如何解决将TextBox绑定到从其他Thread更新的值
|| 只要按下按钮,我就尝试增加一个值。增量值通过绑定到TextBox进行连接。更新底层整数时会发生问题。我得到另一个线程拥有它的异常。 <Button Name=\"Up\"
Content=\"Up\"
PreviewMouseLeftButtonDown=\"Up_PreviewMouseLeftButtonDown\"
PreviewMouseLeftButtonUp=\"Up_PreviewMouseLeftButtonUp\">
</Button>
<TextBox Text=\"{Binding NumericField}\">
初始化期间:
Timer = New Timers.Timer
Timer.Interval = 100
AddHandler Timer.Elapsed,AddressOf Timer_Elapsed
后面的代码:
Private _numericField As Integer
Public Property NumericField As Integer
Get
Return _numericField
End Get
Set(ByVal value As Integer)
_numericField = value
RaiseEvent PropertyChanged(Me,New ComponentModel.PropertyChangedEventArgs(\"NumericField\"))
End Set
End Property
Private Sub Timer_Elapsed(ByVal sender As Object,ByVal e As System.Timers.ElapsedEventArgs)
NumericField += 1
End Sub
Private Sub Up_PreviewMouseLeftButtonDown(ByVal sender As System.Object,ByVal e As System.Windows.Input.MouseButtonEventArgs)
Timer.Start()
End Sub
Private Sub Up_PreviewMouseLeftButtonUp(ByVal sender As System.Object,ByVal e As System.Windows.Input.MouseButtonEventArgs)
Timer.Stop()
End Sub
解决方法
这看起来有点太复杂了。您不能使用RepeatButton吗?
简单的解决方案:
<RepeatButton Click=\"RepeatButton_Click\" Content=\"Up\" />
后面的代码:
Private Sub RepeatButton_Click(ByVal sender As System.Object,ByVal e As System.Windows.RoutedEventArgs)
NumericField += 1
End Sub
使用命令
尽量避免在文件后面的代码中使用不必要的代码。这是使用命令的草图
XAML:
<RepeatButton Command=\"{Binding IncrementField}\" Content=\"Up\"></RepeatButton>
帮助类。可重用于项目中的所有命令:
Public Class ActionCommand
Implements ICommand
Private ReadOnly _executeHandler As Action(Of Object)
Private ReadOnly _canExecuteHandler As Func(Of Object,Boolean)
Public Sub New(ByVal execute As Action(Of Object),ByVal canExecute As Func(Of Object,Boolean))
If execute Is Nothing Then
Throw New ArgumentNullException(\"Execute cannot be null\")
End If
_executeHandler = execute
_canExecuteHandler = canExecute
End Sub
Public Custom Event CanExecuteChanged As EventHandler Implements ICommand.CanExecuteChanged
AddHandler(ByVal value As EventHandler)
AddHandler CommandManager.RequerySuggested,value
End AddHandler
RemoveHandler(ByVal value As EventHandler)
RemoveHandler CommandManager.RequerySuggested,value
End RemoveHandler
RaiseEvent(ByVal sender As Object,ByVal e As System.EventArgs)
CommandManager.InvalidateRequerySuggested()
End RaiseEvent
End Event
Public Sub Execute(ByVal parameter As Object) Implements ICommand.Execute
_executeHandler(parameter)
End Sub
Public Function CanExecute(ByVal parameter As Object) As Boolean Implements ICommand.CanExecute
If (_canExecuteHandler Is Nothing) Then
Return True
End If
Return _canExecuteHandler(parameter)
End Function
End Class
在您的模型中:
_incrementField = New ActionCommand(AddressOf IncrementExecuted,AddressOf IncrementCanExecute)
...
Private Function IncrementCanExecute(ByVal parameter As Object) As Boolean
Return True
End Function
Private Sub IncrementExecuted(ByVal parameter As Object)
NumericField += 1
End Sub
Private _incrementField As ActionCommand
Public ReadOnly Property IncrementField As ActionCommand
Get
Return _incrementField
End Get
End Property
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