停止 RecycleView 对项目进行排序

Question

在我的程序的一部分中，我有一个使用 RecycleBoxLayout 的 RecycleView，它们一起拥有一堆 DownloadItem 实例，这些实例本身继承自 MDCard强>。

recycleview 的问题在于它以一种荒谬的方式对项目进行排序。我希望项目按照添加的顺序显示，而不是按回收视图排序。

示例： RecycleView sorting items

我的 Python 文件：

from kivy.lang import Builder
from kivy.properties import StringProperty, ColorProperty
from kivy.animation import Animation
from kivymd.uix.card import MDCard
from kivymd.app import MDApp


class DownloadItem(MDCard):
    path = StringProperty()
    url_type = StringProperty("file")

    def __init__(self, **kwargs):
        self.paused = False
        self.fill_animation = None
        super(DownloadItem, self).__init__(**kwargs)

    def pause_resume_download(self):
        if not self.paused:
            self.ids.pause_resume_button.icon = "play"
            if self.fill_animation is not None:
                self.fill_animation.cancel(self.ids.progress_bar)
            self.paused = True
        else:
            self.ids.pause_resume_button.icon = "pause"
            self.fill_animation = Animation(value=100, duration=4)
            self.fill_animation.bind(on_complete=lambda *args: Animation(color=self.theme_cls.accent_color,
                                                                            duration=Example.color_duration)
                                        .start(self.ids.progress_bar))
            self.fill_animation.start(self.ids.progress_bar)
            self.paused = False
        Animation(color=app.pause_color if self.paused else self.theme_cls.primary_color,
                    duration=Example.color_duration).start(self.ids.progress_bar)

    def cancel_download(self):
        if self.fill_animation is not None:
            self.fill_animation.cancel(self.ids.progress_bar)
        Animation(color=app.fail_color,
                duration=Example.color_duration).start(self.ids.progress_bar)

class Example(MDApp):
    fail_color = ColorProperty([255 / 255, 99 / 255, 71 / 255, 1.0])
    pause_color = ColorProperty([240 / 255, 163 / 255, 10 / 255, 1.0])
    success_color = ColorProperty(None)
    color_duration = .15


    def __init__(self, **kwargs):
        global app
        super(Example, self).__init__(**kwargs)
        self.kv = Builder.load_file("design.kv")
        self.path = "C:/Users/Family/Downloads/"
        app = self

    def build(self):
        self.theme_cls.theme_style = "Dark"
        return self.kv

    def add_item(self):
        self.kv.ids.downloads_list.data.append({"path": self.path + '/' if self.path[-1] != '/' else self.path,
                                            "url_type": "file"})


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

我的 KV 文件：

#:kivy 2.0.0
<TooltipMDLabel@MDLabel+MDTooltip>
<DownloadItem>:
    orientation: "vertical"
    padding: 10
    spacing: 10
    size_hint_y: None
    height: 100
    elevation: 20
    border_radius: 5
    radius: [5]
    MDBoxLayout:
        adaptive_height: True
        spacing: 5
        MDIcon:
            icon: root.url_type
            size_hint_x: None
            width: self.texture_size[0]
        TooltipMDLabel:
            text: root.path if len(root.path) <= 30 else root.path[:31] + " ..."
            tooltip_text: f"Path: {root.path}\nType: {root.url_type}"
            tooltip_bg_color: app.theme_cls.bg_darkest
            tooltip_text_color: app.theme_cls.opposite_bg_darkest
            size_hint_y: None
            height: self.texture_size[1]
    MDSeparator:
    MDBoxLayout:
        spacing: 10
        MDProgressBar:
            id: progress_bar
            min: 0
            max: 100
            value: 50
            color: app.theme_cls.primary_color
        MDIconButton:
            id: pause_resume_button
            icon: "pause"
            pos_hint: {"center_x": .5, "center_y": .5}
            on_release: root.pause_resume_download()
        MDIconButton:
            icon: "close"
            pos_hint: {"center_x": .5, "center_y": .5}
            on_release: root.cancel_download()
BoxLayout:
    orientation: "vertical"
    spacing: 10
    RecycleView:
        id: downloads_list
        viewclass: "DownloadItem"
        RecycleBoxLayout:
            default_size: None, 100
            default_size_hint: 1, None
            size_hint_y: None
            height: self.minimum_height
            orientation: "vertical"
            padding: 15
            spacing: 15
    MDRaisedButton:
        text: "Add"
        size_hint_x: 1
        on_release: app.add_item()

Answer 1

RecycleView 不对项目进行排序。它们按照它们在data 中出现的顺序显示。您看到的是“回收”行为，您的 DownloadItems 被回收，看起来它们已排序。尝试在每个 DownloadItem 的显示中添加一个计数，您会更清楚地看到发生了什么。