c# - 在 MVVM 中获取 BooleanToVisibilityConverter 的 xaml 绑定代码错误

Question

我在视图中使用了进度条，如下所示：

<ProgressBar  IsIndeterminate="{Binding IsBusy}" Visibility="{Binding IsBusy,Converter={StaticResource BooleanToVisibilityConverter}}" HorizontalAlignment="Left" Height="33" Margin="46,222,0,0" VerticalAlignment="Top" Width="358"/>

• BooleanToVisibilityConverter 在 ViewModel 中定义
• 在视图的 xaml 代码上出现错误 <phone:PhoneApplicationPage.Resources> <BooleanToVisibilityConverter x:Key="BooleanConverter"/> </phone:PhoneApplicationPage.Resources>

*错误是：

名称空间“ http://schemas.microsoft.com/client/2007 ”中不存在名称“BooleanToVisibilityConverter” 。

请告诉我如何解决此错误

Answer 1

您可以像这样定义转换器：

namespace YourNamespace
{
    public class BooleanToVisibilityConverter : IValueConverter
    {

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            return (bool)value ? Visibility.Visible : Visibility.Collapsed;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

构建您的解决方案！在 XAML 中：

<navigation:Page x:Class="MyCustomNamespace"
    xmlns:converters="clr-namespace:YourNamespace">
    <navigation:Page.Resources>
        <converters:BooleanToVisibilityConverter x:Key="BooleanToVisibility" />
    </navigation:Page.Resources>
    <TextBlock Visibility="{Binding BooleanFromViewModel, Convert={StaticResource BooleanToVisibility}" />
</navigation:Page>

Answer 2

<UserControl xmlns:converter="your namespace">
<UserControl.Resources>
<converter:BooleanToVisibilityConverter x:Key="bool2VisibilityConverter" />
</UserControl.Resources>
<TextBlock Visibility={Binding Path=Field, Converter={StaticResource bool2VisibilityConverter}} />
</UserControl>

Answer 3

您需要在 xaml 中定义您的命名空间。在 Window/UserControl 的顶层，您需要定义一个 xml 命名空间：

xmlns:yn="clr-namespace:YourNamespace"

然后你需要参考你BooleanToVisibilityConverter使用的命名空间：

<yn:BooleanToVisibilityConverter ... />