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QListViewItemIterator Class Reference

The QListViewItemIterator class provides an iterator for collections of QListViewItems. More...

#include <qlistview.h>

List of all member functions.

Public Members


Detailed Description

The QListViewItemIterator class provides an iterator for collections of QListViewItems.

Construct an instance of a QListViewItemIterator, with either a QListView* or a QListViewItem* as argument, to operate on the tree of QListViewItems.

A QListViewItemIterator iterates over all items of a list view. This means it always makes the first child of the current item the new current one. If there is no child, the next sibling gets the new current item; and if there is no next sibling, the next sibling of the parent is set to current.

Example:

You often want to get all items which were selected by a user. Here is an example which does this and stores the pointers to all selected items in a QList.


  // Somewhere a list view is generated like this
  QListView *lv = new QListView(this);
  // Enable multiselection
  lv->setMultiSelection( TRUE );

  // Insert the items here

  // ...

  // This function is called to get a list of the selected items of a list view
  QPtrList<QListViewItem> * getSelectedItems( QListView *lv ) {
    if ( !lv )
      return 0;

    // Create the list
    QPtrList<QListViewItem> *lst = new QPtrList<QListViewItem>;
    lst->setAutoDelete( FALSE );

    // Create an iterator and give the list view as argument
    QListViewItemIterator it( lv );
    // iterate through all items of the list view
    for ( ; it.current(); ++it ) {
      if ( it.current()->isSelected() )
        lst->append( it.current() );
    }

    return lst;
  }

  

Using a QListViewItemIterator is a convinient way to traverse the tree of QListViewItems of a QListView. It especially makes operating on a hirarchical QListView easy.

Multiple QListViewItemIterators can also operate on the tree of QListViewItems. A QListView knows about all iterators operating on its QListViewItems. So when a QListViewItem gets removed all iterators that point to this item are updated and point to the new current item after that.

See also QListView and QListViewItem.


Member Function Documentation

QListViewItemIterator::QListViewItemIterator ()

Constructs an empty iterator.

QListViewItemIterator::QListViewItemIterator ( QListViewItem * item )

Constructs an iterator for the QListView of the item. The current iterator item is set to point on the item.

QListViewItemIterator::QListViewItemIterator ( const QListViewItemIterator & it )

Constructs an iterator for the same QListView as it. The current iterator item is set to point on the current item of it.

QListViewItemIterator::QListViewItemIterator ( QListView * lv )

Constructs an iterator for the QListView lv. The current iterator item is set to point on the first child ( QListViewItem ) of lv.

QListViewItemIterator::~QListViewItemIterator ()

Destroys the iterator.

QListViewItem * QListViewItemIterator::current () const

Returns a pointer to the current item of the iterator.

Examples: addressbook/centralwidget.cpp, checklists/checklists.cpp, dirview/dirview.cpp and network/ftpclient/ftpview.cpp.

QListViewItemIterator & QListViewItemIterator::operator++ ()

Prefix ++ makes the next item in the QListViewItem tree of the QListView of the iterator the current item and returns it. If the current item was the last item in the QListView or null, null is returned.

const QListViewItemIterator QListViewItemIterator::operator++ ( int )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Postfix ++ makes the next item in the QListViewItem tree of the QListView of the iterator the current item and returns the item, which was the current one before.

QListViewItemIterator & QListViewItemIterator::operator+= ( int j )

Sets the current item to the item j positions after the current item in the QListViewItem hierarchy. If this item is beyond the last item, the current item is set to null.

The new current item (or null, if the new current item is null) is returned.

QListViewItemIterator & QListViewItemIterator::operator-- ()

Prefix -- makes the previous item in the QListViewItem tree of the QListView of the iterator the current item and returns it. If the current item was the last first in the QListView or null, null is returned.

const QListViewItemIterator QListViewItemIterator::operator-- ( int )

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Postfix -- makes the previous item in the QListViewItem tree of the QListView of the iterator the current item and returns the item, which was the current one before.

QListViewItemIterator & QListViewItemIterator::operator-= ( int j )

Sets the current item to the item j positions before the current item in the QListViewItem hierarchy. If this item is above the first item, the current item is set to null. The new current item (or null, if the new current item is null) is returned.

QListViewItemIterator & QListViewItemIterator::operator= ( const QListViewItemIterator & it )

Assignment. Makes a copy of it and returns a reference to its iterator.

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Qt version 3.0.0-beta1-beta1