Is it possible to set the text of the QTableView corner button?

Question

QTableView has a corner button, occupying the intersection between the horizontal and the vertical header. Clicking this will select all cells in the table. What I'm wondering is if it's possible to set this button's text, and if so, how?

Answer 1

I have implemented a working solution with PyQt 5.3, and it took surprisingly little code. My solution is based on code posted in this question at Qt Centre.

from PyQt5 import QtWidgets, QtCore


class TableView(QtWidgets.QTableView):
    """QTableView specialization that can e.g. paint the top left corner header.
    """
    def __init__(self, nw_heading, parent):
        super(TableView, self).__init__(parent)

        self.__nw_heading = nw_heading
        btn = self.findChild(QtWidgets.QAbstractButton)
        btn.setText(self.__nw_heading)
        btn.setToolTip('Toggle selecting all table cells')
        btn.installEventFilter(self)

        opt = QtWidgets.QStyleOptionHeader()
        opt.text = btn.text()
        s = QtCore.QSize(btn.style().sizeFromContents(
            QtWidgets.QStyle.CT_HeaderSection, opt, QtCore.QSize(), btn).
            expandedTo(QtWidgets.QApplication.globalStrut()))

        if s.isValid():
            self.verticalHeader().setMinimumWidth(s.width())

    def eventFilter(self, obj, event):
        if event.type() != QtCore.QEvent.Paint or not isinstance(
                obj, QtWidgets.QAbstractButton):
            return False

        # Paint by hand (borrowed from QTableCornerButton)
        opt = QtWidgets.QStyleOptionHeader()
        opt.initFrom(obj)
        styleState = QtWidgets.QStyle.State_None
        if obj.isEnabled():
            styleState |= QtWidgets.QStyle.State_Enabled
        if obj.isActiveWindow():
            styleState |= QtWidgets.QStyle.State_Active
        if obj.isDown():
            styleState |= QtWidgets.QStyle.State_Sunken
        opt.state = styleState
        opt.rect = obj.rect()
        # This line is the only difference to QTableCornerButton
        opt.text = obj.text()
        opt.position = QtWidgets.QStyleOptionHeader.OnlyOneSection
        painter = QtWidgets.QStylePainter(obj)
        painter.drawControl(QtWidgets.QStyle.CE_Header, opt)

        return True

Answer 2

You can add text on the corner button by finding a child from QTableWidget and add a QLabel to it by using the vertical layout as below.

QAbstractButton* button = qFindChild< QAbstractButton* >(TableWidget);
if (button) 
{
    QVBoxLayout* lay = new QVBoxLayout(button);
    lay->setContentsMargins(0, 0, 0, 0);
    QLabel* label = new QLabel("No");
    label->setStyleSheet("QLabel {font-face: ArialMT; font-size: 10px; color: #FFFFFF; font-weight: bold; }""QToolTip { color: #ffffff; background-color: #000000; border: 1px #000000; }");
    label->setAlignment(Qt::AlignCenter);
    label->setToolTip("Text");
    label->setContentsMargins(2, 2, 2, 2);
    lay->addWidget(label);
}