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Calling function from reimplemented QApplication / notify

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  • McLionM Offline
    McLionM Offline
    McLion
    wrote on last edited by
    #1

    Hi

    I am having issues calling a function from my main class from the reimplemented QApplication / notifier.
    I am getting:
    @main.cpp:(.text._ZN13MyApplication6notifyEP7QObjectP6QEvent[MyApplication::notify(QObject*, QEvent*)]+0x94): undefined reference to `TouchEventForTCO(int, int, int)'
    collect2: ld returned 1 exit status@

    code snippet:
    @class MyApplication : public QApplication
    {
    public:
    MyApplication(int &argc, char **argv ) : QApplication(argc, argv)
    {
    }

    virtual bool notify ( QObject *receiver, QEvent *event )
    {
      switch( event->type() )
      {
        case QEvent::MouseButtonPress:
        case QEvent::MouseButtonRelease:
        case QEvent::MouseMove:
        case QEvent::MouseButtonDblClick:
        {
          if(bTouchActive)
          { QMouseEvent *TEvent = static_cast<QMouseEvent *>(event);
            QPoint cursorPos = TEvent->globalPos();
            TouchEventForTCO(event->type(), cursorPos.rx(), cursorPos.ry());
            qDebug("Touch/Mouse event type: %d at %d, %d", event->type(), cursorPos.rx(), cursorPos.ry());
          }
          else
    

    @

    Any idea what I am doing wrong?

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    • sierdzioS Offline
      sierdzioS Offline
      sierdzio
      Moderators
      wrote on last edited by
      #2

      Your linker does not see TouchEventForTCO in the libraries/ objects it was given. You probably should include the library where that method comes from.

      (Z(:^

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      • McLionM Offline
        McLionM Offline
        McLion
        wrote on last edited by
        #3

        Yeah, that's what I know as well so far.
        TouchEventForTCO is in class QTGUI_MainWindow and the code snippet posted before in in the qtgui_mainwindow.h where QTGUI_MainWindow is defined. The function itself is in qtgui_mainwindow.cpp and I added an extern to the qtgui_mainwindow.h.

        I just dont know what is wrong or incomplete ?!?

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        • sierdzioS Offline
          sierdzioS Offline
          sierdzio
          Moderators
          wrote on last edited by
          #4

          Again: the error you are getting does not come from the compiler: so all the C++ includes are fine. The linker does not see the (already compiled) object code, which means something is wrong in your build setup. Either a library not included, or qtgui_mainwindow.o is not present.

          (Z(:^

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          • McLionM Offline
            McLionM Offline
            McLion
            wrote on last edited by
            #5

            Hmmm...
            If I only comment out the call
            @TouchEventForTCO(event->type(), cursorPos.rx(), cursorPos.ry());@

            everything builds and runs perfect.
            qtgui_mainwindow.o is present.

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            • T Offline
              T Offline
              topse
              wrote on last edited by
              #6

              run qmake?

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              • McLionM Offline
                McLionM Offline
                McLion
                wrote on last edited by
                #7

                qmake didn't help.

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                • McLionM Offline
                  McLionM Offline
                  McLion
                  wrote on last edited by
                  #8

                  Anybody else an idea what I have set wrong to have the linker giving this error?

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                  • McLionM Offline
                    McLionM Offline
                    McLion
                    wrote on last edited by
                    #9

                    Solved it. Changed call to:
                    @QTGUI_MainWindow::TouchEventForTCO(event->type(), cursorPos.rx(), cursorPos.ry()); @
                    and made TouchEventForTCO() static and public.

                    I don't know if this is the "correct" way .. however, it works :)
                    Thanks everybody for their help.

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                    • McLionM Offline
                      McLionM Offline
                      McLion
                      wrote on last edited by
                      #10

                      Too happy too soon ;)

                      I can now call TouchEventForTCO() and also read the arguments, copy them ... whatever. However, as soon as I call another function from inside TouchEventForTCO() I get back to the same problem and I get:
                      @..\src\qtgui_mainwindow.cpp: In static member function 'static void QTGUI_MainWindow::TouchEventForTCO(int, int, int)':
                      ..\src\qtgui_mainwindow.cpp:1851: error: cannot call member function 'void QTGUI_MainWindow::PrepareForTCO(QByteArray*)' without object
                      @
                      I somehow cant believe that I have to make every function public that need to be called down the line.
                      How do I solve this the correct way in C++?

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                      • T Offline
                        T Offline
                        topse
                        wrote on last edited by
                        #11

                        You are really not having Qt-Trouble, bu C++ trouble...

                        Check C++ - tutorials, what static means pls :-/ In short: Static-Functions are called without an object. So you cant call non-static-functions from within a static function, because non-static function need an object.

                        "static functions" in object oriented world is comparable to "global functions" in functional world, but static functions belong to a classes namespace.

                        Best Regards.

                        1 Reply Last reply
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                        • McLionM Offline
                          McLionM Offline
                          McLion
                          wrote on last edited by
                          #12

                          You're right. It's a C++ issue, not Qt.
                          So, making TouchEventForTCO() static and public is not the correct way, I assume. If not, how do I call QTGUI_MainWindow::TouchEventForTCO from the MyApplication::notify in the other class then (see code snippets above)?

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                          • T Offline
                            T Offline
                            topse
                            wrote on last edited by
                            #13

                            I cant really tell you with that little code-examples... regarding your very first post it seems that you have not implemented your constructor. Another C++-thing...

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