将窗口从绘图捕获到图像 C# 时出现问题

我正在尝试将一些对象绘制到Windows窗体，然后创建该窗体的图像并将其保存到文件夹中。

这是一个由两部分组成的问题...为什么正在绘制到窗口窗体的图像没有显示在创建的图像上？第二个问题是，我如何在没有背景的情况下创建窗口表单绘图的图像，从点 0,0 到点 500,500......

这是我目前拥有的代码....

Form draw = new Drawing();      // Opens the drawing form
draw.Show();
        try
        {
            //Try to draw something...
            System.Drawing.Pen myPen;       
            myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
            System.Drawing.Graphics formGraphics = draw.CreateGraphics();
            formGraphics.DrawLine(myPen, 0, 0, 500, 500);
            myPen.Dispose();
            formGraphics.Dispose();
            var path = this.outputFolder.Text;      // Create variable with output path
            if (!Directory.Exists(path))
            {
                DirectoryInfo di = Directory.CreateDirectory(path);  // Create path if it doesn't exist
            }
            using (var bitmap = new Bitmap(draw.Width, draw.Height))  // Creating the .bmp file from windows form
            {
                draw.DrawToBitmap(bitmap, new Rectangle(0, 0, bitmap.Width, bitmap.Height));
                bitmap.Save(path + "''" + i + ".bmp");
             }
        }
        catch { }

你能看出这里有什么不对劲吗？什么似乎禁止将图形保存到.bmp文件中？

提前感谢！

        Form draw = new Drawing();      // Opens the drawing form
        draw.Show();
        try
        {
            var path = this.outputFolder.Text; // Path where images will be saved to
            if (!Directory.Exists(path))
            {
                DirectoryInfo di = Directory.CreateDirectory(path);     // Create a directory if it does not already exist
            }
            Bitmap bitmap = new Bitmap(Convert.ToInt32(1024), Convert.ToInt32(1024), System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            Graphics g = Graphics.FromImage(bitmap);
            System.Drawing.Pen myPen;
            myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
            g.DrawLine(myPen, 0, 0, 1024, 1024);
            bitmap.Save(path + "''" + i + ".png", ImageFormat.Png);
        }
        catch { }