auto cornerWidget = new QWidget();

    auto bgColor = cornerWidget->palette().color(QPalette::Window).name();

    auto styleSheet = QString("background-color:%1;").arg(bgColor);

    cornerWidget->setStyleSheet(styleSheet);

    ScrollZoomer::setCornerWidget(cornerWidget);

}

void Zoomer::zoom(int up)

{

    ScrollZoomer::zoom(up);

    if(zoomRectIndex() == 0)

    {

        emit unzoomed();

    }

}

void Zoomer::zoom( const QRectF & rect)

{

    // set the zoom base when user zooms in to first level

    if (zoomRectIndex() == 0)

    {

        this->setZoomBase(false);

    }

    ScrollZoomer::zoom(rect);

}

QwtText Zoomer::trackerTextF(const QPointF& pos) const

{

    QwtText b = ScrollZoomer::trackerTextF(pos);

    const QPolygon pa = selection();

    if (pa.count() < 2)

    {

        return b;

    }

    const QRectF rect = invTransform(QRect(pa.first(), pa.last()).normalized());

    QString sizeText = QString(" [%1, %2]").\

        arg(rect.width(), 0, 'g', 4).\

        arg(rect.height(), 0, 'g', 4);

    b.setText(b.text() + sizeText);

    return b;

}

/*

  Copyright © 2017 Hasan Yavuz Özderya

  This file is part of serialplot.

  serialplot is free software: you can redistribute it and/or modify

  it under the terms of the GNU General Public License as published by

  the Free Software Foundation, either version 3 of the License, or

  (at your option) any later version.

  serialplot is distributed in the hope that it will be useful,

  but WITHOUT ANY WARRANTY; without even the implied warranty of

  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License

  along with serialplot.  If not, see <http://www.gnu.org/licenses/>.

*/

#ifndef ZOOMER_H

#define ZOOMER_H

#include <scrollzoomer.h>

class Zoomer : public ScrollZoomer

{

    Q_OBJECT

public:

    Zoomer(QWidget *, bool doReplot=true);

    void zoom(int up);

    void zoom( const QRectF & );

signals:

    void unzoomed();

protected:

    /// Re-implemented to display selection size in the tracker text.

    QwtText trackerTextF(const QPointF &pos) const;

};

#endif // ZOOMER_H