kivy PYTHON中的屏幕管理和加载函数

Question

所以，我正在做这个GUI，它有主屏幕和一个加载屏幕。加载屏幕的使用使得用户可以在程序执行函数时看到应用程序的进度。我希望程序更改为执行函数，并在函数执行后切换回主屏幕。下面是我的代码的一部分，你可以用它在你那端运行这个程序。

# Imports
import kivy
from kivy.app import App    # Imports functions to build the app
from kivy.core.window import Window
from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import ObjectProperty, StringProperty
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.uix.image import Image
import threading
import time

kivy.require('1.10.1')


def function1():
    time.sleep(5)
    print("Done")


def function2():
    time.sleep(5)
    print("Done 2")


class MainScreen(Screen, FloatLayout):  # Main Screen Class that holds every method in the Start Screen

    auction_name = " "
    default = "Select an auction"
    selected_auction = StringProperty('Select an auction')
    x_value = 450
    y_value = 500

    def change_label(self, change):  # Changes the text that shows what auction is selected

        strtst = "Selected: " + change

        if self.selected_auction == self.default and (change == "Copart" or change == "IAAI"):
            self.selected_auction = "Selected: " + change
            self.selected_auction = "Selected: " + change
        elif self.selected_auction == strtst or self.selected_auction == "Main":
            self.selected_auction = self.default
        elif change != self.selected_auction:
            if self.selected_auction == "Selected: Copart and IAAI":
                self.selected_auction = "Selected: " + change
            else:
                if change == "None":
                    self.selected_auction == "TO START, PLEASE SELECT AN AUCTION"
                else:
                    self.selected_auction = "Selected: Copart and IAAI"

    def change_screen(self):
        self.manager.current = "Loading Screen"

    t2 = threading.Thread(target=function1)
    t3 = threading.Thread(target=function2)

    def start_process(self):  # Used to start the web scraping
        if self.selected_auction == 'Selected: Copart':
            self.manager.current = "Loading Screen"
            self.t3.start()
            self.manager.current = "Results Screen"
            self.selected_auction = "Select an auction"
        elif self.selected_auction == 'Selected: IAAI':
            self.manager.current = "Loading Screen"
            self.t2.start()
            self.selected_auction = "Select an auction"
        elif self.selected_auction == 'Selected: Copart and IAAI':
            self.manager.current = "Loading Screen"
            self.t2.start()
            self.t3.start()
        else:
            self.change_label("None")


class LoadingScreen(Screen):

    def cancel(self):
        box = BoxLayout(orientation='vertical')
        padding = Label(text= "If you say yes all progress will be lost!")
        buttons = BoxLayout()
        warning = Image(source="Data/warning.png")
        yes_button = Button(text= "Yes, do cancel it.", on_release=lambda x:self.back(),
                        on_press=lambda *args: pop.dismiss(), size=(250, 120), background_color=(300, 0.5, 0, .7))
        no_button = Button(text="No, don't cancel.", on_press=lambda *args: pop.dismiss(), size=(250, 120),
                       background_color=(.25, 150, .04, 0.5))
        box.add_widget(warning)
        box.add_widget(padding)
        buttons.add_widget(yes_button)
        buttons.add_widget(no_button)
        box.add_widget(buttons)

        pop = Popup(title="Do you wish to cancel?", content=box, size_hint=(None, None), size= (800, 500))
        pop.open()


class Manager(ScreenManager):

    main_screen = ObjectProperty(None)
    loading_screen = ObjectProperty(None)


class MainApp(App):

    choice = ""
    source = StringProperty(None)

    def build(self):
        m = Manager(transition=NoTransition())
        return m


if __name__ == "__main__":
    Window.clearcolor = (.46875, .46875, .4765, 1)
    Window.size = (850, 1000)
    MainApp().run()

在主屏幕中，有一个按钮，当按下该按钮时，应更改屏幕并执行该功能，该功能由start_process()处理。这是我的main.kv文件：

#: import NoTransition kivy.uix.screenmanager.NoTransition
#: import ProgressBar kivy.uix.progressbar
#: import Widget kivy.uix.widget
#: import ListAdapter kivy.adapters.listadapter.ListAdapter
#: import ListItemButton kivy.uix.listview.ListItemButton
#: import Popup kivy.uix.popup
#: import main gui_test

<Manager>:
    id: screen_manager

    main_screen: mainS
    loading_screen: loadingS

    MainScreen:
        id: mainS
        name: "Main Screen"
        manager: screen_manager

    LoadingScreen:
        id: loadingS
        name: "Loading Screen"
        manager: screen_manager


<MainScreen>
    FloatLayout:

        # Start Button
    Button:
        on_release: root.start_process()
        text: "Start"
        font_size: 16
        size_hint: 0.6, 0.12
        pos: root.center_x - (self.width/2), root.y + self.height
        background_normal: ''
        background_down:
        background_color: .25, .75, .04, 1
        font_size: 50

    # COPART BUTTON
    Button:
        size_hint: 0.279, 0.3
        pos: root.x + (0.3 * self.width), root.top - self.height - 160
        on_press: root.change_label("Copart")

    # IAAI BUTTON
    Button:
        id: IAAI_Button
        size_hint: 0.27, 0.3
        pos: root.x + (1.7 * self.width) + 300, root.top - self.height - 160
        on_press: root.change_label("IAAI")

    Label:
        text: root.selected_auction
        font_size: 50

<LoadingScreen>
    FloatLayout:

        Button:
            text: "Cancel"
            size_hint:0.30, 0.1
            pos: root.center_x - (self.width/2), 100
            background_color: 300, 0.5, 0, .4
            on_press: root.cancel()

你对我哪里做错了有什么建议吗？谢谢你的帮助!

Answer 1

以下是运行函数后返回主屏幕的一种方法。将目标函数修改为：

def function1():
    time.sleep(5)
    print("Done")
    Clock.schedule_once(App.get_running_app().show_main_screen)


def function2():
    time.sleep(5)
    print("Done 2")
    Clock.schedule_once(App.get_running_app().show_main_screen)

Clock.schedule_once()安排一些东西在主线程上运行(对UI的更改需要)。

并将MainApp修改为：

class MainApp(App):

    choice = ""
    source = StringProperty(None)

    def build(self):
        self.m = Manager(transition=NoTransition())  # save a reference to `Manager`
        return self.m

    def show_main_screen(self, dt):
        self.m.current = "Main Screen"  # use the saved reference to change the current screen

另外，在你的'kv‘文件中，有几行：

manager: screen_manager

是不需要的。该属性会自动添加到每个Screen中。