Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!cadence!acae037!eversole
From: eversole@acae037.cadence.com (Richard Eversole; x6239)
Newsgroups: comp.os.msdos.programmer
Subject: Re: DOS or MS C Graphics
Message-ID: <1991Mar21.232815.24693@cadence.com>
Date: 21 Mar 91 23:28:15 GMT
References: <65023@eerie.acsu.Buffalo.EDU> <31600013@hpcvra.cv.hp.com.>
Sender: usenet@cadence.com (USENET News)
Reply-To: eversole@acae037.cadence.com (Richard Eversole; x6239)
Organization: Cadence Design Systems, Inc.
Lines: 23

In article <31600013@hpcvra.cv.hp.com.>, everett@hpcvra.cv.hp.com. (Everett Kaser) writes:
|> 
|> About the only way to do this on PC display hardware is to read the current
|> background image (using _getimage()) into a scratch save buffer, then use
|> _putimage(,,,_GPSET) to force your new image onto the screen.  Then, when
|> you want to move your image, you first use _putimage(,,,_GPSET) to replace
|> the previous background image (using the saved image from the scratch buffer)
|> and then repeating the previous _getimage()/_putimage() at the new location.

That will only work if the images involved are rectangular. You need to 
use a mask and GPXOR it first then GPAND the real image. You still have to
save the original background. Be careful about moving the image only a small
amount where the next image overlaps the last image. restore background,
get new back ground, xor mask, and the image.


-- 
  
  =====================================================================

    eversole@cadence.com
  
    Live long and prosper !