Add widget right aligned to a QTableWidget cell

[hbatalha]

I want to add a widget(QPushButton) at the end of a QTableWidget cell.
I know there's QAbstractItemView::setIndexWidget(const QModelIndex &index, QWidget *widget) but it inserts the widget at the beginning of the cell. I want to insert a widget at end.

[VRonin]

Tested now:
tablewidgetdelegate.h

#ifndef TABLEWIDGETDELEGATE_H
#define TABLEWIDGETDELEGATE_H

#include <QTableWidget>
#include <QEvent>
#include <QModelIndex>
#include <QStyleOptionViewItem>
#include <QHoverEvent>

class TableWidgetDelegate : public QTableWidget
{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(TableWidgetDelegate)
#else
    Q_DISABLE_COPY(TableWidgetDelegate)
#endif
public:
    explicit TableWidgetDelegate(QWidget *parent = Q_NULLPTR)
        : QTableWidget(parent)
    {
        viewport()->setAttribute(Qt::WA_Hover,true);
    }
protected:
    bool viewportEvent(QEvent *event) Q_DECL_OVERRIDE
    {
        switch (event->type())
        {
        case QEvent::HoverMove:
        case QEvent::HoverEnter:
        case QEvent::HoverLeave:
        {
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
            QModelIndex index = indexAt(static_cast<QHoverEvent*>(event)->position().toPoint());
            QStyleOptionViewItem options;
            initViewItemOption(&options);
            QAbstractItemDelegate *delegate = itemDelegateForIndex(index);
#else
            QModelIndex index = indexAt(static_cast<QHoverEvent*>(event)->pos());
            QStyleOptionViewItem options = viewOptions();
            QAbstractItemDelegate *delegate = itemDelegate(index);
#endif
            if(delegate){
                QModelIndex buddy = model()->buddy(index);
                options.rect = visualRect(buddy);
                options.state |= (buddy == currentIndex() ? QStyle::State_HasFocus : QStyle::State_None);
                delegate->editorEvent(event, model(), options, buddy);
            }
            break;
        }
        default:
            break;
        }
        return QAbstractItemView::viewportEvent(event);
    }
};
#endif // TABLEWIDGETDELEGATE_H

buttondelegate.h

#ifndef BUTTONDELEGATE_H
#define BUTTONDELEGATE_H

#include <QApplication>
#include <QStyledItemDelegate>
#include <QPushButton>
#include <QMouseEvent>
#include <QToolTip>
#include <QPainter>
#include <QPalette>
#include <QTableWidget>
#include "mybutton.h"

class ButtonDelegate : public QStyledItemDelegate
{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(ButtonDelegate)
#else
    Q_DISABLE_COPY(ButtonDelegate)
#endif
public:
    explicit ButtonDelegate(QObject* parent)
        :QStyledItemDelegate(parent),
         tableWidget(qobject_cast<QTableWidget*>(parent))
    {
        mIsChecked = false;
        isDetailsButton = false;
        isEnabled = true;
        isHidden = false;
    }
    void update()
    {
        tableWidget->viewport()->update();
    }
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        Q_ASSERT(index.isValid());

        bool shouldPaint = false;
        if(isDetailsButton)
        {
            if(index.column() == 0)
                shouldPaint = true;
        }
        else
            shouldPaint = true;

        if(shouldPaint)
        {
            QStyleOptionViewItem opt = option;
            initStyleOption(&opt, index);
            const QWidget *widget = option.widget;

            QStyle *style = widget ? widget->style() : QApplication::style();
            style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
            QStyleOptionButton buttonOption = buttonOptions(opt);

