Python Kivy屏幕管理器Wietet范圍

Question

我試圖通過一個單獨的類中的按鈕來控制屏幕管理器，但是我無法弄清楚按鈕on_press:語句上的設置。

Kivy文件：

<HeaderSection>:
    anchor_x: 'center'
    anchor_y: 'top'
    BoxLayout:
        orientation: 'horizontal'
        size_hint: 1, .1
        id: header
        Label:
            text: 'My App'

<ContentSection>:
    anchor_x: 'center'
    anchor_y: 'center'
    ScreenManager:
        size_hint: 1, .8
        Screen:
            name: 'home'
            Label:
                text: 'First screen'
        Screen:
            name: 'second'
            Label:
                text: 'Second screen'
        Screen:
            name: 'third'
            Label:
                text: 'Third screen'

<FooterSection>:
    anchor_x: 'center'
    anchor_y: 'bottom'
    BoxLayout:
        orientation: 'horizontal'
        size_hint: 1, .1
        Button:
            text: 'first'
            on_press: root.ContentSection.manager.current = 'first'
        Button:
            text: 'second'
            on_press: root.current = 'second'
        Button:
            text: 'third'
            on_press: ContentSection.ScreenManager.current = 'third'

Python檔案：

from kivy.app import App
from kivy.lang import Builder
Builder.load_file('MyApp.kv')
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.uix.image import Image

# Declare sections
class HeaderSection(AnchorLayout):
    pass

class ContentSection(AnchorLayout):
    def build(self):

        # Create the screen manager
        sm = ScreenManager()
        sm.add_widget(FirstScreen(name='first'))
        sm.add_widget(SecondScreen(name='second'))
        sm.add_widget(ThirdScreen(name='third'))
        return sm

class FooterSection(AnchorLayout):
    pass


class MyAppApp(App):
    def build(self):

        #Create the sections

        fl = FloatLayout()
        hs = HeaderSection()
        cs = ContentSection()
        fs = FooterSection()

        fl.add_widget(hs)
        fl.add_widget(cs)
        fl.add_widget(fs)
        return fl


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

我嘗試了各種方法：

on_press: root.parent.ContentSection.ScreenManager.current = 'home'
on_press: root.parent.ContentSection.manager.current = 'home'
on_press: root.ContentSection.manager.current = 'home'

我覺得這是一個范圍界定問題，錯誤提示如下：

AttributeError: 'FooterSection' object has no attribute 'ContentSection'

因此我的應用程序具有以下層次結構：

FloatLayout
    HeaderSection
    ContentSection
        ScreenManager
             FirstScreen
             SecondScreen
             ThirdScreen
    FooterSection
        Button for FirstScreen
        Button for SecondScreen
        Button for ThirdScreen

因此，我需要遍歷FloatLayout的一個級別，然后深入到ContentSection以訪問屏幕管理器。

Answer 1

導航小部件樹對我來說是很痛苦的，並且AFAIK不能以您想要的方式遍歷小部件樹。

但是，您可以簡化小部件樹，確保所有內容共享相同的根，並使用ID。

這是我的操作方法（我還將所有內容都移到了kv語言中）：

千伏

FloatLayout:
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'top'
        Label:
            size_hint: 1, .1
            text: 'My App'
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'center'
        ScreenManager:
            id: manager
            size_hint: 1, .8
            Screen:
                name: 'first'
                Label:
                    text: 'First screen'
            Screen:
                name: 'second'
                Label:
                    text: 'Second screen'
            Screen:
                name: 'third'
                Label:
                    text: 'Third screen'
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'bottom'
        BoxLayout:
            orientation: 'horizontal'
            size_hint: 1, .1
            Button:
                text: 'first'
                on_press: root.ids.manager.current = 'first'
            Button:
                text: 'second'
                on_press: root.ids.manager.current = 'second'
            Button:
                text: 'third'
                on_press: root.ids.manager.current = 'third'

蟒蛇

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.label import Label
from kivy.uix.image import Image



class MyAppApp(App):
    def build(self):
        return Builder.load_file('MyApp.kv')


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