KivyMD // Python如何创建一个加载对话框弹出窗口，该对话框在后台运行代码的同时显示一个旋转的轮子

如何解决KivyMD // Python如何创建一个加载对话框弹出窗口，该对话框在后台运行代码的同时显示一个旋转的轮子

我正在使用current.futures，目前看来我的代码可以按需运行两个函数，但是直到两个函数都完成时才会显示第一个弹出窗口（问题在于，第二个函数会先关闭第一个对话框，然后打开第二个对话框。

这是我完整的.py代码：

from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivymd.app import MDApp
from kivymd.uix.dialog import MDDialog
import concurrent.futures

KV = '''
<Content>
    orientation: "vertical"
    spacing: -40
    
    MDSpinner:
        size_hint: None,None
        size: dp(46),dp(46)
        pos_hint: {'center_x': 0.1}
        active: True
    MDLabel:
        text: "Processing..."
        pos_hint: {'center_x': .7}

FloatLayout:

    MDFlatButton:
        text: "ALERT DIALOG"
        pos_hint: {'center_x': .5,'center_y': .5}
        on_release: app.start()
'''


class Content(BoxLayout):
    pass

class Example(MDApp):
    dialog = None

    def build(self):
        return Builder.load_string(KV)

    def start(self):
        with concurrent.futures.ThreadPoolExecutor() as executor:
            f1 = executor.submit(self.pop_up1())
            f2 = executor.submit(self.test())


    def pop_up1(self):
        '''Displays a pop_up with a spinning wheel'''
        if not self.dialog:
            self.dialog = MDDialog(
                size_hint=(.45,None),auto_dismiss=True,type="custom",content_cls=Content(),)
            self.dialog.open()

    def test(self):
        '''Counts to 1000000 and then it closes pop_up1 and opens pop_up2'''
        for number in range(1000000):
            print(number)
        self.dismiss()
        self.pop_up2()

    def pop_up2(self):
        if not self.dialog:
            self.dialog = MDDialog(
                title="Done",size_hint=(.6,text="Done",)
        self.dialog.open()

    def dismiss(self,*args):
        self.dialog.dismiss()


Example().run()

解决方法

您的代码有几个问题。首先，当您使用构造时：

    with concurrent.futures.ThreadPoolExecutor() as executor:
        f1 = executor.submit(self.pop_up1())
        f2 = executor.submit(self.test())

有一个隐式executor.sutdown()调用，它等待提交的任务完成。请参见documentation。由于您在主线程上使用了此构造，因此所有GUI更新都将被阻止，直到所有提交的任务完成为止。因此，通常不应该在kivy应用的主线程上使用该构造。

第二个问题是MDDialog的创建和显示应该在主线程上完成，因此向pop_up1()提交类似executor的方法可能会出现问题。

第三个问题是您尝试重用MDDialog条件的if not self.dialog:。您仍然无法重用MDDialog。

因此，考虑到所有这些因素，这是代码的修改版本，可以满足我的要求：

from kivy.clock import Clock,mainthread
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivymd.app import MDApp
from kivymd.uix.dialog import MDDialog
import concurrent.futures

KV = '''
<Content>
    orientation: "vertical"
    spacing: -40
    
    MDSpinner:
        size_hint: None,None
        size: dp(46),dp(46)
        pos_hint: {'center_x': 0.1}
        active: True
    MDLabel:
        text: "Processing..."
        pos_hint: {'center_x': .7}

FloatLayout:

    MDFlatButton:
        text: "ALERT DIALOG"
        pos_hint: {'center_x': .5,'center_y': .5}
        on_release: app.start()
'''


class Content(BoxLayout):
    pass

class Example(MDApp):
    dialog = None

    def build(self):
        return Builder.load_string(KV)

    def start(self):
        # this must be done on the main thread
        self.pop_up1()

        executor = concurrent.futures.ThreadPoolExecutor()
        # f1 = executor.submit(self.pop_up1)  # this must be done on the main thread
        f2 = executor.submit(self.test)


    def pop_up1(self):
        '''Displays a pop_up with a spinning wheel'''
        self.dialog = MDDialog(
            size_hint=(.45,None),auto_dismiss=True,type="custom",content_cls=Content(),)
        self.dialog.open()

    def test(self):
        '''Counts to 1000000 and then it closes pop_up1 and opens pop_up2'''
        for number in range(100000):
            print(number)
        self.dismiss()
        Clock.schedule_once( self.pop_up2)  # pop_up2() must be done on the main thread

    def pop_up2(self,*args):
        self.dialog = MDDialog(
            title="Done",size_hint=(.6,text="Done",)
        self.dialog.open()

    @mainthread
    def dismiss(self,*args):
        self.dialog.dismiss()


Example().run()