Why IntMode::data function is always called while the mouse is hover over the view?

[milan]

I do not understand why Data function is called while the mouse is hover over the view? The data function is overriden function for QAbstractListModel.

#ifndef INTMODEL_H
#define INTMODEL_H

#include <QAbstractListModel>
#include <QDebug>

class IntModel : public QAbstractListModel
{
    Q_OBJECT

public:
    explicit IntModel(int count, QObject *parent = nullptr);

    // Basic functionality:
    int rowCount(const QModelIndex &parent = QModelIndex()) const override;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;

    Qt::ItemFlags flags(const QModelIndex &index) const override;
    bool setData(const QModelIndex &index, const QVariant &value, int role) override;
private:
    QList<int> m_values;
};

#endif // INTMODEL_H

#include "intmodel.h"

IntModel::IntModel(int count, QObject *parent) : QAbstractListModel(parent)
{
    for (int i=0; i < count; ++i)
        m_values << i+1;
}

int IntModel::rowCount(const QModelIndex &parent) const
{
    // For list models only the root node (an invalid parent) should return the list's size. For all
    // other (valid) parents, rowCount() should return 0 so that it does not become a tree model.
    if (parent.isValid())
        return 0;
    return  m_values.count();
}

QVariant IntModel::data(const QModelIndex &index, int role) const
{
    qDebug() << "IntModel data called.....";

    if (!index.isValid())
        return QVariant();

    if(role != Qt::DisplayRole )// && role != Qt::EditRole )
        return QVariant();

    if( index.column() == 0 && index.row() < m_values.count() )
        return m_values.at( index.row() );
    else
        return QVariant();
}

Qt::ItemFlags IntModel::flags( const QModelIndex &index ) const
{
    if(!index.isValid())
        return Qt::ItemIsEnabled;
    return Qt::ItemIsSelectable | Qt::ItemIsEditable | Qt::ItemIsEnabled;
}

bool IntModel::setData( const QModelIndex &index, const QVariant &value, int role )
{
    if(role != Qt::EditRole || index.column() != 0 || index.row() >= m_values.count())
        return false;
    if(value.toInt() == m_values.at( index.row()))
        return false;
    m_values[index.row()] = value.toInt();
    emit dataChanged(index, index);
    return true;
}

    schemListView = new QListView;
    intModel = new IntModel(25);
    schemListView ->setModel(intModel);

[Christian Ehrlicher]

When you also output the role I would guess it's the ToolTip role.

[milan]

@Christian-Ehrlicher . No it is not tool-tip role. It is first statement inside IntModel::data function. It is debug statment. But this means on every hover of list view elements, this data function is continously called. I do not understand why this function is called.

[Christian Ehrlicher]

Once again: When you add the role to your debug output you will for sure notice that the data for Qt::ToolTipRole is requested (and maybe Qt::BackgroundRole / TextRole because the item is repainted)