通过另一个屏幕上的按钮按压更改Kivy按钮小部件属性

Question

在我的应用程序中，有一个游戏界面（GameScreen），里面有一个叫做ClueButton1的按钮，上面有一些文字。用户点击这个按钮后，会进入一个提示界面（ClueScreen），这个界面上有4个按钮，每个按钮代表一个答案选项。当用户在提示界面上点击正确的答案按钮（ClueAnswerButton1）时，我想要改变游戏界面上ClueButton1的背景。

我已经尝试给ClueButton1设置一个ID，然后在一个叫做check_choice()的函数中使用这个ID，像这样：GameScreen.cluebutton1id.background_normal = ...，但是出现了错误：

AttributeError: 'kivy.properties.ObjectProperty' object has no attribute 'background_normal'

main.py的代码在这里：

class GameScreen(Screen):
    ...


class ClueScreen(Screen):
    ...

    def check_choice(self):

        if self.choice0.state == 'down':
            if self.choice0.text == self.correct:
                self.message.text = "[color=006600]Correct! Click back to game and keep" \
                        "playing![/color]"
                self.choice0.background_disabled_down = 'atlas://img/myatlas/green_button5'
                self.choice0.disabled = True
                self.choice1.disabled = True
                self.choice2.disabled = True
                self.choice3.disabled = True
                return
            else:
                self.message.text = "Try again"
                self.choice0.background_disabled_down = 'atlas://img/myatlas/red_button5'
                self.choice0.disabled = True      
    ...

而.kv的代码在这里：

<GameScreen>:
    GeneralFloatLayout:
    GeneralAnchorLayout:
        GeneralBoxLayout:
            GameGridLayout:
                ClueButton1:
                    text: root.question
                    on_press: root.manager.current = 'clue_screen';

<ClueScreen>:
    message: message
    choice0: choice0
    choice1: choice1
    choice2: choice2
    choice3: choice3

    ClueBoxLayout:
        ClueLabel:
            text: "[color=0046C3]" + "Put label Here" + "[/color]"
        ClueMessage:
            id: message
        ClueAnswerButton1:
            id: choice0
            on_press: root.check_choice()
        ClueAnswerButton1:
            id: choice1
            on_press: root.check_choice()
        ClueAnswerButton1:
            id: choice2
            on_press: root.check_choice()
        ClueAnswerButton1:
            id: choice3
            on_press: root.check_choice()
        ClueGridLayout:
            ReturnButton:
                text: 'Back to game'
                on_press: root.manager.current = 'game_home'

Answer 1

你正在尝试给类对象设置属性，而不是给它的实例设置。你可以通过 ScreenManager 来获取另一个屏幕的实例。假设你是从根部小部件运行这个代码的（也就是 root.check_choice()）：

self.manager.get_screen('game_home').cluebutton1id.background_normal = 'path/to/image.png'