IValueConvert的例子

在MVVM中经常遇到控制界面显示的问题

下面来一段代码用true和false来控制界面的显示

先写一个类实现接口IValueConvert

 public class BoolToVisibilityConvert:IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool trueOrFalse = (bool)value;
            string str = trueOrFalse ? "Visible" : "Collapsed";
            return str;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            string visibility = (string)value;
            switch (visibility)
            {
                case "Visible":
                    return true;
                case "Hidden":
                    return false;
                case "Collapsed":
                    return false;
                default:
                    return false;
            }
        }
    }

然后再xaml界面定义一下

<Window x:Class="Test1BoolenToVisiableConvert.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:Converter="clr-namespace:Test1BoolenToVisiableConvert"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <Converter:BoolToVisibilityConvert x:Key="booltovisibleConvert"/>
    </Window.Resources>
    <Grid>
        <TextBlock Text="BoolToVisibleConvert" 
                   HorizontalAlignment="Center" VerticalAlignment="Center"
                   Visibility="{Binding ShowText,Converter={StaticResource booltovisibleConvert}}"/>
    </Grid>
</Window>

那么在对应的ViewModel中就可以用了

public class MainWindowViewModel 
    {
        public MainWindowViewModel()
        { ShowText = true; }

        public bool ShowText { get; set; }
    }

简单的一个demo写完了