pyqt5:样式表和来自 qwidget 的继承-百家乐凯发k8

问题描述

我的代码生成一个包含两个 qwidget 的窗口，一个红色 (wg1) 和一个蓝色 (wg2).如果它们变成继承自 qwidget 的 fields(注释掉)，它们的颜色就会消失.

my code generates a window containing two qwidgets, a red (wg1) and a blue (wg2) one. if they become fields (commented out) which inherits from qwidget, their color disappears.

我的问题是:为什么 field(继承自 qwidget)需要有一行

my question is: why is it necessary for a field (which inherits from qwidget), to have the line

self.setattribute(qt.wa_styledbackground, true)

在它的 __init__ 方法中，而 qwidget 不需要这一行?

in its __init__-method while a qwidget doesn't need this line?

import sys
from pyqt5 import qtwidgets
from pyqt5.qtwidgets import qwidget, qapplication, qgridlayout
from pyqt5.qtcore import qt
class field(qwidget):
    def __init__(self, name):
        super().__init__()
        self.name = name
        # self.setattribute(qt.wa_styledbackground, true)# !!!
        
    def mousepressevent(self, event):
        print(f" click makes {self.name} green")
        self.setstylesheet("background: #00ff00;")
if __name__ == "__main__":
    app = qapplication(sys.argv)
    root = qwidget()
    grid = qgridlayout()
    root.setlayout(grid)
    root.resize(300,100)
    wg1 = qwidget()
    wg2 = qwidget()
    # wg1 = field('wg1')
    # wg2 = field('wg2')
    wg1.setstylesheet("background: #aa1111;")
    grid.addwidget(wg1, 0, 0)
    wg2.setstylesheet("background: #1111aa;")
    grid.addwidget(wg2, 0, 2)
    root.show()
    sys.exit(app.exec_())

推荐答案

解释在样式表参考中与 qwidget 相关的部分:

如果您从 qwidget 继承，您需要为您的自定义 qwidget 提供一个paintevent，如下所示:

if you subclass from qwidget, you need to provide a paintevent for your custom qwidget as below:

默认情况下，qwidget 会默认执行此操作，但 qwidget 子类不会，因此您要么设置标志，要么实现paintevent.

by default, qwidget does that by default, but qwidget subclasses do not, so you either set the flag or you implement the paintevent.

无论如何，请考虑使用 样式表选择器 并避免通用/通用语法，因为它们通常会导致复杂的子小部件出现意外行为.

in any case, consider using stylesheet selectors and avoid generic/universal syntax as they often result in unexpected behavior for complex child widgets.