Kivy/Python 如何将一个对象传递给另一个类？

Question

我正在尝试使用 Kivy/KivMD 和 python3 为一个学校项目编写一个网球应用程序，但我遇到了一些我无法解决的问题。

(1) 在我的 main.py 文件中，使用 create_match 方法，我成功地创建了 2 个对象，当按下按钮时，我想将它们用于下一个屏幕。问题是我不知道如何将这 2 个实例/对象传递到我想要的 GameScreen 类中。为了让这件事发挥作用，我只是在 GameScreen 类中手动添加了 2 个其他玩家对象，但这不是我想要的。我该怎么做？

(2) 在 main.kv 文件中，我想修改另一个文件中的 InputScreen 类（input_screen.kv，就像我对 game_screen.kv 所做的那样）。我怎么能在不破坏一切的情况下做到这一点？因为 InputScreen 包含一个按钮（CreateButton），它依赖于 main.kv 文件中的 ScreenManager，所以我有点卡住了......

这是我的两个主要问题，我知道阅读起来有点长，但如果有人能向我解释如何解决这个问题，我将不胜感激。我没有向你展示 Player 类，因为它没有问题，它只是根据网球规则计算每个玩家的分数。

P.S 我知道我应该显示最少的代码，但是 GUI 很难...

ma​​in.py

from kivymd.app import MDApp
from kivy.lang import Builder
from kivy.uix.screenmanager import Screen
from kivymd.uix.button import MDRectangleFlatButton

from App.score import Player


class HomeScreen(Screen):
    pass


class InputScreen(Screen):
    pass


class CreateButton(MDRectangleFlatButton, Player):

    def create_match(self):
        player1 = Player(self.player1_name)
        player2 = Player(self.player2_name)


class GameScreen(Screen, Player):

    player1 = Player('Player1')  # I want that the name is given by the user
    player2 = Player('Player2')


class TennisApp(MDApp):

    def build(self):
        self.theme_cls.primary_palette = "Teal"
        return Builder.load_file("main.kv")


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

ma​​in.kv

#:include game_screen.kv

ScreenManager:
    id: manager

    HomeScreen:
        name: "home_screen"
        id: home_screen
        MDRectangleFlatButton:
            text: "Create a match"
            pos_hint: {'center_x': .5, 'center_y': .5}
            on_release: manager.current = "input_screen"

    InputScreen:
        name : "input_screen"
        id: input_screen
        MDBoxLayout:
            size_hint: .6, .6
            pos_hint: {'center_x': .5, 'center_y': .8}
            spacing: dp(20)
            orientation: 'vertical'
            MDTextField:
                id: entry1
                hint_text: "First player name"
                helper_text_mode: "on_focus"
            MDTextField:
                id: entry2
                hint_text: "Second player name"
                helper_text_mode: "on_focus"
        CreateButton:
            text: "Create a match"
            pos_hint: {'center_x': .5, 'center_y': .2}
            on_release: manager.current = "game_screen"
            on_release: self.create_match()
            player1_name: entry1.text
            player2_name: entry2.text

    GameScreen:

game_screen.kv

<GameScreen>:
    name: "game_screen"
    id: second_screen
    MDBoxLayout:
        orientation: 'vertical'
        pos_hint: {'top': 1}
        adaptive_height: True
        MDBoxLayout:
            orientation: 'horizontal'
            pos_hint: {'center_y': .9}
            adaptive_height: True
            md_bg_color: app.theme_cls.primary_color
            MDLabel:
                text: "Players"
                halign: 'center'
            MDLabel:
                text: "Points"
                halign: 'center'
            MDLabel:
                text: "Games"
                halign: 'center'
            MDLabel:
                text: "Sets"
                halign: 'center'

        MDBoxLayout:
            orientation: 'horizontal'
            pos_hint: {'center_y': .8}
            adaptive_height: True

            MDLabel:
                text: root.player1.get_name()
                halign: 'center'
            MDLabel:
                id: points_label1
                text: '0'
                halign: 'center'
            MDLabel:
                id: games_label1
                text: "0"
                halign: 'center'
            MDLabel:
                id: sets_label1
                text: "0"
                halign: 'center'
        MDBoxLayout:
            adaptive_height: True
            orientation: 'horizontal'
            pos_hint: {'center_y': .7}

