How to update QTableWidget immediately?

tomweb

Hello,
I have a task, startet by user using signal-slot functionality which takes about 5-20 seconds.
This task is mainly a for-next-statement, which calculates some things and fills a QTableWidget with the result, that means about 200 Items.
I want, that the single result items are immedialely displayed. I can do this by calling "myTableWidget->repaint()" .
But that causes the whole window to repaint (even is the visible area is full) and that makes it very very slow (2..3 times slower), compared without using ->repaint().
But without repaint the Widget is only repainted after the for-next Statement (after that 5..20 seconds)
I tried already a timer and repaint all 200ms, but that is not much better.
->update() does not help. Without repaint() the widget is only refreshed after i return from my slot (and after the for-next-statement is finished)

Is there a easy way, to update/repaint ONLY the new items (i only append them at the end) in the QTableWidget? (like Explorer search for files....that list is updated immediately when some new files are found)
I do not want to create a new task...i do not need to replay to user action during filling the TableWidget (no scrolling necessary till i finished)...and i do not want to use QTableView....

is there still a possibility?

Wieland

@tomweb Hi, and welcome to the Qt forum! You could try calling void QCoreApplication::processEvents(QEventLoop::ProcessEventsFlags flags = QEventLoop::AllEvents) instead of repaint(). Maybe that's faster.

SGaist

Hi and welcome to devnet,

What about creating a loop through signals and slots ? That way you can keep your UI responsive.

For example :


void MyClass::processData()
{
    if (_itemList.isEmpty()) {
        return;
    }
    int next = _itemList.takeFirst();
    // process
    _tableWidget->setItem(row, col, new QTableWidgetItem(processingResult));
    QTimer::singleShot(this, 0, &processData)
}

You can even make tweak it and make it interruptible if needed.