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Thread: JPEG plugin problem

  1. #1
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    Angry JPEG plugin problem

    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?
    Last edited by AndyBrice; 10th April 2012 at 15:54.

  2. #2
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    Default Re: JPEG plugin problem

    Shouldn't it be plugins/imageformats?

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    Default Re: JPEG plugin problem

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

    Quote Originally Posted by Lykurg View Post
    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.
    Last edited by AndyBrice; 10th April 2012 at 17:09.

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    Default Re: JPEG plugin problem

    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  5. #5
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    Default Re: JPEG plugin problem

    Quote Originally Posted by wysota View Post
    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.

  6. #6
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    Default Re: JPEG plugin problem

    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.

  7. #7
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    Default Re: JPEG plugin problem

    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>

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