PyQt: zooming with QGraphicsSceneWheelEvent

[danboid]

I am new to both (Py)Qt and Python. I am currently trying to write my first PyQt app in the form of a simple image viewer I have dubbed shufti. So far I have got it to load images files from the command line and... well that's about all so far. Now I want to be able to zoom in and out of the shufti QGraphicsView window by scrolling the mousewheel over the window but I'm having trouble figuring out how that should work.

What I have been able to deduce is that I should be able to achieve this using QGraphicsSceneWheelEvent / QGraphicsSceneWheelEvent.delta and then I'd need to hook that up to adjust the self.view.scale() object within the initUI method, somehow.

I've had a search but I've not been able to find any examples of people using QGraphicsSceneWheelEvent / WheelEvent with PyQt so I'm hoping someone could explain how I might get the two interacting?

Thanks

#!/usr/bin/python3
# -*- coding: utf-8 -*-
#
# shufti - A WIP, PyQt5 persistent image viewer
#
# By Dan MacDonald
#
# 2017
#
# Usage:
#
# python shufti.py path/to/image
 
import sys
from PyQt5 import QtCore
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QMainWindow, QApplication, QGraphicsScene, QGraphicsView
 
class Shufti(QMainWindow):
 
    def __init__(self):
        super().__init__()
        try:
            self.file = open(sys.argv[1], 'r')
        except IOError:
            print('There was an error opening the file')
            sys.exit(1)
 
        if (sys.argv[1]).lower().endswith(('.png', '.jpg', '.jpeg', '.gif', '.bmp', '.pbm', '.pgm', '.ppm', '.xbm', '.xpm')):
            self.initUI()
            self.setWindowTitle("shufti")
            self.resize(self.img.size())
        else:
            print("Unsupported file format")
            sys.exit(1)
 
    def initUI(self):               
 
        self.img = QPixmap(sys.argv[1])
        self.scene = QGraphicsScene()
        self.scene.addPixmap(self.img)
        self.view = QGraphicsView(self.scene, self)
        self.view.resize(self.img.width() + 2, self.img.height() + 2)
        self.show()
 
    def toggleFullscreen(self):
        if self.isFullScreen():
            self.showNormal()
        else:
            self.showFullScreen()
 
    def keyPressEvent(self, event):
        if event.key() == QtCore.Qt.Key_F11 or event.key() == QtCore.Qt.Key_F:
            self.toggleFullscreen()
 
 
if __name__ == '__main__':
 
    app = QApplication(sys.argv)
    shufti = Shufti()
    sys.exit(app.exec_())

#!/usr/bin/python3
# -*- coding: utf-8 -*-
#
# shufti - A WIP, PyQt5 persistent image viewer
#
# By Dan MacDonald
#
# 2017
#
# Usage:
#
# python shufti.py path/to/image

import sys
from PyQt5 import QtCore
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QMainWindow, QApplication, QGraphicsScene, QGraphicsView

class Shufti(QMainWindow):
    
    def __init__(self):
        super().__init__()
        try:
            self.file = open(sys.argv[1], 'r')
        except IOError:
            print('There was an error opening the file')
            sys.exit(1)
        
        if (sys.argv[1]).lower().endswith(('.png', '.jpg', '.jpeg', '.gif', '.bmp', '.pbm', '.pgm', '.ppm', '.xbm', '.xpm')):
            self.initUI()
            self.setWindowTitle("shufti")
            self.resize(self.img.size())
        else:
            print("Unsupported file format")
            sys.exit(1)
        
    def initUI(self):               
        
        self.img = QPixmap(sys.argv[1])
        self.scene = QGraphicsScene()
        self.scene.addPixmap(self.img)
        self.view = QGraphicsView(self.scene, self)
        self.view.resize(self.img.width() + 2, self.img.height() + 2)
        self.show()
        
    def toggleFullscreen(self):
        if self.isFullScreen():
            self.showNormal()
        else:
            self.showFullScreen()
            
    def keyPressEvent(self, event):
        if event.key() == QtCore.Qt.Key_F11 or event.key() == QtCore.Qt.Key_F:
            self.toggleFullscreen()
        
        
if __name__ == '__main__':
    
    app = QApplication(sys.argv)
    shufti = Shufti()
    sys.exit(app.exec_())

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