Question

请参阅以下示例：

<Window 
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:src="clr-namespace:WpfApplication1"
  SizeToContent="WidthAndHeight">
  <Window.DataContext>
    <src:CodeName/>
  </Window.DataContext>
  <TextBox Text="{Binding Code, UpdateSourceTrigger=PropertyChanged}" />
</Window>

Imports System.ComponentModel
Public Class CodeName
  Implements INotifyPropertyChanged

  Private m_Code As String
  Public Property Code() As String
    Get
      Return m_Code
    End Get
    Set(ByVal value As String)
      If Not String.IsNullOrWhiteSpace(value) Then value = "_" & value
      m_Code = value
      RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("Code"))
    End Set
  End Property

  Public Event PropertyChanged(ByVal sender As Object,
    ByVal e As PropertyChangedEventArgs) _
      Implements INotifyPropertyChanged.PropertyChanged
End Class

正如您所看到的，我正在更改已修改的值，以便当用户在TextBox中输入文字时，会更新_到其开头。

当我输入123456789时，TextBox中的结果是：_________987654321而不是_________123456789正如预期的那样。

什么可以是一个简洁的方法来解决它？我不希望我的整个代码变脏，KeyUp等事件会移动插入符号。
另一方面，我确实希望在实体层面完成此任务。

注意：我的“真实”功能是使用破折号等格式化手机号码。

Answer 1

我会使用文本框的textchanged事件将插入符号移到最后，如下所示：

 <TextBox Name="textBox1" Text="{Binding Code, UpdateSourceTrigger=PropertyChanged}" TextChanged="textChangedEventHandler"/>


Private Sub textChangedEventHandler(ByVal sender As Object, ByVal args As TextChangedEventArgs)
   textBox1.CaretIndex = textBox1.Text.Length
End Sub

Answer 2

Public Class TextBoxBehavor
Public Shared Function GetMoveCaretOnTextChange(ByVal element As TextBox) As Boolean
  If element Is Nothing Then Throw New ArgumentNullException("element")
  Return element.GetValue(MoveCaretOnTextChangeProperty)
End Function
Public Shared Sub SetMoveCaretOnTextChange(ByVal element As TextBox, ByVal value As Boolean)
  If element Is Nothing Then Throw New ArgumentNullException("element")
  element.SetValue(MoveCaretOnTextChangeProperty, value)
End Sub
Public Shared ReadOnly MoveCaretOnTextChangeProperty As DependencyProperty =
  DependencyProperty.RegisterAttached("MoveCaretOnTextChange",
    GetType(Boolean), GetType(TextBoxBehavior),
    New FrameworkPropertyMetadata(
      New PropertyChangedCallback(AddressOf MoveCaretOnTextChange_PropertyChanged)))

Private Shared Sub MoveCaretOnTextChange_PropertyChanged(ByVal sender As Object,
  ByVal e As DependencyPropertyChangedEventArgs)
  Dim tb = DirectCast(sender, TextBox)
  Static tb_TextChanged As TextChangedEventHandler =
    Sub(obj, tcea)
      Dim textBox = DirectCast(obj, TextBox)
      textBox.CaretIndex = textBox.Text.Length
    End Sub

  If CBool(e.NewValue) Then
    AddHandler tb.TextChanged, tb_TextChanged
  Else
    RemoveHandler tb.TextChanged, tb_TextChanged
  End If
End Sub
End Class

用法：

<TextBox src:TextBoxBehavior.MoveCaretOnTextChange="True"
  xmlns:src="clr-namespace:WpfApplication1" />

更改基础属性值时TextBox插入符错误

2 个答案: