我有一个GUI应用程序（由PyQt5和QML制成），并希望在插入USB设备或从计算机中拔出USB设备时得到通知。经过一番调查，我发现pyudev可能是要使用的库。但是我在将其与PyQt5和QML结合使用时遇到麻烦。我已经成功使用了pyudev example for MonitorObservor，并且在文档here with PySide和here with Glib中提供了其他示例。我还找到了一个使用PyQt5和窗口小部件应用程序here的示例。但是我在我的PyQt5 QML应用程序上无法实现这一点。我敢肯定，这很容易，所以我想我只是想念一些东西，但我不知道是什么...
这是我到目前为止所拥有的：
import sys
from PyQt5.QtWidgets import QApplication
from PyQt5.QtQml import QQmlApplicationEngine
from PyQt5.QtCore import QUrl
from pyudev import Context, Monitor, Device
from pyudev.pyqt5 import MonitorObserver
from Passerelle import *
# def device_connected(self, device):
def device_connected(self):
print("Test")
print("device action: ", device.action, ", path: ", device.device_path)
if __name__ == "__main__":
app = QApplication(sys.argv)
engine = QQmlApplicationEngine()
p = Passerelle()
engine.rootContext().setContextProperty("passerelle", p)
engine.load(QUrl("main.qml"))
if not engine.rootObjects:
sys.exit(-1)
context = Context()
monitor = Monitor.from_netlink(context)
# monitor.filter_by(subsystem='tty')
observer = MonitorObserver(monitor)
observer.deviceEvent.connect(device_connected)
monitor.start()
ret = app.exec_()
sys.exit(ret)
拔出或重新插入设备时，我已经成功在控制台上打印了“测试”，但似乎无法打印设备信息（取消注释TypeError: device_connected() missing 1 required positional argument: 'device'时，def device_connected(self, device):）。
这里的第一步是能够在控制台上打印设备信息，然后找到一种方法来通知GUI，最后仅在插入或拔出的设备具有指定的VID / PID时才通知GUI。
编辑：我发现了一种使用vid = device.get('ID_VENDOR_ID')和pid = device.get('ID_MODEL_ID')通过VID PID识别设备的方法
对于第二步，我曾考虑过将Passerelle类用作QML后端：
from PyQt5.QtCore import QObject, pyqtSlot, pyqtSignal#, pyqtProperty, QUrl
from pyudev import Context, Monitor
from pyudev.pyqt5 import MonitorObserver
def device_event(observer, device):
print ("event ", device.action, " on device ", device)
class Passerelle(QObject):
sendDeviceEvent = pyqtSignal(int)
def __init__(self, parent=None):
print("Passerelle constructor called")
QObject.__init__(self, parent)
print("end Passerelle constructor")
@pyqtSlot()
def setObserverForDeviceEvents(self):
print("setObserverForDeviceEvents called")
context = Context()
monitor = Monitor.from_netlink(context)
monitor.filter_by(subsystem='usb')
observer = MonitorObserver(monitor)
observer.deviceEvent.connect(self.device_connected)
monitor.start()
print("end setObserverForDeviceEvents")
def device_connected(self, device):
print("Test")
print("device action: ", device.action, ", path: ", device.device_path)
但是我不确定这是一个好主意，因为我在post中读到，在进入qt的主循环之前需要启动监视器。我的理解是：监视程序应在调用app.exec _（）...之前在main.py中启动。
预先感谢您的帮助！
答案 0 :(得分：1)
最好的办法是修改QML中的GUI，为此必须可以从QML访问Monitor和Device对象。只有QObjects会收到通知，因此我将创建2个类，这些类使用q-properties和slot封装到两个类中，并带有一个亮层。
pyqtudev.py
from PyQt5 import QtCore
from pyudev import Context, Monitor, Device
from pyudev.pyqt5 import MonitorObserver
class QtUdevDevice(QtCore.QObject):
def __init__(self, parent=None):
super(QtUdevDevice, self).__init__(parent)
self.m_dev = None
def initialize(self, dev):
self.m_dev = dev
@QtCore.pyqtSlot(result=bool)
def isValid(self):
return self.m_dev is not None
@QtCore.pyqtProperty(str, constant=True)
def devType(self):
if not self.isValid():
return ""
if self.m_dev.device_type is None:
return ""
return self.m_dev.device_type
@QtCore.pyqtProperty(str, constant=True)
def subsystem(self):
if not self.isValid():
return ""
return self.m_dev.subsystem
@QtCore.pyqtProperty(str, constant=True)
def name(self):
if not self.isValid():
return ""
return self.m_dev.sys_name
@QtCore.pyqtProperty(str, constant=True)
def driver(self):
if not self.isValid():
return ""
if self.m_dev.driver is None:
return ""
return self.m_dev.driver
@QtCore.pyqtProperty(str, constant=True)
def deviceNode(self):
if not self.isValid():
return ""
if self.m_dev.device_node is None:
return ""
return self.m_dev.device_node
@QtCore.pyqtProperty(list, constant=True)
def alternateDeviceSymlinks(self):
