🚀 go-pugleaf

fortunat@interpath.com (Jumpstile Turner) 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 had the same problem. It turned out that the data alignment settings
were different for the library and the application, which means that
the application and the library expect the data items in a struct to
be at different adresses. This is why your debugger doesn't see any
change in the variables. You should also take care for redefinitions
of boolean, which is declared to be a (32 bit) int in the jpeg
headers, but to be a (8 bit) character in Microsofts rpc.h.


--
Dr. Johannes Stahl   Abt. Radiodiagnostik
Radiologische Klinik, D66421 Homburg/Saar (GERMANY)
Tel.: +49 6841 164600  Fax: +49 6841 164696
e-mail: rajsta@med-rz.uni-sb.de
http://www.med-rz.uni-sb.de/med_fak/radiodiagnostik/index.html