滚动在 kivy 按钮布局中不起作用

Question

<Builder_Screen>
    ScrollView:
        do_scroll_y:True
        FloatLayout:
            Button:
                text:"Heading"
                size_hint_x: .25
                size_hint_y: .25
                text_size: self.size
                halign:"center"
                valign:"center"
                pos: 0,10
            Button:
                text:"Paragraph"
                halign:"center"
                valign:"center"
                size_hint_x: .25
                size_hint_y: .25
                pos: (0,self.height)

I have some buttons like these with positions like pos: 0, self.height 2, self.height 3 etc. But, the scroll layout does not work as intended. Can you help me regarding that....

Answer 1

According to the documentation , regarding the child of a ScrollView :

By default, the size_hint is (1, 1), so the content size will fit your ScrollView exactly (you will have nothing to scroll). You must deactivate at least one of the size_hint instructions (x or y) of the child to enable scrolling.

So, you probably need to set size_hint_y: None for your FloatLayout . That will cause further problems, because you have size_hint_y values for your Buttons . You can set the heights of your Buttons and eliminate the size_hint_y values. Another approach would be to use a GridLayout :

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import Screen

kv = '''
<Builder_Screen>
    ScrollView:
        do_scroll_y:True
        effect_cls: 'ScrollEffect'
        GridLayout:
            cols: 2
            size_hint_y: None
            height: self.minimum_height
            padding: 5
            spacing: 5
            Button:
                text:"Heading1"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
            Button:
                text:"Paragraph1"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
            Button:
                text:"Heading2"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
            Button:
                text:"Paragraph2"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
            Button:
                text:"Heading3"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
            Button:
                text:"Paragraph3"
                halign:"center"
                valign:"center"
                size_hint_y: None
                height: 48
'''

class Builder_Screen(Screen):
    pass

class TestApp(App):
    def build(self):
        Builder.load_string(kv)
        return Builder_Screen()

TestApp().run()

Note that every Button has an explicit height . That is required if you use height: self.minimum_height for their container.