将两个元素的可见性绑定到一个属性

如何解决将两个元素的可见性绑定到一个属性

| 我有两个菜单项元素-\“ Undelete \”和\“ Delete \”具有互补的可见性：显示一个时，另一个隐藏。在viewmodel的代码中，我有一个依赖项属性FilesSelectedCanBeUndeleted定义如下：

private bool _filesSelectedCanBeUndeleted;
public bool FilesSelectedCanBeUndeleted
{
    get
    {
        return _filesSelectedCanBeUndeleted;
    }
    set
    {
        _filesSelectedCanBeUndeleted = value;
        OnPropertyChanged(\"FilesSelectedCanBeUndeleted\");
    }
}

取消删除按钮的XAML如下所示：

<MenuItem Header=\"Undelete\" Command=\"{Binding UndeleteCommand }\" 
Visibility=\"{Binding Path=FilesSelectedCanBeUndeleted,Converter={StaticResource BoolToVisConverter}}\" >

如您所见，取消删除的可见性已绑定到FilesSelectedCanBeUndeleted 属性（借助于BooleanToVisibilityConveter）。现在我的问题是，如何编写XAML来将Delete按钮的可见性绑定到FilesSelectedCanBeUndeleted属性的\“ NOT \”值？谢谢，

解决方法

这是一个自定义IValueConverter的示例，该示例使您可以反转可见性逻辑。基本上，当您的view-model属性为true时，一个MenuItem将可见，而另一个折叠。因此，您需要像这样定义转换器的两个实例：

<local:BooleanToVisibilityConverter x:Key=\"BooleanToVisibilityConverter\" />
<local:BooleanToVisibilityConverter x:Key=\"ReversedBooleanToVisibilityConverter\" IsReversed=\"true\" />

,您可以将datatrigger应用于您的menuitem，以避免在viemodel中出现其他这样的属性-

        <MenuItem Header=\"Delete\"
                  Command=\"{Binding DeleteCommand }\">
            <MenuItem.Style>
                <Style TargetType=\"{x:Type MenuItem}\">
                    <Setter Property=\"Visibility\" Value=\"Visible\" />
                    <Style.Triggers>
                        <DataTrigger Binding=\"{Binding FilesSelectedCanBeUndeleted}\" Value=\"False\">
                            <Setter Property=\"Visibility\"
                                    Value=\"Collapsed\" />
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </MenuItem.Style>
        </MenuItem>

,在ViewModel上创建新属性，然后仅取反\'FilesSelectedCanBeUndeleted \'，然后将其绑定。,我前一阵子做了一个简单的否定...

    private bool _filesSelectedCanBeUndeleted;
public bool FilesSelectedCanBeUndeleted{    
        get{ 
            return _filesSelectedCanBeUndeleted;    
            }   
        set{        
            _filesSelectedCanBeUndeleted = value;        
            OnPropertyChanged(\"FilesSelectedCanBeUndeleted\");    
            // You have also to notify that the second Prop will change
            OnPropertyChanged(\"FilesSelectedCanBeDeleted\");    
            }}

public bool FilesSelectedCanBeDeleted{
        get{
            return !FilesSelectedCanBeUndeleted;
        }
        }

Xaml可能看起来像这样……

<MenuItem Header=\"Delete\" 
    Command=\"{Binding DeleteCommand }\" 
    Visibility=\"{Binding Path=FilesSelectedCanBeDeleted,Converter={StaticResource BoolToVisConverter}}\" >