General question about 3rd Party Widgets



  • Hello All,
    I'm completely new to QT Creator, but am a profession C++ developer. I've been googling around and cannot seem to find an answer to this question.

    I have downloaded the wwwidgets source (I'm on Ubuntu). My question is: should I be able to set these up to be available to drag onto a form in the GUI designer?

    Thanks in advance.


  • Qt Champions 2017

    Hi and welcome to the forums.
    "downloaded the wwwidgets source"
    What source ? Its unclear what 3rd Party Widgets you have source for.
    i assume these
    http://www.wysota.eu.org/wwwidgets/
    it says "All widgets can be used directly from within Qt Designer"

    So it should produce SO files for Designer.
    Note that to use them in Creator/designer, it should be build in
    release mode and use same Qt version as the Creator you use. or at least close to.
    Also, dont use a gcc too far in version number than the one shown in
    Creators "about" menu where you
    also see the Qt version.
    On windows, this must match 100%, but in linux is a bit more relaxed but
    it would not load a Qt5.8 plugin in a 5.7 Creator.

    If there is no plugin for the widgets , you can still use them visually with the
    promotion feature if u just want to check them out.
    http://doc.qt.io/qt-5/designer-using-custom-widgets.html
    Basically, you first place a widget on a form, then tell Designer the
    name and .h file of a custom widgets. its then used as type so when program runs
    its the promoted-to type/class that you see and not the plain QWidget.
    However, this dont allow setting attributes visually.

    Update:
    Had a look at the source.
    After make install step , you should be able to start Creator and see then in designer.
    If nothing there. Check SO files been copied to plugin folder.
    Its based under Tools
    "C:\Qt\Tools\QtCreator\bin\plugins\designer"
    ( should be same relative location in nix)
    If the SO files are there - but not in Creator-Designer.
    then you can set QT_DEBUG_PLUGINS (export) in a shell and start Creator from same shell to get info when it tried to load the plugins.
    as in
    export QT_DEBUG_PLUGINS=1; /fullpath/qtcreator
    That should give hint on why they are not being loaded.



  • Many thanks for all that information - you're a top bloke !

    After compiling in Release, and running sudo make install, the SO files are copied into /usr/lib/x86_64-linux-gnu/, not the plugin folder you mentioned. I have tried manually moving them, but they still do not appear.

    So I launched QT with the debug plugin set, and can see lots of different .so files being loaded - but none of them are from libwwwidgets4.so etc (There's no mention of them not loading either).

    I'm probably missing something stupid here. Can you help and further ?

    Edit : I have now added the files to /usr/ubuntu-sdk-ide/lib/Qt/plugins/designer
    and they appear as failed plugins under Tools->Form Editor - About QT Plugins due to verification error.
    I'm building a release build by loading the widgets.pro from within the designer, and now manually copying the .so files into the folder above.

    Any advice would be greatly appreciated.


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Designer plugins needs to be built with the same version of Qt as was used to build designer. You may have a mismatch there.


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