Calling function from reimplemented QApplication / notify

McLion

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?

sierdzio

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

McLion

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 ?!?

sierdzio

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.

McLion

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.

topse

run qmake?

McLion

qmake didn't help.

McLion

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

McLion

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.

McLion

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++?

topse

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.

McLion

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)?

topse

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...