katamari.wankuma.com

Public Class UpdateSourceTriggerHelper
    Public Shared ReadOnly UpdateSourceTriggerProperty As DependencyProperty = _
        DependencyProperty.RegisterAttached("UpdateSourceTrigger", GetType(Boolean), GetType(UpdateSourceTriggerHelper), New PropertyMetadata(AddressOf OnUpdateSourceTriggerChanged))

    Public Shared Function GetUpdateSourceTrigger(ByVal d As DependencyObject) As Boolean
        Return CBool(d.GetValue(UpdateSourceTriggerProperty))
    End Function

    Public Shared Sub SetUpdateSourceTrigger(ByVal d As DependencyObject, ByVal value As Boolean)
        d.SetValue(UpdateSourceTriggerProperty, value)
    End Sub

    Private Shared _textBox As TextBox

    Private Shared Sub OnUpdateSourceTriggerChanged(ByVal d As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
        If Not TypeOf d Is TextBox Then
            Exit Sub
        End If
        _textBox = DirectCast(d, TextBox)
        If CBool(e.OldValue) Then
            RemoveHandler _textBox.TextChanged, AddressOf TextBox_TextChanged
        End If
        If CBool(e.NewValue) Then
            AddHandler _textBox.TextChanged, AddressOf TextBox_TextChanged
        End If
    End Sub

    Private Shared Sub TextBox_TextChanged(ByVal sender As Object, ByVal e As EventArgs)
        Dim c = FindFocusableControl(_textBox)
        If c IsNot Nothing Then
            c.Focus()
        End If
        _textBox.Focus()
    End Sub

    Private Shared Function FindFocusableControl(ByVal control As Control) As Control
        Dim ctl = VisualTreeHelper.GetParent(control)
        If TypeOf ctl Is Control Then
            Return DirectCast(ctl, Control)
        Else
            Dim childrenCount = VisualTreeHelper.GetChildrenCount(ctl)
            For i = 0 To childrenCount - 1
                Dim c = TryCast(VisualTreeHelper.GetChild(ctl, i), Control)
                If c IsNot Nothing AndAlso Not c Is control Then
                    Return c
                End If
            Next
        End If
        Return Nothing
    End Function
End Class

<TextBox Text="{Binding Hoge, Mode=TwoWay}" 
	local:UpdateSourceTriggerHelper.UpdateSourceTrigger="True" />