QListView sorting

[fear]

How about reimplementing QListView::sort() and do the sorting there (or forward it elsewhere)? What went wrong when you tried to use it?

Simply these methods are NOT (except QListViewItem::sortChildItems(int, bool) - but it sorts childs of every QListViewItem not QListViewItems) called when user clicks header's column.

void QListViewItem::sort()
{
    if ( !listView() )
	 return;
    lsc = Unsorted;
    enforceSortOrder();
    listView()->triggerUpdate();
}
 
void QListViewItem::enforceSortOrder() const
{
    QListView *lv = listView();
    if ( !lv || lv && (lv->d->clearing || lv->d->sortcolumn == Unsorted) )
	return;
    if ( parentItem &&
	 (parentItem->lsc != lsc || parentItem->lso != lso) )
	((QListViewItem *)this)->sortChildItems( (int)parentItem->lsc,
						 (bool)parentItem->lso );
    else if ( !parentItem &&
	      ( (int)lsc != lv->d->sortcolumn || (bool)lso != lv->d->ascending ) )
	((QListViewItem *)this)->sortChildItems( lv->d->sortcolumn, lv->d->ascending );
}
 
void QListViewItem::sortChildItems( int column, bool ascending )
{
    // we try HARD not to sort.  if we're already sorted, don't.
    if ( column == (int)lsc && ascending == (bool)lso )
	return;
 
    if ( column < 0 )
	return;
 
    lsc = column;
    lso = ascending;
 
    const int nColumns = ( listView() ? listView()->columns() : 0 );
 
    // only sort if the item have more than one child.
    if ( column > nColumns || childItem == 0 || (childItem->siblingItem == 0 && childItem->childItem == 0))
	return;
 
    // make an array for qHeapSort()
    QListViewPrivate::SortableItem * siblings
	= new QListViewPrivate::SortableItem[nChildren];
    QListViewItem * s = childItem;
    int i = 0;
    while ( s && i < nChildren ) {
	siblings[i].numCols = nColumns;
	siblings[i].col = column;
	siblings[i].asc = ascending;
	siblings[i].item = s;
	s = s->siblingItem;
	i++;
    }
 
    // and sort it.
    qHeapSort( siblings, siblings + nChildren );
 
    // build the linked list of siblings, in the appropriate
    // direction, and finally set this->childItem to the new top
    // child.
    if ( ascending ) {
	for( i = 0; i < nChildren - 1; i++ )
	    siblings[i].item->siblingItem = siblings[i+1].item;
	siblings[nChildren-1].item->siblingItem = 0;
	childItem = siblings[0].item;
    } else {
	for( i = nChildren - 1; i > 0; i-- )
	    siblings[i].item->siblingItem = siblings[i-1].item;
	siblings[0].item->siblingItem = 0;
	childItem = siblings[nChildren-1].item;
    }
    for ( i = 0; i < nChildren; i++ ) {
	if ( siblings[i].item->isOpen() )
	    siblings[i].item->sort();
    }
    delete[] siblings;
}

void QListViewItem::sort()
{
    if ( !listView() )
	 return;
    lsc = Unsorted;
    enforceSortOrder();
    listView()->triggerUpdate();
}

void QListViewItem::enforceSortOrder() const
{
    QListView *lv = listView();
    if ( !lv || lv && (lv->d->clearing || lv->d->sortcolumn == Unsorted) )
	return;
    if ( parentItem &&
	 (parentItem->lsc != lsc || parentItem->lso != lso) )
	((QListViewItem *)this)->sortChildItems( (int)parentItem->lsc,
						 (bool)parentItem->lso );
    else if ( !parentItem &&
	      ( (int)lsc != lv->d->sortcolumn || (bool)lso != lv->d->ascending ) )
	((QListViewItem *)this)->sortChildItems( lv->d->sortcolumn, lv->d->ascending );
}

void QListViewItem::sortChildItems( int column, bool ascending )
{
    // we try HARD not to sort.  if we're already sorted, don't.
    if ( column == (int)lsc && ascending == (bool)lso )
	return;

    if ( column < 0 )
	return;

    lsc = column;
    lso = ascending;

    const int nColumns = ( listView() ? listView()->columns() : 0 );

    // only sort if the item have more than one child.
    if ( column > nColumns || childItem == 0 || (childItem->siblingItem == 0 && childItem->childItem == 0))
	return;

