Question

我需要一些帮助为属性网格创建自定义组合框编辑器。如果更改数据库连接，组合框的项目源将动态更改。主要问题是我不知道如何访问所选项目。我尝试使用SelectionChanged事件执行此操作并且它有效。但是在我选择了一个项目之后，如果数据库连接发生了变化，则itemsource不再发生变化。如果有人对我如何做到这一点有另一个想法，我也感谢任何帮助和信息。

编辑器名为SingleSelectEditor，在属性网格中使用如下：

Private _idNameList As ObservableCollection(Of String) = New ObservableCollection(Of String)
    <Category("2. ID Settings"), PropertyOrder(0)>
    <Editor(GetType(SingleSelectEditor), GetType(SingleSelectEditor))>
    Public Property IdNameList As ObservableCollection(Of String)
        Get
            Return _idNameList
        End Get
        Set(value As ObservableCollection(Of String))
            _idNameList = value
        End Set
    End Property

现在用户控件如下所示：

<UserControl x:Class="SingleSelectEditor"
         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"
         d:DesignHeight="26" d:DesignWidth="200">
<Grid >
    <ComboBox Name="SingleSelectComboBox"  SelectedItem="{Binding SelectedString}" >
        <ComboBox.ItemsSource>
            <Binding Path="TestList"  Mode="TwoWay" UpdateSourceTrigger="PropertyChanged"/>
        </ComboBox.ItemsSource>
    </ComboBox>
</Grid>

背后的代码如下所示：

Public Class SingleSelectEditor
    Implements ITypeEditor

    Public Shared ReadOnly ValueProperty As DependencyProperty = _
        DependencyProperty.Register("Value", GetType(ObservableCollection(Of String)), _
        GetType(SingleSelectEditor), New FrameworkPropertyMetadata(Nothing, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault))

    Public Property Value() As ObservableCollection(Of String)
        Get
            Return DirectCast(GetValue(ValueProperty), ObservableCollection(Of String))
        End Get
        Set(value As ObservableCollection(Of String))
            SetValue(ValueProperty, value)
        End Set
    End Property


    Public Function ResolveEditor(ByVal propertyItem As PropertyItem) As FrameworkElement Implements ITypeEditor.ResolveEditor
        Dim binding = New Binding("Value")

        binding.Source = propertyItem
        binding.Mode = If(propertyItem.IsReadOnly, BindingMode.OneWay, BindingMode.TwoWay)

        BindingOperations.SetBinding(Me, ValueProperty, binding)

        Dim sSEVM As SingleSelectViewModel = New SingleSelectViewModel(Value)
        SingleSelectComboBox.DataContext = sSEVM

        Return Me
    End Function
End Class

至少ViewModel看起来像这样：

Public Class SingleSelectViewModel
    Inherits ViewModelBase

    Private _testList As ObservableCollection(Of String) = New ObservableCollection(Of String)

    Public Property TestList As ObservableCollection(Of String)
        Get
            Return _testList
        End Get
        Set(value As ObservableCollection(Of String))
            _testList = value
        End Set
    End Property

    Private _selectedString As String

    Public Property SelectedString As String
        Get
            Return _selectedString
        End Get
        Set(value As String)
            _selectedString = value
        End Set
    End Property

    Public Sub New(ByVal tList As ObservableCollection(Of String))
        TestList = tList
    End Sub
End Class

PropertyGrid的自定义组合框控件

0 个答案: