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            public static void Snapshot(string fileName, Rectangle rectangle)
            {
                //Use a zeropointer to get hold of the screen context
                IntPtr deviceContext = GetDC(IntPtr.Zero);
                using (Bitmap capture = new Bitmap(rectangle.Width, rectangle.Height))
                //Get screen context
                using (Graphics deviceGraphics = Graphics.FromHdc(deviceContext))
                //Get graphics from bitmap
                using (Graphics captureGraphics = Graphics.FromImage(capture))
                {
                    // Blit the image data
                    BitBlt(captureGraphics.GetHdc(), 0, 0,
                        640, rectangle.Height, deviceGraphics.GetHdc(),
                       70, rectangle.Top, SRCCOPY);
                    //Save to disk
                    capture.Save(fileName, System.Drawing.Imaging.ImageFormat.Png);
                }

            }                    

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BOOL StretchBlt(
  HDC 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
  HDC 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
  DWORD dwRop       // raster operation code
);                    

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        public class Capturer
        {
            // Declarations
            [DllImport("coredll.dll")]
            public static extern int BitBlt(IntPtr hdcDest, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hdcSrc, int nXSrc, int nYSrc, uint dwRop);

            [DllImport("coredll.dll")]
            private static extern IntPtr GetDC(IntPtr hwnd);

            const int SRCCOPY = 0x00CC0020;

            [DllImport("gdi32.dll", SetLastError = true)]
            public static extern int StretchBlt(IntPtr hdcDest, int nXDest, int nYDest,int nWidthDest, int nHeightDest, IntPtr hdcSrc, int nXSrc, int nYSrc, int nWidthSrc, int nHeightSrc,
                uint dwRop);



            public static void Snapshot(string fileName, Rectangle rectangle)
            {
                //Use a zeropointer to get hold of the screen context
                IntPtr deviceContext = GetDC(IntPtr.Zero);
                Bitmap newImage = new Bitmap(newImage.Width, newImage.Height);

                //Get screen context
                using (Graphics deviceGraphics = Graphics.FromHdc(deviceContext))
                //Get graphics from bitmap
                using (Graphics captureGraphics = Graphics.FromImage(capture))
                {
                    // Blit the image data
                  /*  BitBlt(captureGraphics.GetHdc(), 0, 0, 640, rectangle.Height, deviceGraphics.GetHdc(),
                       70, rectangle.Top, SRCCOPY);*/

                        StretchBlt(captureGraphics.GetHdc(), 0, 0, 200, 100, deviceGraphics.GetHdc(), 70, 0, 570, 480, SRCCOPY);
                    }


                    //Save to disk
                    capture.Save(fileName, System.Drawing.Imaging.ImageFormat.Png);
                }

            }                    

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Bitmap newImage = new Bitmap(newImage.Width, newImage.Height);                    

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private void SaveScreenshot(string filename, Size size)
{
    using (Bitmap bitmap = new Bitmap(1280, 1024))
        using (Graphics graphics = Graphics.FromImage(bitmap))
        {
            graphics.CopyFromScreen(0, 0, 0, 0, bitmap.Size);
            graphics.DrawImage(bitmap, new Rectangle(Point.Empty, size), new Rectangle(Point.Empty, bitmap.Size), GraphicsUnit.Pixel);
            new Bitmap(bitmap, size).Save(filename);
        }
}