    // make an array for qHeapSort()
    QListViewPrivate::SortableItem * siblings
	= new QListViewPrivate::SortableItem[nChildren];
    QListViewItem * s = childItem;
    int i = 0;
    while ( s && i < nChildren ) {
	siblings[i].numCols = nColumns;
	siblings[i].col = column;
	siblings[i].asc = ascending;
	siblings[i].item = s;
	s = s->siblingItem;
	i++;
    }

    // and sort it.
    qHeapSort( siblings, siblings + nChildren );

    // build the linked list of siblings, in the appropriate
    // direction, and finally set this->childItem to the new top
    // child.
    if ( ascending ) {
	for( i = 0; i < nChildren - 1; i++ )
	    siblings[i].item->siblingItem = siblings[i+1].item;
	siblings[nChildren-1].item->siblingItem = 0;
	childItem = siblings[0].item;
    } else {
	for( i = nChildren - 1; i > 0; i-- )
	    siblings[i].item->siblingItem = siblings[i-1].item;
	siblings[0].item->siblingItem = 0;
	childItem = siblings[nChildren-1].item;
    }
    for ( i = 0; i < nChildren; i++ ) {
	if ( siblings[i].item->isOpen() )
	    siblings[i].item->sort();
    }
    delete[] siblings;
}

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In fact only last method does real sorting. Items were sorted desipte the fact I've reimplemented it.

[wysota]

sort() is a method of the LISTVIEW, not of the ITEM.

[fear]

sort() is a method of the LISTVIEW, not of the ITEM.

I reimplemented it in subclass of QListView.

class KMListView : public KListView
{
	Q_OBJECT
 
	public:
		KMListView(QWidget * parent = 0, const char * name = 0);
		~KMListView();
 
		void setSelected(QListViewItem * item, bool selected);
		void clearSelection();
		QListViewItem * selectedItem() const;
		void sort();
 
	public slots:
		void selectAll();
 
	signals:
		void mouseButtonReleased(const QPoint &);
		void keyPressed(QKeyEvent * e);
		void rightMouseButtonClicked(const QPoint &);
		void sortRequested(const int, const SortOrder);
 
	protected:
		bool acceptDrag(QDropEvent * event) const;
		void contentsMousePressEvent(QMouseEvent * e);
		void contentsMouseReleaseEvent(QMouseEvent * e);
		void contentsMouseMoveEvent(QMouseEvent * e);
		void keyPressEvent(QKeyEvent * e);
		void enforceSortOrder() const;
 
	private:
		bool dndPerm;
};

class KMListView : public KListView
{
	Q_OBJECT

	public:
		KMListView(QWidget * parent = 0, const char * name = 0);
		~KMListView();

		void setSelected(QListViewItem * item, bool selected);
		void clearSelection();
		QListViewItem * selectedItem() const;
		void sort();

	public slots:
		void selectAll();

	signals:
		void mouseButtonReleased(const QPoint &);
		void keyPressed(QKeyEvent * e);
		void rightMouseButtonClicked(const QPoint &);
		void sortRequested(const int, const SortOrder);

	protected:
		bool acceptDrag(QDropEvent * event) const;
		void contentsMousePressEvent(QMouseEvent * e);
		void contentsMouseReleaseEvent(QMouseEvent * e);
		void contentsMouseMoveEvent(QMouseEvent * e);
		void keyPressEvent(QKeyEvent * e);
		void enforceSortOrder() const;

	private:
		bool dndPerm;
};

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void KMListView::sort()
{
	qDebug("sort");
 
	emit sortRequested(sortColumn(), sortOrder());
}

void KMListView::sort()
{
	qDebug("sort");

	emit sortRequested(sortColumn(), sortOrder());
}

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sort() is executed only when I call it:

KMListView * lv = new KMListView(this);
lv->sort();

KMListView * lv = new KMListView(this);
lv->sort();

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[wysota]

Did you enable sorting on the list view? As far as I remember you have to access the header and make it click enabled (I'm not sure though).