            if(! isHidden)
            {
                style->drawControl(QStyle::CE_PushButton, &buttonOption, painter, widget);
            }
        }
        else
            QStyledItemDelegate::paint(painter, option, index);
    }
    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QSize baseSize = QStyledItemDelegate::sizeHint(option,index);
        const QRect butRect = buttonRect(opt);
        return QSize(baseSize.width()+butRect.width(),qMax(butRect.height(),baseSize.height()));
    }
    QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* result = new QWidget(parent);
        result->setGeometry(option.rect);
        QWidget* baseEditor = QStyledItemDelegate::createEditor(result,option,index);
        result->setFocusProxy(baseEditor);
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QRect butRect = buttonRect(opt);
        baseEditor->setObjectName("baseEditor");
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        MyButton* myButton = new MyButton(result);
        myButton->setObjectName("myButton");
        myButton->setText(m_buttonText);
        myButton->setIcon(m_buttonIcon);
        myButton->setEnabled(false);
        myButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
        connect(myButton, &MyButton::clicked, this, &ButtonDelegate::clickedHelper);
        connect(myButton, &MyButton::mouseIn, this, &ButtonDelegate::mouseInHelper);
        return result;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        currentIndex = index;
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setEditorData(baseEditor,index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setModelData(baseEditor,model,index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        editor->setGeometry(opt.rect);
        const QRect butRect = buttonRect(opt);
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        QWidget* myButton = editor->findChild<QWidget*>("myButton");
        Q_ASSERT(myButton);
        myButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
    }
    const QString text() const
    {
        return m_buttonText;
    }
    void setText(const QString &newButtonText)
    {
        m_buttonText = newButtonText;
        update();
    }
    const QIcon &icon() const
    {
        return m_buttonIcon;
    }
    void setIcon(const QIcon &newButtonIcon)
    {
        m_buttonIcon = newButtonIcon;
        update();
    }
    void setChecked(bool checked)
    {
        mIsChecked = checked;
    }
    bool isChecked()
    {
        return mIsChecked;
    }
    void setToolTip(QString tooltip)
    {
        tooltipText = tooltip;
    }
    void setDetailsButton(bool idb)
    {
        isDetailsButton = idb;
        update();
    }
    void setEnabled(bool enabled)
    {
        isEnabled = enabled;
        update();
    }
    void setHidden(bool hide)
    {
        isHidden = hide;
        isEnabled = ! hide;
        update();
    }
    void click()
    {
        mIsChecked = ! mIsChecked;
        clickedHelper();
    }
Q_SIGNALS:
    void clicked(const QModelIndex &index);
    void mouseIn(const QModelIndex &index);
protected:
    bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) override
    {
        Q_ASSERT(event);
        Q_ASSERT(model);
        Qt::ItemFlags flags = model->flags(index);
        if ((option.state & QStyle::State_Enabled) && (flags & Qt::ItemIsEnabled))
        {
            switch (event->type()){
            case QEvent::MouseButtonRelease:{
                QStyleOptionViewItem viewOpt(option);
                initStyleOption(&viewOpt, index);
                QMouseEvent *me = static_cast<QMouseEvent*>(event);
                if (me->button() == Qt::LeftButton)
                {
                    mIsChecked = ! mIsChecked;
                    currentIndex = index;
                    clickedHelper();
                }
            }
                break;
            case QEvent::HoverMove:
            case QEvent::HoverEnter:
            case QEvent::HoverLeave:
                if(index!=currentIndex){
                    currentIndex = index;
                    if(index.isValid())
                        mouseInHelper();
                }
                break;
            default:
                break;
            }
        }
        return QStyledItemDelegate::editorEvent(event,model,option,index);
    }
    virtual QStyleOptionButton buttonOptions(const QStyleOptionViewItem &option, bool skipRct=false) const
    {
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        int buttonIconSize = style->pixelMetric(QStyle::PM_ButtonIconSize, 0, widget);
        QStyleOptionButton buttonOption;
        buttonOption.text = m_buttonText;
        buttonOption.icon = m_buttonIcon;
        buttonOption.iconSize = (QSize(buttonIconSize,buttonIconSize));
        buttonOption.rect = skipRct ? QRect() : buttonRect(option);
        buttonOption.features = QStyleOptionButton::None;
        buttonOption.direction = option.direction;
        buttonOption.fontMetrics = option.fontMetrics;
        buttonOption.palette = option.palette;
        buttonOption.styleObject = option.styleObject;

        if(isEnabled)
            buttonOption.state = QStyle::State_Enabled;
        else
            buttonOption.state &= ~QStyle::State_Enabled;

        return buttonOption;
    }
    virtual QRect buttonRect(const QStyleOptionViewItem &option) const
    {
        const QStyleOptionButton buttonOption = buttonOptions(option, true);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        QSize buttonSize = style->sizeFromContents(QStyle::CT_PushButton, &buttonOption, QSize(), widget);
        buttonSize.setWidth(qMin(buttonSize.width(),option.rect.width()/2));
        return QRect(option.rect.left()+option.rect.width()-buttonSize.width(),option.rect.top(),buttonSize.width(),qMax(buttonSize.height(),option.rect.height()));
/*
        QRect r = option.rect;
        int x = isDetailsButton ? (r.left()+ r.width() - 10) : (r.center().x() - 6);
        int y = isDetailsButton ? r.top() : r.top() + 10;
        int s = isDetailsButton ? 10 : 1;

