将变量从MQTT传递给Kivy

Question

我尝试使用导航绘图器将值从MQTT传递到Kivy仪表板。

有人可以提示我如何更改变量吗？这是我的示例代码。 MQTT正在工作。我使用Python 3.6.6和1.10.1。

mainmenu.py

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.garden.navigationdrawer import NavigationDrawer
from kivy.properties import StringProperty
import paho.mqtt.client as mqtt

class Drawer(NavigationDrawer):
    vartext1 = StringProperty("Button")
    vartext2 = StringProperty("Text")

class MainMenuApp(App):
    def build(self):
        return Drawer()

    def on_start(self):
        topic = "kivy/#"

        def onConnect(client, userdata, flags, rc):
            mqttc.subscribe(topic, 0)

        def onMessage(client, userdata, msg):
            msg.payload = msg.payload.decode("utf-8")
            print ("[INFO   ] [MQTT        ] topic: " + msg.topic +" msg: "+ msg.payload)
            if msg.topic == "kivy/button":
                vartext1 = msg.payload

            if msg.topic == "kivy/text":
                vartext2 = msg.payload

        mqttc = mqtt.Client(client_id="kivy-client", clean_session=True)
        mqttc.on_connect      = onConnect 
        mqttc.on_message      = onMessage
        mqttc.connect("10.0.0.104", 1883, keepalive=60, bind_address="")
        mqttc.loop_start() # start loop to process callbacks! (new thread!)

if __name__ == "__main__":
    MainMenuApp().run()

mainmenu.kv

<Drawer>:
    # Side panel
    BoxLayout:
        padding: 30
        Button:
            text: root.vartext1
    # Main panel
    BoxLayout:
        padding: 30
        Label:
            text: root.vartext2

Answer 1

您可以将“ self”参数传递给mqtt.Client构造函数，如下所示：

parameters = {'self': self}
mqttc = mqtt.Client(client_id="kivy-client", clean_session=True, userdata = parameters)

现在在onMessage过程中，您可以访问该参数：

userdata['self'].vartext1 = msg.payload

因此您的mainmenu.py文件应如下所示：

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.button import Button
from kivy.garden.navigationdrawer import NavigationDrawer
from kivy.properties import StringProperty
import paho.mqtt.client as mqtt

class Drawer(NavigationDrawer):
    vartext1 = StringProperty("Button")
    vartext2 = StringProperty("Text")

class MainMenuApp(App):
    def build(self):
        return Drawer()

    def on_start(self):
        topic = "kivy/#"

        def onConnect(client, userdata, flags, rc):
            mqttc.subscribe(topic, 0)

        def onMessage(client, userdata, msg):
            msg.payload = msg.payload.decode("utf-8")
            print ("[INFO   ] [MQTT        ] topic: " + msg.topic +" msg: "+ msg.payload)
            if msg.topic == "kivy/button":
                userdata['self'].vartext1 = msg.payload

            if msg.topic == "kivy/text":
                userdata['self'].vartext2 = msg.payload

        parameters = {'self': self}
        mqttc = mqtt.Client(client_id="kivy-client", clean_session=True, userdata = parameters)
        mqttc.on_connect      = onConnect 
        mqttc.on_message      = onMessage
        mqttc.connect("10.0.0.104", 1883, keepalive=60, bind_address="")
        mqttc.loop_start() # start loop to process callbacks! (new thread!)

if __name__ == "__main__":
    MainMenuApp().run()