[Python] Change background of QTextEdit with a duration [duplicate]

General overview


I try to make a read only QTextEdit change his background color with a keybinding event. The goal is to make A make the background progressively goes from blue to white.

The problem


So, it works with the following MWE, but the animation didn’t respect the duration. It’s instantaneous.

Minimal working example


import sys
from PyQt6.QtWidgets import QApplication, QLabel, QTextEdit
from PyQt6.QtCore import QPropertyAnimation, Qt
from PyQt6.QtGui import QPalette, QColor

class AnimatedLabel(QTextEdit):
def __init__(self, text):
super().__init__(text)
self.setReadOnly(True) # Readonly to catch the keystroke

self.setStyleSheet("background: blue; background-color 3s;") # Color of the bigining

#\
self.anim = QPropertyAnimation(self, b"styleSheet") #| This
self.anim.setDuration(9000000) #| is the
self.anim.setStartValue("background: blue; background-color 3s;") #| relevant
self.anim.setEndValue("background: white; background-color 3s;") #| part
#/

def keyPressEvent(self, event):
# Keystroke detection for « A »
if event.key() == Qt.Key.Key_A:
print("Pressed")
self.anim.start()

app = QApplication(sys.argv)
label = AnimatedLabel("Foo bar")
label.show()
sys.exit(app.exec())


The question


How to make the background change progressive? I search to make a fading effect.

Edit


Also if I use palette deffenition method like in the following code, the transition take effect but didn’t respect the duration:

palette = QPalette()

palette.setColor(QPalette.ColorRole.Base, QColor(Qt.GlobalColor.red)) # Couleur de fond du QTextEdit
palette.setColor(QPalette.ColorRole.Text, QColor(Qt.GlobalColor.black))
self.setPalette(palette)

self.anim = QPropertyAnimation(self, b"palette") #| This
self.anim.setStartValue(QColor(Qt.GlobalColor.black)) #| relevant
self.anim.setEndValue(QColor(Qt.GlobalColor.white)) #| part
self.anim.setDuration(9000000) #| is the

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