Silverlight 4:如何切换控件可见性

Question

我在Silverlight应用程序中使用MVVM.当需要通过数据管理控件可见性时,我将其"可见性"属性连接到对象的相应属性:

XAML:

<TextBlock Text="Price" Visibility="{Binding PriceVisibility, Mode=OneWay}"/>
<TextBox Text="{Binding TicketPrice, Mode=TwoWay}" Visibility="{Binding PriceVisibility, Mode=OneWay}"/>

CodeBehind(C#):

public string PriceVisibility { get { return PriceVisible ? "Visible" : "Collapsed"; } }

但是从我的角度来看,返回Visibility属性的字符串表示并不是最好的方法.

你能告诉我有没有更好的方法？

谢谢!

Answer 1

我只是使用Reflector来检查PresentationFramework.dll中的类型转换器

已经有一个可以在布尔和可见性之间进行转换的实现.您应该可以在Silverlight应用程序中使用它.

public sealed class BooleanToVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        bool flag = false;
        if (value is bool)
        {
            flag = (bool) value;
        }
        else if (value is bool?)
        {
            bool? nullable = (bool?) value;
            flag = nullable.HasValue ? nullable.Value : false;
        }
        return (flag ? Visibility.Visible : Visibility.Collapsed);
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return ((value is Visibility) && (((Visibility) value) == Visibility.Visible));
    }
}

Answer 2

我遇到了将布尔值绑定到visibility属性的问题,所以我已经实现了自己的布尔值到Visibility Converter,我在大多数应用程序中使用它.

将以下类添加到您的应用程序:

public class BoolVisibilityConverter : IValueConverter{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture){
        bool isVisible = (bool)value;
        return isVisible ? System.Windows.Visibility.Visible : System.Windows.Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture){
        System.Windows.Visibility currVisibility = (System.Windows.Visibility)value;
        return (currVisibility == System.Windows.Visibility.Visible);
    }
}

现在要使用它,您需要将其作为XAML代码中的资源添加.

<UserControl.Resources>
    <Helpers:BoolVisibilityConverter x:Key="boolVisibilityConverter" />
</UserControl.Resources>

在您的示例中使用以下内容:

<TextBlock Text="Price" Visibility="{Binding PriceVisibility, Mode=OneWay, Converter={StaticResource boolVisibilityConverter}}"/>

<TextBox Text="{Binding TicketPrice, Mode=TwoWay}" Visibility="{Binding PriceVisibility, Mode=OneWay, Converter={StaticResource boolVisibilityConverter}}"/>