python-3.x - 使用 pyqt5 读取特定值时更改 QLCDNumber 颜色

Question

我有一个代码可以读取传感器数据并将其输出到 LCD 数字，我正在使用 python3 和 pyqt5。

现在我一直在尝试做的事情是当 LCD 数字达到某个值时更改其背景颜色，但没有成功。例如当该值低于 100 时，LCD 小部件的背景为红色或图像显示太低，如果该值在 100-300 之间，则为绿色，超过 300 则再次变为红色。我希望这是有道理的，有谁知道我如何使用 pyqt5 实现这一目标？

这是我的 LCD 编号代码的相关部分

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

使用 Qt 样式表。

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_())