        return QRect(x, y, s, s);
        */
    }
    virtual bool helpEvent(QHelpEvent *event, QAbstractItemView *view, const QStyleOptionViewItem &option, const QModelIndex &index) override
    {
        if( !event || !view )
            return false;

        if( event->type() == QEvent::ToolTip )
        {
            QVariant tooltip = index.data( Qt::DisplayRole );
            if( QApplication::keyboardModifiers() == Qt::AltModifier )
            {
                QToolTip::showText( event->globalPos(), tooltipText);
            }
            else
            {
                QToolTip::showText( event->globalPos(), tooltipText);
            }

            if( !QStyledItemDelegate::helpEvent( event, view, option, index ) )
                QToolTip::hideText();
            return true;
        }

        return QStyledItemDelegate::helpEvent( event, view, option, index );
    }
private:
    mutable QModelIndex currentIndex;
    QPainter* mPainter;
    QString m_buttonText;
    QIcon m_buttonIcon;
    bool mIsChecked;
    bool isDetailsButton;
    bool isEnabled;
    bool isHidden;
    QString tooltipText;
    QTableWidget* tableWidget;

    void clickedHelper()
    {
        clicked(currentIndex);
    }
    void mouseInHelper()
    {
        mouseIn(currentIndex);
    }
};
#endif // BUTTONDELEGATE_H

mybutton.h

#ifndef MYBUTTON_H
#define MYBUTTON_H
#include <QPushButton>
class MyButton : public QPushButton
{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(MyButton)
#else
    Q_DISABLE_COPY(MyButton)
#endif
public:
    MyButton(QWidget* parent = 0) : QPushButton(parent) {}
    ~MyButton() {};

signals:
    void mouseIn();

protected:
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
    void enterEvent(QEnterEvent*) Q_DECL_OVERRIDE
#else
    void enterEvent(QEvent*) Q_DECL_OVERRIDE
#endif
    {
        emit mouseIn();
    }
};
#endif // MYBUTTON_H

main.cpp

#include <QApplication>
#include "buttondelegate.h"
#include <QModelIndex>
#include "tablewidgetdelegate.h"
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication app(argc,argv);
    TableWidgetDelegate wid;
    wid.setColumnCount(2);
    wid.setRowCount(2);
    ButtonDelegate *butDelegate = new ButtonDelegate(&wid);
    butDelegate->setText("Test");
    QPixmap bluePixmap(20,20);
    bluePixmap.fill(Qt::blue);
    QIcon blueIcon;
    blueIcon.addPixmap(bluePixmap);
    butDelegate->setIcon(blueIcon);
    QObject::connect(butDelegate,&ButtonDelegate::clicked,[](const QModelIndex& index){qDebug() << "Clicked " << index;});
    QObject::connect(butDelegate,&ButtonDelegate::mouseIn,[](const QModelIndex& index){qDebug() << "MouseIn " << index;});
    wid.setItemDelegate(butDelegate);
    wid.show();
    return app.exec();
}

[JoeCFD]

one way to do it.
https://www.qtcentre.org/threads/3416-Center-a-widget-in-a-cell-on-a-QTableWidget
you may try delegate as well

[hbatalha]

@JoeCFD yeah that's one way to do it but it is not a very elegant solution imo.
How would I do it with delegate?

[JoeCFD]

https://forum.qt.io/topic/110557/alignment-for-qcheckbox-in-qtablewidget/13

[hbatalha]

@JoeCFD I was able to solve by doing this:

QPushButton* detailsButton = new QPushButton;
detailsButton->setFixedSize(20, 15);

QHBoxLayout* hLayout = new QHBoxLayout;
hLayout->addStretch();
hLayout->addWidget(detailsButton);
widget->setLayout(hLayout);

ui->table->setItem(row, 0, new QTableWidgetItem(ttitle));
ui->table->setIndexWidget(ui->table->model()->index(row, 0), widget);

Thanks for the help.

[VRonin]

May setIndexWidget burn in hell forever and beyond!
https://forum.qt.io/post/475871

[JoeCFD]

@hbatalha agree that it is not elegant to do it this way. But it is not bad to have your code working at first. Someday, you may be able to find a better way to do it.

[hbatalha]

@VRonin I tried it but I am facing some problems, the buttons are only visible when the row is selected and I can't click it.
Also, how do I get the button and connect it outside the delegate class?

