C#对被遮挡的窗体进行截图

最近在做的一个项目，用的地图控件比较特殊，

在地图上面自己绘制的东东没办法随地图一起导出成图片

只能绕个弯,用截屏的方式了
一开始用的是这样:

        /// <summary>
        /// 截图
        /// </summary>
        /// <returns></returns>
        private Image CaptureScreen()
        {
            Image MyImage = null;

            //获得当前地图控件的大小
            Graphics grapScreen = m_pFremework.Hook.CreateGraphics();

            //Rectangle rect = new Rectangle();
            //rect = Screen.GetWorkingArea(m_pFremework.Hook);//范围不准确,直接使用控件的属性
            Rectangle rect = new Rectangle(0, 0, m_pFremework.Hook.Width, m_pFremework.Hook.Height);
            MyImage = new Bitmap(rect.Width, rect.Height, grapScreen);
            Graphics grapImage = Graphics.FromImage(MyImage);
            IntPtr dc1 = grapScreen.GetHdc();
            IntPtr dc2 = grapImage.GetHdc();
            
            BitBlt(dc2, 0, 0, rect.Width, rect.Height, dc1, 0, 0, 13369376);

            //释放掉DC
            grapScreen.ReleaseHdc(dc1);
            grapImage.ReleaseHdc(dc2);
            return MyImage;
        }

这个函数在win7中没有任何问题,但在xp中发现,任何遮挡到地图控件的窗体都被截下来了
网上搜搜,发现了一个PrintWindow API可以解决这个问题,用下来发现这个只能截整个窗体,
无法单独截取地图控件,这个就简单了,直接使用BitMap的Clone函数裁剪出来地图控件部分就搞定了,
代码是这个样子:

private Image CaptureScreen2()
        {
            Image MyImage = null;
            IntPtr hdc = GetWindowDC(m_pFremework.MdiForm.Handle);
            LPPOINT lphook = new LPPOINT();
            lphook.x = 0;
            lphook.y = 0;

            ClientToScreen(m_pFremework.Hook.Handle, ref lphook);
            ScreenToClient(m_pFremework.MdiForm.Handle, ref lphook);
            Rectangle rect = new Rectangle(lphook.x, lphook.y, m_pFremework.Hook.Width, m_pFremework.Hook.Height);
            if (hdc != IntPtr.Zero)
            {
                IntPtr hdcMem = CreateCompatibleDC(hdc);
                if (hdcMem != IntPtr.Zero)
                {
                    IntPtr hbitmap = CreateCompatibleBitmap(hdc, m_pFremework.MdiForm.Width, m_pFremework.MdiForm.Height);
                    if (hbitmap != IntPtr.Zero)
                    {
                        IntPtr ip = SelectObject(hdcMem, hbitmap);
                        if (ip != IntPtr.Zero)
                        {
                            bool a = PrintWindow(m_pFremework.MdiForm.Handle, hdcMem, 1);
                            DeleteObject(hbitmap);
                            Image tempImg = Image.FromHbitmap(hbitmap);
                            Bitmap b = new Bitmap(tempImg);
                            MyImage = b.Clone(rect, b.PixelFormat);
                        }
                    }
                }
            }

            return MyImage;
        }

==============================分割线==============================
以下是用到的一些windows系统api
==============================分割线==============================

		 [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
        private static extern bool BitBlt(
             IntPtr hdcDest, // 目标 DC的句柄
             int nXDest,
           int nYDest,
           int nWidth,
           int nHeight,
           IntPtr hdcSrc,  // 源DC的句柄
             int nXSrc,
           int nYSrc,
           System.Int32 dwRop  // 光栅的处理数值
             );
			 
        [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
        private static extern IntPtr GetWindowDC(
             IntPtr hwnd
             );

        [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
        private static extern IntPtr CreateCompatibleDC(
             IntPtr hdc
             );

        [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
        private static extern IntPtr CreateCompatibleBitmap(
            IntPtr hdc,
            int nWidth,     // width of bitmap, in pixels
            int nHeight // height of bitmap, in pixels
             );

        [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
        private static extern IntPtr SelectObject(
            IntPtr hdc,// handle to DC
            IntPtr hgdiobj   // handle to object
             );

        [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
        private static extern bool DeleteObject(
            IntPtr hObject  // handle to graphic object
             );

        [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
        private static extern bool PrintWindow(
              IntPtr hwnd,               // Window to copy
              IntPtr hdcBlt,             // HDC to print into
              int nFlags              // Optional flags
             );

        [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
        private static extern int ReleaseDC(
              IntPtr hWnd,  // handle to window
              IntPtr hDC     // handle to DC
             );

        [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
        private static extern bool ScreenToClient(
                IntPtr hWnd,        // handle to window
                ref LPPOINT lpPoint   // screen coordinates
             );

        [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
        private static extern bool ClientToScreen(
                IntPtr hWnd,        // handle to window
                ref LPPOINT lpPoint   // screen coordinates
             );

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public struct LPPOINT
        {
            public int x;
            public int y;
        }
      }

参考网址：http://zhidao.baidu.com/question/29867112.html?fr=qrl&cid=869&index=1