使用 PyQt5 和 pyudev 通知 QML 的“插入 USB 设备"事件 [英] Notify QML for 'usb device inserted' events using PyQt5 and pyudev
问题描述
我有一个 GUI 应用程序(用 PyQt5 和 QML 制作)，并希望在 USB 设备从计算机上插入或拔出时得到通知.经过一番调查，我发现 pyudev 可能是要使用的库.但是我在使用 PyQt5 和 QML 时遇到了麻烦.我已成功使用 监控观察者的 pyudev 示例，并且文档中提供了其他示例，here with PySide 和 此处使用 Glib.我还在此处找到了一个使用 PyQt5 和小部件应用程序的示例.但是我在我的 PyQt5 QML 应用程序上实现这个有困难.我相信这很容易，所以我想我只是遗漏了一些东西，但我不知道是什么......
I have a GUI application (made with PyQt5 and QML) and would like to get notify when a usb device is plugged or unplugged from the computer. After some investigation, I have found that pyudev could be the library to use. But I have trouble using it with PyQt5 and QML. I have succeed to use the pyudev example for MonitorObservor, and there are other example provided in the documentation, here with PySide and here with Glib. I have also found an example using PyQt5 and widgets application here. But I have trouble implementing this on my PyQt5 QML application. I am sure it is very easy, so I think I'm just missing something but I can't found out what...
这是我目前所拥有的:
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)
在拔出或插回设备时，我已成功在控制台上打印测试"，但似乎无法打印设备信息(TypeError: device_connected() missing 1 required positional argument: 'device' 当我取消注释 def device_connected(self, device): 时.
I have succeeded to print "Test" on the console when unplugging or plugging back a device but can't seem to print the device information (TypeError: device_connected() missing 1 required positional argument: 'device' when I uncomment 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，然后找到一种通知 GUI 的方法，最后仅当插入或拔出的设备具有指定的 VID/PID 时才通知 GUI.
Here the first step would be to be able to print the device information on the console, then to find a way to notify the GUI and finally to notify the GUI only if the device plugged or unplugged has a specified VID/PID.
我找到了一种使用 vid = device.get('ID_VENDOR_ID') 和 pid = device.get('ID_MODEL_ID')
I have found a way to identify the device through VID PID using vid = device.get('ID_VENDOR_ID') and pid = device.get('ID_MODEL_ID')
对于第二步，我曾考虑使用 Passerelle 类作为 QML 后端:
For the 2nd step, I had thought of using the Passerelle class as the QML backend:
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)
但我不确定这是个好主意，因为我读到了post 在进入 qt 的主循环之前需要启动监视器.我的理解是:在调用 app.exec_()...
But I am not sure it is a good idea as I read in that post that the monitor needed to be started before entering qt's main loop. Which I understand as : the monitor should be started in main.py before calling app.exec_()...
预先感谢您的帮助！
推荐答案
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，所以我将创建 2 个类，这些类使用 q-properties 和 slot 为两个类包装一个轻层.
The best thing to do is to modify the GUI in QML, for which the Monitor and Device object must be accessible from QML. Only QObjects receive notifications so I will create 2 classes that wrap with a light layer to both classes using q-properties and slots.
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")
}
}
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