在继续运行代码之前等待计时器终止 [英] Waiting for a timer to terminate before continuing running the code

问题描述

以下代码在按下 START 按钮后每秒更新一次按钮的文本.预期的功能是让代码等待"直到计时器停止，然后再继续执行代码.即按下START后，第二个按钮的文字递增到3，然后才会出现I wait!文字在控制台上.

<预><代码>导入系统从 PySide 导入 QtGui、QtCore类示例(QtGui.QWidget):def __init__(self, parent=None):超级(例如，自我).__init__(父母)self.app_layout = QtGui.QVBoxLayout()self.setLayout(self.app_layout)self.setGeometry(300, 300, 50, 50)self.current_count = 0self.count_to = 4self.delay = 1000self.timer = QtCore.QTimer(self)self.timer.timeout.connect(self.updateButtonCount)# 开始按钮start_button = QtGui.QPushButton()start_button.setText('开始')start_button.clicked.connect(self.startCount)self.app_layout.addWidget(start_button)#数字按钮self.number_button = QtGui.QPushButton()self.number_button.setText('0')self.app_layout.addWidget(self.number_button)def updateButtonCount(self):self.number_button.setText("%s" % self.current_count)self.current_count += 1如果 self.current_count == self.count_to:self.timer.stop()def startCount(self):self.current_count = 0self.timer.start(self.delay)# 这个循环挂起 GUI:为真:如果不是 self.timer.isActive():休息打印我等了！"定义主():app = QtGui.QApplication(sys.argv)示例 = 示例()示例.show()sys.exit(app.exec_())如果 __name__ == '__main__':主要的()

上面的代码挂起 GUI，如果我删除 while True: 循环，I waited! 会立即出现在控制台上.

我确定 while True: 循环不是正确的方法，所以我正在寻找建议.

解决方案

我发现有效的解决方案是替换

虽然为真:如果不是 self.timer.isActive():休息

与

while self.timer.isActive():QtGui.QApplication.processEvents()

不过，我不确定这是最好的解决方案.

The following code updates the text of a button every second after the START button was pressed. The intended functionality is for the code to 'wait' until the timer has stopped before continuing on with the execution of the code. That is, after START is pressed, the text of the second button is incremented to 3, and only then should the text I waited! appear on the console.

import sys
from PySide import QtGui, QtCore

class Example(QtGui.QWidget):

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

        self.app_layout = QtGui.QVBoxLayout()
        self.setLayout(self.app_layout)

        self.setGeometry(300, 300, 50, 50)

        self.current_count = 0

        self.count_to = 4
        self.delay = 1000

        self.timer = QtCore.QTimer(self)
        self.timer.timeout.connect(self.updateButtonCount) 

        # start button
        start_button = QtGui.QPushButton()
        start_button.setText('START')
        start_button.clicked.connect(self.startCount)
        self.app_layout.addWidget(start_button)

        # number button
        self.number_button = QtGui.QPushButton()
        self.number_button.setText('0')
        self.app_layout.addWidget(self.number_button)



    def updateButtonCount(self):
        self.number_button.setText("%s" % self.current_count)
        self.current_count += 1
        if self.current_count == self.count_to:
            self.timer.stop()


    def startCount(self):
        self.current_count = 0
        self.timer.start(self.delay)

        # this loop hangs the GUI:
        while True:
            if not self.timer.isActive():
                break

        print 'I waited!'


def main():

    app = QtGui.QApplication(sys.argv)
    example = Example()
    example.show()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

The above code hangs the GUI, and if I remove the while True: loop, the I waited! appears immidiately on the console.

I'm certain that the while True: loop is not the correct way to go about it, so I'm looking for suggestions.

解决方案

The solution I found that works was to replace

while True:
    if not self.timer.isActive():
        break

with

while self.timer.isActive():
    QtGui.QApplication.processEvents()

I'm not certain that this is the best solution, though.

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