Newsgroups:	comp.os.msdos.djgpp
Subject:	Porting the zgv program using djgpp
Distribution:	world
From:	vischne AT ibm DOT net-nospam (root)
Organization:	The Light
MIME-Version:	1.0
NNTP-Posting-Host:	32.100.34.213
Message-ID:	<343e6b21.0@news3.ibm.net>
Date:	10 Oct 97 17:51:29 GMT
Lines:	26
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Linux has an image-file viewer with an outstanding interface.  It's called
zgv, and the source code is available.

I checked it out.  It uses svgalib, which has been ported to djgpp, and it
uses a few calls to the Linux system that are localized in zgv.c and don't
seem to do very much under Dos or Windows32/95/nt.  I got rid of the Linux
calls using an `#ifdef __DJGPP' here and there, and then I discovered that
zgv reads the keyboard using the `read()' library function.  And, it assumes
that it gets back vt100 escape sequences for the function and arrow keys.
So, that got changed to getkey() with a translation table for the DJGPP
<key.h> equivalents of the internal zgv keys (and a line of code that says
that, when getkey() returns '\r', translate that to '\n').  Also, as is
customary with other Dos apps, zgv's use of `fopen(name, "rb")' for image 
files doesn't return what you expect under Unix, so I changed the code to 
indicate success whatever.

Now, I have zgv.exe running in a full-screen, DPMI-enabled, Dos window under
Windows 95.  It accepts keyboard input, but can't find the mouse, something
that also happens under Linux.  And, it reads bitmap files, but not gif or 
jpeg.  I get perfect displays of Linux zgv thumbnail files, and all the keys 
for manipulating intensity, contrast, and size work perfectly.  Only, the 
messagebox about waiting for jpeg decodes never exits.

By the way, zgv.exe (2.8) under Dos looks exactly like zgv.exe under Linux.
Now, if the jpeg handling gets cleared up.

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