How to remove widget added in runtime?

[jiveaxe]

Hi,
i'm working on a database application; i would like to add the possibility for the user to perform custom query with AND/OR clauses. So i thought to add to my program 2 button, one for adding and one for removing clauses; each clause is a custom widget; the list of clause/widget is stored in a QList. The remove function should delete the last added clause from QList and from gui. My problem is I can't remove widgets from the gui after adding them. Here is some code of a sample application i made for the thread (no database handling):

MainDialog::MainDialog(QWidget *parent)
	:QDialog(parent)
{
	...
	groupBox = new QGroupBox("Clauses");
	...
	groupBoxLayout = new QVBoxLayout(groupBox);
	...
	removeConditionButton->setEnabled(false);
	...
	connect(addConditionButton, SIGNAL(clicked()), this, SLOT(addCondition()));
	connect(removeConditionButton, SIGNAL(clicked()), this, SLOT(removeCondition()));
}
 
void MainDialog::addCondition()
{
	QComboBox *comboBox = new QComboBox;
	groupBoxLayout->addWidget(comboBox);
	list.append(comboBox);
	removeConditionButton->setEnabled(true);
}
 
void MainDialog::removeCondition()
{
	list.removeLast();
	if(list.size() == 0)
		removeConditionButton->setEnabled(false);
}

MainDialog::MainDialog(QWidget *parent)
	:QDialog(parent)
{
	...
	groupBox = new QGroupBox("Clauses");
	...
	groupBoxLayout = new QVBoxLayout(groupBox);
	...
	removeConditionButton->setEnabled(false);
	...
	connect(addConditionButton, SIGNAL(clicked()), this, SLOT(addCondition()));
	connect(removeConditionButton, SIGNAL(clicked()), this, SLOT(removeCondition()));
}

void MainDialog::addCondition()
{
	QComboBox *comboBox = new QComboBox;
	groupBoxLayout->addWidget(comboBox);
	list.append(comboBox);
	removeConditionButton->setEnabled(true);
}

void MainDialog::removeCondition()
{
	list.removeLast();
	if(list.size() == 0)
		removeConditionButton->setEnabled(false);
}

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What have I to add to removeCondition()? Or is there a better solution?

Thanks

[marcel]

You also need to remove the widget from the layout:

QWidget *w = list.takeLast();
w->hide();
groupBoxLayout->removeWidget(w);
delete w;

QWidget *w = list.takeLast();
w->hide();
groupBoxLayout->removeWidget(w);
delete w;

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[momesana]

I'm not sure I understand what you want do but you can add and remove widgets from a layout by using Layout::removeWidget(). In your case it may be better to hide/show the widget in contrast to removing it from the layout and deleting it afterwards.
See QWidget::setVisible(bool b), QWidget::show(), QWidget::hide() for more details.

[jiveaxe]

Thank you marcel,
your help is always on time.

One more question: when adding widgets they are placed distant each other occupying the height of the container; how place them grouped from the begin with free space at bottom; i got a layout near it with:

groupBoxLayout->setDirection(QBoxLayout::BottomToTop);

groupBoxLayout->setDirection(QBoxLayout::BottomToTop);

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but the widgets are placed (obviously) inverted; the last added is at top of the container.

Bye

[marcel]

You can try adding a spacer in the vertical layout after you add all the widget. I should occupy all the free space and push the widgets up.

[jiveaxe]

I have found a solution; using QSpacerItem and QLayout::addItem/QLayout::removeItem I remove the spacer before adding a new widget and add it after; the widgets are now grouped at top of container.

Bye

[jpn]

I have found a solution; using QSpacerItem and QLayout::addItem/QLayout::removeItem

Notice QBoxLayout::addSpacing() and QBoxLayout::insertSpacing(). Easier to read and write.

[jiveaxe]

Ok jpn, I'll give them a try.

Thank