Date: Fri, 10 Oct 1997 21:22:22 -0600
From: vischne AT ibm DOT net
Subject: Final clue in porting zgv from Linux to djgpp
Newsgroups: comp.os.msdos.djgpp,gnu.gcc
Message-ID: <876536360.9710@dejanews.com>
Organization: Deja News Posting Service
Lines: 36
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

For some reason my first post on how to ifdef out Linux-
dependent code in the zgv image viewer program was either
lost or deliberately not posted on my ibm.net news server.

I pointed out that djgpp could indeed compile zgv2.8, using
the ported svgalib library, but there was a problem once
you got zgv.exe to run in a Windows 95/DPMI Dos window:

The `decompressing' message box came up, but never went
away.  On a hunch, I disabled the the messagebox function
so that it wasn't called during the jpeg decompression
loop, and zgv suddenly began to display jpegs and gifs
exactly as under Linux:

The final clue is in the readjpeg.c file.  For some reason,
the progress meter doesn't hook properly.  If you set the
pointer to NULL explicitly in the code, the progress meter
doesn't indicate anything, but the corresponding images (jpeg,
etc.) come up -- QUICKLY!

In fact, after using the CYGWIN32 gcc compiler and the Linux
gcc compiler, I can say that (a) DJGPP is at least as fast
as the Linux gcc and (b) runtime applications appear to run
faster than under Linux.


From zgv2.8/readjpeg.c:

/* read the image */
ptr=theimage; row_stride=pixelsize*width;
+++cinfo.progress = (void *)NULL;
+++howfar = (void *)NULL;
if(pixelsize==1)

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