示例:WPF中应用MarkupExtention自定义IValueConverter

一、目的：应用MarkupExtention定义IValueConverter，使得应用起来更简单和高效

二、实现

public abstract class MarkupValueConverterBase : MarkupExtension, IValueConverter
    {
        public abstract object Convert(object value, Type targetType, object parameter, CultureInfo culture);

        public virtual object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            throw new NotImplementedException();
        }
        public override object ProvideValue(IServiceProvider serviceProvider)
        {
            return this;
        }
    }

三、环境

VS2022，.Net 7

四、示例

自定义一个DateTime时间转换年龄的转化器

    public class GetAgeConverter : MarkupValueConverterBase
    {
        public override object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            if (value is DateTime dateTime)
            {
                DateTime now = DateTime.Now;
                int age = now.Year - dateTime.Year;
                if (now.Month < dateTime.Month || (now.Month == dateTime.Month && now.Day < dateTime.Day))
                {
                    age--;
                }
                return age > 0 ? age : 0;
            }
            return this.DefaultValue;
        }
    }

使用方法

            <TextBlock Text="{Binding Source={x:Static s:DateTime.MinValue},Converter={local:GetAgeConverter DefaultValue=50}}"/>

 输出结果

五、需要了解的知识点

IValueConverter 接口 (System.Windows.Data) | Microsoft Learn

MarkupExtension 类 (System.Windows.Markup) | Microsoft Learn

六、源码地址

GitHub - HeBianGu/WPF-ControlDemo: 示例

GitHub - HeBianGu/WPF-ControlBase: Wpf封装的自定义控件资源库

GitHub - HeBianGu/WPF-Control: WPF轻量控件和皮肤库

七、了解更多

System.Windows.Controls 命名空间 | Microsoft Learn