//Snippet: CaptureScreen.cs
//Author:  Palle Kristensen
//Shared:  08-oct-2005
//Keywords:BITMAP,BITBLT,GDI32,GRAPHICS,RELEASEHDC,FROMHWND,GETHDC
//
//Captures the primary desktop screen.
//
//-------------------------------------------------------------
public class ScreenCapture
{
   [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
   private static extern bool BitBlt(
      IntPtr hdcDest, // handle to destination DC
      int nXDest, // x-coord of destination upper-left corner
      int nYDest, // y-coord of destination upper-left corner
      int nWidth, // width of destination rectangle
      int nHeight, // height of destination rectangle
      IntPtr hdcSrc, // handle to source DC
      int nXSrc, // x-coordinate of source upper-left corner
      int nYSrc, // y-coordinate of source upper-left corner
      System.Int32 dwRop // raster operation code
      );

   public static Bitmap PerformCapture()
   { 
      Bitmap bm;

      Graphics grfxScreen = Graphics.FromHwnd(IntPtr.Zero);
   
      // Create a bitmap the size of the screen.
      bm = new Bitmap((int) grfxScreen.VisibleClipBounds.Width, (int) grfxScreen.VisibleClipBounds.Height, grfxScreen);
   
      // Create a Graphics object associated with the bitmap.
      Graphics grfxBitmap = Graphics.FromImage(bm);
   
      // Get hdc's associated with the Graphics objects.
      IntPtr hdcScreen = grfxScreen.GetHdc();
      IntPtr hdcBitmap = grfxBitmap.GetHdc();
   
      // Do the bitblt from the screen to the bitmap.
      BitBlt(hdcBitmap, 0, 0, bm.Width, bm.Height, hdcScreen, 0, 0, 0x00CC0020);
   
      // Release the device contexts.
      grfxBitmap.ReleaseHdc(hdcBitmap);
      grfxScreen.ReleaseHdc(hdcScreen);
   
      // Manually dispose of the Graphics objects.
      grfxBitmap.Dispose();
      grfxScreen.Dispose();
      
      return bm;
   }
}