Kivy 屏幕管理器背景颜色

Question

我是 Kivy 的新手，我只是在学习用几个屏幕构建一个简单的东西。我看了 Kivy Crash Course 视频并想出了以下代码：

Python 文件如下所示（main.py）：

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.tabbedpanel import TabbedPanel
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.graphics.context_instructions import Color
from kivy.uix.label import Label
from kivy.lang.builder import Builder


class sivaLoginScreen(Screen):
    def __init__(self,**kwargs):
        super(sivaLoginScreen,self).__init__(**kwargs)
        with self.canvas.before:
            Color(253,253,152,1)

class sivaTabbedScreen(Screen):
    pass


class sivaScreenManager(ScreenManager):
    pass

# Tell Kivy to directly load a file. If this file defines a root widget, it will be returned by the method.
root_widget = Builder.load_file('siva.kv')

class sivaApp(App):
    def build(self):
        # Initialize root widget
                return root_widget


if __name__ == '__main__':
    # Run application
    sivaApp().run()

kv 文件看起来像这样 (siva.kv)：

sivaScreenManager:
    sivaLoginScreen:


<sivaLoginScreen>:
    name: 'login_screen'
    canvas.before:
        Color:
            rgba: 253, 253, 152, 1
        FloatLayout:
            Label:
                id: login_label
                pos: 100, 100
                text: 'S.I.V.A'
                font_size: '20sp'

当我使用python3 main.py 运行应用程序时，我得到一个黑色的空白屏幕。 我期待一个带有标签的彩色屏幕。你能帮我理解我哪里出错了吗？

Answer 1

你只设置了一种颜色，留下了形状，所以我在这一行添加了它。

<sivaLoginScreen>:
    name: 'login_screen'
    canvas.before:
        Color:
            rgba: 253, 253, 152, 1
        Rectangle:
             pos:self.pos 
             size:self.size