//////////////////////////////////////////////////////////////////////myvideoobject.h

#ifndef MYVIDEOOBJECT_H
#define MYVIDEOOBJECT_H

#include <QVideoWidget>

class QRubberBand;

class MyVideoObject : public QVideoWidget
{
public:
    MyVideoObject(QWidget *parent = nullptr);
protected:
    void mouseMoveEvent(QMouseEvent *ev);
    void mousePressEvent(QMouseEvent *ev);
    void mouseReleaseEvent(QMouseEvent *ev);
    void paintEvent(QPaintEvent *ev);
private:
    QRubberBand *rubberBand;
    QPoint origin;
    QRect rect;
};

#endif // MYVIDEOOBJECT_H




//////////////////////////////////////////////////////////////myvideoobject.cpp


#include "myvideoobject.h"

#include <QMouseEvent>
#include <QPainter>
#include <QRubberBand>

MyVideoObject::MyVideoObject(QWidget *parent):
    QVideoWidget(parent),
    rubberBand(nullptr){}

void MyVideoObject::mousePressEvent(QMouseEvent *ev)
{
    origin = ev->pos();
    if(!rubberBand)
        rubberBand = new QRubberBand(QRubberBand::Rectangle, this);
    rubberBand->setGeometry(QRect(origin,QSize()));
    rubberBand->show();
    QVideoWidget::mousePressEvent(ev);
}

void MyVideoObject::mouseMoveEvent(QMouseEvent *ev)
{
    rubberBand->setGeometry(QRect(origin,ev->pos()).normalized());
    QVideoWidget::mouseMoveEvent(ev);
}

void MyVideoObject::mouseReleaseEvent(QMouseEvent *ev)
{
    rect = rubberBand->geometry();
    update();
    QVideoWidget::mouseReleaseEvent(ev);
}

void MyVideoObject::paintEvent(QPaintEvent *ev)
{
    QVideoWidget::paintEvent(ev);
    QPainter painter(this);
    painter.save();
    painter.setBrush(Qt::red);
    if(!rect.isNull())
        painter.drawRect(rect);
    painter.restore();
}