Masked Blitting of 232-bit BMP images.

Hi,
     I am loading up a 32-bit BMP image using one HBITMP for the color data
and another for the Mask. I am calculating the mask during load-time by
checking the high-byte of the dword value. If it is lesser than 127, I am
setting the pixel in the monochrome mask to RGB(0,0,0) and if it is greater
I am setting it to RGB(255,255,255).
 The mask does seem to get created correctly, but when I use MaskBlt(), the
area to be drawn seems to be as the background. What I mean is that the
background raster OP seems to be affecting the image drawn .. Isn't there
any RASTER NOP which can be used? This is the call I am using to draw the
bitmap :-

      MaskBlt(m_backDC, bX, bY,
              winBmp->width(), winBmp->height(),
              winBmp->getDC(),
              0, 0,
              winBmp->getMask(),
              0, 0,
              MAKEROP4(SRCCOPY,0));

The source image is a red circle (non-masked area). The final blit shows a
black circle for the same area!

Can you please guide me as to what could be going wrong? Any hints, tips,
suggestions would be appreciated.

Regards,
Varun

Not sure exactly the problem:-

try this:- MAKEROP4(SRCCOPY , 00AA0029) or

MAKEROP4(00AA0029 , SRCCOPY)





data
greater
the

Hi Vipin,
               The first version worked perfectly. Thanks a lot! 32-bit BMPs
have a pretty weird format and I think I was reading them wrong. I shifted
to 32-bit TGAs and all worked fine but only with your raster OP code. What
does it  mean btw?

Regards,
Varun

00AA0029  is the rop code for D(Destination).

It says in the areas where there is 1 in the mononchrome mask,
don't overwrite the destination,meaning don't touch the destination pixels
corresponding to those pixels.

thanks
vipin








BMPs

Ok, thats what I needed I guess. A Background Raster NOP. :)

Is there any place where we can get all the code combinations or a
description of the format? Because in the header files (gdi.h) I can only
see a few combinations.

Thanks,
Regards,
Varun

ms-help://MS.MSDNQTR.2002JAN.1033/gdi/pantdraw_6n77.htm








pixels