[VRonin]

@hbatalha said in Add widget right aligned to a QTableWidget cell:

the buttons are only visible when the row is selected

Just remove:

if(!(option.state & QStyle::State_Selected))
            return;

and I can't click it.

You need to adjust the edit trigger of the view: https://doc.qt.io/qt-5/qabstractitemview.html#editTriggers-prop

how do I get the button and connect it outside the delegate class?

create a signal in the delegate, something like Q_SIGNAL void clicked(const QModelIndex &index); and replace connect(editButton,&QPushButton::clicked,[](){qDebug("Edit");}); with connect(editButton,&QPushButton::clicked,this,std::bind(&TailButtonsDelegate::clicked,this,index));

[hbatalha]

@VRonin I getting this error when trying to create a signal in the delegate:

C:\msys64\mingw64\include\c++\10.3.0\functional:460: error: no type named 'type' in 'class std::result_of<void (TailButtonsDelegate::*&(const TailButtonsDelegate*&, QModelIndex&))(const QModelIndex&)>'
C:/msys64/mingw64/include/c++/10.3.0/functional:494:9:   required from 'struct QtPrivate::FunctorReturnType<std::_Bind<void (TailButtonsDelegate::*(const TailButtonsDelegate*, QModelIndex))(const QModelIndex&)>, QtPrivate::List<> >'
C:/Qt/6.2.0/mingw81_64/include/QtCore/qobject.h:306:158:   required from 'static typename std::enable_if<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1), QMetaObject::Connection>::type QObject::connect(const typename QtPrivate::FunctionPointer<Func>::Object*, Func1, const QObject*, Func2, Qt::ConnectionType) [with Func1 = void (QAbstractButton::*)(bool); Func2 = std::_Bind<void (TailButtonsDelegate::*(const TailButtonsDelegate*, QModelIndex))(const QModelIndex&)>; typename std::enable_if<(QtPrivate::FunctionPointer<Func2>::ArgumentCount == -1), QMetaObject::Connection>::type = QMetaObject::Connection; typename QtPrivate::FunctionPointer<Func>::Object = QAbstractButton]'
release\../delegate.h:55:108:   required from here
C:/msys64/mingw64/include/c++/10.3.0/functional:460:8: error: no type named 'type' in 'class std::result_of<void (TailButtonsDelegate::*&(const TailButtonsDelegate*&, QModelIndex&))(const QModelIndex&)>'
  460 |  using _Res_type_impl
      |        ^~~~~~~~~~~~~~

Also, I have a question: what's so wrong with setIndexWidget, creating a delegate seems so complex so I am asking what are the advantages of it over setIndexWidget?

[VRonin]

@hbatalha said in Add widget right aligned to a QTableWidget cell:

I getting this error when trying to create a signal in the delegate:

Can you show your code?

what's so wrong with setIndexWidget, creating a delegate seems so complex so I am asking what are the advantages of it over setIndexWidget?

Try creating 1000 rows and scroll through them. You'll realise very quick what the problem is. setIndexWidget is a HOG on resources

[hbatalha]

@VRonin Sorry for the really late reply, I have been working offline due to internet cut.

@VRonin said in Add widget right aligned to a QTableWidget cell:

Try creating 1000 rows and scroll through them. You'll realise very quick what the problem is. setIndexWidget is a HOG on resources

I Will try that, I am curious to see it

Can you show your code?

#ifndef TAILBUTTONSDELEGATE_H
#define TAILBUTTONSDELEGATE_H

#include <QApplication>
#include <QTableView>
#include <QStandardItemModel>
#include <QStyledItemDelegate>
#include <QHeaderView>
#include <QPushButton>

class TailButtonsDelegate : public QStyledItemDelegate
{
    Q_OBJECT
    Q_DISABLE_COPY(TailButtonsDelegate)

public:
    explicit TailButtonsDelegate(QObject* parent = Q_NULLPTR)
        :QStyledItemDelegate(parent)
    {}
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        Q_ASSERT(index.isValid());
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);


