使用 Signal 将 QImage 从工作线程传递到主 UI 线程以在 pyqt5 GUI 中显示（Python）

Question

I'm trying to define my own signal to display QImage (converted from raw data) upon a button press. The GUI has a button called as connect, and a QLabel that's named as DisplayRect. I'd like to draw this QImage on DisplayRect. The code below prints 'signal received' upon pressing the connect button. I'd like to make it pass QImage so that I can self.DisplayRect.setPixmap(the passed QImage ) Please have a look:

class DPSignal(QObject):
    dpsig = pyqtSignal()
    
    def run(self):
        self.dpsig.emit()
        
        
        
class DisplayThread(QThread):
    def __init__(self, parent):
        super().__init__(parent)
        self.parent = parent
        
        
    def run(self):
        dps = DPSignal()
        dps.dpsig.connect(self.parent.dpupdate)
        dps.run
        
class WindowClass(QMainWindow, form_class):
    def __init__(self):
        super().__init__()
        self.setupUI(self)
        
       self.connectButton.clicked.connect(self.connectFunction)
       
       
       
       
       
    @pyqtSlot()
    def connectFunction(self):
        dpThread = DisplayThread(self)
        dpThread.start()
        
    def dpupdate(self):
        print("signal received")
        
if __name__ == '__main__':
    app = QApplication(sys.argv)
    myWindow = WindowClass()
    myWindow.show()
    app.exec_()

This piece of code below reads binary data from a file and I'd like to add this code to somewhere in DisplayThread so that it passes the processed QImage to the main UI thread. Then main UI thread can (I suppose) self.DisplayRect.setPixmap to display. Thanks for reading

raw = rawpy.imread(...path...)
src = raw.postprocess()
buf = src.data.tobytes()
h, w, ch = src.shape
bytesperline = ch * whileimage = QImage(buf, 1024, 768, bytesperline, QImage.Format_RGB888)

self.DisplayRect.setPixmap(QPixmap.fromImage(image))
self.DisplayRect.show()

Answer 1

You can try moving the object to the QThread using the QObject.moveToThread and then doing the prepocessing in the run method. Then transfer the raw bytes through the signal to the Main Window and create and show the image from the Main Window.

class DPSignal(QObject):
    dpsig = pyqtSignal([bytes, int])
    finished = pyqtSignal()

    def __init__(self, parent):
        super().__init__()
        self.parent = parent

    def run(self):
        raw = rawpy.imread("./file.nef")
        src = raw.postprocess()
        buf = src.data.tobytes()
        h, w, ch = raw.shape
        bpl = w * ch
        self.dpsig.emit(buf, bpl)
        self.finished.emit()


class WindowClass(QMainWindow):
    def __init__(self):
        super().__init__()
        self.connectButton.clicked.connect(self.connectFunction)

    @pyqtSlot()
    def connectFunction(self):
        self.worker = DPSignal(self)
        self.dpThread = QThread()
        self.worker.moveToThread(self.dpThread)
        self.dpThread.started.connect(self.worker.run)
        self.worker.dpsig.connect(self.dpupdate)
        self.worker.finished.connect(self.dpThread.exit)
        self.worker.finished.connect(self.dpThread.deleteLater)
        self.dpThread.start()

    def dpupdate(self, buf, bpl):
        print("signal received")
        image = QImage(buf, 1024, 768, bpl, QImage.Format.Format_RGB888)
        self.DisplayRect.setPixmap(QPixmap.fromImage(image))
        self.DisplayRect.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    myWindow = WindowClass()
    myWindow.show()
    app.exec_()