connect

[mickey]

hi, why do I have this console error?? thanks


//my is a pointer to MainForm class
//I'm inside MyWidget constructor
connect (my->pushButton21, SIGNAL (pressed()), this, SLOT (mySlot()) );
QObject::connect: Cannot connect (null)::pressed() to MyWidget::mySlot()

[jacek]

Maybe because my->pushButton21 is null?

[mickey]

ok. but why is it null? button21 is a button of mainform; how do I use it?

[jacek]

ok. but why is it null? button21 is a button of mainform; how do I use it?
How do you create that "my" object? Maybe you create MyWidget before you initialize button21?

[mickey]

hi, I don't understand qaht you want say.....the situation is this..


MyWidget::MyWidget( QWidget *parent, const char *name, const QGLWidget* shareWidget)
: QGLWidget ( parent, name, shareWidget){
my = (myMainForm*) this->topLevelWidget();
connect (w->pushButton21, SIGNAL (pressed()), this, SLOT (myStartTimer()) );
}

[jacek]

Could you post myMainForm constructor?

[mickey]

do u want this?


myMainForm::myMainForm( QWidget* parent, const char* name, WFlags fl )
: MainForm( parent, name, fl )
{
..............
}

[jacek]

do u want this?
Yes, do you initialize pushButton21 there?

[mickey]

Yes, do you initialize pushButton21 there?
what do you mean? I insert butt21 from designer....

[jacek]

I insert butt21 from designer....
In that case maybe this is wrong:
my = (myMainForm*) this->topLevelWidget();
What happens when you use dynamic_cast?

my = dynamic_cast< myMainForm*>( topLevelWidget() );
Q_CHECK_PTR( my );

[mickey]

a rutime error!!! and application is closed...
and without casting (my way) Q_CHECK_PTR( my ); doens't get any arror...
but my is:

myMainForm* my;

[jacek]

a rutime error!!! and application is closed...
This means that topLevelWidget() might return some other widget than myMainForm.

[mickey]

hi, using that bellow


myw = (myMainForm*) this->topLevelWidget();

it print the follow pointer


my_mainfom in myWidget 0012E388
mainfom this in MainForm 0012E388
my_mainfom this in myMainForm 0012E388

so myw in MyWidget point to mainForm.....have you any idea? thanks

[mikro]

if you created the window in the designer you have to call setupUi( this ); first thing in your classes constructor. Afterwards your pushbutton should exist and you can try to connect it.

[wysota]

if you created the window in the designer you have to call setupUi( this ); first thing in your classes constructor.

He's using Qt3, there is no such thing as setupUi() there.

[mikro]

ooops. sorry, hadn't realized that.:o