        QStyleOptionButton editButtonOption;
        editButtonOption.text = QString(); //use emoji for text, optionally you can use icon + iconSize
        editButtonOption.rect = QRect(option.rect.left()+option.rect.width()-(2*option.rect.height()),option.rect.top(),option.rect.height(),option.rect.height());
        editButtonOption.features = QStyleOptionButton::None;
        editButtonOption.direction = option.direction;
        editButtonOption.fontMetrics = option.fontMetrics;
        editButtonOption.palette = option.palette;
        editButtonOption.styleObject = option.styleObject;
        QStyleOptionButton removeButtonOption(editButtonOption);
        removeButtonOption.text = QString(); //use emoji for text, optionally you can use icon + iconSize
        removeButtonOption.rect = QRect(option.rect.left()+option.rect.width()-option.rect.height(),option.rect.top(),option.rect.height(),option.rect.height());
        style->drawControl(QStyle::CE_PushButton, &editButtonOption, painter, widget);
        style->drawControl(QStyle::CE_PushButton, &removeButtonOption, painter, widget);
    }
    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        const QSize baseSize = QStyledItemDelegate::sizeHint(option,index);
        return QSize(baseSize.width()+(2*baseSize.height()),baseSize.height());
    }
    QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* result = new QWidget(parent);
        result->setGeometry(option.rect);
        QWidget* baseEditor = QStyledItemDelegate::createEditor(result,option,index);
        baseEditor->setObjectName("baseEditor");
        baseEditor->setGeometry(0,0,option.rect.width()-(2*option.rect.height()),option.rect.height());
        QPushButton* editButton = new QPushButton(result);
        editButton->setObjectName("editButton");
        editButton->setGeometry(option.rect.width()-(2*option.rect.height()), 0, option.rect.height(),option.rect.height());
        connect(editButton,&QPushButton::clicked,[]()
        {
            qDebug("Edit");
        });
        QPushButton* removeButton = new QPushButton(result);
        removeButton->setObjectName("removeButton");
        removeButton->setGeometry(option.rect.width()-option.rect.height(), 0, option.rect.height(),option.rect.height());
        connect(editButton,&QPushButton::clicked,this,std::bind(&TailButtonsDelegate::clicked,this,index));
        return result;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setEditorData(baseEditor,index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setModelData(baseEditor,model,index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        Q_UNUSED(index)
        editor->setGeometry(option.rect);
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        baseEditor->setGeometry(0,0,option.rect.width()-(2*option.rect.height()),option.rect.height());
        QWidget* editButton = editor->findChild<QWidget*>("editButton");
        Q_ASSERT(editButton);
        editButton->setGeometry(option.rect.width()-(2*option.rect.height()), 0, option.rect.height(),option.rect.height());
        QWidget* removeButton = editor->findChild<QWidget*>("removeButton");
        Q_ASSERT(removeButton);
        removeButton->setGeometry(option.rect.width()-option.rect.height(), 0, option.rect.height(),option.rect.height());
        editor->setGeometry(option.rect);
    }

    Q_SIGNAL void clicked(const QModelIndex &index);
};

#endif // TAILBUTTONSDELEGATE_H

Also I want to set the button size to setFixedSize(10, 10); but I have been having problems controlling the size. For the time being I have being using this version using setIndexWidget

    QWidget* widget = new QWidget;

    QPushButton* detailsButton = new QPushButton;
    detailsButton->setFixedSize(10, 10);

    QHBoxLayout* hLayout = new QHBoxLayout;
    hLayout->addStretch();
    hLayout->addWidget(detailsButton);
    widget->setLayout(hLayout);

    ui->tableWidget->setIndexWidget(ui->tableWidget->model()->index(row, 0), widget);

So above is what I am trying to achieve using delegate.

[hbatalha]

Also the button is still not clickable

[VRonin]

Sorry for the delay in getting back to you, I've been offline for a few days. Try this:

