python - PyQt4 中的 QThreading PyQtGraph PlotWidgets

Question

作为问题的延续，我得到了解决 here几天前，我有一个 PyQt4 GUI，它嵌入了两个 PyQtGraph 的 PlotWidget，每个都从由按钮触发的线程随机附加数组设置/更新数据。它工作得很好，而且 GUI 响应灵敏。但到了某个点，图形不再显示其各自 PlotWidget 内的更新，我必须最小化/最大化才能看到 PlotWidget 内绘制的更新。代码如下:

import random
import sys

import pyqtgraph as pg
import time
from PyQt4 import QtGui, QtCore


class MyThread(QtCore.QThread):
    def __init__(self, curve, parent=None):
        super(MyThread, self).__init__(parent=parent)
        self.curve = curve
        self.data = [0]
        app.processEvents()#increases the time the drawings are shown

    def run(self):
        app.processEvents() #increases the time the drawings are shown
        while True:
            self.data.append(self.data[-1] + 0.2 * (0.5 - random.random()))
            self.curve.setData(self.data, downsample=10) #crashes without
            time.sleep(0.1)


class LoginWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(LoginWidget, self).__init__(parent)
        layout = QtGui.QHBoxLayout()
        self.button = QtGui.QPushButton('Start Plotting')
        layout.addWidget(self.button)
        self.plot = pg.PlotWidget()
        layout.addWidget(self.plot)
        self.setLayout(layout)
        self.button.clicked.connect(self.plotter)
        app.processEvents()

    def plotter(self):
        self.curve = self.plot.getPlotItem().plot()
        myThread = MyThread(self.curve, self)
        myThread.start()


class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.centralwidget = QtGui.QWidget(self)
        self.setCentralWidget(self.centralwidget)
        self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget)
        self.login_widget_1 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_1)
        self.login_widget_2 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_2)
        self.setCentralWidget(self.centralwidget)


if __name__ == '__main__':
    global app
    app = QtGui.QApplication(sys.argv)
    w = MainWindow()
    w.show()    
    sys.exit(app.exec_())

任何关于我可以做什么而不必最大化/最小化以获得 GUI 中的更新的线索或解决方法都会让我非常高兴。

按照下面答案中 @ImportanceOfBeingErnest 的建议，我尝试遵循 Python Wiki使用信号和槽连接 GUI 和线程，如下所示:

import random
import sys
import pyqtgraph as pg
import time
from PyQt4 import QtGui, QtCore


class MyThread(QtCore.QThread):
    def __init__(self, parent=None):
        super(MyThread, self).__init__(parent=parent)
        self.data = [0]

    def run(self):
        while True:
            self.data.append(self.data[-1] + 0.2 * (0.5 - random.random()))
            self.emit(SIGNAL("output(data)"), self.data)
            time.sleep(0.1)


class LoginWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(LoginWidget, self).__init__(parent)
        self.myThread = MyThread()
        layout = QtGui.QHBoxLayout()
        self.button = QtGui.QPushButton('Start Plotting')
        layout.addWidget(self.button)
        self.plot = pg.PlotWidget()
        layout.addWidget(self.plot)
        self.setLayout(layout)
        self.button.clicked.connect(self.plotter)
        self.connect(self.myThread, SIGNAL("output(data)"), self.plotter)

    def plotter(self, data):
        self.curve = self.plot.getPlotItem().plot()
        self.curve.setData(data, downsample=10)


class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.centralwidget = QtGui.QWidget(self)
        self.setCentralWidget(self.centralwidget)
        self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget)
        self.login_widget_1 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_1)
        self.login_widget_2 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_2)
        self.setCentralWidget(self.centralwidget)


if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

但这给了我错误:

"in self.connect(self.myThread, SIGNAL("output(data)"), self.plotter)
NameError: name 'SIGNAL' is not defined"

通过阅读question from 4 years ago ，我用 QtCore.SIGNAL 替换 SIGNAL 得到以下错误:

"in self.connect(self.myThread, QtCore.SIGNAL("output(data)"), self.plotter)
TypeError: C++ type 'data' is not supported as a slot argument type"

然后忽略 TypeError:

    try:
    self.connect(self.myThread, QtCore.SIGNAL("output(data)"), self.plotter)
except TypeError:
    pass

GUI 启动，但当我最终单击按钮并连接到 self.plotter 函数时，出现以下错误:

"in plotter
self.curve.setData(data, downsample=10)
File "C:\Users\iyv\AppData\Local\Programs\Python\Python34_64\lib\site-
packages\pyqtgraph\graphicsItems\PlotDataItem.py", line 381, in setData
raise Exception('Invalid data type %s' % type(data))
Exception: Invalid data type <class 'bool'>"

我很困惑。我应该联系 PyQtGraph 吗？任何帮助都非常感激。

Answer 1

您需要将 GUI 和线程分开。他们不能共享任何 GUI 对象，例如本例中的绘图小部件!

我不确定您是否需要线程，因为您的数据不是很大并且每秒仅更新 10 次。但如果您决定使用它，则仅使用 signals and slots在线程和 GUI 之间进行通信。

---

下面是程序的修改版本，它使用线程并且工作正常。它使用新样式 signals and slots 。希望这更容易理解，因为您可以仅使用 object 作为数据类型。

在你的程序中没有意义的两件事是:

• 您在绘图槽中重新定义了 self.curve。
• 按下按钮时调用绘图槽。相反，按下按钮应该启动线程。

我已更正它们。

import random
import sys
import pyqtgraph as pg
import time
from PyQt4 import QtGui, QtCore


class MyThread(QtCore.QThread):
    signal = QtCore.pyqtSignal(object)
    def __init__(self, parent=None):
        super(MyThread, self).__init__(parent=parent)
        self.data = [0]

    def __del__(self):
        self.exiting = True
        self.wait()

    def run(self):
        while True:
            self.data.append(random.random())
            self.signal.emit(self.data)
            time.sleep(0.1)


class LoginWidget(QtGui.QWidget):
    def __init__(self, parent=None):
        super(LoginWidget, self).__init__(parent)
        self.myThread = MyThread()
        layout = QtGui.QHBoxLayout()
        self.button = QtGui.QPushButton('Start Plotting')
        layout.addWidget(self.button)
        self.plot = pg.PlotWidget()
        layout.addWidget(self.plot)
        self.setLayout(layout)
        self.curve = self.plot.getPlotItem().plot()
        self.button.clicked.connect(self.start)


    def plotter(self, data):
        self.curve.setData(data)

    def start(self):
        self.myThread.start()
        self.myThread.signal.connect(self.plotter)


class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.centralwidget = QtGui.QWidget(self)
        self.setCentralWidget(self.centralwidget)
        self.horizontalLayout = QtGui.QHBoxLayout(self.centralwidget)
        self.login_widget_1 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_1)
        self.login_widget_2 = LoginWidget(self)
        self.horizontalLayout.addWidget(self.login_widget_2)
        self.setCentralWidget(self.centralwidget)


if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())