Python：如何在停止后刷新QLCDNumbers并再次发射？

Question

我想问一下，怎么才能在开始一些测量后刷新QLCDNumber。为了实现这个，我创建了一个图形界面线程，把信号连接到QLCDNumber，代码是这样的：

class BtDialog(QtGui.QDialog, Dlg):
  def __init__(self):
    QtGui.QDialog.__init__(self)
    self.setupUi(self)
    self.thread = WorkerThread()

    #Configure slots
    self.connect(self.startButton, QtCore.SIGNAL("clicked()"), self.onStart)
    self.connect(self.stopButton, QtCore.SIGNAL("clicked()"), self.onStop)

    #QLCDNumber Slot
    self.connect(self.thread, self.thread.voltage, self.lcdVoltage.display)

 def onStart(self):
    self.thread.start()

 def onStop(self):
     self.emit(self.thread.voltage, 0) #Trying to refresh
     abort()

在这里，我连接了两个按钮，一个是用来启动工作线程的，另一个是用来停止这个过程的。当我停止这个过程时，我想把QLCDNumber刷新为显示'0'，但这并没有成功。

在工作线程中，我是这样初始化信号的：

def __init__(self, parent = None):
    QtCore.QThread.__init__(self, parent)
    self.voltage = QtCore.SIGNAL("voltage")

然后在测量过程中，我用下面的代码发出信号：

self.emit(self.voltage, volt_act)

到目前为止，这一切都正常。但是在停止后，当我想再次启动工作过程时，信号就不再发给QLCDNumber了。为了让它工作，我必须重启图形界面。请问我该如何解决这两个问题：一是刷新QLCDNumber，二是在停止后再次发出信号？

Answer 1

从你发的代码中，我看不出问题出在哪里，不过这段话应该能帮你修改代码。同时，你可以看看这些文档，了解一下新风格的信号/槽连接和更多参考资料（比如模态对话框、定时器等）：

#!/usr/bin/env python
#-*- coding:utf-8 -*-
import time

from PyQt4 import QtGui, QtCore

class MyThread(QtCore.QThread):
    countChange = QtCore.pyqtSignal(int)
    countReset  = QtCore.pyqtSignal(int)

    def __init__(self, parent=None):
        super(MyThread, self).__init__(parent)
        self.stopped = QtCore.QEvent(QtCore.QEvent.User)

    def start(self):
        self.stopped.setAccepted(False)
        self.count = 0

        super(MyThread, self).start()

    def run(self):
        while not self.stopped.isAccepted():
            self.count += 1
            self.countChange.emit(self.count)
            time.sleep(1)

        self.countReset.emit(0)

    def stop(self):
        self.stopped.setAccepted(True)

class MyWindow(QtGui.QDialog):
    def __init__(self, parent=None):
        super(MyWindow, self).__init__(parent)

        self.lcdNumber = QtGui.QLCDNumber(self)

        self.pushButtonStart = QtGui.QPushButton(self)
        self.pushButtonStart.setText("Start")
        self.pushButtonStart.clicked.connect(self.on_pushButtonStart_clicked)

        self.pushButtonStop = QtGui.QPushButton(self)
        self.pushButtonStop.setText("Stop")
        self.pushButtonStop.clicked.connect(self.on_pushButtonStop_clicked)

        self.pushButtonDone = QtGui.QPushButton(self)
        self.pushButtonDone.setText("Done")
        self.pushButtonDone.clicked.connect(self.on_pushButtonDone_clicked)

        self.layoutHorizontal = QtGui.QHBoxLayout(self)
        self.layoutHorizontal.addWidget(self.lcdNumber)
        self.layoutHorizontal.addWidget(self.pushButtonStart)
        self.layoutHorizontal.addWidget(self.pushButtonStop)
        self.layoutHorizontal.addWidget(self.pushButtonDone)

        self.thread = MyThread(self)
        self.thread.countChange.connect(self.lcdNumber.display)
        self.thread.countReset.connect(self.lcdNumber.display)

    @QtCore.pyqtSlot()
    def on_pushButtonStart_clicked(self):
        self.thread.start()

    @QtCore.pyqtSlot()
    def on_pushButtonStop_clicked(self):
        self.thread.stop()

    @QtCore.pyqtSlot()
    def on_pushButtonDone_clicked(self):
        sys.exit()

if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    app.setApplicationName('MyWindow')

    main = MyWindow()
    main.exec_()

    sys.exit(app.exec_())