#ifndef TAILBUTTONDELEGATE_H
#define TAILBUTTONDELEGATE_H

#include <QApplication>
#include <QStyledItemDelegate>
#include <QPushButton>
#include <QMouseEvent>
class TailButtonDelegate : public QStyledItemDelegate
{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(TailButtonDelegate)
#else
    Q_DISABLE_COPY(TailButtonDelegate)
#endif
public:
    explicit TailButtonDelegate(QObject* parent = Q_NULLPTR)
        :QStyledItemDelegate(parent)
    {}
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        Q_ASSERT(index.isValid());
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
        QStyleOptionButton buttonOption = buttonOptions(opt);
        style->drawControl(QStyle::CE_PushButton, &buttonOption, painter, widget);
    }
    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QSize baseSize = QStyledItemDelegate::sizeHint(option,index);
        const QRect butRect = buttonRect(opt);
        return QSize(baseSize.width()+butRect.width(),qMax(butRect.height(),baseSize.height()));
    }
    QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* result = new QWidget(parent);
        result->setGeometry(option.rect);
        QWidget* baseEditor = QStyledItemDelegate::createEditor(result,option,index);
        result->setFocusProxy(baseEditor);
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QRect butRect = buttonRect(opt);
        baseEditor->setObjectName("baseEditor");
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        QPushButton* extraButton = new QPushButton(result);
        extraButton->setObjectName("extraButton");
        extraButton->setText(m_buttonText);
        extraButton->setIcon(m_buttonIcon);
        extraButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
        connect(extraButton,&QPushButton::clicked,this,&TailButtonDelegate::clickedHelper);
        return result;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        currentIndex = index;
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setEditorData(baseEditor,index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setModelData(baseEditor,model,index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        editor->setGeometry(opt.rect);
        const QRect butRect = buttonRect(opt);
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        QWidget* extraButton = editor->findChild<QWidget*>("extraButton");
        Q_ASSERT(extraButton);
        extraButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
    }
    const QString buttonText() const
    {
        return m_buttonText;
    }
    void setButtonText(const QString &newButtonText)
    {
        m_buttonText = newButtonText;
    }
    const QIcon &buttonIcon() const
    {
        return m_buttonIcon;
    }
    void setButtonIcon(const QIcon &newButtonIcon)
    {
        m_buttonIcon = newButtonIcon;
    }
Q_SIGNALS:
    void buttonClicked(const QModelIndex &index);
protected:
    bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) Q_DECL_OVERRIDE{
        Q_ASSERT(event);
        Q_ASSERT(model);
        Qt::ItemFlags flags = model->flags(index);
        if ((option.state & QStyle::State_Enabled) && (flags & Qt::ItemIsEnabled)){
            if (event->type() == QEvent::MouseButtonRelease) {
                QStyleOptionViewItem viewOpt(option);
                initStyleOption(&viewOpt, index);
                const QRect butRect = buttonRect(viewOpt);
                QMouseEvent *me = static_cast<QMouseEvent*>(event);
                if (me->button() == Qt::LeftButton && butRect.contains(me->pos())){
                    currentIndex = index;
                    clickedHelper();
                }
            }
        }
        return QStyledItemDelegate::editorEvent(event,model,option,index);
    }
    virtual QStyleOptionButton buttonOptions(const QStyleOptionViewItem &option, bool skipRct=false) const{
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        int buttonIconSize = style->pixelMetric(QStyle::PM_ButtonIconSize, 0, widget);
        QStyleOptionButton buttonOption;
        buttonOption.text = m_buttonText;
        buttonOption.icon = m_buttonIcon;
        buttonOption.iconSize = (QSize(buttonIconSize,buttonIconSize));
        buttonOption.rect = skipRct ? QRect() : buttonRect(option);
        buttonOption.features = QStyleOptionButton::None;
        buttonOption.direction = option.direction;
        buttonOption.fontMetrics = option.fontMetrics;
        buttonOption.palette = option.palette;
        buttonOption.styleObject = option.styleObject;
        buttonOption.state = option.state;
        return buttonOption;
    }
    virtual QRect buttonRect(const QStyleOptionViewItem &option) const{
        const QStyleOptionButton buttonOption = buttonOptions(option,true);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        QSize buttonSize = style->sizeFromContents(QStyle::CT_PushButton, &buttonOption, QSize(), widget);
        buttonSize.setWidth(qMin(buttonSize.width(),option.rect.width()/2));
        return QRect(option.rect.left()+option.rect.width()-buttonSize.width(),option.rect.top(),buttonSize.width(),qMax(buttonSize.height(),option.rect.height()));
    }
private:
    mutable QModelIndex currentIndex;
    QString m_buttonText;
    QIcon m_buttonIcon;
    void clickedHelper(){buttonClicked(currentIndex);}
};

#endif // TAILBUTTONDELEGATE_H

Then you can use it with something like:

int main(int argc, char *argv[])
{
    QApplication app(argc,argv);
    QTableWidget wid(2,2);
    TailButtonDelegate *butDelegate = new TailButtonDelegate(&wid);
    butDelegate->setButtonText("Test");
    QPixmap bluePixmap(20,20);
    bluePixmap.fill(Qt::blue);
    QIcon blueIcon;
    blueIcon.addPixmap(bluePixmap);
    butDelegate->setButtonIcon(blueIcon);
    QObject::connect(butDelegate,&TailButtonDelegate::buttonClicked,[](const QModelIndex& index){qDebug() << "Clicked " << index;});
    wid.setItemDelegate(butDelegate);
    wid.show();
    return app.exec();