            MDLabel:
                text: root.player2.get_name()
                halign: 'center'
            MDLabel:
                id: points_label2
                text: "0"
                halign: 'center'
            MDLabel:
                id: games_label2
                text: "0"
                halign: 'center'
            MDLabel:
                id: sets_label2
                text: "0"
                halign: 'center'

    MDRectangleFlatButton:  # I know this repetition is ugly, I will change it later
        text: "{} wins the point".format(root.player1.get_name())
        pos_hint: {'center_x': .3, 'center_y':.2}
        on_press: root.player1.points_win(root.player2)
        on_release: points_label1.text = root.player1.get_points_amount()
        on_release: points_label2.text = root.player2.get_points_amount()
        on_release: games_label2.text = root.player2.get_games_amount()
        on_release: games_label1.text = root.player1.get_games_amount()
        on_release: sets_label2.text = root.player2.get_sets_amount()
        on_release: sets_label1.text = root.player1.get_sets_amount()
    MDRectangleFlatButton:
        text: "{} wins the point".format(root.player2.get_name())
        pos_hint: {'center_x': .7, 'center_y':.2}
        on_press: root.player2.points_win(root.player1)
        on_release: points_label2.text = root.player2.get_points_amount()
        on_release: points_label1.text = root.player1.get_points_amount()
        on_release: games_label2.text = root.player2.get_games_amount()
        on_release: games_label1.text = root.player1.get_games_amount()
        on_release: sets_label2.text = root.player2.get_sets_amount()
        on_release: sets_label1.text = root.player1.get_sets_amount()

Answer 1

首先，您不需要将类传递给另一个类以便在那里使用它。类就像存储方法或属性等基本功能的蓝图。为了使结构充满生命，您必须创建一个类的实例，其中可以将变量传递给类以使其更加独特或满足您的需求。您正在做的是使 GameScreen 类继承 Player 类。这会将 Player 类的方法和属性添加到 Gamescreen 类中，这并不是必需的。这本身就是一个巨大的话题，那里有很多很好的解释，如果你想了解更多，那就开始搜索吧。

回到您的问题。您想知道如何将内容传递到课程中。我会给你一个简短的例子，我基于一个 Player 类创建了两个玩家，并将它们传递给 Arena 类，这是比赛发生的屏幕。

当你定义一个类时，你也可以定义一个 init 方法。此方法采用您在创建实例时传递给类的所有属性。在这种情况下，我将 player_list 传递给 arena 类，这是您想要做的。在您的班级中，您可以对传递的对象做一些事情。我决定将属性命名为 player，然后将它们添加到 Playground。我希望它对您的项目有所帮助。继续前进，我相信你会成功的。

示例：

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.core.window import Window
from kivy.uix.screenmanager import Screen, ScreenManager

Window.size = 600, 400

class Player(Button):
    def __init__(self, name, **kwargs):
        super(Player, self).__init__(**kwargs)
        self.name = name
        self.text = self.name
        self.size_hint = None, None
        self.size = Window.width, Window.height*0.1
        self.on_press = self.hit_the_ball

    def hit_the_ball(self):
        self.parent.parent.field.text = self.text + " played his turn!"

class Arena(Screen):
    def __init__(self, players, **kwargs):
        super(Arena, self).__init__(**kwargs)

        self.playground = BoxLayout(orientation="vertical", size_hint=(None, None), size=Window.size)

        self.field = Label(text="", size_hint=(None, None), size=(Window.width, Window.height*0.8))

        self.playground.add_widget(players[0])
        self.playground.add_widget(self.field)
        self.playground.add_widget(players[1])

        self.add_widget(self.playground)


class MyApp(App):

    def build(self):
        player1 = Player(name="Player1")
        player2 = Player(name="Player2")

        players_list = (player1, player2)

        arena = Arena(players_list)
        WMan  = ScreenManager()
        WMan.add_widget(arena)

        return WMan


MyApp().run()