sub OnPropertyChanged(ByVal propertyName As String)
        Dim handler As PropertyChangedEventHandler = Me.PropertyChangedEvent
        If handler IsNot Nothing Then
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
        End If
    End Sub
End Class

Answer 1

首先，我认为最好是在项目容器本身上处理事件，而不是在项目内的内容呈现器上。现在我想到了这一点，这可能就是为什么你看不到事件的原因。容器可能正在吞食事件以供选择。

但是无论哪种方式，如果你不能捕捉MouseDown/GotFocus事件，你可以使用PreviewMouseDown/PreviewGotFocus事件。如果您不确定这些意味着什么，您应该阅读有关wpf事件路由体系结构以及冒泡和隧道事件的信息。