C# 控件 RichTextBox 显示行号，并且与Panel相互联动

我们在使用到WINFORM窗体工作中，要求RichTextBox 加入行号；

之前有看到大牛们写的，但是太复杂繁多，而且有用双TextBox进行联动，非常不错，今天我们尝试RichTextBox +Panel相互联动如下效果.

左侧灰色为Panel，右侧为RichTextBox 控件

1：准备Panel画布如下代码，当接到文件字符后进行坐标解析，绘制行号。

 private void showLineNo()
         {
             //获得当前坐标信息
             Point p = this.txtFileView.Location;
             int crntFirstIndex = this.txtFileView.GetCharIndexFromPosition(p);

             int crntFirstLine = this.txtFileView.GetLineFromCharIndex(crntFirstIndex);

             Point crntFirstPos = this.txtFileView.GetPositionFromCharIndex(crntFirstIndex);

             p.Y += this.txtFileView.Height;

             int crntLastIndex = this.txtFileView.GetCharIndexFromPosition(p);

             int crntLastLine = this.txtFileView.GetLineFromCharIndex(crntLastIndex);
             Point crntLastPos = this.txtFileView.GetPositionFromCharIndex(crntLastIndex);

             //准备画图
             Graphics g = this.panel2.CreateGraphics();

             Font font = new Font(this.txtFileView.Font, this.txtFileView.Font.Style);

             SolidBrush brush = new SolidBrush(Color.Green);

             //画图开始

             //刷新画布

             Rectangle rect = this.panel2.ClientRectangle;
             brush.Color = this.panel2.BackColor;

             g.FillRectangle(brush, , , this.panel2.ClientRectangle.Width, this.panel2.ClientRectangle.Height);

             brush.Color = Color.White;//重置画笔颜色

             //绘制行号

             int lineSpace = ;

             if (crntFirstLine != crntLastLine)
             {
                 lineSpace = (crntLastPos.Y - crntFirstPos.Y) / (crntLastLine - crntFirstLine);

             }

             else
             {
                 lineSpace = Convert.ToInt32(this.txtFileView.Font.Size);

             }
             int brushX = this.panel2.ClientRectangle.Width - Convert.ToInt32(font.Size * );

             int brushY = crntLastPos.Y + Convert.ToInt32(font.Size * 0.21f);
             for (int i = crntLastLine; i >= crntFirstLine; i--)
             {

                 g.DrawString((i + ).ToString(), font, brush, brushX, brushY);

                 brushY -= lineSpace;
             }

             g.Dispose();

             font.Dispose();

             brush.Dispose();
         }

2：事件准备（启用）如下事件

控件加载事件

 private void txtFileView_TextChanged(object sender, EventArgs e)
         {
             showLineNo();
         }

控件滚动事件（当算出的行数大于本控件长度）

 private void txtFileView_VScroll(object sender, EventArgs e)
         {
             showLineNo();
         }

完成后，直接启用运行，Demo事例中的效果就出来，方便大家用于各种应用上.