QTableWidget draw/Paint over widget in a cell ?

[Dariusz]

Hey

I have a QTableWidget with QWidget in each cell with my lineedits/buttons/checkboxes etc etc. I would like to draw a custom graphic over all these widgets - mainly drop indicator, as I have a different implementation than what Qt offers. I've subclassed the drag/dorp/etc events and detected the QRect / interconnecting areas where I'd like to draw but when I subclassed the :

void testTable::paintEvent(QPaintEvent *event) {
    QTableWidget::paintEvent(event);
    QPainter paint(viewport());
    paint.setPen(Qt::blue);
    paint.drawText(rect(), Qt::AlignCenter, "The Text");
    paint.drawLine(0, 0, 100, 100);
    //paintDropIndicator();
}

To do a test, it ended up painting the line under the QWidget that I have inserted in the cell.

How can I paint the desired effect over the QWidget in cell?

TIA

[VRonin]

The painting is done by the delegate, you need to subclass QStyledItemDelegate and reimplement paint.

@Dariusz said in QTableWidget draw/Paint over widget in a cell ?:

I have a QTableWidget with QWidget in each cell

You should consider abandon this evil way and just go the delegate way instead

[mrjj]

Hi
Since you want to draw on top of the actual widget, drawing on the viewport() wont work as
its under.
One way is to user an overlay widget
https://stackoverflow.com/questions/19199863/draw-rectangular-overlay-on-qwidget-at-click
ITs completely transparent and non clickable ( setAttribute(Qt::WA_TransparentForMouseEvents);
and you can use that for paint area.

[Dariusz]

@VRonin sounds like the correct way to do it, will try it out thanks!

@mrjj sounds like ninja way of doing it! Thanks that definitely juggle up some ideas for ninja stuff! Thanks!

Regards
Dariusz

[mrjj]

@Dariusz
Yes drawing on top of other widgets is kinda hax-ish. :) In all cases.
Doing with a delegate is much better and as a bonus also have better performance on large data sets.

[Dariusz]

I just tried using delegate, I don't get a paint call on it while I drag/drop items in view. The only thing that gets calles is treeWidget::paint and my dragMoveEvent()...

Did I break something or do I need to force delegate paint somehow ?

[Christian Ehrlicher]

You won't get a paint event at all during drag'n'drop I would guess since the cursor is not directly painted by Qt when I'm correct.