Important: Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

Add a QCheckBox as a header to a QTableWidget



  • I want to accomplish this:

    Screenshot_6.png


  • Lifetime Qt Champion


  • Moderators



  • @mrjj I honestly was expecting something a lot simpler.

    @Chris-Kawa the example the mousepress event doesn't work very well when I use it.
    I have a dialog which its class is a member of MainWindow, I have an action that when triggered will open that dialog that contains the tablewidget, when I have it open and I click on the box I have to close the dialog and open it again to see that it's been checked and vice-versa.


  • Moderators

    @hbatalha said in Add a QCheckBox as a header to a QTableWidget:

    when I have it open and I click on the box I have to close the dialog and open it again to see that it's been checked and vice-versa.

    Then you must've done something differently. The example I linked to certainly does not behave like that and I see nothing in it that would make it so. Can you share your custom header implementation and the part of code where you create the dialog and set the header?



  • @Chris-Kawa

    Then you must've done something differently.

    I just copied and pasted.

    Can you share your custom header implementation and the part of code where you create the dialog and set the header?

    class MyHeader : public QHeaderView
    {
    public:
    
        MyHeader(Qt::Orientation orientation, QWidget * parent = nullptr) : QHeaderView(orientation, parent)
        {}
    protected:
    
        void paintSection(QPainter *painter, const QRect &rect, int logicalIndex) const
        {
            painter->save();
            QHeaderView::paintSection(painter, rect, logicalIndex);
            painter->restore();
            if (logicalIndex == 0)
            {
                QStyleOptionButton option;
                option.rect = QRect(5,5,15,15);
                if (isOn)
                    option.state = QStyle::State_On;
                else
                    option.state = QStyle::State_Off;
                this->style()->drawPrimitive(QStyle::PE_IndicatorCheckBox, &option, painter);
            }
        }
    
        void mousePressEvent(QMouseEvent *event)
        {
            qDebug() << "here";
            if (isOn)
                isOn = false;
            else
                isOn = true;
            this->update();
            QHeaderView::mousePressEvent(event);
        }
    private:
    
        bool isOn;
    };
    
    
    
    HistoryWindow::HistoryWindow(QWidget *parent) :
        QDialog(parent),
        ui(new Ui::historyWindow)
    {
        ui->setupUi(this);
    
        this->setWindowTitle(tr("History"));
    
        ui->search_lineEdit->setPlaceholderText(tr("Search"));
    
        setStyleSheet("QLineEdit{"
                      "    color: white;" //TEXT COLOR
                      "}"
                      "QLineEdit[text=\"\"]{"
                      "    color: gray;" //TEXTHOLDER COLOR
                      "}");
        connect(ui->search_lineEdit, &QLineEdit::textChanged, [=] { style()->polish(ui->search_lineEdit); });
    
        ui->search_lineEdit->setFocusPolicy(Qt::ClickFocus);
    
        MyHeader* h = new MyHeader(Qt::Horizontal, ui->table);
        ui->table->setHorizontalHeader(h);
    
        ui->table->setColumnWidth(0, 318);
        ui->table->setColumnWidth(1, 70);
        ui->table->setShowGrid(false);
        ui->table->horizontalScrollBar()->hide();
        ui->table->setSelectionMode(QAbstractItemView::NoSelection);
        ui->table->setFocusPolicy(Qt::NoFocus);
        ui->search_lineEdit->clearFocus();
    
    }
    
    HistoryWindow::~HistoryWindow()
    {
        delete ui;
    }
    

  • Moderators

    Sigh... right, don't you just love when internet examples are buggy? :P

    Here's a fixed version:

    class MyHeader : public QHeaderView
    {
    public:
        using QHeaderView::QHeaderView;
    
    protected:
    
        void paintSection(QPainter* painter, const QRect &rect, int logicalIndex) const override
        {
            painter->save();
            QHeaderView::paintSection(painter, rect, logicalIndex);
            painter->restore();
    
            if (model() && logicalIndex >= 0)
            {
                QStyleOptionButton option;
                option.init(this);
    
