Pyqt5 Stylesheet Animation

I am using PyQt5 to build an app with multiple buttons. What I am trying to accomplish is to create a blinking background color (yellow-red) for some of my buttons. btn1.setStyleSh

Solution 1:

You ought not to animate stylesheets because there are the vagueness which specifically value must be animated (interpolated). There are not internal parser of stylesheet into PyQt5 classes. Nevertheless there are ways to solve the problem. Below is working example for animated QLabel (background-color of QLabel).

Main idea consists in using the custom QtCore.QPropertyAnimation. In this case its name is zcolor. Also you ought to create property QtCore.pyqtProperty in class derived from QLabel (and any other class).

Moreover you can use several animation in your class, in example you can switch between three types of animation (No animation, type 1, type 2).

Of course some params of some widgets can be animated via QtGui.QPalette.Window without parse of ss (see three strings in comment starting with # pal = self.palette()), however the way via stylesheets is more flexible IMHO.

import sys
import re

from PyQt5.QtWidgets import (QApplication, QFormLayout, QLabel, QDialog, QLineEdit, QPushButton)

from PyQt5 import QtCore, QtGui


classAnimatedLabel(QLabel):
    def__init__(self):
        QLabel.__init__(self)

        color1 = QtGui.QColor(255, 0, 0)
        color2 = QtGui.QColor(255, 144, 0)
        color3 = QtGui.QColor(255, 255, 0)
        color4 = QtGui.QColor(224, 192, 192)

        color5 = QtGui.QColor(192, 224, 192)
        color6 = QtGui.QColor(192, 192, 192)
        color7 = QtGui.QColor(212, 208, 200)

        self.co_get = 0
        self.co_set = 0

        byar = QtCore.QByteArray()
        byar.append('zcolor')
        self.color_anim = QtCore.QPropertyAnimation(self, byar)
        self.color_anim.setStartValue(color4)
        self.color_anim.setKeyValueAt(0.15, color1)
        self.color_anim.setKeyValueAt(0.3, color2)
        self.color_anim.setKeyValueAt(0.5, color3)
        self.color_anim.setKeyValueAt(0.75, color2)
        self.color_anim.setEndValue(color4)
        self.color_anim.setDuration(2000)
        self.color_anim.setLoopCount(1)

        self.color_anim_ok = QtCore.QPropertyAnimation(self, byar)
        self.color_anim_ok.setStartValue(color5)
        self.color_anim_ok.setKeyValueAt(0.5, color6)
        self.color_anim_ok.setEndValue(color7)
        self.color_anim_ok.setDuration(1000)
        self.color_anim_ok.setLoopCount(-1)

        self.custom_anim = QtCore.QPropertyAnimation(self, byar)

    defparseStyleSheet(self):
        ss = self.styleSheet()
        sts = [s.strip() for s in ss.split(';') iflen(s.strip())]
        return sts

    defgetBackColor(self):
        self.co_get += 1# print(fuin(), self.co_get)return self.palette().color(self.pal_ele)

    defsetBackColor(self, color):
        self.co_set += 1
        sss = self.parseStyleSheet()
        bg_new = 'background-color: rgba(%d,%d,%d,%d);' % (color.red(), color.green(), color.blue(), color.alpha())

        for k, sty inenumerate(sss):
            if re.search('\Abackground-color:', sty):
                sss[k] = bg_new
                breakelse:
            sss.append(bg_new)

        # pal = self.palette()# pal.setColor(self.pal_ele, color)# self.setPalette(pal)
        self.setStyleSheet('; '.join(sss))

    pal_ele = QtGui.QPalette.Window
    zcolor = QtCore.pyqtProperty(QtGui.QColor, getBackColor, setBackColor)


# this class is only for testclassSomeDia2(QDialog):
    def__init__(self, parent=None):
        """Sets up labels in form"""
        QDialog.__init__(self, parent)

        self.co_press = 0

        self.setModal(True)
        self.setWindowTitle('Animation Example')

        self.edit_pad =  QLineEdit('-1')
        self.edit_rad =  QLineEdit('-1')
        self._mapHeight = QLineEdit('0')

        self.layout = QFormLayout()
        self.lab_pad = QLabel('Padding (px):')
        self.lab_rad = QLabel('Radius (px):' )
        self.layout.addRow(self.lab_pad, self.edit_pad)
        self.layout.addRow(self.lab_rad, self.edit_rad)

        self.anila = AnimatedLabel()
        self.anila.setText('Label for animation:')
        # self.anila.setStyleSheet('padding: 0 4px; border-radius: 4px;')
        self.layout.addRow(self.anila, self._mapHeight)

        self.ok = QPushButton()
        self.ok.setText('OK -- change animation')
        self.ok.clicked.connect(self._okPress)

        self.layout.addRow(self.ok)
        self.layout.setLabelAlignment(QtCore.Qt.AlignRight)

        self.setLayout(self.layout)
        self.set_initial_data()

    defset_initial_data(self):
        pad_vali = QtGui.QIntValidator(0, 20)
        rad_vali = QtGui.QIntValidator(0, 10)

        self.edit_pad.setValidator(pad_vali)
        self.edit_rad.setValidator(rad_vali)

        pad, rad = 4, 4
        self.edit_pad.setText(str(pad))
        self.edit_rad.setText(str(rad))

        self.set_ss(pad,rad)

        # slots
        self.edit_pad.textChanged.connect(self.change_padrad)
        self.edit_rad.textChanged.connect(self.change_padrad)

    defset_ss(self, pad, rad):
        self.anila.setStyleSheet('padding: 0 %dpx; border-radius: %dpx;' % (pad, rad))
        for lab in [self.lab_rad, self.lab_pad]:
            lab.setStyleSheet('padding: 0 %dpx;' % pad)

    defchange_padrad(self):
        try:
            pad = int(self.edit_pad.text())
            rad = int(self.edit_rad.text())
            # print(pad, rad)
            self.set_ss(pad, rad)
        except Exception as ex:
            print(type(ex).__name__)

    def_okPress(self, flag):
        # print('OK PRESS', flag)
        self.co_press += 1
        typ = self.co_press % 3if0 == typ:
            print('Animation NO')
            self.anila.color_anim.stop()
            self.anila.color_anim_ok.stop()
        elif1 == typ:
            print('Animation type 1')
            self.anila.color_anim_ok.stop()
            self.anila.color_anim.start()
        elif2 == typ:
            print('Animation type 2')
            self.anila.color_anim.stop()
            self.anila.color_anim_ok.start()


if __name__ == "__main__":

    app = QApplication(sys.argv)

    dia = SomeDia2()
    dia.show()

    app.exec_()