PyQt5系列教程(七)控件

软硬件环境

• Windows 10
• Python 3.4.2
• PyQt 5.5.1
• PyCharm 5.0.4

前言

控件是PyQt应用程序的基石。PyQt5自带很多不同的控件，包括像button、check box、slider等等。在本节中我们将学习几个非常有用的控件:QCheckBox、ToggleButton、QSlider、QProgressBar和QCalendarWidget。

QCheckBox

一个QCheckBox会有2种状态:选中和为选中。它有一个选择框和一个label组成，它常常被用来表示应用的某些特性是可启用或不启用的。

# -*- coding: utf-8 -*-__author__ = '[e-mail]'"""ZetCode PyQt5 tutorial In this example, a QCheckBox widgetis used to toggle the title of a window.author: Jan Bodnarwebsite: zetcode.com last edited: January 2015"""import sysfrom PyQt5.QtWidgets import QWidget, QCheckBox, QApplicationfrom PyQt5.QtCore import Qtclass Example(QWidget):    def __init__(self):        super().__init__()        self.initUI()    def initUI(self):              cb = QCheckBox('Show title', self)        cb.move(20, 20)        cb.toggle()        cb.stateChanged.connect(self.changeTitle)        self.setGeometry(300, 300, 250, 150)        self.setWindowTitle('QCheckBox')        self.show()    def changeTitle(self, state):        if state == Qt.Checked:            self.setWindowTitle('QCheckBox')        else:            self.setWindowTitle('')if __name__ == '__main__':    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())

程序执行效果如下

在这个例子中，我们创建了一个选择框，它状态的变化会引起窗口标题的变化。

cb = QCheckBox('Show title', self)

这条语句是QCheckBox的构造函数，它的label是”Show title”。

cb.toggle()

设置默认是选中状态

cb.stateChanged.connect(self.changeTitle)

将自定义的槽函数changeTitle和信号stateChanged绑定起来，槽函数changeTitle会改变窗口的标题

def changeTitle(self, state):if state == Qt.Checked:    self.setWindowTitle('QCheckBox')else:    self.setWindowTitle('')

选中状态下，窗口标题设置为”QCheckBox”,否则设置为空

Toggle button

Toggle button是一种特殊的QPushButton(按钮),它也有2种状态，按下和未按下，我们通过点击它来区分2种不同的状态。实际很多情况下都会用到它。

# -*- coding: utf-8 -*-__author__ = '[e-mail]'"""ZetCode PyQt5 tutorialIn this example, we create three toggle buttons.They will control the background colour of aQFrame.author: Jan Bodnarwebsite: zetcode.comlast edited: January 2015"""import sysfrom PyQt5.QtWidgets import (QWidget, QPushButton,    QFrame, QApplication)from PyQt5.QtGui import QColorclass Example(QWidget):    def __init__(self):        super().__init__()        self.initUI()    def initUI(self):        self.col = QColor(0, 0, 0)        redb = QPushButton('Red', self)        redb.setCheckable(True)        redb.move(10, 10)        redb.clicked[bool].connect(self.setColor)        redb = QPushButton('Green', self)        redb.setCheckable(True)        redb.move(10, 60)        redb.clicked[bool].connect(self.setColor)        blueb = QPushButton('Blue', self)        blueb.setCheckable(True)        blueb.move(10, 110)        blueb.clicked[bool].connect(self.setColor)        self.square = QFrame(self)        self.square.setGeometry(150, 20, 100, 100)        self.square.setStyleSheet("QWidget { background-color: %s }" %            self.col.name())        self.setGeometry(300, 300, 280, 170)        self.setWindowTitle('Toggle button')        self.show()    def setColor(self, pressed):        source = self.sender()        if pressed:            val = 255        else: val = 0        if source.text() == "Red":            self.col.setRed(val)        elif source.text() == "Green":            self.col.setGreen(val)        else:            self.col.setBlue(val)        self.square.setStyleSheet("QFrame { background-color: %s }" %            self.col.name())if __name__ == '__main__':    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())

代码执行效果如下所示

本例中我们创建了3个toggle button和一个QWidget，将QWidget的背景色设置成了黑色，左边的3个toggle button会改变右边QWidget的颜色。

redb = QPushButton('Red', self)redb.setCheckable(True)

为了创建toggle button,我们首先创建一个QPushButton，然后调用方法setCheckable()。后面的信号和槽的绑定，相信大家都很熟悉了，这里就不说了。

