Kivy旋转木马内切换屏幕的按钮

Question

我正在尝试创建一个按钮来更改/返回到轮播中的上一个屏幕。

我习惯于在 .kv 文件中管理我的按钮，但轮播不可能，如果我这样做，只会在最后一张幻灯片上创建一个按钮。

我需要按钮出现在每张幻灯片上，所以我这样做了，效果很好，只是我不知道如何将按钮链接到 ScreenManager。

我的python文件的一部分：

class MyCarousel(Carousel):
    def __init__(self, **kwargs):
        super(MyCarousel, self).__init__(**kwargs)
        self.direction = "right"
        log_file = open_logfile()
        for i in range(log_file['len']):
            src = log_file['path'][(log_file['len']) - (i + 1)] + "_file_resize.jpg"
            button = Button(size_hint=(.15,.25),\
                    pos_hint={'center_x': .05, 'y': .65},\
                    background_color=(1, 1, 1, 1),\
                    border=(0, 0, 0, 0),\
                    on_release=***???***
                    background_normal="Interface_PNG/bouton/Bouton_retour.png",\
                    background_down="Interface_PNG/bouton/Bouton_retour_fonce.png")
            image = AsyncImage(source=src, allow_stretch=True, size_hint=(1, 1), pos_hint={'center_x': .5, 'y': 0})
            layout = FloatLayout()
            layout.add_widget(image)
            layout.add_widget(button)
            self.add_widget(layout)
        self.loop = True

class StartScreen(Screen):
    pass

class GalleryPhoto(Screen):
    def call_next(self, dt):
        self.manager.current = "start"

class RootScreen(ScreenManager):
    pass

class PhotoboothApp(App):
    def build(self):
        sm = RootScreen()
        self.start_screen = StartScreen()
        self.gallery_photo = GalleryPhoto()
        sm.add_widget(self.start_screen)
        sm.add_widget(self.gallery_photo)
        return sm

我的 kv 文件的一部分：

<StartScreen>:
    name: "start"
    canvas.before:
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Image:
            source: "Interface_PNG/Page_1.png"
            allow_stretch : True
            keep_ratio : False
            size_hint: 1, 1
        Button:
            background_color: 0, 0, 0, 0
            on_release: root.manager.current = "gallery"

<GalleryPhoto>:
    name: "gallery"
    FloatLayout:
        Image:
            source: "Interface_PNG/Page_8.png"
            allow_stretch: True
            keep_ratio: False
            size_hint: 1, 1
        MyCarousel:

我想在 python 中做类似的事情：

 MyCarousel:
     Button:
        on_release: root.manager.current = "start"

我认为这很简单，但我有点迷茫......欢迎任何帮助。

Answer 1

• 在class MyCarousel() 中实现change_screen() 方法
• 将按钮绑定到change_screen()方法
• 使用App.get_running_app().root 访问实例化的根ScreenManager 对象。

片段 - py

class MyCarousel(Carousel):
    def __init__(self, **kwargs):
        ...
            button = Button(size_hint=(.15,.25), pos_hint={'center_x': .05, 'y': .65},
                            background_color=(1, 1, 1, 1), border=(0, 0, 0, 0),
                            on_release=self.change_screen(),

            ...

    def change_screen(self, instance):
        App.get_running_app().root.current = 'start'

示例

main.py

​​>

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.carousel import Carousel
from kivy.uix.image import AsyncImage
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder


class MyCarousel(Carousel):
    def __init__(self, **kwargs):
        super(MyCarousel, self).__init__(**kwargs)
        self.direction = "right"

        for i in range(10):
            src = "http://placehold.it/480x270.png&text=slide-%d&.png" % i
            image = AsyncImage(source=src, allow_stretch=True, size_hint=(1, 1), pos_hint={'center_x': .5, 'y': 0})
            button = Button(size_hint=(.15, .25), pos_hint={'center_x': .05, 'y': .65},
                            text='StartScreen',
                            on_release=self.change_screen)

            layout = FloatLayout()
            layout.add_widget(image)
            layout.add_widget(button)
            self.add_widget(layout)
        self.loop = True

    def change_screen(self, instance):
        App.get_running_app().root.current = 'start'


class StartScreen(Screen):
    pass


class GalleryPhoto(Screen):
    pass


class RootScreen(ScreenManager):
    pass


Builder.load_file("main.kv")


class TestApp(App):
    title = "Photobooth"

    def build(self):
        return RootScreen()


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

main.kv

<RootScreen>:
    StartScreen:
    GalleryPhoto:


<StartScreen>:
    name: "start"
    canvas.before:
        Rectangle:
            pos: self.pos
            size: self.size
    FloatLayout:
        Image:
            source: "kivy-logo.png"
            allow_stretch : True
            keep_ratio : True   # False
            size_hint: 1, 1
        Button:
            background_color: 0, 0, 0, 0
            on_release: root.manager.current = "gallery"

<GalleryPhoto>:
    name: "gallery"
    FloatLayout:
        Image:
            source: "kivymd_logo.png"
            allow_stretch: True
            keep_ratio: False
            size_hint: 1, 1
        MyCarousel:

输出