自动更新 UI WPF 窗体中的值

Question

>我有一个类如下：

Public Class BillAmounts
    Implements INotifyPropertyChanged
    Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
    Private Sub NotifyPropertyChange(ByVal info As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
    End Sub
    Private _LabourCostValue As Double
    Private _TransportPriceValue As Double
    Private _ItemsTotalCost_ As Double
    Private _FinalPriceValue As Double
    Property TransportPrice As Double
        Get
            Return _TransportPriceValue
        End Get
        Set(ByVal value As Double)
            If Not _TransportPriceValue = value Then
                _TransportPriceValue = value
                _FinalPriceValue = TransportPrice + LabourCost + ItemsTotalCost_
                PriceCalculationNotification()
            End If
        End Set
    End Property
    Property LabourCost As Double
        Get
            Return _LabourCostValue
        End Get
        Set(ByVal Value As Double)
            If Not _LabourCostValue = Value Then
                _LabourCostValue = Value
                _FinalPriceValue = TransportPrice + LabourCost + ItemsTotalCost_
                PriceCalculationNotification()
            End If
        End Set
    End Property
    Property ItemsTotalCost_ As Double
        Get
            Return _ItemsTotalCost_
        End Get
        Set(ByVal value As Double)
            If Not _ItemsTotalCost_ = value Then
                _ItemsTotalCost_ = value
                FinalPrice = TransportPrice + LabourCost + ItemsTotalCost_
                'NotifyPropertyChange("ItemsTotalCost_")
                PriceCalculationNotification()
            End If
        End Set
    End Property
    ReadOnly Property TotalPrice As Double
        Get
            Try
                Return ItemsTotalCost_ + TransportPrice + LabourCost
            Catch ex As Exception
                Return 0
            End Try
        End Get
        'Set(ByVal value As Double)
        '    If Not _TotalpriceValue = value Then
        '        _TotalpriceValue = value
        '        NotifyPropertyChange("TotalPrice")
        '    End If
        'End Set
    End Property
    Property FinalPrice As Double
        Get
            Return _FinalPriceValue
        End Get
        Set(ByVal value As Double)
            If Not _FinalPriceValue = value Then
                _FinalPriceValue = value
                PriceCalculationNotification()
            End If
        End Set
    End Property
    ReadOnly Property Discount_ As Double
        Get
            '_Discount_ = FinalPrice - TotalPrice
            'Return _Discount_
            Return FinalPrice - TotalPrice
        End Get
    End Property
    Public Sub New()
        _TransportPriceValue = 0
        _LabourCostValue = 0
        _ItemsTotalCost_ = 0
        _FinalPriceValue = 0
    End Sub
    Private Sub PriceCalculationNotification()
        NotifyPropertyChange("TransportPrice")
        NotifyPropertyChange("LabourCost")
        NotifyPropertyChange("Discount_")
        NotifyPropertyChange("TotalPrice")
        NotifyPropertyChange("FinalPrice")
    End Sub
End Class

我绑定了如下字段：

<StackPanel Name="AmountStack" Orientation="Vertical" >
                <Grid Margin="5">
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition />
                        <ColumnDefinition />
                        <ColumnDefinition Width="30"/>
                        <ColumnDefinition />
                        <ColumnDefinition />
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition />
                        <RowDefinition />
                    </Grid.RowDefinitions>
                    <TextBlock Text="Transport"  Grid.Column="0" Grid.Row="0" VerticalAlignment="Center" />
                    <TextBox Text="{Binding TransportPrice}" Name="TransportTxtBox" Grid.Column="1" Grid.Row="0" VerticalAlignment="Center" />
                    <TextBlock Text="Labour"  Grid.Column="3" Grid.Row="0" VerticalAlignment="Center" />
                    <TextBox Text="{Binding LabourCost}" Name="labourTxtBox" Grid.Column="4" Grid.Row="0" VerticalAlignment="Center" />
                    <TextBlock Text="Total Amount =" VerticalAlignment="Center" Grid.Column="0" Grid.Row="1"/>
                    <TextBox Text="{Binding TotalPrice}" Name="TotalTextBox"  IsReadOnly="True" Grid.Column="1" Grid.Row="1" />
                    <TextBlock Text="Discount= " VerticalAlignment="Center" Grid.Column="3" Grid.Row="1"/>
                    <TextBox Text="{Binding Path=Discount_, Mode=OneWay}" IsReadOnly="True" Name="DiscountTextBox" Grid.Column="4" Grid.Row="1" />
                </Grid>
                <StackPanel  Orientation="Horizontal" HorizontalAlignment="Center" Margin="0,5,0,0">
                    <TextBlock Text="Total Amount = " VerticalAlignment="Center" />
                    <TextBox Text="{Binding Path=FinalPrice}" Name="FinalTotalTextBox" Width="130" />
                </StackPanel>
            </StackPanel>

和

AmountStack.DataContext = Bill.Amounts

但是，问题是TOtalAMount正在自动更新，但FinalPrice没有得到更新。 我做过的任何原因/错误。 我已经尝试了很多方法，但无法正常工作。 我不明白的是总金额正在更新，但最终价格没有。 谢谢。

Answer 1

不要使用 Private _FinalPriceValue 在 Setter TransportPrice 和 LabourCost 中分配值。每次都使用FinalPrice正确提高PriceCalculationNotification()。

Answer 2

我不

记得来源了，但关键是当有只读属性时，绑定有时无法正常工作并正在等待下一个版本中的修复，我通过手动编码文本更改事件解决了更改。