c# - 仅捕获表单一部分的屏幕截图？

Question

我目前有一个winform，在运行时，我需要截取其中的一部分并将其保存为图像。特别是，我想要一个名为“panel1”的面板的屏幕截图。我已经能够找到有关如何获取整个网络表单或整个屏幕的屏幕截图的信息……但我很难找到有关仅获取屏幕一部分的信息。

有没有人有任何信息可以为我指明正确的方向？即使是我应该寻找的 MSDN 网站上的文档名称也会有很大的帮助！谢谢！

Answer 1

派生的Control类有一个方法。你可以用那个。PanelDrawToBitmap()

http://msdn.microsoft.com/en-us/library/system.windows.forms.control.drawtobitmap.aspx

Answer 2

查看Graphics.CopyFromScreen的文档。您将 2 组 X/Y 坐标传递给它——屏幕上的坐标和位图中的坐标。

Answer 3

     #region - Capture & Graphic API  -

        #region GDI32
        public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter

        [DllImport("gdi32.dll")]
        public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest,
            int nWidth, int nHeight, IntPtr hObjectSource,
            int nXSrc, int nYSrc, int dwRop);

        [DllImport("gdi32.dll")]
        public static extern bool StretchBlt(
              IntPtr hdcDest,      // handle to destination DC
              int nXOriginDest, // x-coord of destination upper-left corner
              int nYOriginDest, // y-coord of destination upper-left corner
              int nWidthDest,   // width of destination rectangle
              int nHeightDest,  // height of destination rectangle
              IntPtr hdcSrc,       // handle to source DC
              int nXOriginSrc,  // x-coord of source upper-left corner
              int nYOriginSrc,  // y-coord of source upper-left corner
              int nWidthSrc,    // width of source rectangle
              int nHeightSrc,   // height of source rectangle
              int dwRop       // raster operation code
            );


        [DllImport("gdi32.dll")]
        public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth,
            int nHeight);
        [DllImport("gdi32.dll")]
        public static extern IntPtr CreateCompatibleDC(IntPtr hDC);
        [DllImport("gdi32.dll")]
        public static extern bool DeleteDC(IntPtr hDC);
        [DllImport("gdi32.dll")]
        public static extern bool DeleteObject(IntPtr hObject);
        [DllImport("gdi32.dll")]
        public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
        #endregion

        #region - USER32 -
        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }

        [DllImport("user32.dll")]
        public static extern IntPtr GetDesktopWindow();
        [DllImport("user32.dll")]
        public static extern IntPtr GetWindowDC(IntPtr hWnd);
        [DllImport("user32.dll")]
        public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);
        [DllImport("user32.dll")]
        public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect);

        #endregion

    #endregion


   private void run_test()
   {

        Rectangle rc = new Rectangle();
        Image img = ScreenToImage(ref rc, false);

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

   }


    private Image ScreenToImage(ref Rectangle rcDest, bool IsPapaer)
    {
        IntPtr handle = this.Handle;

        //this.Handle
        // get te hDC of the target window
        IntPtr hdcSrc = GetWindowDC(handle);
        // get the size
        RECT windowRect = new RECT();
        GetWindowRect(handle, ref windowRect);
        int nWidth = windowRect.right - windowRect.left;
        int nHeight = windowRect.bottom - windowRect.top;

        if (IsPapaer)
        {
            float fRate = (float)rcDest.Width/nWidth;
            //float fHeight = nHeight * fRate;
            //rcDest.Height = (int)(nHeight * fRate);
            //rcDest.Width = (int)(rcDest.Width);// * fRate);
            rcDest.X = 0;
            rcDest.Y = 0;
            rcDest.Height = (int)(nHeight * fRate);
            //rcDest.Width = (int)(nWidth * fRate);
        }
        else
        {
            rcDest.X = 0;
            rcDest.Y = 0;
            rcDest.Height = nHeight;
            rcDest.Width = nWidth;
        }

        // create a device context we can copy to
        IntPtr hdcDest = CreateCompatibleDC(hdcSrc);
        // create a bitmap we can copy it to,
        // using GetDeviceCaps to get the width/height
        IntPtr hBitmap = CreateCompatibleBitmap(hdcSrc, rcDest.Width, rcDest.Height);
        // select the bitmap object
        IntPtr hOld = SelectObject(hdcDest, hBitmap);
        // bitblt over
        StretchBlt(hdcDest, rcDest.X, rcDest.Y, rcDest.Width, rcDest.Height, hdcSrc, 0, 0, nWidth, nHeight, SRCCOPY);
        // restore selection
        SelectObject(hdcDest, hOld);
        // clean up 
        DeleteDC(hdcDest);
        ReleaseDC(handle, hdcSrc);

        // get a .NET image object for it
        Image img = Image.FromHbitmap(hBitmap);
        // free up the Bitmap object
        DeleteObject(hBitmap);
        return img;
    }