如何用不同的方法发信号通知GUI中的插槽? [英] How to signal slots in a GUI from a different process?

问题描述

上下文: 在Python中，主线程产生第二个进程(使用多处理模块)，然后启动GUI(使用PyQt4).此时，主线程将阻塞，直到关闭GUI.第二个进程始终处于处理状态，理想情况下应以异步方式将信号发送到GUI中的特定插槽.

Context: In Python a main thread spawns a 2nd process (using multiprocessing module) and then launches a GUI (using PyQt4). At this point the main thread blocks until the GUI is closed. The 2nd process is always processing and ideally should emit signal(s) to specific slot(s) in the GUI in an asynchronous manner.

问题: Python和PyQt4提供了哪些方法/工具来实现该目标，以及如何实现?最好以软中断的方式而不是轮询.

Question: Which approach/tools are available in Python and PyQt4 to achieve that and how? Preferably in a soft-interrupt manner rather than polling.

抽象地讲，我能想到的解决方案是在主线程中实例化的工具/处理程序"，它假设从GUI实例中获取了可用的插槽，并与第二个进程中所获取的信号相连接，并假设我向该工具提供了一些预期或硬编码的信息.可以实例化到第三个进程/线程.

Abstractly speaking, the solution I can think of is a "tool/handler" instantiated in the main thread that grabs the available slots from the GUI instance and connects with the grabbed signals from the 2nd process, assuming I provide this tool some information of what to expect or hard coded. This could be instantiated to a 3rd process/thread.

推荐答案

这是一个示例Qt应用程序，它演示了如何将信号从子进程发送到母进程中的插槽.我不确定这是正确的方法，但是否可行.

This is an example Qt application demonstrating sending signals from a child process to slots in the mother process. I'm not sure this is right approach but it works.

我将进程区分为 mother 和 child ，因为Qt上下文中已经使用了 parent 这个词.
母进程有两个线程.母进程的主线程通过multiprocessing.Queue将数据发送到子进程.子进程通过multiprocessing.Pipe将处理后的数据和信号签名发送到母进程的第二个线程.母进程的第二个线程实际上发出信号.

I differentiate between process as mother and child, because the word parent is alread used in the Qt context.
The mother process has two threads. Main thread of mother process sends data to child process via multiprocessing.Queue. Child process sends processed data and signature of the signal to be sent to the second thread of mother process via multiprocessing.Pipe. The second thread of mother process actually emits the signal.

Python 2.X，PyQt4:

Python 2.X, PyQt4:

from multiprocessing import Process, Queue, Pipe
from threading import Thread
import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class Emitter(QObject, Thread):

    def __init__(self, transport, parent=None):
        QObject.__init__(self,parent)
        Thread.__init__(self)
        self.transport = transport

    def _emit(self, signature, args=None):
        if args:
            self.emit(SIGNAL(signature), args)
        else:
            self.emit(SIGNAL(signature))

    def run(self):
        while True:
            try:
                signature = self.transport.recv()
            except EOFError:
                break
            else:
                self._emit(*signature)

class Form(QDialog):

    def __init__(self, queue, emitter, parent=None):
        super(Form,self).__init__(parent)
        self.data_to_child = queue
        self.emitter = emitter
        self.emitter.daemon = True
        self.emitter.start()
        self.browser = QTextBrowser()
        self.lineedit = QLineEdit('Type text and press <Enter>')
        self.lineedit.selectAll()
        layout = QVBoxLayout()
        layout.addWidget(self.browser)
        layout.addWidget(self.lineedit)
        self.setLayout(layout)
        self.lineedit.setFocus()
        self.setWindowTitle('Upper')
        self.connect(self.lineedit,SIGNAL('returnPressed()'),self.to_child)
        self.connect(self.emitter,SIGNAL('data(PyQt_PyObject)'), self.updateUI)

    def to_child(self):
        self.data_to_child.put(unicode(self.lineedit.text()))
        self.lineedit.clear()

    def updateUI(self, text):
        text = text[0]
        self.browser.append(text)

class ChildProc(Process):

    def __init__(self, transport, queue, daemon=True):
        Process.__init__(self)
        self.daemon = daemon
        self.transport = transport
        self.data_from_mother = queue

    def emit_to_mother(self, signature, args=None):
        signature = (signature, )
        if args:
            signature += (args, )
        self.transport.send(signature)

    def run(self):
        while True:
            text = self.data_from_mother.get()
            self.emit_to_mother('data(PyQt_PyObject)', (text.upper(),))

if __name__ == '__main__':

    app = QApplication(sys.argv)
    mother_pipe, child_pipe = Pipe()
    queue = Queue()
    emitter = Emitter(mother_pipe)
    form = Form(queue, emitter)
    ChildProc(child_pipe, queue).start()
    form.show()
    app.exec_()

为了方便起见，Python 3.X，PySide:

And as convenience also Python 3.X, PySide:

from multiprocessing import Process, Queue, Pipe
from threading import Thread

from PySide import QtGui, QtCore

class Emitter(QtCore.QObject, Thread):

    def __init__(self, transport, parent=None):
        QtCore.QObject.__init__(self, parent)
        Thread.__init__(self)
        self.transport = transport

    def _emit(self, signature, args=None):
        if args:
            self.emit(QtCore.SIGNAL(signature), args)
        else:
            self.emit(QtCore.SIGNAL(signature))

    def run(self):
        while True:
            try:
                signature = self.transport.recv()
            except EOFError:
                break
            else:
                self._emit(*signature)

class Form(QtGui.QDialog):

    def __init__(self, queue, emitter, parent=None):
        super().__init__(parent)
        self.data_to_child = queue
        self.emitter = emitter
        self.emitter.daemon = True
        self.emitter.start()
        self.browser = QtGui.QTextBrowser()
        self.lineedit = QtGui.QLineEdit('Type text and press <Enter>')
        self.lineedit.selectAll()
        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.browser)
        layout.addWidget(self.lineedit)
        self.setLayout(layout)
        self.lineedit.setFocus()
        self.setWindowTitle('Upper')
        self.lineedit.returnPressed.connect(self.to_child)
        self.connect(self.emitter, QtCore.SIGNAL('data(PyObject)'), self.updateUI)

    def to_child(self):
        self.data_to_child.put(self.lineedit.text())
        self.lineedit.clear()

    def updateUI(self, text):
        self.browser.append(text[0])

class ChildProc(Process):

    def __init__(self, transport, queue, daemon=True):
        Process.__init__(self)
        self.daemon = daemon
        self.transport = transport
        self.data_from_mother = queue

    def emit_to_mother(self, signature, args=None):
        signature = (signature, )
        if args:
            signature += (args, )
        self.transport.send(signature)

    def run(self):
        while True:
            text = self.data_from_mother.get()
            self.emit_to_mother('data(PyQt_PyObject)', (text.upper(),))

if __name__ == '__main__':

    app = QApplication(sys.argv)
    mother_pipe, child_pipe = Pipe()
    queue = Queue()
    emitter = Emitter(mother_pipe)
    form = Form(queue, emitter)
    ChildProc(child_pipe, queue).start()
    form.show()
    app.exec_()

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