asked on

Capture screen image in monochrome using BitBlt

Hi,

I am using BitBlt to capture parts of my screen but I then (thanks to AlexFM's help) have to convert to Monochrome (see https://www.experts-exchange.com/questions/21824554/Convert-bitmap-from-24-bit-to-monochrome.html#16524842)

I wondered if there was a way to directly copy an area of screen directly into a monochrome bitmap to save the conversion processing time and to simplify my process.

Many thanks.

James.

AlexFM

Please show your capture code.

JAMES

ASKER

This is the code :-

            public Bitmap GetWindowCaptureAsBitmap(IntPtr handle, int x, int y, int width, int height)
            {
                  Win32.Rect rc = new Win32.Rect();
                  if (!Win32.GetWindowRect(handle, ref rc))
                        return null;

                  // create a bitmap from the visible clipping bounds of the graphics object from the window
                  // Bitmap bitmap = new Bitmap(rc.Width, rc.Height);
                  Bitmap bitmap = new Bitmap(width, height);

                  // create a graphics object from the bitmap
                  Graphics gfxBitmap = Graphics.FromImage(bitmap);

                  // get a device context for the bitmap
                  IntPtr hdcBitmap = gfxBitmap.GetHdc();

                  // get a device context for the window
                  IntPtr hdcWindow = Win32.GetWindowDC(handle);

                  // bitblt the window to the bitmap
                  Win32.BitBlt(hdcBitmap, 0, 0, width, height, hdcWindow, x, y, (int)Win32.TernaryRasterOperations.SRCCOPY);

                  // release the bitmap's device context
                  gfxBitmap.ReleaseHdc(hdcBitmap);
                  Win32.ReleaseDC(handle, hdcWindow);

                  // dispose of the bitmap's graphics object
                  gfxBitmap.Dispose();

                  // return the bitmap of the window
                  return bitmap;
            }

Thanks.

ASKER CERTIFIED SOLUTION

AlexFM

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

JAMES

ASKER

Again, Alex, many thanks for your help.

I will capture in colour and use your previous routine to convert.

Cheers.

James.