[英]Notify QML for 'usb device inserted' events using PyQt5 and pyudev
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.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。 After some investigation, I have found that pyudev could be the library to use.
经过一番调查,我发现 pyudev 可能是要使用的库。 But I have trouble using it with PyQt5 and QML.
但是我在使用 PyQt5 和 QML 时遇到了麻烦。 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 .
我已经成功地将pyudev 示例用于 MonitorObservor ,并且文档中还提供了其他示例, 这里是 PySide ,这里是 Glib 。 I have also found an example using PyQt5 and widgets application here .
我还发现使用PyQt5和窗口小部件应用的例子在这里。 But I have trouble implementing this on my PyQt5 QML application.
但是我在我的 PyQt5 QML 应用程序上实现这个有困难。 I am sure it is very easy, so I think I'm just missing something but I can't found out what...
我相信这很容易,所以我想我只是错过了一些东西,但我无法找到......
Here is what I have so far: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)
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):
).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'
when I uncomment def device_connected(self, device):
。
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.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。
Edit: 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')
编辑:我找到了一种使用
vid = device.get('ID_VENDOR_ID')
和pid = device.get('ID_MODEL_ID')
通过 VID PID 识别设备的方法
For the 2nd step, I had thought of using the Passerelle class as the QML backend:对于第二步,我曾考虑使用 Passerelle 类作为 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)
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.但是我不确定这是一个好主意,因为我在那个帖子中读到了在进入 qt 的主循环之前需要启动监视器。 Which I understand as : the monitor should be started in main.py before calling app.exec_()...
我的理解是:在调用 app.exec_() 之前,应该在 main.py 中启动监视器...
Thank you in advance for your help !预先感谢您的帮助 !
The best thing to do is to modify the GUI in QML, for which the Monitor and Device object must be accessible from QML.最好的做法是修改 QML 中的 GUI,为此必须可以从 QML 访问 Monitor 和 Device 对象。 Only QObjects receive notifications so I will create 2 classes that wrap with a light layer to both classes using q-properties and slots.
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 将轻层包装到两个类。
pyqtudev.py 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主文件
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主文件
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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