Point screenPoint = 控件.PointToScreen(new Point());

Rectangle rect = new Rectangle(screenPoint, chartCellLine.Size);

Image img = new Bitmap(rect.Width, rect.Height);

Graphics g = Graphics.FromImage(img);

g.CopyFromScreen(rect.X - , rect.Y - , , , rect.Size);

img.Save(strPicPath, System.Drawing.Imaging.ImageFormat.Jpeg);

//截图窗体上任意位置的控件