JPEG plugin problem

[AndyBrice]

The JPEG .dll dynamic plugin works fine on my Windows development machine, but I can't get it to work when my software is deployed to a clean Windows machine.

I have tried searching the Qt documentation, this forum, stackoverflow.com, Google etc and fiddling with paths and qt.conf. No luck.

I am deploying like this:


myapp.exe
Qt*4.dll
\Microsoft.VC80.CRT
--- Microsoft.VC80.CRT.manifest
--- msvcp80.dll
--- msvcr80.dll
\imageformats
--- qjpeg4.dll


The .exe runs fine and can handle PNG and other formats, but QImage::load() just returns false every time for JPEG.

I have looked at qjpeg4.dll in the MS Depends tool and it only requires the same DLLs as my .exe (QtCore4.dll, QtGui4.dll, msvcp80.dll, msvcr80.dll).

I am using the standard Qt 4.8.0 Windows build downloaded from Nokia.

The main problem is the complete lack of any feedback or error message. QImage::load() just returns false for JPEG. No other clue. It is very frustrating. Any ideas?

[Lykurg]

Shouldn't it be plugins/imageformats?

[AndyBrice]

Probably should have posted this in http://www.qtcentre.org/forums/5-Ins...and-Deployment. Apologies.

Shouldn't it be plugins/imageformats?

Not from what I read in the Qt documentation. But I did try this and it didn't work.

---

Added after 1 15 minutes:

This is displayed in the plugin cache in the Windows registry after the .exe is run:

40800
0
Windows msvc release full-config
2012-01-19T22:18:20

So it looks like the plugin DLL is being found.

[wysota]

Check what QImageReader::supportedImageFormats() returns.

[AndyBrice]

Check what QImageReader::supportedImageFormats() returns.

Only the built in formats are listed (e.g. PNG). JPG/JPEG is not listed.

I have added:

DEFINES += QT_NO_PLUGIN_CHECK

Still no clue.

[Michael Druckenmiller Sr]

The first question I have is where are you running your script from.

I had a similar problem.

I had copied my entire Python 2-7-2 directory to an App directory on portable media.

Everything worked fine except for a .jpeg graphic I had included in a textBrowser to help the operator know what to do.

BTW there is a jpeg plugin that comes standard.


What I discovered is that when you install pyQT two qt.conf files are generated one in my Python root and one in pyQt4 root in site-packages.

If the paths in those .conf's are not correct QT can not find it's libraries.

They can be edited in Notepad (assuming windows).

Hopefully, your issue is this simple.

[AndyBrice]

I found the problem:

http://lists.qt.nokia.com/pipermail/...er/013783.html

I just rebuilt the plugin with:

CONFIG-=embed_manifest_dll

Another one of these stupid side-by-side assembly/manifest issues that have wasted so much of my time. I must have spent 8 hours trying to work this out. How is that an improvement over 'DLL Hell'? <Thinks dark thoughts about Microsoft>