[英]Kivy kv file behaves different from Builder.load_string
我正在嘗試在Kivy上實現2屏幕應用程序。 我已經按照他們的示例進行了操作,如果在main.py中調用了“ Builder.load_string”,該示例將起作用。
但是,如果我注釋掉並創建一個.kv文件,我只會得到一個空白屏幕。 我究竟做錯了什么?
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
#Builder.load_string("""
#<MainScreen>:
#BoxLayout:
#Button:
#text: 'Goto settings'
#on_press: root.manager.current = 'settings'
#Button:
#text: 'Quit'
#<SettingsScreen>:
#BoxLayout:
#Button:
#text: 'My settings button'
#Button:
#text: 'Back to menu'
#on_press: root.manager.current = 'main'
#""")
# Declare both screens
class MainScreen(Screen):
pass
class SettingsScreen(Screen):
pass
# Create the screen manager
sm = ScreenManager()
sm.add_widget(MainScreen(name='main'))
sm.add_widget(SettingsScreen(name='settings'))
class TestApp(App):
def build(self):
return sm
if __name__ == '__main__':
TestApp().run()
這是testapp.kv
<MainScreen>:
BoxLayout:
Button:
text: 'Goto settings'
on_press: root.manager.current = 'settings'
Button:
text: 'Quit'
<SettingsScreen>:
BoxLayout:
Button:
text: 'My settings button'
Button:
text: 'Back to menu'
on_press: root.manager.current = 'main'
kv文件在調用run時但在build方法之前由App類加載。 您在此之前實例化小部件(在App類聲明上方),因此kv規則尚未加載並且不適用。 要修復它,請將實例化移動到build方法。
編輯:更改:
# Create the screen manager
sm = ScreenManager()
sm.add_widget(MainScreen(name='main'))
sm.add_widget(SettingsScreen(name='settings'))
class TestApp(App):
def build(self):
return sm
至
class TestApp(App):
def build(self):
# Create the screen manager
sm = ScreenManager()
sm.add_widget(MainScreen(name='main'))
sm.add_widget(SettingsScreen(name='settings'))
return sm
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