IValueConverter的基础用法

1、我们在做工控项目的时候通常设置配方的上下限

这个时候要求OK数在上下限范围之内，否则NG

首先我们绑定一个简单的List用来展示数据,我这里用学生Age来展示

<ListView ItemsSource="{Binding DataList}" Margin="20">
   <ListView.View>
          <GridView>
              <GridViewColumn Width="80" Header="Id" DisplayMemberBinding="{Binding Id}"/>
              <GridViewColumn Width="100" Header="名称" DisplayMemberBinding="{Binding Name}"/>
              <GridViewColumn Width="200" Header="年龄" DisplayMemberBinding="{Binding Age}"/>
          </GridView>
   </ListView.View>
</ListView>

2、我们需要年龄在18岁之下是绿色，否则是蓝色的背景

 <Window.Resources>
        <cvt:RangeToBooleanConverter x:Key="RangeToBooleanConverter"/>
    </Window.Resources>
    <Grid>
        <ListView ItemsSource="{Binding DataList}" Margin="20">
            <ListView.ItemContainerStyle>
                <Style TargetType="ListViewItem">
                    <Style.Triggers>
                        <DataTrigger Binding="{Binding Age, Converter={StaticResource RangeToBooleanConverter}, ConverterParameter='18-100'}" Value="True">
                            <Setter Property="Background" Value="Green"/>
                        </DataTrigger>
                        <DataTrigger Binding="{Binding Age, Converter={StaticResource RangeToBooleanConverter}, ConverterParameter='0-17'}" Value="True">
                            <Setter Property="Background" Value="Blue"/>
                        </DataTrigger>
                    </Style.Triggers>
                </Style>
            </ListView.ItemContainerStyle>
            <ListView.View>
                <GridView>
                    <GridViewColumn Width="80" Header="Id" DisplayMemberBinding="{Binding Id}"/>
                    <GridViewColumn Width="100" Header="名称" DisplayMemberBinding="{Binding Name}"/>
                    <GridViewColumn Width="200" Header="年龄" DisplayMemberBinding="{Binding Age}"/>
                </GridView>
            </ListView.View>
        </ListView>
    </Grid>

3、接下来我们看自己定义的RangeToBooleanConverter

public class RangeToBooleanConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value != null && value is int intValue && parameter != null && parameter is string rangeString)
        {
            var range = rangeString.Split('-');
            if (range.Length == 2 && int.TryParse(range[0], out int minValue) && int.TryParse(range[1], out int maxValue))
            {
                return intValue >= minValue && intValue <= maxValue;
            }
        }

        return false;
    }

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