python - 活动期间 GUI 没有变化?(Python3.6、PyQt5)
问题描述
我正在尝试在操作期间更改按钮的样式。
当按下按钮时,我想让它们变成蓝色,然后读取 rfid 卡,然后通过 ID 将按钮的颜色更改为绿色或红色(在代码中只是红色以便更容易)。
问题在于将按钮样式更改为蓝色无济于事(绿色和红色效果很好)。它正在等待完成“clicked()”方法吗?如何告诉 PyQt5 “现在就做!” ?
编辑:我将伪代码修改为可重现的示例。
#!/usr/bin/python3
import sys
import time
from PyQt5.QtWidgets import *
class MainScreen(QWidget):
def __init__(self):
QWidget.__init__(self)
self.button = QPushButton("TEXT")
self.button.clicked.connect(self.clicked)
self.changeButtonColor("black") # set default style
self.grid = QGridLayout(self)
self.grid.addWidget(self.button)
self.show()
def changeButtonColor(self, color):
self.button.setStyleSheet("QPushButton{ \
color: "+color+"; font: bold 18px;}")
def clicked(self):
self.changeButtonColor("blue") # nothing happening (this is my problem!)
uid = self.readCard() # reading ID from rfid card
self.changeButtonColor("red")
def readCard(self):
#return rfid.read() # in real case
time.sleep(2)
return "12345678"
def main():
app = QApplication(sys.argv)
window = MainScreen()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
解决方案
void QTimer::singleShot(int ms, const QObject *receiver, const char *member)
这个静态函数在给定的时间间隔后调用一个槽。
使用此函数非常方便,因为您无需费心使用 timerEvent 或创建本地 QTimer 对象。
import sys
import time
from PyQt5.QtWidgets import *
from PyQt5 import QtCore
class MainScreen(QWidget):
def __init__(self):
QWidget.__init__(self)
self.button = QPushButton("TEXT")
self.button.clicked.connect(self.clicked)
self.changeButtonColor("black")
self.grid = QGridLayout(self)
self.grid.addWidget(self.button)
self.show()
def changeButtonColor(self, color):
self.button.setStyleSheet("QPushButton{ \
color: "+color+"; font: bold 18px;}")
def clicked(self):
self.changeButtonColor("blue") # nothing happening (this is my problem!)
# time.sleep(2) # reading ID from rfid card
# self.changeButtonColor("red")
QtCore.QTimer.singleShot(2000, lambda: self.changeButtonColor("red")) # <---
def main():
app = QApplication(sys.argv)
window = MainScreen()
sys.exit(app.exec_())
更新
import sys
import time
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import *
class Worker(QtCore.QObject): # +++
started = QtCore.pyqtSignal()
finished = QtCore.pyqtSignal()
data = QtCore.pyqtSignal(str)
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.running = False
self.stop = 5
@QtCore.pyqtSlot()
def read_data_from_sensor(self):
self.started.emit()
time.sleep(1) # We simulate the blocking process
while self.running and self.stop:
dt = time.strftime("%Y-%m-%d %H:%M:%S")
self.data.emit(dt)
time.sleep(1) # We simulate the blocking process
self.stop -= 1
self.finished.emit()
class MainScreen(QWidget):
def __init__(self):
QWidget.__init__(self)
self.button = QPushButton("TEXT Start")
self.button.clicked.connect(self.clicked)
self.changeButtonColor("black")
self.label_data = QtWidgets.QLabel(self, alignment=QtCore.Qt.AlignCenter)
self.label_data.setText('Pending')
self.grid = QGridLayout(self)
self.grid.addWidget(self.label_data)
self.grid.addWidget(self.button)
self.show()
### vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
self._worker = Worker()
self._worker.started.connect(self.on_started)
self._worker.finished.connect(self.on_finished)
self._worker.data.connect(self.update_label)
self._thread = QtCore.QThread(self)
self._thread.start()
self._worker.moveToThread(self._thread)
@QtCore.pyqtSlot()
def on_started(self):
self.label_data.setText("Start to read")
self.button.setText("TEXT Stop")
self.button.setEnabled(True)
self._worker.stop = 5
@QtCore.pyqtSlot()
def on_finished(self):
self.label_data.setText("Pending")
self.button.setText("TEXT Start")
self.button.setEnabled(True)
self.changeButtonColor("red") # <---
self._worker.running = False
self._worker.stop = 5
@QtCore.pyqtSlot(str)
def update_label(self, data):
self.label_data.setText(data)
### ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
def changeButtonColor(self, color):
self.button.setStyleSheet("QPushButton{ \
color: "+color+"; font: bold 18px;}")
def clicked(self):
self.changeButtonColor("blue") # nothing happening (this is my problem!)
# time.sleep(2) # reading ID from rfid card
# self.changeButtonColor("red")
# QtCore.QTimer.singleShot(2000, lambda: self.changeButtonColor("red")) # <---
### vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
if self._worker.running:
self._worker.running = False
else:
self._worker.running = True
QtCore.QTimer.singleShot(0, self._worker.read_data_from_sensor)
self.button.setEnabled(False)
### ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
def main():
app = QApplication(sys.argv)
window = MainScreen()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
推荐阅读
- r - 如何从倒置的钟形曲线中采样
- docker - 带有运行命令的docker文件未执行
- c# - 不存在从对象类型 System.Windows.Forms.DataGridViewTextBoxCell 到已知托管提供程序本机类型的映射
- javascript - 如何通过Javascript检查iOS.12.2+中的运动/方向permissionState?
- python-3.x - 无法在 VSCode 上的 Jupyter 笔记本中使用 cx_Oracle 进行连接
- javascript - 如何解释 Observable.of(Math.random()) 总是返回相同的值?
- scala - Spark 2.3:减去数据帧但保留重复值(Scala)
- c# - 在 .NET 核心项目中使用来自 UWP api 的 Miracast 无法接收视频帧
- fpga - PCIe UIO 多 DWORD 访问问题
- ios - 在 swift 5 中为 UITextField 设置底部边框的问题