3 Questions on QListView

[jiveaxe]

Hi everybody,
i was learning qlistview and writing simple application for testing. First of all the sample code:

#include <QApplication>
#include <QVBoxLayout>
#include <QListView>
#include <QLabel>
#include <QStringListModel>
#include <QStringList>
 
class MyWidget: public QWidget
{
Q_OBJECT
 
public:
MyWidget(QWidget *parent=0);
 
private slots:
void currentSelected(const QModelIndex &);
 
private:
QListView *listView;
QLabel *selectedItemText;
QStringListModel *model;
};
 
MyWidget::MyWidget(QWidget *parent)
:QWidget(parent)
{
listView = new QListView;
selectedItemText = new QLabel;
 
model = new QStringListModel();
QStringList list;
list << "lemons" << "melons" << "oranges" << "pears"
<< "grapes" << "apples" << "potatoes";
model->setStringList(list);
 
listView->setModel(model);
 
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(listView);
layout->addWidget(selectedItemText);
setLayout(layout);
 
connect(listView, SIGNAL(clicked(const QModelIndex&)),
this, SLOT(currentSelected(const QModelIndex &)));
}
 
void MyWidget::currentSelected(const QModelIndex &current)
{
selectedItemText->setText(current.data().toString());
}
 
int main(int argc, char *argv[])
{
QApplication app( argc, argv );
 
QWidget *window = new QWidget;
window->setWindowTitle("Sample ListView");
 
MyWidget *myWidget = new MyWidget;
 
QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(myWidget);
window->setLayout(mainLayout);
window->show();
 
return app.exec();
}
 
#include "main.moc"

#include <QApplication>
#include <QVBoxLayout>
#include <QListView>
#include <QLabel>
#include <QStringListModel>
#include <QStringList>

class MyWidget: public QWidget
{
Q_OBJECT

public:
MyWidget(QWidget *parent=0);

private slots:
void currentSelected(const QModelIndex &);

private:
QListView *listView;
QLabel *selectedItemText;
QStringListModel *model;
};

MyWidget::MyWidget(QWidget *parent)
:QWidget(parent)
{
listView = new QListView;
selectedItemText = new QLabel;

model = new QStringListModel();
QStringList list;
list << "lemons" << "melons" << "oranges" << "pears"
<< "grapes" << "apples" << "potatoes";
model->setStringList(list);

listView->setModel(model);

QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(listView);
layout->addWidget(selectedItemText);
setLayout(layout);

connect(listView, SIGNAL(clicked(const QModelIndex&)),
this, SLOT(currentSelected(const QModelIndex &)));
}

void MyWidget::currentSelected(const QModelIndex &current)
{
selectedItemText->setText(current.data().toString());
}

int main(int argc, char *argv[])
{
QApplication app( argc, argv );

QWidget *window = new QWidget;
window->setWindowTitle("Sample ListView");

MyWidget *myWidget = new MyWidget;

QVBoxLayout *mainLayout = new QVBoxLayout;
mainLayout->addWidget(myWidget);
window->setLayout(mainLayout);
window->show();

return app.exec();
}

#include "main.moc"

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My questions are:

1) How start the application with some item already selected?
With the code above when an item is selected the QLabel is filled with the item data; but when the application starts no item is selected and the label is empty.

2) How bind the function currentSelected(const QModelIndex &) with up/down arrows keys?
In the application if I move the selection with the up/arrow keys the highlighted item changes but the label is not updated with the text of the highlighted item. I want the behavior of mouse single click with up/arrow keys.

3) How change the double-click event?
Now when an item is double-clicked the item goes in edit mode; i don't want this. Double-click like single-click is sufficient for me.

Hoping i was clear, thanks in advance for helping me.
Giuseppe

[marcel]

1. Use setCurrentIndex(model()->index(0));

2.

connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
this, SLOT(currentSelected(const QModelIndex &)));
}

connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
this, SLOT(currentSelected(const QModelIndex &)));
}

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The last parameter in the signal will be ignored by the slot.

3. listView->setEditTriggers(QAbstractItemView::NoEditTriggers );

Regards

[jiveaxe]

Thanks marcel for your help; I noticed that code 2) solves question 1) too.

Can I post you a new Question? How word wrap text in a listview? I have used

listView->setWordWrap(true);

listView->setWordWrap(true);

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but nothing happens; what's wrong? missing something else?

Thanks a lot,
Giuseppe

[marcel]

What do you expect it to do?

wordWrap : bool This property holds the item text word-wrapping policy.
If this property is true then item text text is wrapped where necessary at word-breaks; otherwise it is not wrapped at all. This property is false by default.

So, if you have a really long word, then it won't be wrapped. If you have multiple words, then they will be wrapped as necessary.

A possible solution is( that is guaranteed to work), is to create your own item delegate ( a delegate dictates the look and feel of an item ).

When you paint the delegate, then you can take care of the wrapping too.

Regards

[jiveaxe]

Ok, marcel; now open the manual and search for delegate to learn using it.