}

[VRonin]

@hbatalha said in Add widget right aligned to a QTableWidget cell:

Also I want to set the button size to setFixedSize(10, 10);

To do this in the example above you'd need to tweak the buttonRect() method to something like

virtual QRect buttonRect(const QStyleOptionViewItem &option) const{
    return QRect(option.rect.left()+option.rect.width()-10,option.rect.top(),10,10);
}

[hbatalha]

@VRonin It's working greatly, thanks, but I want to access some QPushButton methods, namely setCheckable, isChecked, setChecked, setToolTip. Also I want to emit signal when the mouse enters the button, I tried doind that but it's not working.
This is what I have tried to get a signal when mouse enters the button

#ifndef TAILBUTTONSDELEGATE_H
#define TAILBUTTONSDELEGATE_H

#include <QApplication>
#include <QStyledItemDelegate>
#include <QPushButton>
#include <QMouseEvent>

class MyButton : public QPushButton
{
    Q_OBJECT

public:
    MyButton(QWidget* parent = 0) : QPushButton(parent) {}
    ~MyButton() {};

signals:
    void mouseIn();

protected:
    void enterEvent(QEnterEvent*) override
    {
        emit mouseIn();
    }
};

class TailButtonDelegate : public QStyledItemDelegate
{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(TailButtonDelegate)
#else
    Q_DISABLE_COPY(TailButtonDelegate)
#endif
public:
    explicit TailButtonDelegate(QObject* parent = Q_NULLPTR)
        :QStyledItemDelegate(parent)
    {}
    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        Q_ASSERT(index.isValid());
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
        QStyleOptionButton buttonOption = buttonOptions(opt);
        style->drawControl(QStyle::CE_PushButton, &buttonOption, painter, widget);
    }
    QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QSize baseSize = QStyledItemDelegate::sizeHint(option,index);
        const QRect butRect = buttonRect(opt);
        return QSize(baseSize.width()+butRect.width(),qMax(butRect.height(),baseSize.height()));
    }
    QWidget* createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* result = new QWidget(parent);
        result->setGeometry(option.rect);
        QWidget* baseEditor = QStyledItemDelegate::createEditor(result,option,index);
        result->setFocusProxy(baseEditor);
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        const QRect butRect = buttonRect(opt);
        baseEditor->setObjectName("baseEditor");
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        MyButton* myButton = new MyButton(result);
        myButton->setObjectName("myButton");
        myButton->setText(m_buttonText);
        myButton->setIcon(m_buttonIcon);
        myButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
        connect(myButton, &MyButton::clicked, this, &TailButtonDelegate::clickedHelper);
        connect(myButton, &MyButton::mouseIn, this, &TailButtonDelegate::mouseInHelper);
        return result;
    }
    void setEditorData(QWidget *editor, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        currentIndex = index;
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setEditorData(baseEditor,index);
    }
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        QStyledItemDelegate::setModelData(baseEditor,model,index);
    }
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const Q_DECL_OVERRIDE
    {
        QStyleOptionViewItem opt = option;
        initStyleOption(&opt, index);
        editor->setGeometry(opt.rect);
        const QRect butRect = buttonRect(opt);
        QWidget* baseEditor = editor->findChild<QWidget*>("baseEditor");
        Q_ASSERT(baseEditor);
        baseEditor->setGeometry(0,0,opt.rect.width()-butRect.width(),opt.rect.height());
        QWidget* myButton = editor->findChild<QWidget*>("myButton");
        Q_ASSERT(myButton);
        myButton->setGeometry(opt.rect.width()-butRect.width(), 0, butRect.width(),butRect.height());
    }
    const QString buttonText() const
    {
        return m_buttonText;
    }
    void setButtonText(const QString &newButtonText)
    {
        m_buttonText = newButtonText;
    }
    const QIcon &buttonIcon() const
    {
        return m_buttonIcon;
    }
    void setButtonIcon(const QIcon &newButtonIcon)
    {
        m_buttonIcon = newButtonIcon;
    }
Q_SIGNALS:
    void clicked(const QModelIndex &index);
    void mouseIn(const QModelIndex &index);
protected:
    bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index) Q_DECL_OVERRIDE
    {
        Q_ASSERT(event);
        Q_ASSERT(model);
        Qt::ItemFlags flags = model->flags(index);
        if ((option.state & QStyle::State_Enabled) && (flags & Qt::ItemIsEnabled))
        {
            if (event->type() == QEvent::MouseButtonRelease)
            {
                QStyleOptionViewItem viewOpt(option);
                initStyleOption(&viewOpt, index);
                const QRect butRect = buttonRect(viewOpt);
                QMouseEvent *me = static_cast<QMouseEvent*>(event);
                if (me->button() == Qt::LeftButton && butRect.contains(me->pos()))
                {
                    currentIndex = index;
                    clickedHelper();
                }
            }
            if (event->type() == QEvent::Enter)
            {
                {
                    currentIndex = index;
                    mouseInHelper();
                }
            }
        }
        return QStyledItemDelegate::editorEvent(event,model,option,index);
    }
    virtual QStyleOptionButton buttonOptions(const QStyleOptionViewItem &option, bool skipRct=false) const
    {
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        int buttonIconSize = style->pixelMetric(QStyle::PM_ButtonIconSize, 0, widget);
        QStyleOptionButton buttonOption;
        buttonOption.text = m_buttonText;
        buttonOption.icon = m_buttonIcon;
        buttonOption.iconSize = (QSize(buttonIconSize,buttonIconSize));
        buttonOption.rect = skipRct ? QRect() : buttonRect(option);
        buttonOption.features = QStyleOptionButton::None;
        buttonOption.direction = option.direction;
        buttonOption.fontMetrics = option.fontMetrics;
        buttonOption.palette = option.palette;
        buttonOption.styleObject = option.styleObject;
        buttonOption.state = option.state;
        return buttonOption;
    }
    virtual QRect buttonRect(const QStyleOptionViewItem &option) const
    {
        const QStyleOptionButton buttonOption = buttonOptions(option,true);
        const QWidget *widget = option.widget;
        QStyle *style = widget ? widget->style() : QApplication::style();
        QSize buttonSize = style->sizeFromContents(QStyle::CT_PushButton, &buttonOption, QSize(), widget);
        buttonSize.setWidth(qMin(buttonSize.width(),option.rect.width()/2));
        return QRect(option.rect.left()+option.rect.width()-10,option.rect.top(),10,10);
    }
private:
    mutable QModelIndex currentIndex;
    QString m_buttonText;
    QIcon m_buttonIcon;
    void clickedHelper()
    {
        clicked(currentIndex);
    }
    void mouseInHelper()
    {
        mouseIn(currentIndex);
    }
};