[fear]

My settings:

lvi->setSelectionMode(QListView::Extended);
lvi->setShowSortIndicator(true);
lvi->setShadeSortColumn(true);
lvi->setResizeMode(QListView::NoColumn);
lvi->setDropVisualizer(false);
lvi->setAllColumnsShowFocus(true);

lvi->setSelectionMode(QListView::Extended);
lvi->setShowSortIndicator(true);
lvi->setShadeSortColumn(true);
lvi->setResizeMode(QListView::NoColumn);
lvi->setDropVisualizer(false);
lvi->setAllColumnsShowFocus(true);

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Problem is I don't know what actually sorts items! As I mentioned sort() is not called (but QListViewItems are sorted!).

[KMAPSRULE]

I think What you want to do is overload the < operator in the List Item.

This example is from a QT 4.1 QTreeWidgetItem I had to implement sorting on when the TreeView Headers were Clicked, but the Idea should be the Same for the QT3 QListViewItem:

bool operator<(const QTreeWidgetItem & other) const
      {
            int column = treeWidget()->sortColumn();
            if ( column == 0 || column == 2 )
            {
                   int thisInt = text(column).toInt();
                   int otherInt = other.text(column).toInt();
                   return thisInt < otherInt;
            }
            // sort date and time columns as one
            else if (  column == 3  ||  column == 4  )
            {
                QDate thisDate = QDate::fromString(text(3), "yyyy/MM/dd");
                QDate otherDate = QDate::fromString(other.text(3), "yyyy/MM/dd");
                if (  thisDate == otherDate  )
                {
                    QTime thisTime  = QTime::fromString(text(4));
                    QTime otherTime = QTime::fromString(other.text(4));
                    return thisTime < otherTime;
                }
                else
                {
                    return thisDate < otherDate;
                }
            }
            else if (  column == 5 )
            {
                QTime thisTime = QTime::fromString(text(column), "h:mm:ss");
                QTime otherTime = QTime::fromString(other.text(column), "h:mm:ss");
                return thisTime < otherTime;
            }
 
 
           return QTreeWidgetItem::operator <(other); //otherwise use base class
 
      }//end operator < overload

bool operator<(const QTreeWidgetItem & other) const
      {
            int column = treeWidget()->sortColumn();
            if ( column == 0 || column == 2 )
            {
                   int thisInt = text(column).toInt();
                   int otherInt = other.text(column).toInt();
                   return thisInt < otherInt;
            }
            // sort date and time columns as one
            else if (  column == 3  ||  column == 4  )
            {
                QDate thisDate = QDate::fromString(text(3), "yyyy/MM/dd");
                QDate otherDate = QDate::fromString(other.text(3), "yyyy/MM/dd");
                if (  thisDate == otherDate  )
                {
                    QTime thisTime  = QTime::fromString(text(4));
                    QTime otherTime = QTime::fromString(other.text(4));
                    return thisTime < otherTime;
                }
                else
                {
                    return thisDate < otherDate;
                }
            }
            else if (  column == 5 )
            {
                QTime thisTime = QTime::fromString(text(column), "h:mm:ss");
                QTime otherTime = QTime::fromString(other.text(column), "h:mm:ss");
                return thisTime < otherTime;
            }


           return QTreeWidgetItem::operator <(other); //otherwise use base class

      }//end operator < overload

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[fear]

I can't do it because operator< is part of SortableItem class.

[KMAPSRULE]

Right,
Sorry About that, havent used QT3 in a while or QT4, I'm getting rusty
in QT3 QListView you need to reimplement compare()
see this thread

[fear]

I've reimplemented compare in this way:

int KMListViewItem::compare(QListViewItem * i, int col, bool ascending) const
{
	qDebug("compare()");
 
	Q_UNUSED(i);
	Q_UNUSED(col);
	Q_UNUSED(ascending);
 
	return 0;
}

int KMListViewItem::compare(QListViewItem * i, int col, bool ascending) const
{
	qDebug("compare()");

	Q_UNUSED(i);
	Q_UNUSED(col);
	Q_UNUSED(ascending);

	return 0;
}

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It should work but it doesn't (items are moved). I think the only solution is to use setSorting(-1) and then use QHeader's setSortIndicator.

[wysota]

Try implementing a real compare function. This one is not valid.

[fear]

I think the only solution is to use setSorting(-1) and then use QHeader's setSortIndicator.

I made it this way and now it works! Reimplementing compare() isn't good idea because list view will still iterate over items.

[wysota]

http://doc.trolltech.com/qq/qq01-sor...listviews.html

[wysota]

At worst you can reimplement compare() from QListViewItem.