如何删除 main.kv 文件中的小部件？

Question

我环顾四周，但未能找到解决问题的方法。在我的 main.kv 文件中，我有不断显示的“home_screen”和“settings_screen”小部件按钮（无论用户在哪个屏幕上）。

问题是，当用户未登录并在“login_screen”时，这两个按钮在那里并保持活动状态，允许用户简单地访问“[=43=” ]”或“settings_screen”，然后再登录。

我想做的是，只要用户在登录屏幕上，就从屏幕上删除这两个小部件。我觉得自己走在正确的轨道上，但可能没有正确引用小部件。没有出现任何错误，它只是什么都不做。

我已经尝试运行在 change_screen() 函数中使用我的“if”语句和它的所有必要组件，并且还尝试赋予它自己的功能（如我的示例所示）。我已经用 while 语句尝试过它（除非我把它放在一个线程中，否则它似乎会阻塞应用程序）。我尝试了几种不同的方法来引用小部件和编写 remove_widget() 行的方法。

我提供了我能提供的最基本的功能示例，以便有人可以自己尝试运行。请帮忙。

main.py

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

class HomeScreen(Screen):
    pass
class LoginScreen(Screen):
    pass

GUI = Builder.load_file("main.kv")
class TestApp(App):
    def build(self):
        return GUI

    def change_screen(self, screen_name):
        screen_manager = self.root.ids['screen_manager']
        screen_manager.current = screen_name
        self.home_setting_widgets(screen_name)

    def home_setting_widgets(self, screen_name):
        home_button = self.root.ids["home_button"]
        settings_button = self.root.ids["settings_button"]
        if screen_name == "login_screen":                  # if i'm on the login screen
            self.root.remove_widget(home_button)           # remove widgets
            self.root.remove_widget(settings_button)

TestApp().run()

main.kv

#:include kv/loginscreen.kv
#:include kv/homescreen.kv
GridLayout:
    cols: 1
    FloatLayout:
        GridLayout:
            rows: 1
            pos_hint: {"top": 1, "left": 1}
            size_hint: 1, .05
            Button:
                id: home_button
                text: "home"
            Button:
                id: settings_button
                text: "settings"
        ScreenManager:
            size_hint: 1, .95
            pos_hint: {"top": .95, "left": 1}
            id: screen_manager
            LoginScreen:
                name: "login_screen"
                id: login_screen
            HomeScreen:
                name: "home_screen"
                id: home_screen

loginscreen.kv

<LoginScreen>:
    FloatLayout:
        TextInput:
            size_hint: .7, .08
            pos_hint: {"top": .8, "center_x": .5}
        TextInput:
            size_hint: .7, .08
            pos_hint: {"top": .7, "center_x": .5}
        Button:
            text: "login"
            pos_hint:  {"top": .2, "center_x": .5}
            size_hint: .5, .08
            on_release:
                app.change_screen("home_screen")

homescreen.kv

<HomeScreen>:
    Button:
        text: "back"
        pos_hint:  {"top": .2, "center_x": .5}
        size_hint: .5, .08
        on_release:
            app.change_screen("login_screen")

这是一个基本布局，但仍可重现。谢谢:)

Answer 1

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

class HomeScreen(Screen):
    pass
class LoginScreen(Screen):
    pass

GUI = Builder.load_file("main.kv")
class TestApp(App):
    def build(self):
        return GUI

    def change_screen(self, screen_name):
        screen_manager = self.root.ids['screen_manager']
        screen_manager.current = screen_name
        self.home_setting_widgets(screen_name)

    def home_setting_widgets(self, screen_name):
        home_button = self.root.ids["home_button"]
        settings_button = self.root.ids["settings_button"]
        grid_layout = self.root.children[0].children[1]
        print("I remove from my widget, not from my root", grid_layout)
        if screen_name == "login_screen":  # if i'm on the login screen
            grid_layout.remove_widget(home_button)  # remove widgets
            grid_layout.remove_widget(settings_button)


TestApp().run()

我同意应该有错误message/warning。

如何删除 main.kv 文件中的小部件？

How can I remove widgets in my main.kv file?

python

function

widget

while-loop

kivy