Kivy开发疑问：MDSwiper组件为何出现重复标签？

我正在尝试制作一个包含列表项的MDSwiper组件，但始终出现重复标签。我尝试调整多种布局以及SwiperItem的插入方式，未在网上找到类似问题案例。我是Kivy新手，推测是简单问题。

Python代码 #

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.widget import Widget

from kivymd.app import MDApp
from kivymd.uix.list import TwoLineListItem
from kivymd.uix.swiper.swiper import MDSwiperItem

class MySwiperItem(MDSwiperItem):
    pass

class DemoApp(MDApp):
    
    def build(self):
        self.theme_cls.theme_style = "Dark"
        return Builder.load_file('demo.kv')
    
    
    def on_start(self):
        SwiperTest = MySwiperItem()
        SwiperTest.ids.header.text = "test"
        SwiperTest.ids.list.add_widget(
            TwoLineListItem(
                text = "text1",
                secondary_text = "text2"
            )
        )
        self.root.ids.swiper.add_widget(SwiperTest)

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

Kv语言文件 #

<DrawerClickableItem@MDNavigationDrawerItem>
    focus_color: "#e7e4c0"
    text_color: "#4a4939"
    icon_color: "#4a4939"
    ripple_color: "#c5bdd2"
    selected_color: "#0c6c4d"

<DrawerLabelItem@MDNavigationDrawerItem>
    text_color: "#4a4939"
    icon_color: "#4a4939"
    focus_behavior: False
    selected_color: "#4a4939"
    _no_ripple_effect: True

<MySwiperItem>:
    orientation: "vertical"            
    MDLabel:
        id: header
        font_style: "H5"
        size_hint_y: None
        height: self.texture_size[1] + dp(40)
        pos_hint: {"center_x": .5, "top": 1}
        md_bg_color: "grey"

    MDScrollView:
        MDList:
            id: list
                
MDScreen:
    MDNavigationLayout:
        MDScreenManager:
            MDScreen:
                orientation: "vertical"
                MDTopAppBar:
                    id: nav_bar
                    title: "Smart Indoor Watering System"
                    elevation: 4
                    pos_hint: {"top": 1}
                    md_bg_color: "#e7e4c0"
                    specific_text_color: "#4a4939"
                    left_action_items: [["menu", lambda x: nav_drawer.set_state("open")]]
                
                MDSwiper:
                    id: swiper
                    size_hint_y: None
                    height: root.height - nav_bar.height - dp(40)
                    y: root.height - self.height - nav_bar.height - dp(20)

        MDNavigationDrawer:
            id: nav_drawer
            radius: (0, 16, 16, 0)
            MDNavigationDrawerMenu:
                MDNavigationDrawerHeader:
                    title: "Header title"
                    title_color: "#4a4939"
                    text: "Header text"
                    spacing: "4dp"
                    padding: "12dp", 0, 0, "56dp"

                MDNavigationDrawerLabel:
                    text: "Mail"

                DrawerClickableItem:
                    icon: "gmail"
                    right_text: "+99"
                    text_right_color: "#4a4939"
                    text: "Inbox"

                DrawerClickableItem:
                    icon: "send"
                    text: "Outbox"

                MDNavigationDrawerDivider:

                MDNavigationDrawerLabel:
                    text: "Labels"

                DrawerLabelItem:
                    icon: "information-outline"
                    text: "Label"

                DrawerLabelItem:
                    icon: "information-outline"
                    text: "Label"

问题根源在于MDSwiper默认开启了**循环滑动（loop）**模式，它会自动复制首尾的SwiperItem来实现无缝循环效果，这就导致你添加的单个MySwiperItem被重复显示。

只需要在Kv文件的MDSwiper配置里添加loop: False即可解决：

MDSwiper:
    id: swiper
    size_hint_y: None
    height: root.height - nav_bar.height - dp(40)
    y: root.height - self.height - nav_bar.height - dp(20)
    loop: False  # 添加这一行关闭循环模式

另外补充一点：你的MySwiperItem继承自MDSwiperItem，而MDSwiperItem本身并不是BoxLayout，在Kv里直接设置orientation: "vertical"其实是无效的，正确的做法是在MySwiperItem内部嵌套一个BoxLayout来承载子控件：

<MySwiperItem>:
    BoxLayout:
        orientation: "vertical"            
        MDLabel:
            id: header
            font_style: "H5"
            size_hint_y: None
            height: self.texture_size[1] + dp(40)
            pos_hint: {"center_x": .5, "top": 1}
            md_bg_color: "grey"

        MDScrollView:
            MDList:
                id: list

这样能确保布局的层级正确，避免潜在的布局异常问题。

内容的提问来源于stack exchange，提问作者Ash Ketchup