c# - 使用OR代替AND的MultiDataTrigger

我正在尝试在自己的DataTriggers上设置多个Button。我做了一些研究，发现MultiDataTrigger允许您执行此操作。如果Visibility或Button，我希望将自己的CCTVPath == string.Empty的PermissionsFlag == false属性设置为false。到目前为止，这就是我所拥有的。

<Button Grid.Column="3" x:Name="cctvFeedButton" Content="Live Feed"
        Width="100" FontSize="16" HorizontalAlignment="Right" Margin="5" Click="OnCCTVButtonClick">
    <Button.Style>
        <Style TargetType="Button">
            <Style.Triggers>
                <MultiDataTrigger>
                    <MultiDataTrigger.Conditions>
                        <Condition Binding="{Binding CCTVPath}" Value=""/>
                        <Condition Binding="{Binding PermissionsFlag}" Value="False"/>
                    </MultiDataTrigger.Conditions>
                    <Setter Property="Visibility" Value="Hidden"/>
                </MultiDataTrigger>
            </Style.Triggers>
        </Style>
    </Button.Style>
</Button>

在我的代码后面，我像这样设置PermissionsFlag；

public bool PermissionsFlag { get; set; }

private void OnPageLoaded(object sender, RoutedEventArgs e)
{
    PermissionsFlag = false;
}

如您所见，PermissionsFlag绝对是错误的，并且肯定有空的CCTVPath，但是Button从未被隐藏。我究竟做错了什么？

更新:

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    private bool _permissionsFlag;
    public bool Flag
    {
        get { return _permissionsFlag; }
        set
        {
            _permissionsFlag = value;
            OnPropertyChanged("PermissionsFlag");
        }
    }

    private void OnPageLoaded(object sender, RoutedEventArgs e)
    {
        Flag = false;
        CCTVImageCollection = GetImages();
        imageListBox.ItemsSource = CCTVImageCollection;
        DataContext = this;
    }

在我的XAML中:

<Button.Style>
         <Style TargetType="Button">
               <Style.Triggers>
                      <DataTrigger Binding="{Binding PermissionsFlag}" Value="False">
                            <Setter Property="Visibility" Value="Hidden"/>
                      </DataTrigger>
               </Style.Triggers>
         </Style>
 </Button.Style>

最佳答案

将条件转换为两个独立的DataTriggers

<Style.Triggers>
    <DataTrigger Binding="{Binding CCTVPath}" Value="">
        <Setter Property="Visibility" Value="Hidden"/>
    </DataTrigger>
    <DataTrigger Binding="{Binding PermissionsFlag}" Value="False">
        <Setter Property="Visibility" Value="Hidden"/>
    </DataTrigger>
</Style.Triggers>

确保绑定(bind)路径正确(检查“VS输出”窗口以获取可能的异常消息)

还:不仅仅依赖Button的隐藏状态，在代码(OnCCTVButtonClick)中正确实现权限。在这里阅读原因:

How to Snoop proof your wpf application?

自动属性PermissionsFlag(public bool PermissionsFlag { get; set; })不会将更改通知 View 。

可以实现INotifyPropertyChanged接口(interface)(在我的测试窗口中是这样完成的:public partial class Window3 : Window, INotifyPropertyChanged)，然后在属性更改时引发事件。

这是我用来测试的完整的工作示例

public partial class Window3 : Window, INotifyPropertyChanged
{
    public Window3()
    {
        InitializeComponent();
        this.DataContext = this;
        //PermissionsFlag = true;
        CCTVPath = "youtube.com";
    }

    private bool _permissionsFlag = false;
    private string _cctvPath;

    public bool PermissionsFlag
    {
        get { return _permissionsFlag; }
        set
        {
            _permissionsFlag = value;
            OnPropertyChanged("PermissionsFlag");
        }
    }

    public string CCTVPath
    {
        get { return _cctvPath; }
        set
        {
            _cctvPath = value;
            OnPropertyChanged("CCTVPath");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}

窗口xaml:

<Window x:Class="WpfDemos.Views.Window3"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window3" Height="300" Width="300">
    <StackPanel>
        <CheckBox Name="chkPermissionsFlag"
                  Content="PermissionsFlag"
                  IsChecked="{Binding Path=PermissionsFlag, UpdateSourceTrigger=PropertyChanged}"/>

        <TextBox Text="{Binding Path=CCTVPath, UpdateSourceTrigger=PropertyChanged}"/>

        <Button x:Name="cctvFeedButton" Content="Live Feed"
                    Width="100" FontSize="16" HorizontalAlignment="Right" Margin="5">
            <Button.Style>
                <Style TargetType="Button">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding Path=CCTVPath}" Value="">
                            <Setter Property="Visibility" Value="Hidden"/>
                        </DataTrigger>
                        <DataTrigger Binding="{Binding Path=PermissionsFlag}" Value="False">
                            <Setter Property="Visibility" Value="Hidden"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </Button.Style>
        </Button>
    </StackPanel>
</Window>

关于c# - 使用OR代替AND的MultiDataTrigger，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/38396419/