return list(self.m_dev.device_links)
@QtCore.pyqtProperty(str, constant=True)
def sysfsPath(self):
if not self.isValid():
return ""
return self.m_dev.sys_path
@QtCore.pyqtProperty(int, constant=True)
def sysfsNumber(self):
if not self.isValid():
return -1
if self.m_dev.sys_number is None:
return -1
return int(self.m_dev.sys_number)
@QtCore.pyqtSlot(str, result=str)
def property(self, name):
if not self.isValid():
return ""
v = self.m_dev.properties.get(name)
return v if v is not None else ""
@QtCore.pyqtSlot(str, result=bool)
def hasProperty(self, name):
if not self.isValid():
return False
return self.m_dev.properties.get(name) is not None
@QtCore.pyqtProperty(list, constant=True)
def deviceProperties(self):
if not self.isValid():
return []
return list(self.m_dev.properties)
@QtCore.pyqtProperty(list, constant=True)
def sysfsProperties(self):
if not self.isValid():
return []
return list(self.m_dev.attributes.available_attributes)
@QtCore.pyqtProperty(QtCore.QObject, constant=True)
def parentDevice(self):
if not self.isValid:
return
if self.m_dev.parent:
parent_device = QtUdevDevice()
parent_device.initialize(self.m_dev.parent)
return parent_device
@QtCore.pyqtProperty(str, constant=True)
def action(self):
if not self.isValid():
return ""
if self.m_dev.action is None:
return ""
return self.m_dev.action
def __repr__(self):
if self.isValid():
return "UdevDevice({})".format(self.sysfsPath())
return "Invalid UdevDevice"
class QtMonitorObserver(QtCore.QObject):
deviceEvent = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
deviceAdded = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
deviceRemoved = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
deviceChanged = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
deviceOnlined = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
deviceOfflined = QtCore.pyqtSignal(QtUdevDevice, arguments=["device"])
def __init__(self, parent=None):
super(QtMonitorObserver, self).__init__(parent)
context = Context()
self._monitor = Monitor.from_netlink(context)
self._observer = MonitorObserver(self._monitor, self)
self._observer.deviceEvent.connect(self.setup_new_signals)
@QtCore.pyqtSlot()
def start(self):
self._monitor.start()
@QtCore.pyqtSlot(str)
def filter_by(self, filter):
self._monitor.filter_by(subsystem=filter)
@QtCore.pyqtSlot(str)
def filter_by_tag(self, tag):
self._monitor.filter_by_tag(tag)
@QtCore.pyqtSlot()
def remove_filter(self):
self._monitor.remove_filter()
@QtCore.pyqtSlot(Device)
def setup_new_signals(self, device):
new_signals_map = {
'add': self.deviceAdded,
'remove': self.deviceRemoved,
'change': self.deviceChanged,
'online': self.deviceOnlined,
'offline': self.deviceOfflined,
}
signal = new_signals_map.get(device.action)
qtdevice = QtUdevDevice()
qtdevice.initialize(device)
if signal:
signal.emit(qtdevice)
self.deviceEvent.emit(qtdevice)
main.py
import os
import sys
from PyQt5 import QtCore, QtGui, QtQml
from pyqtudev import QtMonitorObserver
def run():
app = QtGui.QGuiApplication(sys.argv)
engine = QtQml.QQmlApplicationEngine()
observer = QtMonitorObserver()
engine.rootContext().setContextProperty("observer", observer)
directory = os.path.dirname(os.path.abspath(__file__))
engine.load(QtCore.QUrl.fromLocalFile(os.path.join(directory, 'main.qml')))
if not engine.rootObjects():
return -1
return app.exec_()
if __name__ == "__main__":
sys.exit(run())
main.qml
import QtQuick 2.11
import QtQuick.Window 2.2
import QtQuick.Controls 2.2
ApplicationWindow {
visible: true
width: Screen.width/2
height: Screen.height/2
Connections {
target: observer
onDeviceEvent: {
console.log(device, device.name, device.action, device.parentDevice)
if(device.hasProperty("ID_VENDOR_ID")){
console.log(device.property("ID_VENDOR_ID"))
}
}
}
Component.onCompleted: {
observer.start()
observer.filter_by("usb")
}
}