Again thanks

[marcel]

OK.
A hint: I think you can use QStyleOptionViewItem::rect. This is the dimension of the item. You can do the wrapping relative to its size. A QStyleOptionViewItem object is passed to the delegate's paint method.

Regards

[jiveaxe]

I have to return on marcel' replay to my first post; i have noticed that using, as in answer to question 1, this code:

currentSelected(model->index(2));

currentSelected(model->index(2));

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(with 2 instead of 0 (zero)) the item selected is the first (with index = 0). If, instead, putting a comment in front of the marcel's code in answer 2 the correct item is displayed in the label.

Where is the problem?

Bye

[marcel]

Could you post your code?
Only the relevant sections.

Regards

[jiveaxe]

Take as sample the code in my first post; i have inserted after the connect statement in constructor

connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
			this, SLOT(currentSelected(const QModelIndex &)));
 
currentSelected(model->index(2));

connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
			this, SLOT(currentSelected(const QModelIndex &)));

currentSelected(model->index(2));

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[marcel]

Do you change the selection programatically after this code?

Regards

[jiveaxe]

No, i hope.
Here the complete code:

#include <QApplication>
#include <QVBoxLayout>
#include <QListView>
#include <QLabel>
#include <QStringListModel>
#include <QStringList>
 
class MyWidget: public QWidget
{
	Q_OBJECT
 
	public:
		MyWidget(QWidget *parent=0);
 
	private slots:
		void currentSelected(const QModelIndex &);
 
	private:
		QListView *listView;
		QLabel *selectedItemText;
		QStringListModel *model;
};
 
MyWidget::MyWidget(QWidget *parent)
	:QWidget(parent)
{
	listView = new QListView;
	listView->setWordWrap(true);
	listView->setEditTriggers(QAbstractItemView::NoEditTriggers );
	selectedItemText = new QLabel;
 
	model = new QStringListModel();
	QStringList list;
	list << "lemons" << "melons" << "oranges" << "pears"
			<< "grapes" << "apples" << "potatoes";
	model->setStringList(list);
 
	listView->setModel(model);
 
	QVBoxLayout *layout = new QVBoxLayout;
	layout->addWidget(listView);
	layout->addWidget(selectedItemText);
	setLayout(layout);
 
	connect(listView, SIGNAL(clicked(const QModelIndex&)),
					 this, SLOT(currentSelected(const QModelIndex &)));
	connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
			this, SLOT(currentSelected(const QModelIndex &)));
 
	currentSelected(model->index(2));
}
 
void MyWidget::currentSelected(const QModelIndex &current)
{
	selectedItemText->setText(current.data().toString());
}
 
int main(int argc, char *argv[])
{
	QApplication app( argc, argv );
 
	QWidget *window = new QWidget;
	window->setWindowTitle("Sample ListView");
 
	MyWidget *myWidget = new MyWidget;
 
	QVBoxLayout *mainLayout = new QVBoxLayout;
	mainLayout->addWidget(myWidget);
 	window->setLayout(mainLayout);
	window->show();
 
	return app.exec();
}
 
#include "main.moc"

#include <QApplication>
#include <QVBoxLayout>
#include <QListView>
#include <QLabel>
#include <QStringListModel>
#include <QStringList>

class MyWidget: public QWidget
{
	Q_OBJECT

	public:
		MyWidget(QWidget *parent=0);

	private slots:
		void currentSelected(const QModelIndex &);

	private:
		QListView *listView;
		QLabel *selectedItemText;
		QStringListModel *model;
};

MyWidget::MyWidget(QWidget *parent)
	:QWidget(parent)
{
	listView = new QListView;
	listView->setWordWrap(true);
	listView->setEditTriggers(QAbstractItemView::NoEditTriggers );
	selectedItemText = new QLabel;

	model = new QStringListModel();
	QStringList list;
	list << "lemons" << "melons" << "oranges" << "pears"
			<< "grapes" << "apples" << "potatoes";
	model->setStringList(list);

	listView->setModel(model);

	QVBoxLayout *layout = new QVBoxLayout;
	layout->addWidget(listView);
	layout->addWidget(selectedItemText);
	setLayout(layout);

	connect(listView, SIGNAL(clicked(const QModelIndex&)),
					 this, SLOT(currentSelected(const QModelIndex &)));
	connect(listView->selectionModel(), SIGNAL(currentChanged(const QModelIndex&, const QModelIndex&)),
			this, SLOT(currentSelected(const QModelIndex &)));

	currentSelected(model->index(2));
}

void MyWidget::currentSelected(const QModelIndex &current)
{
	selectedItemText->setText(current.data().toString());
}

int main(int argc, char *argv[])
{
	QApplication app( argc, argv );

	QWidget *window = new QWidget;
	window->setWindowTitle("Sample ListView");

	MyWidget *myWidget = new MyWidget;

	QVBoxLayout *mainLayout = new QVBoxLayout;
	mainLayout->addWidget(myWidget);
 	window->setLayout(mainLayout);
	window->show();

	return app.exec();
}

#include "main.moc"

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Regards,
Giuseppe