我們在使用到WINFORM表單作業中，要求RichTextBox 加入行號；
之前有看到大牛們寫的，但是太復雜繁多，而且有用雙TextBox進行聯動，非常不錯，今天我們嘗試RichTextBox +Panel相互聯動如下效果.
左側灰色為Panel，右側為RichTextBox 控制元件
1：準備Panel畫布如下代碼，當接到檔案字符后進行坐標決議，繪制行號，
1 private void showLineNo() 2 { 3 //獲得當前坐標資訊 4 Point p = this.txtFileView.Location; 5 int crntFirstIndex = this.txtFileView.GetCharIndexFromPosition(p); 6 7 int crntFirstLine = this.txtFileView.GetLineFromCharIndex(crntFirstIndex); 8 9 Point crntFirstPos = this.txtFileView.GetPositionFromCharIndex(crntFirstIndex);10 11 p.Y += this.txtFileView.Height;12 13 int crntLastIndex = this.txtFileView.GetCharIndexFromPosition(p);14 15 int crntLastLine = this.txtFileView.GetLineFromCharIndex(crntLastIndex);16 Point crntLastPos = this.txtFileView.GetPositionFromCharIndex(crntLastIndex);17 18 //準備畫圖19 Graphics g = this.panel2.CreateGraphics();20 21 Font font = new Font(this.txtFileView.Font, this.txtFileView.Font.Style);22 23 SolidBrush brush = new SolidBrush(Color.Green);24 25 //畫圖開始26 27 //重繪畫布28 29 Rectangle rect = this.panel2.ClientRectangle;30 brush.Color = this.panel2.BackColor;31 32 g.FillRectangle(brush, 0, 0, this.panel2.ClientRectangle.Width, this.panel2.ClientRectangle.Height);33 34 brush.Color = Color.White;//重置畫筆顏色35 36 //繪制行號37 38 int lineSpace = 0;39 40 if (crntFirstLine != crntLastLine)41 {42 lineSpace = (crntLastPos.Y - crntFirstPos.Y) / (crntLastLine - crntFirstLine);43 44 }45 46 else47 {48 lineSpace = Convert.ToInt32(this.txtFileView.Font.Size);49 50 }51 int brushX = this.panel2.ClientRectangle.Width - Convert.ToInt32(font.Size * 3);52 53 int brushY = crntLastPos.Y + Convert.ToInt32(font.Size * 0.21f);54 for (int i = crntLastLine; i >= crntFirstLine; i--)55 {56 57 g.DrawString((i + 1).ToString(), font, brush, brushX, brushY);58 59 brushY -= lineSpace;60 }61 62 g.Dispose();63 64 font.Dispose();65 66 brush.Dispose();67 }View Code
2：事件準備（啟用）如下事件
控制元件加載事件
1 private void txtFileView_TextChanged(object sender, EventArgs e)2 {3 showLineNo();4 }View Code
控制元件滾動事件（當算出的行數大于本控制元件長度）
1 private void txtFileView_VScroll(object sender, EventArgs e)2 {3 showLineNo();4 }View Code
完成后，直接啟用運行，Demo事例中的效果就出來，方便大家用于各種應用上.
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標籤：WinForm