Change QLCDNumber colour when a specific Value is read using pyqt5 - python-3.x

Question

I have a code which reads sensor data and outputs it to a LCD number I am using python3 and pyqt5.
Now What i've been tyring to do with no luck is change the background colour of the LCD number when it reaches a certain value. e.g. when the value falls below 100 the background of the LCD widget is red or an image appears saying too low, if it is between 100-300 it is green and over 300 it goes red again. I hope this makes sense, does anyone know how I can achieve this using pyqt5?
here are the relevant segments of my code for the LCD Number
class Worker(QtCore.QThread):
valueFound = QtCore.pyqtSignal(int, name="valueFound")
...
def run(self):
while self.runFlag:
self.valueFound.emit(self.Pressure_Reading())
...
self.worker = Worker(self)
self.worker.valueFound.connect(self.OnValueFound)
....
def OnValueFound(self, value):
self.ui.lcdNumber.display(value)

Answer 1

Use Qt Style Sheets.
import sys
from random import randint
from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.QtCore import QTimer
from ui import Ui_MainWindow
class Form(QMainWindow):
def __init__(self):
super().__init__()
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.i = 0
self.voltageMin = 180
self.voltageMax = 180
self.ui.lcdNumberCur.display(self.i)
self.ui.lcdNumberCur.setStyleSheet("QLCDNumber { background-color: yellow }")
self.ui.pushButton.clicked.connect(self.startTimer)
self.timer = QTimer(self)
self.timer.setInterval(1000)
self.timer.timeout.connect(self.updateData)
self.show()
def startTimer(self):
if self.ui.pushButton.text() == "Start Timer":
self.timer.start(1000)
self.ui.pushButton.setText("Stop Timer")
else:
self.ui.pushButton.setText("Start Timer")
self.timer.stop()
def updateData(self):
voltage = randint(80, 350) # <--- insert your average voltage here
self.ui.lcdNumberCur.display(voltage)
if voltage > self.voltageMax:
self.voltageMax = voltage
self.ui.lcdNumberMax.display(self.voltageMax)
if self.voltageMax > 300:
self.ui.lcdNumberMax.setStyleSheet("""QLCDNumber {
background-color: red;
color: white; }""")
else:
self.ui.lcdNumberMax.setStyleSheet("""QLCDNumber
{ background-color: green;
color: yellow;
}""")
elif voltage < self.voltageMin:
self.voltageMin = voltage
self.ui.lcdNumberMin.display(self.voltageMin)
if self.voltageMin < 90:
self.ui.lcdNumberMin.setStyleSheet("""QLCDNumber {
background-color: red;
color: white; }""")
else:
self.ui.lcdNumberMin.setStyleSheet("""QLCDNumber
{ background-color: green;
color: yellow;
}""")
if __name__ == '__main__':
app = QApplication(sys.argv)
frm = Form()
sys.exit(app.exec_())