如何用Signal控制QProgressBar

Question

按下按钮开始 100 轮循环。使用 QLabel.setText() 我们从 clicked() 函数的范围内更新 self.label。

除了更新 self.label 我们还想更新 progressbar。但是由于 progressbar 是一个局部变量，我们不能从 onClick() 函数内部更新它。

import time

class ProgressBar(QtGui.QProgressBar):
    def __init__(self, parent=None, total=20):
        super(ProgressBar, self).__init__(parent=parent)

        self.setMinimum(1)
        self.setMaximum(105)        
        self.setTextVisible(True) 

    def set_to_value(self, value):
        self.setValue(value)
        QtGui.qApp.processEvents()

    def closeEvent(self, event):
        self._active=False


class Dialog(QtGui.QDialog):
    def __init__(self):
        super(QtGui.QDialog,self).__init__()

        layout = QtGui.QVBoxLayout()
        self.setLayout(layout)
        self.label = QtGui.QLabel('idle...')
        layout.addWidget(self.label)

        progressbar = ProgressBar(self)
        layout.addWidget(progressbar) 

        button = QtGui.QPushButton('Process')
        button.clicked.connect(self.onClick)
        layout.addWidget(button) 

    def onClick(self):
        for i in range(101):
            message = '...processing %s of 100'%i
            self.label.setText(message)
            QtGui.qApp.processEvents()
            time.sleep(1)


if __name__ == '__main__':
    app = QtGui.QApplication([])
    dialog = Dialog()
    dialog.resize(300, 100)
    dialog.show()
    app.exec_()

Answer 1

将进度条声明为：

self.progressbar = ProgressBar(self)

Answer 2

代码声明了一个本地 progressbar 对象连接到自定义“customSignal”，使用：

QtCore.QObject.connect(self, QtCore.SIGNAL("customSignal(int)"), progressbar, QtCore.SLOT("setValue(int)"))

将四个参数传递给 QtCore.QObject.connect()。

第一个参数 self 是将发出信号的对象。由于执行 "sleep-every-second-processing" 的函数是在主 Dialog 实例下声明的，因此我们在此处传递 self。

第二个参数是信号本身的名称：'customSignal'.

progressbar 对象用作第三个参数，其方法 setValue 用作倒数第四个参数。

class ProgressBar(QtGui.QProgressBar):
    def __init__(self, parent=None):
        super(ProgressBar, self).__init__(parent=parent)

class Dialog(QtGui.QDialog):
    def __init__(self):
        super(QtGui.QDialog,self).__init__()
        layout = QtGui.QVBoxLayout()
        self.setLayout(layout)
        self.label = QtGui.QLabel('idle...')
        layout.addWidget(self.label)

        progressbar = ProgressBar(self)
        QtCore.QObject.connect(self, QtCore.SIGNAL("customSignal(int)"), progressbar, QtCore.SLOT("setValue(int)"))

        layout.addWidget(progressbar) 

        button = QtGui.QPushButton('Process')
        button.clicked.connect(self.clicked)
        layout.addWidget(button) 

    def clicked(self):
        for value in range(101):
            message = '...processing %s of 100'%value
            self.label.setText(message)
            self.emit(QtCore.SIGNAL("customSignal(int)"), value)
            QtGui.qApp.processEvents()
            time.sleep(1)


if __name__ == '__main__':
    app = QtGui.QApplication([])
    dialog = Dialog()
    dialog.resize(300, 100)
    dialog.show()
    app.exec_()

--------------------

除了链接到进度条方法外，这是同一解决方案的变体。导入时间

class ProgressBar(QtGui.QProgressBar):
    def __init__(self, parent=None):
        super(ProgressBar, self).__init__(parent=parent)

    def set_to_value(self, value):
        self.setValue(value)
        QtGui.qApp.processEvents()
        return True

    def closeEvent(self, event):
        self._active=False

class Dialog(QtGui.QDialog):
    def __init__(self):
        QtGui.QDialog.__init__(self, parent=None)
        layout = QtGui.QVBoxLayout()
        self.setLayout(layout)
        self.label = QtGui.QLabel('idle...')
        layout.addWidget(self.label)

        progressbar = ProgressBar(self)
        QtCore.QObject.connect(self, QtCore.SIGNAL("customSignal(int)"), progressbar.set_to_value )
        layout.addWidget(progressbar) 

        button = QtGui.QPushButton('Process')
        button.clicked.connect(self.clicked)
        layout.addWidget(button) 

    def clicked(self):
        for value in range(101):
            message = '...processing %s of 100'%value
            self.label.setText(message)
            self.emit(QtCore.SIGNAL("customSignal(int)"), value)
            QtGui.qApp.processEvents()
            time.sleep(1)

if __name__ == '__main__':
    app = QtGui.QApplication([])
    dialog = Dialog()
    dialog.resize(300, 100)
    dialog.show()
    app.exec_()

======================

此代码现在将自定义信号链接到 Qt 中称为 Slot 的函数。

from PySide import QtCore, QtGui
import time

class ProgressBar(QtGui.QProgressBar):
    def __init__(self, parent=None):
        super(ProgressBar, self).__init__(parent=parent)

    @QtCore.Slot(int)
    def set_to_value(self, value):
        self.setValue(value)
        QtGui.qApp.processEvents()
        return True

    def closeEvent(self, event):
        self._active=False

class Dialog(QtGui.QDialog):
    def __init__(self):
        QtGui.QDialog.__init__(self, parent=None)
        layout = QtGui.QVBoxLayout()
        self.setLayout(layout)
        self.label = QtGui.QLabel('idle...')
        layout.addWidget(self.label)

        progressbar = ProgressBar(self)
        # QtCore.QObject.connect(self, QtCore.SIGNAL("customSignal(int)"), progressbar.set_to_value )
        QtCore.QObject.connect(self, QtCore.SIGNAL("customSignal(int)"), progressbar, QtCore.SLOT("set_to_value(int)"))

        layout.addWidget(progressbar) 

        button = QtGui.QPushButton('Process')
        button.clicked.connect(self.clicked)
        layout.addWidget(button) 

    def clicked(self):
        for value in range(101):
            message = '...processing %s of 100'%value
            self.label.setText(message)
            self.emit(QtCore.SIGNAL("customSignal(int)"), value)
            QtGui.qApp.processEvents()
            time.sleep(1)

if __name__ == '__main__':
    dialog = Dialog()
    dialog.resize(300, 100)
    dialog.show()

如何用Signal控制QProgressBar

How to control QProgressBar with Signal

python

qt

pyqt

qprogressbar

--------------------

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