[FIXED] Apply Qt pseudo states on other QtObjects

Issue

I have the following test script.

from PyQt5.QtWidgets import *
import sys


class MW(QMainWindow):
    def __init__(self):
        super(MW, self).__init__()
        widget = QWidget()
        widget.setStyleSheet('QWidget {background-color:#000000; color:#FFFFFF}'
                             "QPushButton:hover {background-color:#202020}")

        self.setCentralWidget(widget)
        box = QVBoxLayout(widget)
        but1_box = QHBoxLayout()
        but1 = QPushButton("Button 1")

        lab1 = QLabel("Label 1")

        but1_box.addWidget(but1)
        but1_box.addWidget(lab1)
        box.addLayout(but1_box)

        but2_box = QHBoxLayout()
        but2 = QPushButton("Button 2")

        lab2 = QLabel("Label 2")

        but2_box.addWidget(but2)
        but2_box.addWidget(lab2)
        box.addLayout(but2_box)
        self.show()


app = QApplication(sys.argv)
mw = MW()
sys.exit(app.exec_())

If I hover over the PushButton it changes its color to a gray and I want that the associated Label changes its color while hovering over the button.

Solution

It is not possible to implement directly using the pseudo-states of the Qt Style Sheet but you will have to use an eventFilter that detects the changes of the hover (enter and leave) and that modifies the stylesheet of the other elements

from PyQt5.QtCore import pyqtSignal, QEvent, QObject
from PyQt5.QtWidgets import (
    QApplication,
    QHBoxLayout,
    QLabel,
    QMainWindow,
    QPushButton,
    QVBoxLayout,
    QWidget,
)
import sys


class HoverListener(QObject):
    entered = pyqtSignal()
    leaved = pyqtSignal()

    def __init__(self, widget):
        super(HoverListener, self).__init__(widget)
        self._widget = widget
        self.widget.installEventFilter(self)

    @property
    def widget(self):
        return self._widget

    def eventFilter(self, obj, event):
        if obj == self.widget:
            if event.type() == QEvent.Enter:
                self.entered.emit()
            elif event.type() == QEvent.Leave:
                self.leaved.emit()
        return super(HoverListener, self).eventFilter(obj, event)


class MW(QMainWindow):
    def __init__(self):
        super(MW, self).__init__()
        widget = QWidget()
        widget.setStyleSheet(
            "QWidget {background-color:#000000; color:#FFFFFF}"
            "QPushButton:hover {background-color:#202020}"
        )

        self.setCentralWidget(widget)

        but1 = QPushButton("Button 1")
        lab1 = QLabel("Label 1")

        hover_listener1 = HoverListener(but1)
        hover_listener1.entered.connect(
            lambda label=lab1: label.setStyleSheet("background-color:#202020")
        )
        hover_listener1.leaved.connect(lambda label=lab1: label.setStyleSheet(""))

        but2 = QPushButton("Button 2")
        lab2 = QLabel("Label 2")

        hover_listener2 = HoverListener(but2)
        hover_listener2.entered.connect(
            lambda label=lab2: label.setStyleSheet("background-color:#202020")
        )
        hover_listener2.leaved.connect(lambda label=lab2: label.setStyleSheet(""))

        box = QVBoxLayout(widget)
        but1_box = QHBoxLayout()
        but1_box.addWidget(but1)
        but1_box.addWidget(lab1)
        box.addLayout(but1_box)
        but2_box = QHBoxLayout()
        but2_box.addWidget(but2)
        but2_box.addWidget(lab2)
        box.addLayout(but2_box)
        self.show()


app = QApplication(sys.argv)
mw = MW()
sys.exit(app.exec_())

Answered By - eyllanesc