Question

背景：我想实现一个GUI，以使用PySide2控制一堆客户端（通过RPC调用与“服务器”控制硬件，例如电机，摄像机等），

以前的方法：通常，我要做的是创建GUI并将UI信号连接到Client插槽，反之亦然。对于更简单的应用程序来说，这非常合适。

问题：我希望我的GUI能够正确表示对客户端的允许调用。最简单的示例：执行client1.doXY()之后，我想禁用执行该命令的按钮，并仅在doZY()完成后将其重新激活。尽管上述方法完全有可能做到这一点，但是当事情变得更加复杂时，这是错误的：当GUI元素取决于多个客户端的状态时。

方法：因此，我认为将有限状态机用作客户端和GUI之间的中间层是一个好主意，并且遇到pytransitions，这看起来非常有希望。但是，我正在努力找到将这两个世界结合在一起的正确方法。

问题：

通常来说，具有这样一个图层是一种有效的设计方法吗？
尤其是如工作代码示例所示，我必须将客户端移至单独的线程，以避免在客户端执行阻塞调用时GUI冻结。尽管我的代码工作正常，但在创建其他qt信号以连接ClientState和Client对象时需要一定的开销。是否可以更优雅地完成此操作（即没有其他xy_requested信号，但是以某种方式从ClientState到Client函数的直接调用仍然在{{1}中调用Client函数}线程而不是主线程？

工作示例：

代码：

Client

Answer 1

通常来说，具有这样一层的设计方法是否有效？

是的，这是有效的，并且在复杂的应用程序中，FSM可以简化逻辑，因此可以实现。

关于恕我直言的简化，我更喜欢验证在这种情况下Qt中是否存在类似的工具，因为它们通过事件或信号与Qt的元素友好地交互。在这种情况下，至少有两个选项：

The State Machine Framework:

import time
from functools import partial
from PySide2 import QtCore, QtGui, QtWidgets
import numpy as np


class Client(QtCore.QObject):
    # Client signals
    sig_move_done = QtCore.Signal()
    sig_disconnected = QtCore.Signal()
    sig_connected = QtCore.Signal()

    @QtCore.Slot(int)
    def client_move(self, dest):
        print(f"Client moving to {dest}...")
        time.sleep(3)  # some blocking function
        if np.random.rand() < 0.5:
            print("Error occurred during movement...")
            self.sig_disconnected.emit()
        else:
            print("Movement done...")
            self.sig_move_done.emit()

    @QtCore.Slot()
    def client_disconnect(self):
        # do something then...  on success do:
        self.sig_disconnected.emit()

    @QtCore.Slot()
    def client_connect(self):
        # do something ... on success do:
        self.sig_connected.emit()


class GUI(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setWindowTitle("State")

        self.btn_move = QtWidgets.QPushButton("move")
        self.btn_connect = QtWidgets.QPushButton("(re-)connect")

        self.client = Client()
        self._thread = QtCore.QThread(self)
        self._thread.start()
        self.client.moveToThread(self._thread)

        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(self.btn_move)
        lay.addWidget(self.btn_connect)
        self.resize(320, 120)

        # states
        self.unknown_state = QtCore.QState()
        self.ready_state = QtCore.QState()
        self.moving_state = QtCore.QState()

        # transitions
        self.ready_state.addTransition(self.btn_move.clicked, self.moving_state)
        self.moving_state.addTransition(self.client.sig_move_done, self.ready_state)
        self.ready_state.addTransition(self.client.sig_disconnected, self.unknown_state)
        self.moving_state.addTransition(self.client.sig_disconnected, self.unknown_state)
        self.unknown_state.addTransition(self.btn_connect.clicked, self.ready_state)
        self.unknown_state.addTransition(self.client.sig_connected, self.ready_state)

        self.unknown_state.entered.connect(self.on_unknown_state_enter)
        self.ready_state.entered.connect(self.on_ready_state_enter)
        self.moving_state.entered.connect(self.on_moving_state_enter)

        state_machine = QtCore.QStateMachine(self)
        state_machine.addState(self.ready_state)
        state_machine.addState(self.moving_state)
        state_machine.addState(self.unknown_state)

        state_machine.setInitialState(self.unknown_state)
        state_machine.start()

    def on_unknown_state_enter(self):
        print("unknown_state")
        self.btn_move.setDisabled(True)
        self.btn_connect.setEnabled(True)

    def on_ready_state_enter(self):
        print("ready_state")
        self.btn_move.setEnabled(True)
        self.btn_connect.setDisabled(True)

    def on_moving_state_enter(self):
        print("moving_state")
        self.btn_move.setDisabled(True)
        self.btn_connect.setDisabled(True)
        dest = np.random.randint(1, 100)
        wrapper = partial(self.client.client_move, dest)
        QtCore.QTimer.singleShot(0, wrapper)

    def closeEvent(self, event):
        self._thread.quit()
        self._thread.wait()
        super().closeEvent(event)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)

    w = GUI()
    w.show()

    sys.exit(app.exec_())

Qt SCXML:

