Dynamically created buttons.

[wysota]

It will clear also verticalLayout?

No, it won't.

[BalaQT]

hi,

void QVector::clear ()
Removes all the elements from the vector and releases the memory used by the vector.

u need to remove the widgets from the layout.
use

void QLayout::removeWidget ( QWidget * widget )

void QLayout::removeWidget ( QWidget * widget )

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hope it helps
Thnks
Bala

[Tomasz]

So, it is as I thought. But what if I do something like that:

QVector<QPushButton*> btn;
 
btn.clear();       
 
for(int j=0; j<HOW_MANY_BUTTONS; j++)
{
      QPushButton *b = new QPushButton;
      b->setGeometry(0,0,40,40);
      btn << b;
      ui->verticalLayout->addWidget(btn[j],Qt::AlignVCenter);
}

QVector<QPushButton*> btn;

btn.clear();       

for(int j=0; j<HOW_MANY_BUTTONS; j++)
{
      QPushButton *b = new QPushButton;
      b->setGeometry(0,0,40,40);
      btn << b;
      ui->verticalLayout->addWidget(btn[j],Qt::AlignVCenter);
}

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Can I then remove item from layout using:

ui->verticalLayout->removeWidget(btn[i]);

ui->verticalLayout->removeWidget(btn[i]);

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Or maybe different pointer points on that widget?

thanks in advance
best regards
Tomasz

[BalaQT]

Can I then remove item from layout using ui->verticalLayout->removeWidget(btn[i]);

yes surely u can

Or maybe different pointer points on that widget?

no its the same pointer

hope it helps
Bala

[Tomasz]

But if I remove that widget from layout, pointer stays in vector? And I can use it again or just remove it from vector too?

thanks in advance
best regards
Tomasz

[BalaQT]

But if I remove that widget from layout, pointer stays in vector?

yes pointer stays in vector, since u didnt remove it from Vector.

And I can use it again

yes, surely u can use it again.

or just remove it from vector too?

if u dont want that widget then remove it from vector too..

layout and vector are different...

for ur understanding ... vector is holding the widget pointer.
that widget will be added to the layout by addWidget
and removed by removeWidget

hope it helps
Bala

[Tomasz]

One more question to end that thread. I've got my buttons, now I'm connecting them to QSignalMapper:

QVector<QPushButton*> btn;
 
btn.clear();       
 
for(int j=0; j<HOW_MANY_BUTTONS; j++)
{
      QPushButton *b = new QPushButton;
      b->setGeometry(0,0,40,40);
      btn << b;
      ui->verticalLayout->addWidget(btn[j],Qt::AlignVCenter);
      connect(btn[j], SIGNAL(clicked()), sigMap, SLOT(map()));
      sigMap->setMapping(btn[j], j);
}
 
connect(sigMap, SIGNAL(mapped(int)), this, SLOT(func(int)));

QVector<QPushButton*> btn;

btn.clear();       

for(int j=0; j<HOW_MANY_BUTTONS; j++)
{
      QPushButton *b = new QPushButton;
      b->setGeometry(0,0,40,40);
      btn << b;
      ui->verticalLayout->addWidget(btn[j],Qt::AlignVCenter);
      connect(btn[j], SIGNAL(clicked()), sigMap, SLOT(map()));
      sigMap->setMapping(btn[j], j);
}

connect(sigMap, SIGNAL(mapped(int)), this, SLOT(func(int)));

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What will now happen with QSignalMapper if I remove buttons from layout and vector? Should I clean somehow signal mapper? What happen with all connections?

thanks in advance
best regards
Tomasz

[wysota]

If you "remove" buttons from the layout and vector nothing will happen and connections to the mapper will still be maintained. But if you delete the buttons, all their connections will be broken.

From a technical point of view your vector doesn't hold buttons, it holds pointers to buttons. So you are not removing buttons from the vector (or the layout as a matter of fact) but pointers to buttons.

[Tomasz]

So the safest way to do the cleaning is to: remove widgets from layout, then DELETE all created buttons with:

delete(btn[x]); // btn is vector with pointers

delete(btn[x]); // btn is vector with pointers

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and at the end - i can safely clear vector, and then connections will be broken, and QSignalMapper will be 'clean'? Yes? And then I can create everything again?

thanks in advance
best regards
Tomasz

[wysota]

It's enough to delete the buttons. They will be taken out of layouts.

qDeleteAll(btn); 
btn.clear();

qDeleteAll(btn); 
btn.clear();

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[Tomasz]

One more question - should I use disconnect() to disconnect all signals (from created buttons) from slots.

thanks in advance
best regards
Tomasz

[wysota]

One more question - should I use disconnect() to disconnect all signals (from created buttons) from slots.

Why don't you try it first with and without disconnecting and then answer your own question?

[BalaQT]

hi,

should I use disconnect() to disconnect all signals

u should disconnect all the buttons.
one button's disconnect will disconnect only that signal.

hope it helps
Bala