选择下一个/上一个Kivy RecycleView按钮上的行按

Question

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

我试图实现的是将现有的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，但我正在努力寻找一种方法来使用它。

下面是从kivy.uix.recycleview例子

# -*- 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() 

任何建议或协助，将不胜感激修改RecycleView的简化示例。

Answer 1

我想如果我们添加一个get_next/previous_node，或许将来会更好。无论如何，这就是你所做的。

修改按钮，以便：

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() 

而在KV编辑SelectableRecycleBoxLayout如下：

SelectableRecycleBoxLayout: 
    id: controller 
    key_selection: 'selectable' 

最后，这里的SelectableRecycleBoxLayout应该是什么样子：

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]) 

也需要在数据中指定应该如何选择：self.ids.media_list.data = [{'text': str(x), 'selectable': True} for x in range(100)]（请注意，在您的示例中您忘记了ids部分）。