Simple_State_Machine.scxml

<?xml version="1.0" encoding="UTF-8"?>
<scxml xmlns="http://www.w3.org/2005/07/scxml" version="1.0" binding="early" xmlns:qt="http://www.qt.io/2015/02/scxml-ext" name="Simple_State_Machine" qt:editorversion="4.10.0" initial="unknown">
    <qt:editorinfo initialGeometry="150.82;359.88;-20;-20;40;40"/>
    <state id="ready">
        <qt:editorinfo stateColor="#ff974f" geometry="425.83;190.46;-60;-50;120;100" scenegeometry="425.83;190.46;365.83;140.46;120;100"/>
        <transition type="internal" event="move" target="moving">
            <qt:editorinfo endTargetFactors="35.02;9.52" movePoint="-34.84;14.59" startTargetFactors="32.33;90.16"/>
        </transition>
        <transition type="internal" event="disconnect" target="unknown">
            <qt:editorinfo endTargetFactors="91.87;60.92" movePoint="9.38;9.36" startTargetFactors="6.25;63.37"/>
        </transition>
    </state>
    <state id="unknown">
        <qt:editorinfo stateColor="#89725b" geometry="150.82;190.46;-60;-50;120;100" scenegeometry="150.82;190.46;90.82;140.46;120;100"/>
        <transition type="internal" target="ready" event="connect">
            <qt:editorinfo endTargetFactors="6.34;41.14" movePoint="0;7.30" startTargetFactors="91.13;39.41"/>
        </transition>
    </state>
    <state id="moving">
        <qt:editorinfo stateColor="#a508d0" geometry="425.83;344.53;-60;-50;120;100" scenegeometry="425.83;344.53;365.83;294.53;120;100"/>
        <transition type="internal" event="disconnect" target="unknown">
            <qt:editorinfo movePoint="2.08;17.72"/>
        </transition>
        <transition type="internal" event="stopped" target="ready">
            <qt:editorinfo endTargetFactors="68.30;90.08" movePoint="62.50;10.32" startTargetFactors="68.69;5.74"/>
        </transition>
    </state>
</scxml>

import os
import time
from functools import partial
from PySide2 import QtCore, QtGui, QtWidgets, QtScxml
import numpy as np


class Client(QtCore.QObject):
    # Client signals
    sig_move_done = QtCore.Signal()
    sig_disconnected = QtCore.Signal()
    sig_connected = QtCore.Signal()

    @QtCore.Slot(int)
    def client_move(self, dest):
        print(f"Client moving to {dest}...")
        time.sleep(3)  # some blocking function
        if np.random.rand() < 0.5:
            print("Error occurred during movement...")
            self.sig_disconnected.emit()
        else:
            print("Movement done...")
            self.sig_move_done.emit()

    @QtCore.Slot()
    def client_disconnect(self):
        # do something then...  on success do:
        self.sig_disconnected.emit()

    @QtCore.Slot()
    def client_connect(self):
        # do something ... on success do:
        self.sig_connected.emit()


class GUI(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setWindowTitle("State")

        self.btn_move = QtWidgets.QPushButton("move")
        self.btn_connect = QtWidgets.QPushButton("(re-)connect")

        self.client = Client()
        self._thread = QtCore.QThread(self)
        self._thread.start()
        self.client.moveToThread(self._thread)

        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(self.btn_move)
        lay.addWidget(self.btn_connect)
        self.resize(320, 120)

        current_dir = os.path.dirname(os.path.realpath(__file__))
        filename = os.path.join(current_dir, "Simple_State_Machine.scxml")

        machine = QtScxml.QScxmlStateMachine.fromFile(filename)
        machine.setParent(self)

        for error in machine.parseErrors():
            print(error.toString())

        machine.connectToState("unknown", self, QtCore.SLOT("on_unknown_state_enter(bool)"))
        machine.connectToState("ready", self, QtCore.SLOT("on_ready_state_enter(bool)"))
        machine.connectToState("moving", self, QtCore.SLOT("on_moving_state_enter(bool)"))


        self.btn_connect.clicked.connect(partial(machine.submitEvent, "connect"))
        self.btn_move.clicked.connect(partial(machine.submitEvent, "move"))

        self.client.sig_disconnected.connect(partial(machine.submitEvent, "disconnect"))
        self.client.sig_connected.connect(partial(machine.submitEvent, "connect"))
        self.client.sig_move_done.connect(partial(machine.submitEvent, "stopped"))

        machine.start()

    @QtCore.Slot(bool)
    def on_unknown_state_enter(self, active):
        if active:
            print("unknown_state")
            self.btn_move.setDisabled(True)
            self.btn_connect.setEnabled(True)

    @QtCore.Slot(bool)
    def on_ready_state_enter(self, active):
        if active:
            print("ready_state")
            self.btn_move.setEnabled(True)
            self.btn_connect.setDisabled(True)

    @QtCore.Slot(bool)
    def on_moving_state_enter(self, active):
        if active:
            print("moving_state")
            self.btn_move.setDisabled(True)
            self.btn_connect.setDisabled(True)
            dest = np.random.randint(1, 100)
            wrapper = partial(self.client.client_move, dest)
            QtCore.QTimer.singleShot(0, wrapper)

    def closeEvent(self, event):
        self._thread.quit()
        self._thread.wait()
        super().closeEvent(event)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)

    w = GUI()
    w.show()

    sys.exit(app.exec_())

如何正确组合PySide2和pytransitions以为GUI应用程序实现状态机

1 个答案:

通常来说，具有这样一层的设计方法是否有效？

The State Machine Framework:

Qt SCXML: