Python/Kivy动态行垂直滚动条异常问题求助

Hey there! Let's fix that annoying extra spacing issue in your Kivy ScrollView. I've gone through your code and spotted a few key problems causing those gaps. Here's how to get your dynamic rows to stack neatly without extra space:

1. Fix the ScrollView Structure #

Your current ScrollView wraps the Rows component in an unnecessary horizontal BoxLayout with a fixed height, which forces extra empty space. Instead, we'll make Rows the direct child of the ScrollView and let its height adapt to content:

Modified demo.kv ScrollView section:

ScrollView:
    Rows:
        id: rows
        size_hint_y: None
        height: self.minimum_height  # Auto-adjust height to fit all rows

2. Clean Up the Row Layout #

The top: 200 property on your first button was causing unwanted vertical offset, and we need to ensure each Row has a fixed, compact height:

Modified demo.kv rule:

<Row>:
    size_hint_y: None
    height: 40  # Match the GridLayout's row height to avoid empty space
    GridLayout:
        cols: 2
        row_force_default: True
        row_default_height: 40
        spacing: 0  # Remove gap between buttons
        padding: 0  # Remove inner padding
        Button:
            text: root.button_text
            size_hint_x: None
            width: 100  # Fixed width for consistency
        Button:
            text: 'World 1'
            size_hint_x: 1  # Fill remaining space

3. Eliminate Row-to-Row Spacing #

By default, BoxLayout adds small spacing between widgets. We'll disable this in the Rows class to make rows stack tightly:

Modified demo.py Rows class:

class Rows(BoxLayout):
    orientation = "vertical"
    row_count = 0
    def __init__(self, **kwargs):
        super(Rows, self).__init__(**kwargs)
        self.spacing = 0  # Remove gap between rows
        self.add_row()
    def add_row(self):
        self.row_count += 1
        self.add_widget(Row(button_text=str(self.row_count)))

Full Modified Code #

demo.py

import kivy
from kivy.uix.screenmanager import Screen
from kivy.app import App
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import StringProperty

Window.clearcolor = (0.5, 0.5, 0.5, 1)
Window.size = (500, 400)

class user(Screen):
    def add_more(self):
        self.ids.rows.add_row()

class Row(BoxLayout):
    button_text = StringProperty("")

class Rows(BoxLayout):
    orientation = "vertical"
    row_count = 0
    def __init__(self, **kwargs):
        super(Rows, self).__init__(**kwargs)
        self.spacing = 0
        self.add_row()
    def add_row(self):
        self.row_count += 1
        self.add_widget(Row(button_text=str(self.row_count)))

class Test(App):
    def build(self):
        self.root = Builder.load_file('demo.kv')
        return self.root

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

demo.kv

<Button@Button>:
    font_size: 15
    font_name: 'Verdana'
<Label@Label>:
    font_size: 15
    font_name: 'Verdana'
<TextInput@TextInput>:
    font_size: 15
    font_name: 'Verdana'
    padding_y: 3
<Row>:
    size_hint_y: None
    height: 40
    GridLayout:
        cols: 2
        row_force_default: True
        row_default_height: 40
        spacing: 0
        padding: 0
        Button:
            text: root.button_text
            size_hint_x: None
            width: 100
        Button:
            text: 'World 1'
            size_hint_x: 1
user:
    BoxLayout:
        orientation: "vertical"
        padding : 20, 5
        BoxLayout:
            orientation: "horizontal"
            spacing: 10, 10
            size: 450, 40
            size_hint: None, None
            Label:
                size_hint_x: .2
                text: "Test 1"
                text_size: self.size
                valign: 'bottom'
                halign: 'center'
            Label:
                size_hint_x: .8
                text: "Test 2"
                text_size: self.size
                valign: 'bottom'
                halign: 'center'
        ScrollView:
            Rows:
                id: rows
                size_hint_y: None
                height: self.minimum_height
        BoxLayout:
            orientation: "horizontal"
            size_hint_x: .2
            size_hint_y: .2
            Button:
                text: "+Add More"
                on_press: root.add_more()
        BoxLayout:
            orientation: "horizontal"
            padding : 10, 5
            spacing: 10, 10
            size_hint: .5, .35
            pos_hint: {'x': .25, 'y':.25}
            Button:
                text: 'Ok'
            Button:
                text: 'Cancel'

With these changes, your rows will stack tightly without extra spacing, and the ScrollView will correctly scroll when you add enough rows to exceed its visible area.

内容的提问来源于stack exchange，提问作者Veragi