使用鼠标更改QTableView中的列宽

Question

I need behaviour in QTableView for changing of column width not only with help of QHeaderView , but directly on QTableView area itself. It will be good if I can set cursor pointer between cells in QTableView area and change the column width with "click and drag" on QTableView area itself.

Answer 1

Actually I don't see anything wrong with such behaviour. Especially for read-only table views where it could be really convenient.

Fastest way to implement this to install event handler which will catch mouse events and issue resize commands. Obviously you will have to calculate manually if mouse is over/around column separator.

UPD: to get an idea if cursor is around vertical axes you can use following method:

/* Returns the x-coordinate in contents coordinates of the given column. */
int x = tableView->columnViewportPosition(int column); 

mouse event will give you mouse position and then you can easily see if it matches any of column axes.

UPD2: I would even implement it in a bit more complicated way to handle mousemove together with header resize/scroll events within one eventHandler... to cache column positions in a sorted list, to optimise time spent in mousemove handler.. so, you will get binary search and distance check.. but its of course depends how heavy is interface in general..

Answer 2

Here a partial answer, showing how to access column separators

/** sense mouse position */
bool FreezeTableWidget::eventFilter(QObject *, QEvent *event) {
    if (event->type() == QEvent::MouseMove) {
        QMouseEvent *m = static_cast<QMouseEvent*>(event);
        QPoint p = m->pos();
        QRect r = visualRect(indexAt(p));
        if (abs(p.x() - r.x()) < 3) // || abs(p.x() - r.right()) < 3)
            setCursor(Qt::SplitHCursor);
        else
            unsetCursor();
    }
    return false;
}

eventFilter is a virtual function, but you must register it to get it called. I added in the FreezeTableWidget constructor:

qApp->installEventFilter(this);

edit : about position check, the suggestion from evilruff also works (albeit the computational efficiency argument is irrilevant), but in general I think that you could try an alternative, more general approach: namely to use the horizontalHeader item as a surrogate handler, because there we already have all the required, working, logic.

If you like to experiment with (and learn about) these GUI details, try to shift the vertical mouse position, and give the event to the header... I think it could work, and will be simpler than tracking the state by yourself.

Answer 3

Thanks to all!

Below is my result with source code, that implement behaviour like in the question (little bit dirty, but with general idea):

#define DELTA_SPLIT 4
static bMouseBetweenCols= false;
static int nResizeColumn= -1;

void CHeaderTableView::mouseMoveEvent(QMouseEvent * event)
{
    QMouseEvent *m = static_cast<QMouseEvent*>(event);
    QPoint p = m->pos();
    QRect r = visualRect(indexAt(p));

    if (bMouseBetweenCols && nResizeColumn != -1)
    {
        QTableView* pT= dynamic_cast<QTableView*>(parent());
        if (pT)
        {
            Q_ASSERT(pT->horizontalHeader());

            int nMinSectionSize= pT->horizontalHeader()->minimumSectionSize();
            int nSectionSize= p.x() - columnViewportPosition(nResizeColumn);

            if (nSectionSize >= nMinSectionSize)
            {
                pT->horizontalHeader()->resizeSection(nResizeColumn, nSectionSize);
            }
        }
    }

    if (    abs(p.x() - r.right()) <= DELTA_SPLIT
        ||  abs(p.x() -  r.left()) <= DELTA_SPLIT)
    {
        setCursor(Qt::SplitHCursor);

        event->ignore();
        return;
    }
    else
        unsetCursor();

    QTableView::mouseMoveEvent(event);
}

void CHeaderTableView::mousePressEvent(QMouseEvent *event)
{
    QMouseEvent *m = static_cast<QMouseEvent*>(event);
    QPoint p = m->pos();
    QRect r = visualRect(indexAt(p));

    if (    abs(p.x() - r.right()) <= DELTA_SPLIT
        ||  abs(p.x() -  r.left()) <= DELTA_SPLIT)
    {
        QTableView* pT= dynamic_cast<QTableView*>(parent());
        if (pT)
        {
            nResizeColumn= pT->horizontalHeader()->visualIndex(indexAt(p).column());

            if (abs(p.x() - r.left()) <= DELTA_SPLIT) { nResizeColumn--; }

            nResizeColumn= pT->horizontalHeader()->logicalIndex(nResizeColumn);

            if (nResizeColumn >= 0)
                bMouseBetweenCols= true;

            event->ignore();
            return;
        }
    }

    QTableView::mousePressEvent(event);
}

void CHeaderTableView::mouseReleaseEvent(QMouseEvent *event)
{
    QMouseEvent *m = static_cast<QMouseEvent*>(event);
    QPoint p = m->pos();
    QRect r = visualRect(indexAt(p));

    if (    abs(p.x() - r.right()) <= DELTA_SPLIT
        ||  abs(p.x() -  r.left()) <= DELTA_SPLIT)
    {
        bMouseBetweenCols= false;
        nResizeColumn= -1;

        event->ignore();
        return;
    }

    bMouseBetweenCols= false;
    nResizeColumn= -1;

    QTableView::mouseReleaseEvent(event);
}

void CHeaderTableView::mouseDoubleClickEvent(QMouseEvent *event)
{
    QMouseEvent *m = static_cast<QMouseEvent*>(event);
    QPoint p = m->pos();
    QRect r = visualRect(indexAt(p));

    if (    abs(p.x() - r.right()) <= DELTA_SPLIT
        ||  abs(p.x() -  r.left()) <= DELTA_SPLIT)
    {
        QTableView* pT= dynamic_cast<QTableView*>(parent());
        if (pT)
        {
            int nDblClickColumn= pT->horizontalHeader()->visualIndex(indexAt(p).column());

            if (abs(p.x() - r.left()) <= DELTA_SPLIT) { nDblClickColumn--; }

            nDblClickColumn= pT->horizontalHeader()->logicalIndex(nDblClickColumn);
            pT->resizeColumnToContents(nDblClickColumn);
        }

        event->ignore();
        return;
    }

    QTableView::mouseDoubleClickEvent(event);
}