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- Path: macshack.com!not-for-mail
- From: mikemc@macshack.com (Mike McCammant)
- Newsgroups: comp.graphics.algorithms,comp.lang.c++,comp.os.ms-windows.programmer.graphics,comp.os.ms-windows.programmer.multimedia,comp.os.ms-windows.programmer.win32
- Subject: Re: IJG JPEG Engine and Win32
- Date: 3 Jan 1996 22:09:36 -0500
- Organization: Mac's Shack - The "Whole Family" Internet Solution c/o macshack@randomc.com
- Message-ID: <4cfgdg$mhl@macshack.com>
- References: <4cemir$6vb@redstone.interpath.net>
- Reply-To: mikemc@macshack.com
- NNTP-Posting-Host: localhost.macshack.com
-
- In article <4cemir$6vb@redstone.interpath.net>,
- Jumpstile Turner <fortunat@interpath.com> wrote:
- > Hi all. Has anyone successfully compiled and linked the IJG JPEG engine
- >with a Win32 compiler? I can compile it fine and the resulting LIB file works
- >great when linking it into the included test applications; however, if I try
- >to link it with my GUI apps I get some really odd errors. It links fine but
- >doesn't work! I'm using Borland C++ 4.52 (maybe this is my problem. (-: )
- >Basically stepping through with the debugger there is an assignment statement
- >in one of the modules that just doesn't do anything. I mean nothing. If I do
- >the assignment by hand with the debugger it works. For example, the
- >assignment is as follows:
- >
- > cinfo->output_width = cinfo->image_width;
- >
- >cinfo->output_width is 0 and cinfo->image_width is say 289. After the above
- >assignment nothing changes. I'm far from a c++ expert and I've never
- >encountered something like this before. If someone has compiled this lib
- >under Win32 I'd appreciate it if they could mail it my way. I'd like to see
- >if its my compiler settings or just my ignorance. ;) The big problem I can't
- >figure is that the compiled lib works fine linked with the test programs. I
- >tried copying the code from the examples line for line but it just won't work
- >under the GUI.
-
- I also have the libs "working", compiled under VC++ 2.2. There are some
- weird problems, mainly with the cinfo variables not tracking right. It is
- probably something dumb on my part. I had a problem with:
-
- if( cinfo.next_scanline < cinfo.image_height) {
- blah blah...;
- jpeg_write_scanlines(blah);
- }
-
- cinfo.next_scanline stays at 0. I fixed this by adding a tracking
- uint variable scanline into the loop and compared it to cinfo.image_height.
-
- scanline = 0;
-
- while( (cinfo.next_scanline < cinfo.image_height) &&
- ((unsigned int) scanline < cinfo.image_height) ) {
- blah blah...;
- jpeg_write_scanlines(blah);
- scanline++;
- }
-
- Although this did not fix the lib, it did get my project going.
-
- It seems that the cinfo variables do not auto-increment at all.
-
- I was going to compile/link project with all the modules directly
- instead of using a static lib, that way I could debug it all
- easier. Well, too much code, too little time. Plus the project
- was working so why? ;)
-
- If you do figure out what it is, I would like to fix my libs too.
-
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- --
- Mike - mikemc@macshack.com - Home of the JEO-Counter, graphic WWW counter
- /---------------------------------------\ My opinions belong to me,
- | Visit us at http://www.macshack.com | myself and I, not my employer,
- \......................................./ the government or my wife...:)
-