#242 Problems using djvulibre.dll

[Michal Rudolf]

I am developing djview4poliqarp, a tool based on djvulibre/djview4: https://bitbucket.org/mrudolf/djview-poliqarp. Recently the code was ported to Qt 5 and since then I am not able to run Windows version.

My (not so much) educated guess is that the problem is caused by interaction between Qt and DjVuLibre DLL (see the crash log attached). Maybe you will be able to suggest where to look for a solution?

PS. I tried newest version of Qt 4.8.x (4.8.6) and djview4poliqarp crashes there as well. Before I used 4.8.3 in Windows with no problems at all.

[Leon Bottou]

1- I understand that the linux version works well.
Did you try running "valgrind" on the linux version?

2- Which version of the djvulibre library are you using :
- your fork or the default version?
- if the default, which version?
- what is DDJVUAPI_VERSION in ddjvu.h?

3- How did you merge my changes to djview into your code?
Are you using a subset of the files that you keep in order?

4- Windows specific questions:
* Are you sure you use the same version
for the dll (.dll) and the import library (.lib)
* Are you sure the version of Qt you are using
was compiled with the same compiler (msvc11 vs msvc12)
as your code (otherwise you pull multiple versions of
msvcrt into the same program...)

Otherwise there is unfortunately very little I can do for you.
I might close this bug very soon...

• L.

On Thursday, September 04, 2014 08:09:01 PM Michal Rudolf wrote:

---

[bugs:#242] Problems using djvulibre.dll

Status: open
Group: djview
Created: Thu Sep 04, 2014 08:09 PM UTC by Michal Rudolf
Last Updated: Thu Sep 04, 2014 08:09 PM UTC
Owner: nobody

I am developing djview4poliqarp, a tool based on djvulibre/djview4:
https://bitbucket.org/mrudolf/djview-poliqarp. Recently the code was ported
to Qt 5 and since then I am not able to run Windows version.

My (not so much) educated guess is that the problem is caused by interaction
between Qt and DjVuLibre DLL (see the crash log attached). Maybe you will
be able to suggest where to look for a solution?

PS. I tried newest version of Qt 4.8.x (4.8.6) and djview4poliqarp crashes
there as well. Before I used 4.8.3 in Windows with no problems at all.

---

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[Janusz]

As a user of the program in question (at the moment the only one) I thank you for your answer.

Michał is away for a few days (till Monday) and may not have acces to e-mail till his return, but I think I'm able to answer the Linux question.

I've compiled it on Debian jessie (testing) with QT5 and from the user point of view it seems to work correctly but it has not yet been intensively tested.

Following an advice on the Internet about using valgrind (I never used it before) I've run

valgrind --leak-check=full -v djview4poliqarp`

and got

ERROR SUMMARY: 685 errors from 497 contexts (suppressed: 2 from 1)

I enclose the complete log.

Best regards

Janusz

[Michal Rudolf]

Thanks for quick answer!

1- I understand that the linux version works well.
Did you try running "valgrind" on the linux version?
Yes, OS X and Linux versions work find.

2- Which version of the djvulibre library are you using :
- your fork or the default version?
- if the default, which version?
- what is DDJVUAPI_VERSION in ddjvu.h?
Default, DDJVUAP_VERSION=21

3- How did you merge my changes to djview into your code?
Are you using a subset of the files that you keep in order?
Yes, I update the qdjvu* files from git from time to time.

4- Windows specific questions:
Are you sure you use the same version
for the dll (.dll) and the import library (.lib) Are you sure the version of Qt you are using
was compiled with the same compiler (msvc11 vs msvc12)
as your code (otherwise you pull multiple versions of
msvcrt into the same program...)
I guess this is the source of the problems. Unfortunately, I don't have MSVC, so I have to use MINGW. I suspect that never versions of Qt for Windows use slightly different MINGW version which causes the problems with the DLL I compile myself.

One more think to try is to try to build DjvuLibre on Windows, but I guess that requires installing a lot of Unix tools there (for now I am crosscompiling djvulibre on Linux using MINGW)

Maybe it is possibly to compile and link djvulibre statically? I guess that may solve the problem, but I wasn't able to do it (I tried ./configure --enable-static, but it fails when using Windows MINGW).

Best regards

[Leon Bottou]

I always compile the windows version of djview with visual studio because this
ends up being less trouble. You should try with the free "Visual Studio
Express for Windows Desktop" available from http://www.visualstudio.com/en-us/downloads/.

See the instructions inside the INSTALL file of the djview tarball. Instead of
compiling Qt yourself, you can use precompiled versions of Qt for the correct
visual studio version.

I will close the bug report for now.

• L.

[Leon Bottou]

Closing the bug report.

Note that using old versions of Qt is quite okay under windows, since you also have to distribute the DLLs.