python - 使用 QThreadpool 进行多线程时，如何使用 QPainter 在 Qlabel 上绘图？

Question

如果我的描述不完美，请原谅，我对 PyQt 和 Python 还是很陌生。如果您有关于如何改进问题的建议，请告诉我。

我正在尝试使用 QPainter 绘制 Pixmap-QLabel，它是 QMainWindow 的一部分。QPainter 在循环中被调用，因为绘图会在固定持续时间后更新。在 Pixmap 上绘图按预期工作，我遇到的问题是标签总是在新窗口中打开，而不是放在原始 QMainWindow 内的 QLabel 上。

我怀疑其原因是我从由 QThreadpool 对象创建的 Worker-class-object 调用 QPainter。如果我从 GUI 的初始化内部调用 QPainter，则 Pixmap-label 会按预期创建为 QMainWindow 的一部分。不幸的是，多线程是必要的，因此 GUI 在 QLabel 更新时保持响应。

GUI 本身是用 QtCreator 创建的，并简单地加载到脚本中。

这是我的代码：

import os
import sys
import time

from PyQt5 import QtWidgets, QtCore, uic
from PyQt5.QtWidgets import QLabel, QPushButton, QMainWindow
from PyQt5.QtGui import QPixmap, QPainter, QPen, QPaintEvent
from PyQt5.QtCore import *

class Ui(QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        self.counter = 0

        # load ui which can be designed with Qt Creator
        uic.loadUi("ui/paintEvent_Loop.ui", self)

        # find the QLabel where the picture should be placed
        self.pixmap_label = self.findChild(QtWidgets.QLabel, "pixmap_label")

        # creating the pixmap-label here works as intended
        '''self.draw_label = PixmapLabel(self.pixmap_label)
        self.draw_label.setGeometry(130, 50, 911, 512)
        self.draw_label.show()'''

        self.label = self.findChild(QLabel, "label")

        # find the button with the name "cancel_button"
        self.cancel_button = self.findChild(QtWidgets.QPushButton, "cancel_button")
        self.cancel_button.clicked.connect(self.close_application)

        # find the start_button button
        self.start_button = self.findChild(QtWidgets.QPushButton, "start_button")
        self.start_button.clicked.connect(self.start_loop)

        self.pause_cont_button = self.findChild(QPushButton, "pause_cont_button")
        self.pause_cont_button.clicked.connect(self.toggle_pause_continue)
        self.pause_cont_button.hide()

        # create the QThreadPool object to manage multiple threads
        self.threadpool = QThreadPool()
        print("Multithreading with maximum %d threads" % self.threadpool.maxThreadCount())

        self.run_loop = True

        # show application
        self.show()

    def close_application(self):
        app.quit()

    def toggle_pause_continue(self):
        """
        changes the value of boolean run_loop to pause and continue the loop through the samples in the chosen scene
        :return:
        """
        if self.run_loop:
            self.run_loop = False
        else:
            self.run_loop = True

    def start_loop(self):
        # hide start_button and show pause_cont_button
        self.start_button.hide()
        self.pause_cont_button.show()
        self.pause_cont_button.setCheckable(True)

        # start one further thread managed by threadpool
        worker = Worker()
        self.threadpool.start(worker)


class PixmapLabel(QLabel):

    def __init__(self, parent=None):
        super(PixmapLabel, self).__init__(parent=parent)

    def paintEvent(self, a0: QPaintEvent) -> None:

        # initiate QPainter instance
        painter = QPainter(window.draw_label)

        # open image
        picture = QPixmap(os.getcwd() + '/test-image.png')
        myPicturePixmap = picture.scaled(self.size(), QtCore.Qt.KeepAspectRatio)
        self.setPixmap(myPicturePixmap)

        # draw red box on it
        painter.drawPixmap(self.rect(), myPicturePixmap)
        pen = QPen(Qt.red, 3)
        painter.setPen(pen)
        painter.drawRect(10, 10, 100, 100)


class Worker(QRunnable):
    # worker thread
    def __init__(self):
        super().__init__()

    @pyqtSlot()
    def run(self):
        print("Thread start")

        for self.i in range(0, 50):

            # create pixmap_label with drawings
            # FIXME: make pixmap-label part of original GUI
            window.draw_label = PixmapLabel(window.pixmap_label)
            window.draw_label.setGeometry(130, 50, 911, 512)
            window.draw_label.show()

            window.label.setText(str(self.i))

            while window.run_loop == False:
                time.sleep(0.05)

            # show image for 0.5 seconds, then update image
            time.sleep(0.5)
            window.draw_label.destroy()
            time.sleep(0.05)



        # print in terminal to know that we are finished
        print("Thread complete")


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    window = Ui()
    app.exec_()

我正在使用的图像：

标签： pythonpyqtpyqt5