如何根据更改属性激活命令

Question

我的 WPF-（弹出）控件中有两个按钮。
第一个是取消按钮，它只是关闭弹出窗口并始终启用。

第二个是确定按钮，只有在更改了三个（绑定的）文本框之一时才应启用该按钮。

问题是，在文本框失去焦点之前，绑定属性的值没有改变。因此该按钮到那时才处于活动状态，因此无法使用鼠标单击它。

    <TextBox x:Name="tbFunction" Text="{Binding FunctionSign}" Grid.Column="1" Grid.Row="1" VerticalContentAlignment="Center" Margin="2" Padding="10 0 0 0"/>
    <TextBox x:Name="tbSpecs" Text="{Binding Specs}" Grid.Column="1" Grid.Row="1" VerticalContentAlignment="Center" Margin="2" Padding="10 0 0 0"/>
    <TextBox x:Name="tbSupplement" Text="{Binding Supplement}" Grid.Column="1" Grid.Row="1" VerticalContentAlignment="Center" Margin="2" Padding="10 0 0 0"/>

    <!-- Footer -->
    <Border Grid.Row="3" Padding="{Binding InnerContentPadding}">
        <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
            <Button Style="{StaticResource OkCancelButton}" Command="{Binding CloseCommand}" Content="Abbrechen"/>
            <Button Style="{StaticResource OkCancelButton}" Command="{Binding AddressChangedCommand}" Content="Ok"/>
        </StackPanel>
    </Border>

负责的视图模型代码：

    //Private Members
    private bool mPropertiesChanged = false;
    private string mFunctionSign;
    private string mSpecs;
    private string mSupplement;


    //the canExecute-method
    private bool SelectionChanged(object paramer)
    {
        return mPropertiesChanged;
    }

    //Public Properties
    public string FunctionSign
    {
        get
        {
            return mFunctionSign;
        }
        set
        {
            mFunctionSign = value;
            mPropertiesChanged = true;
            OnPropertyChanged(nameof(FunctionSign));
        }
    }
    public string Specs
    {
        get
        {
            return mSpecs;
        }
        set
        {
            mSpecs = value;
            mPropertiesChanged = true;
            OnPropertyChanged(nameof(Specs));
        }
    }
    public string Supplement
    {
        get
        {
            return mSupplement;
        }
        set
        {
            mSupplement = value;
            mPropertiesChanged = true;
            OnPropertyChanged(nameof(Supplement));
        }
    }

由于更改了其中一个属性并且相应的文本框失去了焦点，因此一切正常。

有没有办法让这个 mPropertiesChanged 为真，而文本框仍然有焦点？

Answer 1

将绑定的 UpdateSourceTrigger 设置为 PropertyChanged:

Text="{Binding FunctionSign, UpdateSourceTrigger=PropertyChanged}"

这将导致为每个击键设置源属性。默认值为 LostFocus.

如何根据更改属性激活命令

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如何根据更改属性激活命令