WPF转换器

以下是学习笔记：

https://www.bilibili.com/video/BV1gq4y1D76d?p=55&spm_id_from=pageDriver&vd_source=3f21d2e208ef0bf2c49a9be7560735e5

1,转换器的作用：将值的类型转换另外一种类型

例子说明:当IsGorwing值为true,IsGorwing就变向上箭头绿色显示；否则向下箭头，红色提示。

 2,定义转换器

    /// <summary>
    /// 转换器（布尔到箭头的转换）
    /// </summary>
    public class BoolToArrowConverter : IValueConverter//需要继承IValueConverter
    {
        /// <summary>
        /// modle向view转换
        /// </summary>
        /// <param name="value"></param>
        /// <param name="targetType"></param>
        /// <param name="parameter"></param>
        /// <param name="culture"></param>
        /// <returns></returns>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value != null && bool.Parse(value.ToString()))//如果为true,转换向上的箭头
            {
                return "↑";
            }
            else
            {
                return "↓";
            }
        }

        /// <summary>
        /// view向modle转换
        /// </summary>
        /// <param name="value"></param>
        /// <param name="targetType"></param>
        /// <param name="parameter"></param>
        /// <param name="culture"></param>
        /// <returns></returns>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }

　　

3，使用转换器

【3.1】引用转换器所在的命名空间

xmlns:converter_suibian="clr-namespace:Zhaoxi.CourseManagement.Converter"

　　

【3.2】定义资源

    <UserControl.Resources>
        <converter_suibian:BoolToArrowConverter x:Key="BoolToArrowConverter_suibian"/>
        <converter_suibian:BoolToBrushConverter x:Key="BoolToBrushConverter_suibian"/>
    </UserControl.Resources>

　　

【3.3】绑定属性，添加转换器

                                                <TextBlock Text="{Binding IsGrowing ,Converter={StaticResource BoolToArrowConverter_suibian}}" 
                                                           Foreground="{Binding IsGrowing,Converter={StaticResource BoolToBrushConverter_suibian}}" Grid.Column="1" VerticalAlignment="Center" Margin="10,0,0,0"/>
                                                <TextBlock Text="{Binding ChangeRate}" Grid.Column="1" 
                                                           Foreground="{Binding IsGrowing,Converter={StaticResource BoolToBrushConverter_suibian}}" Grid.Row="1" VerticalAlignment="Center" Margin="10,0,0,0"/>