.net - 我可以在让用户等待之前更新 WPF 状态栏文本吗？

Question

我有一个带有状态栏的 WPF 应用程序。

<StatusBar Grid.Row="1"
           Height="23"
           Name="StatusBar1"
           VerticalAlignment="Bottom">
    <TextBlock Name="TextBlockStatus" />
</StatusBar>

当我做少量工作时，我想在那里显示文本并切换到沙漏等待光标。

此代码将更新光标，但状态栏 文本不更新 ...

Cursor = Cursors.Wait
TextBlockStatus.Text = "Loading..."
System.Threading.Thread.Sleep(New TimeSpan(0, 0, 3))
TextBlockStatus.Text = String.Empty
Cursor = Cursors.Arrow

更新

灵感来自 Alexandra的 answer ...

它有效如果我这样做，但我对这个解决方案一点也不满意。有没有更简单的方法？

Delegate Sub Load1()
Sub Load2()
    System.Threading.Thread.Sleep(New TimeSpan(0, 0, 3))
End Sub
Dim Load3 As Load1 = AddressOf Load2

Sub Load()
    Cursor = Cursors.Wait
    TextBlockStatus.Text = "Loading..."
    Dispatcher.Invoke(DispatcherPriority.Background, Load3)
    TextBlockStatus.Text = String.Empty
    Cursor = Cursors.Arrow
End Sub

我宁愿它看起来像这样......

Sub Load()
    Cursor = Cursors.Wait
    TextBlockStatus.Text = "Loading..."

    'somehow put all the Dispatcher, Invoke, Delegate,
     AddressOf, and method definition stuff here'

    TextBlockStatus.Text = String.Empty
    Cursor = Cursors.Arrow
End Sub

或者甚至更好...

Sub Load()
    Cursor = Cursors.Wait
    ForceStatus("Loading...")
    System.Threading.Thread.Sleep(New TimeSpan(0, 0, 3))
    ForceStatus(String.Empty)
    Cursor = Cursors.Arrow
End Sub

Sub ForceStatus(ByVal Text As String)
    TextBlockStatus.Text = Text
    'perform magic'
End Sub

更新

我还尝试将 TextBlock 绑定(bind)到公共(public)属性并实现 INotifyPropertyChanged作为 IanGilham suggested .这个 不工作 .

XAML:

<TextBlock Text="{Binding Path=StatusText}"/>

视觉基础:

Imports System.ComponentModel
Partial Public Class Window1
    Implements INotifyPropertyChanged

    Private _StatusText As String = String.Empty
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged

    Property StatusText() As String
        Get
            Return _StatusText
        End Get
        Set(ByVal value As String)
            _StatusText = value
            OnPropertyChanged("StatusText")
        End Set
    End Property

    Shadows Sub OnPropertyChanged(ByVal name As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
    End Sub
    ...

    Sub Load()
        ...
        Cursor = Cursors.Wait
        StatusText = "Loading..."
        System.Threading.Thread.Sleep(New TimeSpan(0, 0, 3))
        StatusText = String.Empty
        Cursor = Cursors.Arrow
        ...
    End Sub
...

Answer 1

您应该使用 BackgroundWorker .这项工作将在一个单独的线程中进行，这意味着您的 UI 线程将是免费的，您的应用程序仍将是响应式的。

它不会是一个非常紧凑的代码解决方案，但它对您的用户来说是最强大和最友好的。