открытие файла и его передача в PaintEvent

Доброго времени суток.

#include <QMainWindow>
#include <QPicture>
#include <QImage>
#include <QPainter>
#include <QFileDevice>
#include <QFileDialog>
#include <QWidgets>


MainWindow::MainWindow(QWidget *parent):QWidget(parent)
{
       setPalette(QPaette(QT::white));
       setWindowTitle("Image")
}

void MainWindow::paintEvent(QPaintEvent *)
{
    QString fileName  = QFileDialog::getOpenFileName(this, tr("Open file"), QDir::currentPath());
    QImage img(fileName); 

    QPainter painter(this);
    painter.drawImage(0,0, img.scaled(this->size())); 
}

#include <QMainWindow>
#include <QPicture>
#include <QImage>
#include <QPainter>
#include <QFileDevice>
#include <QFileDialog>
#include <QWidgets>


MainWindow::MainWindow(QWidget *parent):QWidget(parent)
{
       setPalette(QPaette(QT::white));
       setWindowTitle("Image")
       QString fileName  = QFileDialog::getOpenFileName(this, tr("Open file"), QDir::currentPath());
       m_img = QImage(fileName); 
}

void MainWindow::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.drawImage(0,0, m_img.scaled(this->size())); 
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QImage m_img;
};

#endif // MAINWINDOW_H

#include "MainWindow.h"
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent)
	: QMainWindow(parent), ui(new Ui::MainWindowClass)

{
	ui->setupUi(this);
	

	setWindowTitle(tr("Viewer"));

	connect(ui->actionExit, SIGNAL(triggered()), this, SLOT(close()));
	connect(ui->actionAbout_app, SIGNAL(triggered()), this, SLOT(about_app()));
	connect(ui->actionAbout_qt, SIGNAL(triggered()), this, SLOT(about_qt()));
	connect(ui->actionOpen_file, SIGNAL(triggered()), this, SLOT(open()));
	
	connect(ui->horizontalScrollBar, SIGNAL(valueChanged(int)), ui->m_imagevw, SLOT(horScroll(int)));

}

void MainWindow::open()
{
	ui->m_imagevw->imageview::openFile();
}

void MainWindow::about_app()
{
	QMessageBox::about(this, tr("About "), tr("<b>B</b>."));
}
void MainWindow::about_qt()
{
	QMessageBox::aboutQt(this, QStringLiteral("About QT"));
}

#pragma once
#include <QtWidgets/QMainWindow>
#include "imageview.h"
#include "ui_MainWindow.h"
#include <QtWidgets/QWidget>
#include <QFileDevice>
#include <QTemporaryFile>
#include <QFileDialog>

namespace Ui
{
	class MainWindowClass;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = Q_NULLPTR);
	QString m_fileIn;

private slots:
	void open();
	void about_app();
	void about_qt();
private:
    Ui::MainWindowClass *ui;
	imageview *my_imageview;

};

#include "imageview.h"

imageview::imageview(QWidget *parent)
	: QWidget(parent)
{
	ui.setupUi(this);
	setPalette(QPalette(Qt::white));
	setWindowTitle("Image");
	openFile();
}

void imageview::openFile()
{
	m_fileName = QFileDialog::getOpenFileName(this, tr("Open File"), QDir::currentPath());
	  m_img = QImage(m_fileName); 
	m_img = img;
	update();
}



void imageview::paintEvent(QPaintEvent *event)
{
		QPainter painter(this);
		painter.drawImage(0, 0, m_img.scaled(this->size()));
}

#pragma once

#include <QWidget>
#include <QtGui>
#include <QFileDevice>
#include <QTemporaryFile>
#include <QPushButton.h>
#include <QFileDialog>
#include <iostream>
#include <QImage>
#include "ui_imageview.h"
namespace Ui
{
	class imageview;
}

class imageview : public QWidget
{
	Q_OBJECT

public:
	imageview(QWidget *parent = Q_NULLPTR);
	void openFile();


protected:
	void paintEvent(QPaintEvent *event);

private:
	Ui::imageview ui;
	QString m_fileName;
	QImage m_img;
};

void MainWindow::open()
{
	ui->m_imagevw->imageview::openFile();
}

void MainWindow::open()
{
	ui->m_imagevw->openFile();
}

imageview *my_imageview;

void imageview::paintEvent(QPaintEvent *event)
{
		QPainter painter(this);
		painter.drawImage(0, 0, m_img.scaled(this->size()));
}

void imageview::openFile()
{
	m_fileName = QFileDialog::getOpenFileName(this, tr("Open File"), QDir::currentPath());
	  m_img = QImage(m_fileName); 
	m_img = img; // Это очевидно не может быть здесь
	update();
}