kivy PYTHON 中的屏幕管理和加载功能

Question

所以，我正在做这个具有主屏幕和加载屏幕的 GUI。使用加载屏幕，以便用户可以在程序执行功能时看到应用程序的进度。我希望程序更改以执行功能并在执行功能后切换回主屏幕。这是我的代码的一部分，您可以使用它来运行程序。

# 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，按下该按钮应更改屏幕并执行功能，使用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()

你对我做错了什么有什么建议吗？感谢您的帮助！

Answer 1

这是在运行函数后返回主屏幕的一种方法。修改目标函数为：

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() 安排在主线程上运行某些东西（更改 UI 所必需的）。

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

此外，在您的“kv”文件中，以下行：

manager: screen_manager

不需要。该属性会自动添加到每个Screen。