                QRect checkbox_rect = style()->subElementRect(QStyle::SubElement::SE_CheckBoxIndicator, &option, this);
                checkbox_rect.moveCenter(rect.center());
    
                bool checked = model()->headerData(logicalIndex, orientation(), Qt::CheckStateRole).toBool();
    
                option.rect = checkbox_rect;
                option.state = checked ? QStyle::State_On : QStyle::State_Off;
    
                style()->drawPrimitive(QStyle::PE_IndicatorCheckBox, &option, painter);
            }
        }
    
        void mouseReleaseEvent(QMouseEvent* event) override
        {
            QHeaderView::mouseReleaseEvent(event);
            if(model())
            {
                int section = logicalIndexAt(event->pos());
                if (section >= 0)
                {
                    bool checked = model()->headerData(section, orientation(), Qt::CheckStateRole).toBool();
                    model()->setHeaderData(section, orientation(), !checked, Qt::CheckStateRole);
                    viewport()->update();
                }
            }
        }
    };
    

    Just a note - for simplicity this version toggles the checkbox whenever you click anywhere in the header section. You should probably shrink this area to only the actual checkbox. You have all the info in the example - just get the checkbox rectangle and see if the click was inside it.



  • @Chris-Kawa thanks for the code.

    I believe that instead of this line

    option.init(this);

    you meant
    option.initFrom(this); becasue the compiler complains about the non-existence of init

    A question:
    How can I add MyHeader only to the first colum like in the buggy example, instead of adding to all the columns in the header?

    Edit: To add MyHeader only to the first colum I just edited this line:

    if (model() && logicalIndex >= 0)
    

    to

    if (model() && logicalIndex == 0)
    


  • @Chris-Kawa How would I implement a clicked() signal mechanism?


  • Lifetime Qt Champion

    @hbatalha

    Hi
    you would define a signal in .h ( in the class)

    ..
    signals:
    void Clicked();

    then use it with the keyword emit
    in void mouseReleaseEvent(QMouseEvent* event)
    in the spot where you check/uncheck ( maybe after viewport()->update(); )
    like

    emit clicked();
    

    Do not i didn't put a parameter here to the clicked signal but in real world you might want to consider adding an int/id to say which section was clicked.


  • Moderators

    Just to add to what @mrjj said - a click is when you press and release mouse button on the same widget.

    Having said that you shouldn't just always emit it in release event. You should record in press event which section was pressed, then in release check if it's the same one and only then emit a clicked signal.

    If you release on different section than the one you press on nothing should happen. This is for the purpose of user realizing mid-click that they pressed on the wrong area. They can then move the mouse away and release and this is basically cancelling the click.



  • @Chris-Kawa @mrjj Done.

    Is there a way to control the checkbox programatically, sending the signal and get the checkbox checked. I need the checkbox default state to be checked and I need to uncheck it when I uncheck any checkbox in the rows in the qtablewidget. Like in the OP image.


  • Lifetime Qt Champion

    @hbatalha
    hi
    it uses the model so you can just set it in model

     model->setHeaderData(section, orientation(), true/false, Qt::CheckStateRole);
    


  • @mrjj said in Add a QCheckBox as a header to a QTableWidget:

    model->setHeaderData(section, orientation(), true/false, Qt::CheckStateRole);

    what would be the value of section?


  • Lifetime Qt Champion

    @hbatalha
    just 0,1,2,3,4 for the sections.
    unless you allow drag to reorder then you have to use
    https://doc.qt.io/qt-5/qheaderview.html#visualIndex
    to map to the right index/ID



  • @mrjj I gave it 0.

    Everything is working perfect.

    Thank you all!!!



  • @mrjj just 0,1,2,3,4 for the sections.
    unless you allow drag to reorder then you have to use
    https://doc.qt.io/qt-5/qheaderview.html#visualIndex https://www.worktime.com/employee-time-tracking-software
    to map to the right index/ID

    Hello,
    the question is too simple, but I'm a beginner, please tell me what parameters of the indexer should be?

    Thank you


  • Lifetime Qt Champion

    @lisukovigor492
    Hi
    you mean for the
    int QHeaderView::visualIndex(int logicalIndex) ?

    well its for when its reordered. then say index 5 is in front and then comes 2 and so on.
    The issues is they are no longer in order.

    so you use

    int realIndex = HeaderView->visualIndex(0)
    and IF the header is reorderd it will then tell you what index is a section 0.
    like 7. or what ever what dragged there.

    there is also
    int QHeaderView::logicalIndex(int visualIndex)

    I might recall it reverse. :) but they allow to map between the sections you see on screen and their real Id/indexs.

    But this is only important if you allow user to move the sections around.

    To get to know them, you could enable it and then
    drag some around and the see what therse functions returns for the sections.

    its all just integers values so nothing fancy at all.


Log in to reply