Kivy中的RecycleView模块

Question

新成员，第一个职位。我会尽量具体和清楚。下面的代码来自kivy关于RecycleView module 的网页。我想使用这段代码，但是，我不希望使用KV lang和Builder，而是用纯python3编写代码。我试图将RecycleBoxLayout类添加为小部件，但完全失败了，结果只是一个黑色窗口。只有添加了“viewclass”才起作用。很明显，这里有些东西我不明白或者遗漏了。我还附上了我重写代码的尝试。在

任何帮助都将不胜感激。提前谢谢你。在

原始代码：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.recycleview import RecycleView

Builder.load_string('''
<RV>:
    viewclass: 'Label'
    RecycleBoxLayout:
    default_size: None, dp(56)
    default_size_hint: 1, None
    size_hint_y: None
    height: self.minimum_height
    orientation: 'vertical'
''')

class RV(RecycleView):
    def __init__(self, **kwargs):
        super(RV, self).__init__(**kwargs)
        self.data = [{'text': str(x)} for x in range(100)]

class TestApp(App):
    def build(self):
        return RV()


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

我的尝试失败：

^{pr2}$

Answer 1

我也在寻找同样的东西，我不喜欢kv-lang，而且还没有确信它比用代码做任何事情都好。在

来自https://kivy.org/docs/api-kivy.uix.recycleview.html#kivy.uix.recycleview.RecycleView的示例将按如下方式创建。在

from kivy.app import App
from kivy.graphics import Color, Rectangle
from kivy.uix.recycleview import RecycleView
from kivy.uix.recycleview.views import RecycleDataViewBehavior
from kivy.uix.label import Label
from kivy.properties import BooleanProperty
from kivy.uix.recycleboxlayout import RecycleBoxLayout
from kivy.uix.behaviors import FocusBehavior
from kivy.uix.recycleview.layout import LayoutSelectionBehavior

class SelectableRecycleBoxLayout(FocusBehavior, LayoutSelectionBehavior,
                                 RecycleBoxLayout):
    ''' Adds selection and focus behaviour to the view. '''
    def __init__(self, **kw):
        super().__init__(**kw, default_size=(0, 28), default_size_hint=(1, None), size_hint_y=None,
                         touch_multiselect=True, multiselect=True, orientation='vertical')

        self.bind(minimum_height=self._min)

    def _min(self, inst, val):
        self.height = val

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

    def __init__(self, **kw):
        super().__init__(**kw)
        self.canvas.before.clear()
        with self.canvas.before:
            if self.selected:
                Color(.0, 0.9, .1, .3)
            else:
                Color(0, 0, 0, 1)
            self.rect = Rectangle(size=self.size, pos=self.pos)
        self.bind(size=self._update_rect, pos=self._update_rect)

    def _update_rect(self, inst, value):
        self.rect.pos = inst.pos
        self.rect.size = inst.size

    def refresh_view_attrs(self, rv, index, data):
        ''' Catch and handle the view changes '''
        self.index = index
        return super().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]))
        self.canvas.before.clear()
        with self.canvas.before:
            if self.selected:
                Color(.0, 0.9, .1, .3)
            else:
                Color(0, 0, 0, 1)
            self.rect = Rectangle(size=self.size, pos=self.pos)


class RV(RecycleView):
    def __init__(self, **kwargs):
        super(RV, self).__init__(**kwargs)
        self.add_widget(SelectableRecycleBoxLayout())
        self.viewclass = 'SelectableLabel'
        self.data = [{'text': str(x)} for x in range(100)]


class TestApp(App):
    def build(self):
        return RV()

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

KV等级的顺序很重要。不知道什么东西需要放在哪里，但是自我数据需要在添加小部件后进行修改。在

Answer 2

我不是Kivy的专家，但我强烈建议您尽量使用kv lang。它只不过是一个简洁的python，它将使您的代码更加简洁。
如果您阅读RecycleBoxLayout的文档，它是高度实验性的，那么您应该使用有效的方法。

也就是说，你的代码看起来不错，但是有几个问题。

1）更换 self.viewclass = Label与{}和
2）您尚未在python代码中为您的height、size和{}参数。在