PyQt5多线程

Question

为什么代码不起作用？？视频工作文件，当我试图在第二个标签中显示文本时，它也会显示 up.but 如果我想像 setText() 中的当前时间一样连续更改值，我该怎么办？我是多线程新手。

import sys
import cv2
from PyQt5.QtCore import QThread, pyqtSignal, Qt
from PyQt5.QtGui import QPixmap, QImage
from PyQt5.QtWidgets import QApplication, QWidget, QLabel
import datetime


class App(QWidget):
    def __init__(self):
        super().__init__()
        self.title = 'PyQt5 Video'
        self.left = 100
        self.top = 100
        self.width = 640
        self.height = 480
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
        self.resize(1800, 1200)
        # create a label
        label = QLabel(self)
        label.move(280, 120)
        label.resize(640, 480)
        label1 = QLabel(self)
        label1.move(680, 820)
        th = Thread(self)
        th.changePixmap.connect(lambda p: label.setPixmap(p))
        th.changeLabel.connect(lambda n:label1.setText("A"))
        th.start()

class Thread(QThread):
    changePixmap = pyqtSignal(QPixmap)
    changeLabel = pyqtSignal(QLabel)

    def __init__(self, parent=None):
        QThread.__init__(self, parent=parent)

    def run(self):
        cap = cv2.VideoCapture(0)
        n=QLabel()
        while True:
            ret, frame = cap.read()
            rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            convertToQtFormat = QImage(rgbImage.data, rgbImage.shape[1], rgbImage.shape[0], QImage.Format_RGB888)
            convertToQtFormat = QPixmap.fromImage(convertToQtFormat)
            p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.changePixmap.emit(p)
            now = datetime.datetime.now()
            sec = now.second
            try:
                self.changeLabel.emit(n)
            except Exception as e:
                print(str(e))

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    ex.show()
    sys.exit(app.exec_())

Answer 1

您不应向主视图发送新的小部件 (QLabel)，因为这将是一个新标签，而不是原始标签，您应该发送 str 类型的文本。

class Thread(QThread):
    changePixmap = pyqtSignal(QPixmap)
    changeLabel = pyqtSignal(str)

    def run(self):
        [...]
        now = datetime.datetime.now()
        sec = now.second
        self.changeLabel.emit(str(sec))

然后连接到setText函数：

th.changeLabel.connect(label1.setText)

完整代码：

import sys
import cv2
from PyQt5.QtCore import QThread, pyqtSignal, Qt
from PyQt5.QtGui import QPixmap, QImage
from PyQt5.QtWidgets import QApplication, QWidget, QLabel
import datetime


class App(QWidget):
    def __init__(self):
        super().__init__()
        self.title = 'PyQt5 Video'
        self.left = 100
        self.top = 100
        self.width = 640
        self.height = 480
        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)
        self.resize(1800, 1200)
        # create a label
        # create a label
        label = QLabel(self)
        label.move(280, 120)
        label.resize(640, 480)
        label1 = QLabel(self)
        label1.move(580, 620)
        self.th = Thread(self)
        self.th.changePixmap.connect(label.setPixmap)
        self.th.changeLabel.connect(label1.setText)
        self.th.start()

    def closeEvent(self, event):
        self.th.stop()
        QWidget.closeEvent(self, event)

class Thread(QThread):
    changePixmap = pyqtSignal(QPixmap)
    changeLabel = pyqtSignal(str)

    def __init__(self, parent=None):
        QThread.__init__(self, parent=parent)
        self.isRunning = True

    def run(self):
        cap = cv2.VideoCapture(0)
        while self.isRunning:
            ret, frame = cap.read()
            rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            convertToQtFormat = QImage(rgbImage.data, rgbImage.shape[1], rgbImage.shape[0], QImage.Format_RGB888)
            convertToQtFormat = QPixmap.fromImage(convertToQtFormat)
            p = convertToQtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.changePixmap.emit(p)
            now = datetime.datetime.now()
            sec = now.second
            self.changeLabel.emit(str(sec))

    def stop(self):
        self.isRunning = False
        self.quit()
        self.wait()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    ex.show()
    sys.exit(app.exec_())

注意：我添加了停止方法来停止线程并正确关闭，为此我还覆盖了closeEvent方法。另一个变化，因为我的屏幕不是那么大，所以我移动了label1。

PyQt5多线程

PyQt5 multi thread

python

pyqt

qthread

python-3.x

pyqt5