QSlider

QSlider是一个滑动条，允许你在某一范围内拖动。有时候这种方式比输入数字或者使用spin box更加自然。

# -*- coding: utf-8 -*-__author__ = '[e-mail]'"""ZetCode PyQt5 tutorial This example shows a QSlider widget.author: Jan Bodnarwebsite: zetcode.com last edited: January 2015"""import sysfrom PyQt5.QtWidgets import (QWidget, QSlider,     QLabel, QApplication)from PyQt5.QtCore import Qtfrom PyQt5.QtGui import QPixmapclass Example(QWidget):    def __init__(self):        super().__init__()        self.initUI()    def initUI(self):              sld = QSlider(Qt.Horizontal, self)        sld.setFocusPolicy(Qt.NoFocus)        sld.setGeometry(30, 40, 100, 30)        sld.valueChanged[int].connect(self.changeValue)        self.label = QLabel(self)        self.label.setPixmap(QPixmap('mute.png'))        self.label.setGeometry(160, 40, 80, 30)        self.setGeometry(300, 300, 280, 170)        self.setWindowTitle('QSlider')        self.show()    def changeValue(self, value):        if value == 0:            self.label.setPixmap(QPixmap('mute.png'))        elif value > 0 and value <= 30:            self.label.setPixmap(QPixmap('min.png'))        elif value > 30 and value < 80:            self.label.setPixmap(QPixmap('med.png'))        else:            self.label.setPixmap(QPixmap('max.png'))if __name__ == '__main__':    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_()) 

代码运行效果如下所示，我这没有加入图片，所以看不到右侧图片的变化。我这里只解释下QSlider的使用，信号和曹函数跟之前都是一样的。

sld = QSlider(Qt.Horizontal, self)sld.setFocusPolicy(Qt.NoFocus)sld.setGeometry(30, 40, 100, 30)sld.valueChanged[int].connect(self.changeValue)

QSlider构造函数中传入Qt.Horizontal，创建的是一个横向的slider

QProgressBar

ProgressBar一般用来表示任务的进度，也有横向和众向之分。你可以设置进度条的最小值和最大值，默认是0和99。

# -*- coding: utf-8 -*-__author__ = '[e-mail]'"""ZetCode PyQt5 tutorialThis example shows a QProgressBar widget.author: Jan Bodnarwebsite: zetcode.comlast edited: January 2015"""import sysfrom PyQt5.QtWidgets import (QWidget, QProgressBar,    QPushButton, QApplication)from PyQt5.QtCore import QBasicTimerclass Example(QWidget):    def __init__(self):        super().__init__()        self.initUI()    def initUI(self):        self.pbar = QProgressBar(self)        self.pbar.setGeometry(30, 40, 200, 25)        self.btn = QPushButton('Start', self)        self.btn.move(40, 80)        self.btn.clicked.connect(self.doAction)        self.timer = QBasicTimer()        self.step = 0        self.setGeometry(300, 300, 280, 170)        self.setWindowTitle('QProgressBar')        self.show()    def timerEvent(self, e):        if self.step >= 100:            self.timer.stop()            self.btn.setText('Finished')            return        self.step = self.step + 1        self.pbar.setValue(self.step)    def doAction(self):        if self.timer.isActive():            self.timer.stop()            self.btn.setText('Start')        else:            self.timer.start(100, self)            self.btn.setText('Stop')if __name__ == '__main__':    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())

代码运行效果如下所示

这里使用一个计时器来启动进度条

self.timer = QtCore.QBasicTimer()def timerEvent(self, e):if self.step >= 100:    self.timer.stop()    self.btn.setText('Finished')    returnself.step = self.step + 1self.pbar.setValue(self.step)

每个QObject及其子类都有个timerEvent()事件处理器，需要我们重新实现，它的第一个参数是超时时间

QCalendarWidget

QCalendarWidget是一个以月份为基础的日历控件，用来供用户选择日期

# -*- coding: utf-8 -*-__author__ = '[e-mail]'"""ZetCode PyQt5 tutorialThis example shows a QCalendarWidget widget.author: Jan Bodnarwebsite: zetcode.comlast edited: January 2015"""import sysfrom PyQt5.QtWidgets import (QWidget, QCalendarWidget,    QLabel, QApplication)from PyQt5.QtCore import QDateclass Example(QWidget):    def __init__(self):        super().__init__()        self.initUI()    def initUI(self):        cal = QCalendarWidget(self)        cal.setGridVisible(True)        cal.move(20, 20)        cal.clicked[QDate].connect(self.showDate)        self.lbl = QLabel(self)        date = cal.selectedDate()        self.lbl.setText(date.toString())        self.lbl.move(130, 260)        self.setGeometry(300, 300, 350, 300)        self.setWindowTitle('Calendar')        self.show()    def showDate(self, date):        self.lbl.setText(date.toString())if __name__ == '__main__':    app = QApplication(sys.argv)    ex = Example()    sys.exit(app.exec_())

代码运行效果如下所示

参考文献

http://zetcode.com/gui/pyqt5/widgets/