[SOLVED] mainWidget()

[mickey]

I'd like to do this below but don't work....w is null (000000):

MainForm* w;
w=(MainForm*) qApp->mainWidget()
cout << w;

MainForm* w;
w=(MainForm*) qApp->mainWidget()
cout << w;

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Why this?

[zlatko]

So you never set main widget for your app before

[jpn]

So you never set main widget for your app before

Or it's not type of MainWindow*..

[jacek]

Or it's not type of MainWindow*..

This would be true only in case of dynamic_cast<>.

[mickey]

the code above is in mywidget class;
I set mainWidget in main.cpp:

int main( int argc, char ** argv )
{
    QApplication a( argc, argv );
 
    MainForm w;
	w.resize(600,500);
	a.setMainWidget(&w);
    w.show();
    a.connect( &a, SIGNAL( lastWindowClosed() ), &a, SLOT( quit() ) );
    return a.exec();
}

int main( int argc, char ** argv )
{
    QApplication a( argc, argv );
 
    MainForm w;
	w.resize(600,500);
	a.setMainWidget(&w);
    w.show();
    a.connect( &a, SIGNAL( lastWindowClosed() ), &a, SLOT( quit() ) );
    return a.exec();
}

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[jacek]

Where do you invoke "qApp->mainWidget()"?

[mickey]

in mywidget.h (in constructor):

MyWidget::MyWidget( QWidget *parent, const char *name)
        :  QGLWidget ( parent, name, shareWidget )
{	
	 setFormat(QGLFormat(DoubleBuffer | DepthBuffer));
	w=(MainForm*) qApp->mainWidget();
}

MyWidget::MyWidget( QWidget *parent, const char *name)
        :  QGLWidget ( parent, name, shareWidget )
{	
	 setFormat(QGLFormat(DoubleBuffer | DepthBuffer));
	w=(MainForm*) qApp->mainWidget();
}

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[jacek]

MainForm w; // <-- here you invoke qApp->mainWidget()
w.resize(600,500);
a.setMainWidget(&w); // <-- and here you set the main widget

MainForm w; // <-- here you invoke qApp->mainWidget()
w.resize(600,500);
a.setMainWidget(&w); // <-- and here you set the main widget

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How do do you expect it to work?

Edit: You can use "this", instead of qApp->mainWidget().

[mickey]

this? In constructor widget? I don't understand; this below don't compile.

w=(MainForm*) this->mainWidget();

w=(MainForm*) this->mainWidget();

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Do you say this?

[jacek]

Do you say this?

I meant:

w = this;

w = this;

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Edit: OK, I just noticed that you have MainForm and MyWidget. In this case you can probably use parent.

[mickey]

It compile but Bug error occurs....
Furthermore I must code this below.....and sender and receiver are the same and don't work connect....

connect(this, SIGNAL(myUpdate()), w ,SLOT(updateWidgets()) );

connect(this, SIGNAL(myUpdate()), w ,SLOT(updateWidgets()) );

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[jacek]

It compile but Bug error occurs....
Furthermore I must code this below.....and sender and receiver are the same and don't work connect....

Then try "w = parent" if the main window is the parent of your widget.

[mickey]

This don't work:

Then try "w = parent" if the main window is the parent of your widget.

( console says "parent" isn't the correct receiver() for my connect)
This works:

w= (MainForm*)this->topLevelWidget();

w= (MainForm*)this->topLevelWidget();

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Thanks for help!