Kivy不使用操作栏上的按钮更改屏幕

Question

我引用的代码来自ikolim的答案：Why is my Kivy Actionbar gone?

这是我的python代码：

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager,Screen
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.lang import Builder
from kivy.core.window import Window

Window.clearcolor = (1,1,1,1)

Builder.load_file("designdawkalamomarunong.kv")


class Menu(BoxLayout):
    manager = ObjectProperty(None)

class Add(Screen):
    pass

class Help(Screen):
    pass

class Credits(Screen):
    pass

class Manager(ScreenManager):
    addScreen = ObjectProperty(None)
    helpScreen = ObjectProperty(None)
    creditsScreen = ObjectProperty(None)

class AntsApp(App):

    def build(self):
        return Menu()


if __name__ == '__main__':
    AntsApp().run()

这是猕猴桃代码：

<Menu>:
    manager: screen_manager
    orientation: "vertical"
    ActionBar:
        size_hint_y: 0.1
        ActionView:
            ActionPrevious:
            ActionButton:
                text: "Add"
                on_release: app.root.current = "add"
            ActionButton:
                text:"Help"
                on_release: app.root.current = "help"
            ActionButton:
                text: "Credits"
                on_release: app.root.current = "credits"
    Manager:
        id: screen_manager

<Add>:
    text: "hello boi"

<Help>:
    text: "hello world"

<Credits>:
    text: "goodbye world lol"

<Manager>:
    id: screen_manager
    addScreen: addScreen
    helpScreen: helpScreen
     creditsScreen: creditsScreen

    Add:
        id: addScreen
        name: 'add'
        manager: screen_manager

    Help:
        id: helpScreen
        name: 'help'
        manager: screen_manager

    Credits:
        id: creditsScreen
        name: 'credits'
        manager: screen_manager

当我运行它时，这是输出：

当我单击操作栏上的按钮时，它不会返回任何内容。我还应该添加其他内容吗？预先谢谢你：）

编辑： 尝试这样做：

<Add>:
    Button:
        text: "hello boi"

它有效，但是当我尝试这样做时：

<Add>:
    Label:
        text: "hello boi"

它不起作用。我在这里想念什么？

Answer 1

问题

kv文件

1. 用app.root.current替换所有出现的root.manager.current，因为root是BoxLayout小部件，而不是ScreenManager小部件。
2. 每个屏幕在Label之前都缺少text小部件。
3. 在“屏幕”的每个类规则中将“按钮”小部件实例化为子级时，该文本都是可见的。但是，当将Button小部件替换为Label时，该文本将不可见。原因是因为Label的默认颜色文本是白色（rgba=1, 1, 1, 1），而BoxLayout的颜色也是白色。因此，您将无法看到文本。如果使用“标签”小部件，请添加color: (0, 0, 0, 1) # black color text。

示例

kv文件

#:kivy 1.11.0

<Menu>:
    manager: screen_manager
    orientation: "vertical"
    ActionBar:
        size_hint_y: 0.1
        ActionView:
            ActionPrevious:
            ActionButton:
                text: "Add"
                on_release: root.manager.current = "add"
            ActionButton:
                text:"Help"
                on_release: root.manager.current = "help"
            ActionButton:
                text: "Credits"
                on_release: root.manager.current = "credits"
    Manager:
        id: screen_manager

<Add>:
    Label:
        text: "hello boi"
        color: 0, 0, 0, 1   # black color text

<Help>:
    Label:
        text: "hello world"
        color: 0, 0, 0, 1   # black color text

<Credits>:
    Label:
        text: "goodbye world lol"
        color: 0, 0, 0, 1   # black color text

<Manager>:
    addScreen: addScreen
    helpScreen: helpScreen
    creditsScreen: creditsScreen

    Add:
        id: addScreen
        name: 'add'

    Help:
        id: helpScreen
        name: 'help'

    Credits:
        id: creditsScreen
        name: 'credits'

输出