[SOLVED] List of visible rows in the viewport of QTableView

[Sam]

Hi,

Is there anyway I can get the list of visible rows in the viewport of QTableView. Currently in the viewportEvent() of QTableView I can get the firstRow and the lastRow by using

QModelIndex firstRowIndex = indexAt(QPoint(viewport()->rect().x()+5,viewport()->rect().y()+5));
QModelIndex lastRowIndex = indexAt(QPoint(viewport()->rect().x()+5,viewport()->rect().height()-5));

The requirement is to iterate/update something specific to the visible Rows in the viewport. If the some rows between the first/last row are hidden then I cannot use a for loop which will consume more time (e.g firstRow = 10, lastRow = 9500; )

Regards
Sam

[SGaist]

Hi,

IIRC, you can use visualRect to build that list.

Hope it helps

[Sam]

Hi SGaist,

Thanks for your reply, with visualRect I need to pass the QModelIndex. In order to get the list of rows/items in the viewport of the tableView I now calculate using the height eg.

int height = 0;
while (height < viewport()->rect().height())  // viewport() of tableView
{
  qDebug() << indexAt(QPoint(viewport()->rect().x(),height)).row());
  height += 25;
}

[SGaist]

Are you sure about 25 ? You have to be sure that your rows are 50px high otherwise you might miss some

[Sam]

Yes, this approach is temporary and I too don't like to do it this way. In fact for my requirement this does not make any difference even if I get the list of rows in the visible viewport(). I'll try to explain in brief what I am trying to achieve.

I came across an article : Widgets on a header which works perfect for a horizontalHeaderView and also so a verticalHeaderView with few rows. Currently I am implementing the same for a VerticalHeaderView where I have a panel of buttons (eg add/delete) when we click on these button it add/delete a row.

The only issue right now is performance, if the model is filled with a lot of rows then creating new panels is a time consuming process. My initial idea was to create the instance of these panel only for the visible rows in the viewport but it creates a lag/flickering when the viewport gets updated while scrolling the tableView.

Another approach is to paint/render a fake panel and create a new instance when the mouse hover/enter the verticalHeader (don't know if this is even possible, with tableView cells this is easy to implement with delegate).

Thanks for your time !

[SGaist]

What do you need to render exactly ?

[alex_malyu]

Are you sure indexAt() for every row is not slower then just iterating between indexes and checking that row is not hidden?