最近,我一直在努力理解pyqtProperty的用法.在下面的代码段中,我尝试创建一个自定义按钮,单击该按钮将更改其文本和外观.我想将逻辑和外观分开,所以我创建了自定义属性“ state”,该属性在样式表中使用.

结果对我来说有点奇怪.程序抛出“ CustomButton”对象没有属性“ _state”异常,但仍会运行.单击按钮后,按钮的文本会更改,但颜色保持不变.

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

import sys
from PyQt4 import QtGui, QtCore

STYLE = '''
CustomButton {
    margin: 50px;
    padding: 10px;
}
CustomButton[state='true'] {
    background: yellowgreen;
}
CustomButton[state='false'] {
    background: orangered;
}
'''


class CustomButton(QtGui.QPushButton):
    def __init__(self):
        super(CustomButton, self).__init__()
        self.setText('ON')
        self.setStyleSheet(STYLE)
        self._state = True

    def g_state(self):
        return self._state

    def s_state(self, value):
        self._state = value

    state = QtCore.pyqtProperty(bool, fget=g_state, fset=s_state)

    def mousePressEvent(self, event):
        print 'clicked'
        if self.state == True:
            self.state = False
            self.setText('OFF')
        else:
            self.state = True
            self.setText('ON')


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

解决方法:

这里有几个问题.

首先,重新实现的mousePressEvent应该调用基类实现,以保留正常的行为.

其次,对属性的更改不会自动触发样式更改,因此您需要在代码中显式地进行更改.

另外,值得注意的是pyqtProperty可以用作装饰器,这可能会稍微提高代码的可读性.

因此,经过这些更改,代码可能看起来像这样：

    ...

    @QtCore.pyqtProperty(bool)
    def state(self):
        return self._state

    @state.setter
    def state(self, value):
        self._state = value

    def mousePressEvent(self, event):
        print 'clicked'
        if self.state:
            self.state = False
            self.setText('OFF')
        else:
            self.state = True
            self.setText('ON')
        self.style().unpolish(self)
        self.style().polish(self)
        self.update()
        super(CustomButton, self).mousePressEvent(event)