因为我们这个控件是实现背景渐变及文字填充，所以override Paint事件以完成自画。

为了完成override，现在以下的准备工作（写几个在Paint事件用的着的事件）.

//使用角度的方法渐近重画Button

          private void DrawButtonWithAngle(Graphics dbg)

         {

              LinearGradientBrush brush=new LinearGradientBrush(new Rectangle(0,0,this.Width,this.Height),froColor,backColor,angle);

              dbg.FillRectangle(brush,0,0,this.Width,this.Height);

              brush.Dispose();

         }

         ////使用模式的方法渐近重画Button

          private void DrawButtonWithMode(Graphics dbg,LinearGradientMode Mode)

         {

              LinearGradientBrush brush=new LinearGradientBrush(new Rectangle(0,0,this.Width,this.Height),froColor,backColor,Mode);

              dbg.FillRectangle(brush,0,0,this.Width,this.Height);

              brush.Dispose();

         }

         //重画Button的文本(Text),不使用图案填充

          private void DrawButtonText(Graphics dbg)

         {

              StringFormat format=new StringFormat();

              format.LineAlignment=StringAlignment.Center;

              format.Alignment=StringAlignment.Center;

              dbg.DrawString(this.Text,this.Font,new SolidBrush(this.ForeColor),new Rectangle(0,0,this.Width,this.Height),format);

         }

          //override DrawButtonText函数，使之可以用图案填充文本

          private  void DrawButtonText(Graphics dbg, HatchStyle hs)

         {

              StringFormat format=new StringFormat();

              format.LineAlignment=StringAlignment.Center;

              format.Alignment=StringAlignment.Center;