無法獲取按鈕在基維工作

Question

我想讓這個按鈕工作，並不能找出什麼是錯的。 我真的可以使用一些幫助，因爲我是新的基維。當我運行代碼時，彈出按鈕，但是當你點擊它時，什麼都不會發生。爲什麼它不工作？

順便說一句，我知道一旦你到了下一頁，什麼都不會發生，但現在我只想到那裏。

這裏是完整的代碼和kv文件。

import kivy 
kivy.require('1.9.1') 

from kivy.app import App 
from kivy.uix.widget import Widget 
from kivy.uix.gridlayout import GridLayout 
from kivy.uix.textinput import TextInput 
from kivy.uix.label import Label 
from kivy.uix.button import Button 

class StartScreen(Widget): 
    def __init__(self, **kwargs): 
     super(StartScreen,self).__init__(**kwargs) 
     self.StartGame = Button(text="Start Game") 
     self.StartGame.bind(on_press=self.on_press) 
     self.add_widget(self.StartGame) 

def on_press(self,instance): 

    return LoginScreen() 

class LoginScreen(GridLayout): 
    def __init__(self, **kwargs): 
     super(LoginScreen,self).__init__(**kwargs) 
     self.cols = 2 



class MyApp(App): 
def build(self): 
    return StartScreen() 



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

KV文件

#:kivy 1.9.1 



<StartScreen>: 
    Label: 
    font_size: 120 
    center_x: root.width/2 
    top: root.top - 100 
    text: "Starfire" 



<LoginScreen> 
    f_username: username 
    f_password: password 
    GridLayout: 
    rows: 2 
    padding: 5 
    spacing: 5 
    Label: 
     text: "User Name:" 
    TextInput: 
     id: username 
    Label: 
     text: 'Password' 
    TextInput: 
     id: password 
     password: True 

Answer 1

返回從on_press方法的插件不會使它的根對象。

def on_press(self,instance): 
    return LoginScreen() # will not do anything like you expected* 

你需要看看彈出和ScreenManager：

https://kivy.org/docs/api-kivy.uix.screenmanager.html

https://kivy.org/docs/api-kivy.uix.popup.html?highlight=popup#module-kivy.uix.popup

選擇什麼套房你。

Answer 2

這是一個工作示例：

from kivy.app import App 
from kivy.uix.screenmanager import ScreenManager, Screen, SlideTransition 


screen_manager = ScreenManager(transition=SlideTransition()) 


class RootScreen(Screen): 

    settings_button = Button(text='Settings') 
    settings_button.bind(on_press=screen_manager.switch_to(SettingsScreen()) 


class SettingsScreen(Screen): 
    pass 


class WifiApp(App): 

    def build(self): 
     screen_manager.add_widget(RootScreen(name='main')) 
     screen_manager.add_widget(SettingsScreen(name='settings')) 
     return screen_manager 


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