python - Kivy 和 Python 线程——如何在它们之间获取数据

Question

我在使用 python(线程)和 kivy 时遇到了一些问题:

这是一些代码:

import kivy
import threading 
import time
from kivy.app import App
from kivy.uix.button import Button

class Thread(threading.Thread):
    def __init__(self):
        threading.Thread.__init__(self)  
        self.counter = 0        
    def run(self):
        while True:
            print "Thread is running "+str(self.counter)
            app.button.text = self.set_button(self.counter)
            app.button.text = str(self.counter)
            time.sleep(0.5)
    def count(self):
        self.counter += 1
        app.button.text = str(self.counter)     
    def set_button(self, value):
        app.button.text = str(value)

class MyApp(App):
    def __init__ (self, thread_object):
        App.__init__(self) 
        self.thread_object = thread_object      
    def callback(self,instance):
        print('The button <%s> is being pressed' % instance.text)
        self.thread_object.count()
    def build(self):
        self.button = Button(text='Hello World')
        self.button.bind(on_press=self.callback)
        return self.button

thread = Thread()
thread.start()
app = MyApp(thread)
app.run()

现在 - 这段代码用一个按钮打开一个 kivy 应用程序。任务是:按下按钮，一些数据应该出现在线程代码中(它通过“计数”方法完成。

问题是相反的方式——线程代码应该改变按钮的文本。我试过两种方法:

• 直接写:app.button.text = str(self.counter)

• 通过方法“set_button”编写:app.button.text = self.set_button(self.counter)

它们都显示错误“属性错误:‘MyApp’对象没有属性‘按钮’”。

有没有什么方法可以直接交换数据而无需请求，甚至不用在此处使用“thread_object”做指针操作

def __init__ (self, thread_object):

感谢您的帮助。

Answer 1

这可能会解决您所有的问题。这就是我在处理线程和 kivy 语言时喜欢的编码方式。

这是thread.py文件

import threading   
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import NumericProperty

class Thread(BoxLayout):
    counter = NumericProperty(0)

    def Counter_function(self):
        self.counter += 1
        self.ids.lbl.text = "{}".format(self.counter)

    def First_thread(self):
        threading.Thread(target = self.Counter_function).start()
        self.counter += 1
        self.ids.lbl.text = "{}".format(self.counter)

class MyApp(App):
    def build(self):
        self.load_kv('thread.kv')
        return Thread() 

if __name__ == "__main__":
    app = MyApp()
    app.run()

这是thread.kv文件

<Thread>:
    Button:
        text: "use thread"
        on_release: root.First_thread()
    Button:
        text: "Hit me"
        on_release: root.Counter_function()
    Label:
        id: lbl
        text: "Numbers"

现在，您在评论中说您在动态加载 GUI 方面遇到了困难。所以，这里有一个例子。线程.py

import threading   
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import NumericProperty
from kivy.lang.builder import Builder
from kivy.uix.button import Button

Builder.load_string('''
[SideBar@BoxLayout]:
    content: content
    orientation: 'vertical'
    size_hint: .2,1
    BoxLayout:
        orientation: 'vertical'
        # just add a id that can be accessed later on
        id: content

<Root>:
    Button:
        center_x: root.center_x
        text: 'press to add_widgets'
        size_hint: .2, .2
        on_press:
            sb.content.clear_widgets()
            root.load_content(sb.content)
    SideBar:
        id: sb
''')

class Root(BoxLayout):

    def load_content(self, content):
        for but in range(20):
            content.add_widget(Button(text=str(but)))

class MyApp(App):
    def build(self):
        return Root()

if __name__ == "__main__":
    app = MyApp()
    app.run()