#endif // TAILBUTTONSDELEGATE_H

but it is not working.

[hbatalha]

Also I would like have the button in the middle of the cell(top - bottom), this when set the size to (10,10)

[hbatalha]

Update: I was able to solve all the problems mentioned above except for the mouse over event signal.
So now I just want a way to signal when the mouse goes over the delegate, I have tried many "solutions" none has worked yet for me.

[VRonin]

Sorry for the choppy response. Your delegate code is doing the right thing (just minor note it should handle QEvent::HoverEnter instead of QEvent::Enter), the problem is that hover events are not passed by the view to the delegate. You need to subclass your view and reimplement viewportEvent to something like: (warning: untested code)

class HoverDelegateView : public QTableView{
    Q_OBJECT
#if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
    Q_DISABLE_COPY_MOVE(HoverDelegateView)
#else
    Q_DISABLE_COPY(HoverDelegateView)
#endif
public:
    explicit HoverDelegateView(QWidget *parent = Q_NULLPTR)
        : QTableView(parent)
    {}
protected:
    bool viewportEvent(QEvent *event) Q_DECL_OVERRIDE
    {
        switch (event->type()){
        case QEvent::HoverMove:
        case QEvent::HoverEnter:
        case QEvent::HoverLeave:{
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
            QModelIndex index = indexAt(static_cast<QHoverEvent*>(event)->position().toPoint());
            QStyleOptionViewItem options;
            initViewItemOption(&options);
#else
            QModelIndex index = indexAt(static_cast<QHoverEvent*>(event)->pos());
            QStyleOptionViewItem options = viewOptions();
#endif
            QModelIndex buddy = model()->buddy(index);
            options.rect = visualRect(buddy);
            options.state |= (buddy == currentIndex() ? QStyle::State_HasFocus : QStyle::State_None);
            QAbstractItemDelegate *delegate = itemDelegate(index);
            delegate->editorEvent(event, model(), options, buddy);
            break;
        }
        default:
            break;
        }
        return QAbstractItemView::viewportEvent(event);
    }
};

[hbatalha]

@VRonin I understood what you said, the concept behind it. In the code there are two undeclared identifiers: viewOptions and index though.