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c++qtqcheckbox

Qcheckbox minimum one option is always checked in QT -c++

I have a QT application with qcheckboxes. I would like to achive that one checkbox is always checked and i can check as much as i want, but one is always must be checked. How can i do this?

Solution

  • There is probably a more elegant way to do this, but I'd suggest just using signals.

    Somewhere, probably constructor, you would connect the signal

    connect( chkOne, &QCheckBox::toggled, this, &Test::onCheckboxOne );

    Then, in the function you've connected it to, simply check whether anything else is checked. For this, I used a variable called total_checked.

    void Test::onCheckboxOne( bool checked ) {
    disconnect( chkOne, &QCheckBox::toggled, this, &Test::onCheckboxOne );
    if ( !checked ) {
        if ( total_checked == 1 )
            this->chkOne->setCheckState( Qt::Checked );
        else
            --total_checked;
    } else {
        ++total_checked;
    }
    connect( chkOne, &QCheckBox::toggled, this, &Test::onCheckboxOne );
}

    This would become impractical if you have a lot of checkboxes, unless (once non are selected), you want a specific checkbox set, in which case the above would be a handler for all checkbox signals.