Pygame not returning events while embedded in PyQt

Question

I'm testing out an application and the UI uses PyQt4 with Pygame embedded into it. It uses a timer to "update" itself so to speak and in the timerEvent function Pygame attempts to retrieve all detected events. Issue is, Pygame isn't detecting any events.

Here's a minimalist version of my code

#!/etc/python2.7
from PyQt4 import QtGui
from PyQt4 import QtCore
import pygame
import sys

class ImageWidget(QtGui.QWidget):
    def __init__(self,surface,parent=None):
        super(ImageWidget,self).__init__(parent)
        w=surface.get_width()
        h=surface.get_height()
        self.data=surface.get_buffer().raw
        self.image=QtGui.QImage(self.data,w,h,QtGui.QImage.Format_RGB32)

        self.surface = surface

        self.timer = QtCore.QBasicTimer()
        self.timer.start(500, self)

    def timerEvent(self, event):
        w=self.surface.get_width()
        h=self.surface.get_height()
        self.data=self.surface.get_buffer().raw
        self.image=QtGui.QImage(self.data,w,h,QtGui.QImage.Format_RGB32)
        self.update()

        for ev in pygame.event.get():
            if ev.type == pygame.MOUSEBUTTONDOWN:
                print "Mouse down"

    def paintEvent(self,event):
        qp=QtGui.QPainter()
        qp.begin(self)
        qp.drawImage(0,0,self.image)
        qp.end()


class MainWindow(QtGui.QMainWindow):
    def __init__(self,surface,parent=None):
        super(MainWindow,self).__init__(parent)
        self.setCentralWidget(ImageWidget(surface))



pygame.init()
s=pygame.Surface((640,480))
s.fill((64,128,192,224))
pygame.draw.circle(s,(255,255,255,255),(100,100),50)

app=QtGui.QApplication(sys.argv)
w=MainWindow(s)
w.show()
app.exec_()

How can I get Pygame events while the Pygame window is embedded in a PyQt application?

You cannot and should not combine 2 libraries that have their own eventloop, for example now the Qt eventloop is blocking the pygame eventloop. — eyllanesc, Jan 13 '20 at 20:48
I don't understand the need to use pygame if Qt covers all the features of pygame — eyllanesc, Jan 13 '20 at 20:52
I'm currently using it to develop a simulation program. I can use Qt for the controls - buttons and such - and then use Pygame for the sprites and physics. Pygame seems to be easier to program for such a job — Edgecase, Jan 13 '20 at 20:55
If you call easier to build everything from scratch then pygame is easier, but if you want to use already built elements then use Qt Graphics Framework (QGraphicsView, QGraphicsScene, etc) — eyllanesc, Jan 13 '20 at 20:56
The simulation program is already mostly made using Pygame. Just testing it out with Qt — Edgecase, Jan 13 '20 at 20:59

score 1 · Answer 1 · answered Mar 17 '23 at 17:14

A functional code implementation:

import time
import contextlib
from PySide6.QtCore import QObject, Signal, Qt, QThread
from PySide6.QtGui import QImage, QPixmap
from PySide6.QtWidgets import QMainWindow, QLabel, QWidget, QVBoxLayout, QApplication

with contextlib.redirect_stdout(None):
    import pygame

DISPLAY_WIDTH = 800
DISPLAY_HEIGHT = 600


class PygameWorker(QObject):
    send_image = Signal(QImage)

    def run(self):
        # Initialise screen
        pygame.init()

        screen = pygame.display.set_mode((DISPLAY_WIDTH, DISPLAY_HEIGHT),
                                            pygame.OPENGL)

        # Fill background
        background = pygame.Surface(screen.get_size())
        background = background.convert()
        background.fill((250, 250, 250))

        # Display some text
        font = pygame.font.Font(None, 36)
        text = font.render("Hello There", 1, (10, 10, 10))
        textpos = text.get_rect()
        textpos.centerx = background.get_rect().centerx
        background.blit(text, textpos)

        # Blit everything to the screen
        screen.blit(background, (0, 0))

        while not QThread.currentThread().isInterruptionRequested():
            screen.blit(background, (0, 0))

            # Get the display image
            image_str = pygame.image.tostring(pygame.display.get_surface(), "RGB", False)
            buffer = QImage(image_str, DISPLAY_WIDTH, DISPLAY_HEIGHT, QImage.Format_RGB888)
            if buffer.isNull():
                print("Buffer is null")
                continue

            self.send_image.emit(buffer)
            time.sleep(0.1)
        print("Thread finished")


class PygameReceiver(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        self.main_widget = QWidget()
        self.setCentralWidget(self.main_widget)

        self.main_layout = QVBoxLayout()
        self.main_widget.setLayout(self.main_layout)

        self.pygame_worker = PygameWorker()
        self.pygame_worker.send_image.connect(self.update_image)
        self.pygame_worker_thread = QThread()
        self.pygame_worker.moveToThread(self.pygame_worker_thread)
        self.pygame_worker_thread.started.connect(self.pygame_worker.run)
        self.pygame_worker_thread.start()

        self.image_label = QLabel()
        self.image_label.setAlignment(Qt.AlignCenter)
        self.main_layout.addWidget(self.image_label)

    def update_image(self, image):
        qpixmap = QPixmap.fromImage(image)
        self.image_label.setPixmap(qpixmap)

    def closeEvent(self, event):
        self.pygame_worker_thread.requestInterruption()
        self.pygame_worker_thread.quit()
        self.pygame_worker_thread.wait()
        QMainWindow.closeEvent(self, event)


if __name__ == "__main__":
    app = QApplication()
    window = PygameReceiver()
    window.show()
    app.exec()

score 0 · Answer 2 · edited Oct 18 '22 at 18:06

0

You can not.

TL; DR;

You cannot and should not combine 2 libraries that have their own event loop, for example now the Qt eventloop is blocking the pygame event loop.

edited Oct 18 '22 at 18:06

Rabbid76

202,892
27
131
174

answered Jan 13 '20 at 20:49

eyllanesc

235,170
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1

@Rabbid76 The first part of your answer is the same as what I indicated, in the other parts you only indicate possible solutions. In the case of pygame window it is possible to use it in Qt but it is an unnecessary effort since Qt can do the same as pygame. For this reason I point out that it is not good, and although it is possible it is better to only use Qt or only pygame. – eyllanesc Dec 12 '21 at 18:16

Rabbid76 · Accepted Answer · 2021-12-21T22:30:41.280

Fist of all do not mix frameworks. The frameworks may interact poorly or completely conflict with one another. Getting it to work on your system doesn't mean it will work on another system or with a different version of any of the frameworks. Mixing frameworks always means some kind of undefined behavior.

In your example your create an image (pygame.Surface) with the Pygame library and display it in QWidget. You never create a Pygame window. Therefore the Pygame event handling cannot work. You need to use Qts event handling.

Anyway, if you just want to do some image processing or draw some pictures and display them in a Qt application, I suggest using OpenCV (cv2). This library is designed for powerful image manipulation and the images can be viewed nicely using a Qt user interface.

This is an older issue, but I appreciate the time you took to write out this solution. Thank you — Edgecase, Dec 31 '21 at 22:24

Pygame not returning events while embedded in PyQt

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