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Thread: plugin in a library

  1. #1
    Join Date
    May 2008
    Posts
    61
    Thanks
    9
    Qt products
    Qt4
    Platforms
    Unix/X11 Windows

    Default plugin in a library

    hi,

    i have been trying to import plugins to a library and link that library to another application.

    the library pro file is as the following:
    Qt Code:
    1. TEMPLATE = lib
    2. HEADERS += testFile.h
    3. SOURCE += testFile.cpp
    4. CONFIG += debug static
    5. RESOURCES += testFile.qrc # the images are stored as resources
    6. QTPLUGIN += qjpeg
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    I use the Q_IMPORT_PLUGIN(qjpeg) in the library source file.

    the content of the application pro file is as follows:
    Qt Code:
    1. TEMPLATE = app
    2. SOURCES += main.cpp
    3. CONFIG += debug qt x11
    4. LIBS += libTestFile.a # the library mentioned above
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    the code block is as follows:
    Qt Code:
    1. int main(int argc, char* argv[])
    2. {
    3. QApplication app(argc, argv);
    4. testFile file1; // constructs a toolbar having an icon (a jpeg image is used as icon)
    5. file1.show(); // shows the toolbar
    6. return app.exec();
    7. }
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    without using the libraries and embedding the library code into the application code, the jpeg file is displayed correctly.

    when using libraries, the jpeg plugin's static library is not linked to my library and when I compile the application, I get an error message regarding the Q_IMPORT_PLUGIN (undefined reference to qt_plugin_instance_qjpeg()). when I add
    Qt Code:
    1. QTPLUGIN += jpeg
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    to the pro file of the application, the application is built but the image is not visible on the toolbar.

    how can I embed the images to the library and use it in the application ?

  2. #2
    Join Date
    May 2008
    Posts
    61
    Thanks
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    Qt products
    Qt4
    Platforms
    Unix/X11 Windows

    Default Re: plugin in a library

    I have found the reason why the image is not displayed.

    since the resource is linked to a static library, it is necessary to call
    Qt Code:
    1. Q_INIT_RESOURCE(resourceName)
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    in the application in order to use the resources properly.

  3. #3
    Join Date
    May 2008
    Posts
    61
    Thanks
    9
    Qt products
    Qt4
    Platforms
    Unix/X11 Windows

    Default Re: plugin in a library

    is it possible to link the jpeg library to the custom created library or is it a must to link it to the main application ?

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