QTableWidget internal drag animation

UnitScan

This is my QTableWidget: http://imgur.com/a/0V4rh

When I drag a line to move it to a different location, while dragging appears a copy of the line anchored to the mouse cursor. I want to know: can I change the drag 'drop animation? For example, highlight the top edge of the destination row?

Some hint?

raven-worx

you need to reimplement the dragEnter()/dragMove()/dropEvent() of your target widget.
With the position (taken from the event) you can determine the index at this position using QAbstractItemView::indxAt() and use QAbstractItemView::visualRect() to store the rect. Overload the paintEvent() and do your drawing on top with the rect.

UnitScan

This is my attempt:

void MainWindow::onTracklistMoved(int old_row, int new_row) {
    QTableWidgetItem *itemat = tracklist->itemAt(new_row,0);
    QRect rect = tracklist->visualItemRect(itemat);
}

Called on row internal move (note: I need to paint the entire row, not the single cell)

void DTableWidget::paintEvent(QPaintEvent *event)
{
    QRect rect = event->rect();
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setPen(Qt::black);
    painter.drawText(rect, Qt::AlignCenter,
                      "Data");
    painter.drawRect(rect);
}

Where

• DTableWidget = QTableWidget subclass, with reimplemented dragEnterEvent. dragMoveEvent, dragLeaveEvent, dropEvent, keyPressEvent and paintEvent method.
Whole DTableWidget class: header and source

At the app lauch, QtCreator send me these errors:

QWidget::paintEngine: Should no longer be called
QPainter::begin: Paint device returned engine == 0, type: 1
QPainter::setRenderHint: Painter must be active to set rendering hints
QPainter::setPen: Painter not active
QPainter::drawRects: Painter not active

Can you help me?

raven-worx

your paintEvent() handler isn't correct. Should look like this:

void DTableWidget::paintEvent(QPaintEvent *event)
{
    QTableWidget::paintEvent();  //let it paint the default stuff!

    QPainter painter(this->viewport());  //you need to paint on the viewport
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setPen(Qt::black);
    painter.drawText(rect, Qt::AlignCenter,  "Data");   // you need to take the rect you computed before
    painter.drawRect(rect);
}

If you need the rect for the whole line you need to take the rect of all sibling items (column count) in the row. QRect has a united() method to "concatenate" 2 rects into 1 surrounding rect.

UnitScan

Very well. Last question: how can I remove the copy of the row anchored to the mouse cursor while dragging?

UnitScan

[SOLVED]

To remove the row copy achored to the mouse cursor while dragging, you must reimplement the startDrag() method:

void DTableWidget::startDrag(Qt::DropActions supportedActions) {
    QModelIndexList indexes = selectedIndexes();
    if (indexes.count() > 0) {
        QMimeData *data = model()->mimeData(indexes);
        if (!data)
            return;
        QDrag *drag = new QDrag(this);
        drag->setMimeData(data);
        Qt::DropAction defaultDropAction = Qt::IgnoreAction;
        if (defaultDropAction != Qt::IgnoreAction && (supportedActions & defaultDropAction)) 
            defaultDropAction = defaultDropAction;
        else if (supportedActions & Qt::CopyAction && dragDropMode() != QAbstractItemView::InternalMove) 
            defaultDropAction = Qt::CopyAction;
        drag->exec(defaultDropAction);
    }
}