[整理]如何做一个语法着色控件

定义字体属性
 在C#中有一个叫做FONT的类能够满足需求。 其他属性及方法介绍请参考MSDN
 注意事项
 笔者在尝试的过程中发现屏幕中显示的内容会随着用户的输入，出现闪烁。究其原因可能是因为Windows一直在重新绘制窗口造成的，为了回避这个问题，我们可以使用SuspendLayout()和ResumeLayout()暂停和恢复画面重新绘制的过程。

 做完这几步，我们的语法着色控件也就大功告成了。下面是全部源代码。在VS2008 Express版本上调试通过。
 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using System.Text.RegularExpressions; using System.Drawing; using System.ComponentModel;  namespace Base {     public partial class SQLEditor : RichTextBox     {                  /// <summary>         /// 关键字列表         /// </summary>         private IList<String> _KeyWords = new List<String>()         {             "SELECT", "UPDATE", "DELETE", "INSERT", "DROP", "FROM", "WHERE", "ALERT", "CREATE", "TABLE",             "VALUES", "NULL",             "AND", "OR", "NOT", "IN", "INTO", "UNION", "AS", "IS",             "COUNT", "MAX", "MIN", "AVG",             "WAIT", "NOWAIT", "WITHOUT", "LOCK", "GROUP", "ORDER", "BY",             "JOIN", "LEFT", "RIGHT", "CASE", "WHEN", "ELSE", "END",             "COMMIT", "ROLLBACK"         };         [CategoryAttribute("KeyWords"), Description("关键字列表")]         public IList<String> KeyWords         {             get             {                 return this._KeyWords;             }             set             {                 this._KeyWords = value;             }         }          /// <summary>         /// 关键字颜色(默认为蓝色)         /// </summary>         private Color _KeyWordsColor = Color.Blue;         [CategoryAttribute("KeyWordsColor"), Description("关键字颜色")]         public Color KeyWordsColor         {             get             {                 return this._KeyWordsColor;             }             set             {                 this._KeyWordsColor = value;             }         }          // TODO 数字，字符串属性          /// <summary>         /// 分隔符         /// </summary>         Regex tokens = new Regex(@"[\s\r\n\t\(\)\;]");          /// <summary>         /// 接受输入时语法着色         /// </summary>         /// <param name="e"></param>         protected override void OnTextChanged(EventArgs e)         {             base.OnTextChanged(e);              // TODO DEBUG             Console.WriteLine("POINT:" + this.SelectionStart + "|" + "SIZE:" + this.Text.Length);              // 暂停屏幕刷新,防止闪烁             SuspendLayout();              // 缓存输入焦点位置             int inputPoint = this.SelectionStart;              String[] wrk_words = tokens.Split(this.Text.ToUpper());              // 判断是否有必要进行着色             if (this.Text.Length == 0) return;              // 克隆关键字列表             IList<String> C_KeyWords = new List<String>(this._KeyWords);             // 关键字开始坐标             int iStart = 0;              // 初始化             this.SelectionStart = 0;             this.SelectionLength = this.Text.Length;             this.SelectionColor = Color.Black;             this.SelectionFont = new Font("Courier New", 10, FontStyle.Regular);              // 逐字匹配             foreach (String word in wrk_words)             {                 foreach (String keyw in C_KeyWords)                 {                     // 判断当前值是否为关键字                     if (word.Equals(keyw))                     {                         // 查找坐标                         iStart = this.Text.ToUpper().IndexOf(keyw);                          // 判断是否存在处理对象                         while (iStart >= 0)                         {                             this.SelectionStart = iStart;                             this.SelectionLength = keyw.Length;                              this.SelectionColor = Color.Blue;                             this.SelectionFont = new Font("Courier New", 10, FontStyle.Bold);                              // 获取下一次处理开始坐标                             iStart = this.Text.ToUpper().IndexOf(keyw, this.SelectionStart + 1);                              this.SelectionStart = this.Text.Length;                             this.SelectionLength = 0;                         }                     }                     // break;                  }              }              // 计算输入点的位置，如果不在末尾，则说明用户在修改前面的内容，否则将焦点移到末尾             this.SelectionStart = (inputPoint < this.Text.Length) ? inputPoint : this.Text.Length;             this.SelectionLength = 0;              ResumeLayout();         }     } }