python - 按下按钮时选择下一个/上一个 Kivy RecycleView 行

Question

我正在开发一个 Kivy 媒体播放器并使用 RecycleView 来显示我的媒体列表。

我试图实现的是将现有行选择从按钮选择更改为 RecycleView 列表中的下一行或上一行。

我可以看到LayoutSelectionBehavior类看起来像合适的方法，但我正在努力寻找使用它的方法。

下面是根据 kivy.uix.recycleview 修改的 RecycleView 的简化示例示例

# -*- coding: utf-8 -*-
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.recycleview import RecycleView
from kivy.uix.recycleview.views import RecycleDataViewBehavior
from kivy.uix.label import Label
from kivy.properties import BooleanProperty, StringProperty, NumericProperty 
from kivy.uix.recycleboxlayout import RecycleBoxLayout
from kivy.uix.behaviors import FocusBehavior
from kivy.uix.recycleview.layout import LayoutSelectionBehavior


kv = """

<SelectableLabel>:
    # Draw a background to indicate selection
    canvas.before:
        Color:
            rgba: (0.4, 0.4, 0.4, 1) if self.selected else (0.5, 0.5, 0.5, 1)
        Rectangle:
            pos: self.pos
            size: self.size

<KivyPlayer>:
    canvas:
        Color:
            rgba: 0.3, 0.3, 0.3, 1
        Rectangle:
            size: self.size
            pos: self.pos
    orientation: 'vertical'
    BoxLayout:  
        orientation: 'vertical'
        BoxLayout:
            Button:
                id: next_track
                text: "Next Track"
            Button:
                id: previous_track
                text: "Previous Track"
        BoxLayout:
            RecycleView:
                id: media_list
                viewclass: 'SelectableLabel'
                scroll_type: ['bars', 'content']
                scroll_wheel_distance: dp(114)
                bar_width: dp(10)
                SelectableRecycleBoxLayout:
                    default_size: None, dp(56)
                    default_size_hint: 1, None
                    size_hint_y: None
                    height: self.minimum_height
                    orientation: 'vertical'
                    # multiselect: True
                    touch_multiselect: True
                    spacing: dp(2)


"""

Builder.load_string(kv)

class SelectableRecycleBoxLayout(FocusBehavior, LayoutSelectionBehavior,
                                 RecycleBoxLayout):
    ''' Adds selection and focus behaviour to the view. '''


class SelectableLabel(RecycleDataViewBehavior, Label):
    ''' Add selection support to the Label '''
    index = None
    selected = BooleanProperty(False)
    selectable = BooleanProperty(True)

    def refresh_view_attrs(self, rv, index, data):
        ''' Catch and handle the view changes '''
        self.index = index
        return super(SelectableLabel, self).refresh_view_attrs(
            rv, index, data)

    def on_touch_down(self, touch):
        ''' Add selection on touch down '''
        if super(SelectableLabel, self).on_touch_down(touch):
            return True
        if self.collide_point(*touch.pos) and self.selectable:
            return self.parent.select_with_touch(self.index, touch)

    def apply_selection(self, rv, index, is_selected):
        ''' Respond to the selection of items in the view. '''
        self.selected = is_selected
        if is_selected:
            print("selection changed to {0}".format(rv.data[index]))
        else:
            print("selection removed for {0}".format(rv.data[index]))


class KivyPlayer(BoxLayout):
    ''' Main Kivy class for creating the initial BoxLayout '''

    def __init__(self, **kwargs):
        super(KivyPlayer, self).__init__(**kwargs)

       # Set media_list data
        self.ids.media_list.data = [{'text': str(x)} for x in range(100)]


class KivyApp(App):
    def build(self):
        return KivyPlayer()


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

如有任何建议或帮助，我们将不胜感激。

Answer 1

我想如果我们添加一个 get_next/previous_node 就好了，也许在将来。不管怎样，这就是你要做的。

修改按钮:

BoxLayout:
    Button:
        id: next_track
        text: "Next Track"
        on_release: controller.select_next()
    Button:
        id: previous_track
        text: "Previous Track"
        on_release: controller.select_previous()

并编辑kv中的SelectableRecycleBoxLayout，如下所示:

SelectableRecycleBoxLayout:
    id: controller
    key_selection: 'selectable'

最后，SelectableRecycleBoxLayout 应该是这样的:

class SelectableRecycleBoxLayout(FocusBehavior, LayoutSelectionBehavior,
                                 RecycleBoxLayout):
    ''' Adds selection and focus behaviour to the view. '''

    def get_nodes(self):
        nodes = self.get_selectable_nodes()
        if self.nodes_order_reversed:
            nodes = nodes[::-1]
        if not nodes:
            return None, None

        selected = self.selected_nodes
        if not selected:  # nothing selected, select the first
            self.select_node(nodes[0])
            return None, None

        if len(nodes) == 1:  # the only selectable node is selected already
            return None, None

        last = nodes.index(selected[-1])
        self.clear_selection()
        return last, nodes

    def select_next(self):
        last, nodes = self.get_nodes()
        if not nodes:
            return

        if last == len(nodes) - 1:
            self.select_node(nodes[0])
        else:
            self.select_node(nodes[last + 1])

    def select_previous(self):
        last, nodes = self.get_nodes()
        if not nodes:
            return

        if not last:
            self.select_node(nodes[-1])
        else:
            self.select_node(nodes[last - 1])

您还需要在数据中指定可选择的内容，如下所示:self.ids.media_list.data = [{'text': str(x), 'selectable': True} for x in range (100)](请注意，您忘记了示例中的 ids 部分)。