python - Kivy 标签文本淡入

Question

我正在尝试使用 kivy 中的动画工具使标签中的一些文本淡入淡出，但我无法让它工作，而且我在互联网上找不到任何帮助。继承人的代码:

.py:

class TestScreen(Screen):
    def animate (self):
        anim = Animate(opacity=1, duration=2)
        anim.start(self.lbl)

.kv

<TestScreen>
    lbl: label
    Label
        id: label
        text: "Welcome"

Answer 1

• 将Animate更改为Animation
• opacity=1表示标签可见，你要的是opacity=0
• 你应该调用animate函数某处

这是完整的工作示例(Python 2.7):

from __future__ import absolute_import, division, print_function, unicode_literals
__metaclass__ = type

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


Builder.load_string(b'''
<RootWidget>:
    lbl: label
    Label
        id: label
        text: "Welcome"
''')


class RootWidget(Screen):
    def __init__(self, **kwargs):
        super(RootWidget, self).__init__(**kwargs)
        self.animate()

    def animate(self):
        anim = Animation(opacity=0, duration=2)
        anim.start(self.lbl)


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


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