using QHeaderView

mzimmers

Hi all -

In this ancient post, the grandmaster advises someone who wanted to do the same thing I want to do: get the columns in a QTableView to expand when the parent widget is resized.

I think I understand the concept, but I'm having trouble connecting the dots between retrieving the header data, and setting it.

    // format the column widths.
    QVariant qv;
    QHeaderView *qhv = new QHeaderView(Qt::Horizontal);
    bool rc;
    
    for (int i = 0; i < m_nbrTableRowsVisible; ++i)
    {
        
        qv = m_modelDevice->getModel()->headerData(0, Qt::Horizontal);
//    what do I do here?
        rc = m_modelDevice->getModel()->setHeaderData(0, Qt::Horizontal, qv);
    }

Can someone clue me in? Thanks...

jsulm

@mzimmers said in using QHeaderView:

// what do I do here?

Well, call https://doc.qt.io/qt-5/qheaderview.html#setSectionResizeMode on qv before setting it?

mzimmers

@jsulm ahh...thanks for the tip. That led me to do some more looking, and I discovered the qvariant_cast() method; that was a new one on me. Does this look better?

    QVariant qv;
    QHeaderView *qhv = new QHeaderView(Qt::Horizontal);
    bool rc;

    for (int i = 0; i < m_nbrTableRowsVisible; ++i)
    {

        qv = m_modelDevice->getModel()->headerData(0, Qt::Horizontal);
        qhv = qvariant_cast<QHeaderView *>(qv);
        qhv->setSectionResizeMode(QHeaderView::Stretch);
        qv = QVariant::fromValue(qhv);
        rc = m_modelDevice->getModel()->setHeaderData(0, Qt::Horizontal, qv);
    }

Unfortunately, I can't test it because there's still something wrong with how Creator is handling my Widget class, but...that's another post in another forum.

jsulm

@mzimmers said in using QHeaderView:

QHeaderView *qhv = new QHeaderView(Qt::Horizontal);

Why do you create here a QHeaderView instance?

mzimmers

@jsulm good point. Better?

    QVariant qv;
    QHeaderView *qhv;
    bool rc;

    for (int i = 0; i < m_nbrTableRowsVisible; ++i)
    {
        qv = m_modelDevice->getModel()->headerData(0, Qt::Horizontal);
        qhv = qvariant_cast<QHeaderView *>(qv);
        qhv->setSectionResizeMode(QHeaderView::Stretch);
        qv = QVariant::fromValue(qhv);
        rc = m_modelDevice->getModel()->setHeaderData(0, Qt::Horizontal, qv);
    }

(The bool rc is just for my debugging purposes.)

Christian Ehrlicher

@mzimmers said in using QHeaderView:

qhv = qvariant_cast<QHeaderView *>(qv);

Are you serious? Why should a model return a pointer to a view??
Take a look at the documentation of your view to see how to access the headers!

mzimmers

@Christian-Ehrlicher ahh, yes. When the fog lifts, it can be a beautiful view:

    QHeaderView *qhv;
    qhv = ui->tableView->horizontalHeader();
    qhv->setSectionResizeMode(QHeaderView::Stretch);

Thanks for helping me get unwrapped from around the axle, Christian.

For icing on the cake, I don't suppose there's any way to combine this feature with a "resize to contents" functionality? One of my columns (the last one) needs a little more space than the others...not sure what the best way to go about this might be.

Thanks...