[转载]C#3.0新特性 扩展方法

using System.Windows.Controls;
using System.Windows.Documents;

namespace ExtensionRichTextBox
{
    /// <summary>
    /// RTB扩展取值和设值方法
    /// </summary>
    public static class RTBExtension
    {
        /// <summary>
        /// 取RTB值
        /// </summary>
        /// <param name="?"></param>
        /// <returns></returns>
        public static string GetRTBValue(this RichTextBox rtb)
        {
            string Text = string.Empty;
            for (int i = 0; i < rtb.Blocks.Count; i++)
            {
                Paragraph p = (Paragraph)rtb.Blocks[i];
                for (int j = 0; j < p.Inlines.Count; j++)
                {
                    Run r = (Run)p.Inlines[j];
                    Text += r.Text;
                }
            }
            return Text;
        }

        public static void SetRTBValue(this RichTextBox rtb, string data)
        {
            Paragraph p = new Paragraph();
            Run r = new Run();
            r.Text = data;
            p.Inlines.Add(r);
            rtb.Blocks.Clear();
            rtb.Blocks.Add(p);
        }

    }
}

public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 设置值
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            RTBExtension.SetRTBValue(this.richTextBox1, this.txtBlock1.Text);
        }
        /// <summary>
        /// 取值
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, RoutedEventArgs e)
        {
            this.txtBlock1.Text = RTBExtension.GetRTBValue(this.richTextBox1);
        }
    }