How to draw a circle with spinbox coordinates

[rdelgado]

Not in MiWidget, but in SpinVariable.

You do not emit a signal at the moment from SpinVariable.

Sorry but I don't understand.
I emit it right here, I think:

QObject::connect(spin1, SIGNAL(valueChanged(int)), area, SLOT(setposicionX(int)));
QObject::connect(spin2, SIGNAL(valueChanged(int)), area, SLOT(setposicionY(int)));

QObject::connect(spin1, SIGNAL(valueChanged(int)), area, SLOT(setposicionX(int)));
QObject::connect(spin2, SIGNAL(valueChanged(int)), area, SLOT(setposicionY(int)));

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Right there, when the spinbox value is changed it should trigger the setposicion functions.

Thanks for the help!

[Lykurg]

There you only connect! In your class SpinVariable you have to add a signal forwarding as said:

spinvariable::spinvariable(QWidget *parent) :
    QWidget(parent)
{
        spinbox = new QSpinBox;
        label = new QLabel;
 
        QHBoxLayout *layout = new QHBoxLayout;
 
        layout->addWidget(label);
        layout->addWidget(spinbox);
 
        setLayout(layout);
        QObject::connect(spinbox, SIGNAL(valueChanged(int)), this, SIGNAL(valueChanged(int)));
}

spinvariable::spinvariable(QWidget *parent) :
    QWidget(parent)
{
        spinbox = new QSpinBox;
        label = new QLabel;

        QHBoxLayout *layout = new QHBoxLayout;

        layout->addWidget(label);
        layout->addWidget(spinbox);

        setLayout(layout);
        QObject::connect(spinbox, SIGNAL(valueChanged(int)), this, SIGNAL(valueChanged(int)));
}

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The

QObject::connect(spin1, SIGNAL(valueChanged(int)), area, SLOT(setposicionX(int)));

QObject::connect(spin1, SIGNAL(valueChanged(int)), area, SLOT(setposicionX(int)));

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never came to action, since such a signal is never emitted!

[tbscope]

spinvariable::spinvariable(QWidget *parent) :
    QWidget(parent)
{
        spinbox = new QSpinBox;
        label = new QLabel;
 
        QHBoxLayout *layout = new QHBoxLayout;
 
        layout->addWidget(label);
        layout->addWidget(spinbox);
 
        setLayout(layout);
 
        QObject::connect(spinbox, SIGNAL(valueChanged(int)), this, SIGNAL(valueChanged(int)));
}

spinvariable::spinvariable(QWidget *parent) :
    QWidget(parent)
{
        spinbox = new QSpinBox;
        label = new QLabel;
 
        QHBoxLayout *layout = new QHBoxLayout;
 
        layout->addWidget(label);
        layout->addWidget(spinbox);
 
        setLayout(layout);

        QObject::connect(spinbox, SIGNAL(valueChanged(int)), this, SIGNAL(valueChanged(int)));
}

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Edit: too late again ;-)

[rdelgado]

Hi!

It worked! Thank you very much.

Now, I am a little confused. Why do I have to connect the valueChanged() signal of the spinbox to itself?
Is it because I am using a PushButton to trigger and event?
I mean, I've been reading and doing a lot of Qt tutorials and this is the first time I see that. I followed the cannonball tutorial to write my program and if you check it you'll see they don't do that. Whenever the slider is moved in their program, it updates the variable values in the cannonball drawing area.

I thought that whenever a spinbox or a slider is changed, it emits its valueChanged() signal, and the only thing you have to do is to connect it to whatever you want to do.

So if you please can clarify me that I'll appreciate.

Thanks again!

[Lykurg]

You don't connect the signal to itself. To use a signal you need direct access to the object. In MiWidget you cant access your spinbox, you only can access your class spinvariable. It has a spinbox inside, but that don't matter, for the connect it is only a widget and a widget has no value changed signal. So you have to forward the signal. From the spinbox to the class spinvariable and from there to your MiWidget.

Another option would be to declare a public pointer to your spinbox but that would be a bad design.

[rdelgado]

Hi,

Now I see it, as you said, from the spinbox to the class, and from there to MiWidget!
I get it now. In the others examples I looked, all the spinboxes and sliders where part of the same class.

Thank you very much for the help. I'll keep learning!