在 kivy Python 中，如何修复布局管理器下拉列表的位置？

Question

In kivy 1.11.1. and python 3. I have in my root class a FloatLayout which contains a Label and a dropdown[text input + RecycleView], but when writing example in my text input, the text input goes up and hide my label, I would like it to be fixes and the dropdown going down. I try to dive into the refresh_view_layout method but without success. Any ideas ?? thanks for you're help :). Here is my python file :

from kivy.app import App
from kivy.uix.textinput import TextInput
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.properties import NumericProperty, ListProperty, BooleanProperty, ObjectProperty, StringProperty
from kivy.uix.recycleview import RecycleView
from kivy.uix.recyclegridlayout import RecycleGridLayout
from kivy.uix.recycleview.views import RecycleDataViewBehavior
from kivy.uix.label import Label
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. '''

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:
            self.parent.parent.parent.children[1].text = self.text # ajout test
            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]))
    
class RV(RecycleView):
    def __init__(self, **kwargs):
        super(RV, self).__init__(**kwargs)

class DropDownWidget(BoxLayout):
    txt_input = ObjectProperty()
    rv = ObjectProperty()
    
class MyTextInput(TextInput):
    txt_input = ObjectProperty()
    flt_list = ObjectProperty()
    word_list = ListProperty()
    #this is the variable storing the number to which the look-up will start
    starting_no = NumericProperty(1)
    suggestion_text = ''

    def __init__(self, **kwargs):
        super(MyTextInput, self).__init__(**kwargs)
        
    def on_text(self, instance, value):
        #find all the occurrence of the word
        self.parent.ids.rv.data = []
        matches = [self.word_list[i] for i in range(len(self.word_list)) if self.word_list[i][:self.starting_no] == value[:self.starting_no]]
        
        #display the data in the recycleview
        display_data = []
        for i in matches:
            display_data.append({'text':i})
        self.parent.ids.rv.data = display_data
        
        #ensure the size is okay
        if len(matches) <= 10:
            self.parent.height = (50 + (len(matches)*20))
        else:
            self.parent.height = 240
        
    def keyboard_on_key_down(self, window, keycode, text, modifiers):
        if self.suggestion_text and keycode[1] == 'tab':
            self.insert_text(self.suggestion_text + ' ')
            return True
        return super(MyTextInput, self).keyboard_on_key_down(window, keycode, text, modifiers)

class Body(FloatLayout):
    def __init__(self, **kwargs):
        super(Body, self).__init__(**kwargs)
        self.add_widget(Label(text = 'This Label is hidden by the dropdown if you type in the text input : "row" or "example" \n and I would like the Text Input to be fixed and not going up when changing text', 
                              pos_hint = {'center_x':.5,'center_y':.6},
                              color = [100,100,100,1]))
        widget_1 = DropDownWidget(pos_hint = {'center_x':.5,'center_y':.5}, \
                               size_hint = (None, None), size = (600, 60))
        widget_1.ids.txt_input.word_list = ['row1', 'row2', 'row3', 'row4', 'row5', 'line1','line2',
                                            'example1','example2','example3','example4','example5','example6','example7','example8','example9','example10']
        self.add_widget(widget_1)
        
class MyApp(App):
    
    def build(self):
        return Body()

if __name__ == "__main__":
    MyApp().run()

and my kv file :

<Body>:
    canvas:
        Color:
            rgba:(1, 1, 1, 1) # white
        Rectangle:
            pos: self.pos
            size: self.size
            
<DropDownWidget>:
    canvas:
        Color:
            rgba:(1, 1, 1, 1)
        Rectangle:
            pos: self.pos
            size: self.size
            
    orientation: 'vertical'
    spacing: 2
    txt_input: txt_input
    rv: rv

    MyTextInput:
        id: txt_input
        size_hint_y: None
        height: 50
        
    RV:
        id: rv
    
<MyTextInput>:
    readonly: False
    multiline: False

<SelectableLabel>:
    # Draw a background to indicate selection
    id: selabel
    color: 0,0,0,1
    canvas.before:
        Color:
            rgba: (0, 0, 1, .5) if self.selected else (1, 1, 1, 1)
        Rectangle:
            pos: self.pos
            size: self.size
<RV>:
    canvas:
        Color:
            rgba: 0,0,0,.2

        Line:
            rectangle: self.x +1 , self.y, self.width - 2, self.height -2
         
    bar_width: 10
    scroll_type:['bars']
    viewclass: 'SelectableLabel'
    SelectableRecycleBoxLayout:
        default_size: None, dp(20)
        default_size_hint: 1, None
        size_hint_y: None
        height: self.minimum_height
        orientation: 'vertical'
        multiselect: False

Answer 1

Actually, when I run your code, I don't see the behavior that you described. But if you add the Label and DropDownWidget to the kv , you can take advantage of the bindings that kv sets up for you. Here is how I might do this (there are lots of options). First, I added a ListProperty to the DropDownWidget to hold the word_list :

class DropDownWidget(BoxLayout):
    txt_input = ObjectProperty()
    rv = ObjectProperty()
    word_list = ListProperty([])

And the Body class can just be:

class Body(FloatLayout):
    pass

Then, the beginning of the kv can be:

<Body>:
    canvas:
        Color:
            rgba:(1, 1, 1, 1) # white
        Rectangle:
            pos: self.pos
            size: self.size
    Label:
        id: lab
        text: 'This Label is hidden by the dropdown if you type in the text input : "row" or "example"'
        pos_hint: {'center_x':.5,'center_y':.6}
        color: [100,100,100,1]
        size_hint: None, None
        size: self.texture_size  # use minimal size for the Label
    DropDownWidget:
        pos_hint: {'center_x':.5}
        y: lab.y - self.height  # position DropDownWidget just below the Label
        size_hint: None, None
        size: 600, 60
        word_list: ['row1', 'row2', 'row3', 'row4', 'row5', 'line1','line2', 'example1','example2','example3','example4','example5','example6','example7','example8','example9','example10']
            
<DropDownWidget>:
    canvas:
        Color:
            rgba:(1, 1, 1, 1)
        Rectangle:
            pos: self.pos
            size: self.size

    orientation: 'vertical'
    spacing: 2
    txt_input: txt_input
    rv: rv

    MyTextInput:
        id: txt_input
        size_hint_y: None
        height: 50
        word_list: root.word_list  # use the word_list from DropDownWidget
        
    RV:
        id: rv

The remainder of the kv is unchanged.