英文:
How to use, how to go back to the previous screen from left_action_items of MDTopAppBar in KivyMD?
问题
抱歉，我无法执行代码，但你的问题似乎是在Kivy应用程序中，点击登录页面（Login_screen）中的左箭头（arrow-left）时返回到名为 'Screen_principal' 的第一个屏幕的问题。你所提供的代码中的 lambda 表达式似乎设置了当前屏幕为 'Screen_principal'，但是这并没有按预期工作。
可能的问题可能与 lambda 函数中对 'screen_manager' 的引用有关，因为在代码中并没有明确定义 'screen_manager'。在 lambda 函数中，尝试使用 sm.current = 'Screen_principal' 来直接引用 ScreenManager（屏幕管理器）来切换到第一个屏幕，看看能否解决问题。
英文:
I created an app with a NavigationDrawer and everything work correctely, but the problem is to return to the first screen. I want to go back to the first screen (the Screen with name: 'Screen_*principal') when I click in the arrow-left in the MDTopAppBar in Login_*screen but nothing that I did worked.
KV file:
#: import RiseInTransition kivy.uix.screenmanager.RiseInTransition
#: import SlideTransition kivy.uix.screenmanager.SlideTransition
<CustomizeScreen@MDBoxLayout>
orientation: 'vertical'
text: ''
padding: 100
MDLabel:
text: root.text
halign: 'center'
pos_hint: {'center_x': .5}
MDFillRoundFlatButton:
text: 'Regresar'
pos_hint: {'center_x': .5}
on_release:
app.root.current = 'screen_principal'
app.root.transition = SlideTransition(direction= 'left' )
<DrawerClickableItem@MDNavigationDrawerItem>
focus_color: "#e7e4c0"
text_color: "#4a4939"
icon_color: "#4a4939"
ripple_color: "#c5bdd2"
selected_color: "#0c6c4d"
<DrawerLabelItem@MDNavigationDrawerItem>
text_color: "#4a4939"
icon_color: "#4a4939"
focus_behavior: False
selected_color: "#4a4939"
_no_ripple_effect: True
<Screen_principal>:
MDNavigationLayout:
MDScreen:
MDTopAppBar:
title: "Navigation Drawer"
elevation: 4
pos_hint: {"top": 1}
md_bg_color: "#e7e4c0"
specific_text_color: "#4a4939"
left_action_items: [["menu", lambda x: nav_drawer.set_state("open")]]
MDNavigationDrawer:
id: nav_drawer
radius: (0, 16, 16, 0)
MDNavigationDrawerMenu:
MDNavigationDrawerHeader:
title: "LOCATE YOU"
source: "icono.png"
spacing: "4dp"
padding: "12dp", 0, 0, "56dp"
DrawerClickableItem:
icon: "login"
text_right_color: "#4a4939"
text: "Iniciar Sesion"
on_press:
root.manager.current = "Login_screen"
DrawerClickableItem:
icon: "new-box"
text: "Registrarse"
text_right_color: "#4a4939"
on_press:
root.current = "screen_register"
DrawerClickableItem:
icon: "information-outline"
text: "Informacion"
text_right_color: "#4a4939"
on_press:
root.current = "scr1"
DrawerClickableItem:
icon: "microsoft-teams"
text: "Equipo"
text_right_color: "#4a4939"
on_press:
root.current = "scr1"
<Login_screen>:
MDBoxLayout:
orientation: 'vertical'
MDTopAppBar:
title: "Login"
md_bg_color: "#e7e4c0"
left_action_items: [["arrow-left", lambda *args : setattr(screen_manager, "current", "Screen_principal")]]
MDBoxLayout:
orientation: 'vertical'
size_hint_y: 0.3
Image:
source: 'usuario.png'
pos_hint: {'center_x': 0.5}
MDLabel:
text: 'Iniciar Sesion'
halign: 'center'
color: '#FF5A1E'
font_size: '35dp'
bold: True
pos_hint: {'center_y': .5}
MDBoxLayout:
orientation: 'vertical'
size_hint_y: 0.3
spacing: '12dp'
MDTextField:
id: user
hint_text: "Nombre de usuario"
icon_right: "account"
font_size: '25dp'
icon_right_color: '#FF5A1E'
pos_hint: {'center_x': 0.5}
MDTextField:
id: password
password:True
icon_right: "key-variant"
font_size: '25dp'
icon_right_color: '#FF5A1E'
hint_text: "Contrasena"
pos_hint: {'center_x': 0.5}
MDLabel:
id: signal_login
text: ''
halign: 'center'
color: '#FF5A1E'
font_size: '15dp'
MDBoxLayout:
orientation: 'vertical'
size_hint_y:0.4
spacing: '25dp'
MDFillRoundFlatButton:
id: bt_ingresar
text: 'Ingresar'
pos_hint: {'center_x':0.5}
on_release:
x = app.login_data()
root.current = 'open_screen' if x == True else None
MDFillRoundFlatButton:
md_bg_color: 1,1,1,1
Python file:
from kivymd.app import MDApp
from kivy.uix.screenmanager import ScreenManager
from kivy.lang import Builder
from kivy.uix.gridlayout import GridLayout
from kivy.core.window import Window
import requests
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.properties import BooleanProperty, ObjectProperty
Builder.load_file('diseno.kv')
class Screen_principal(Screen):
pass
class Login_screen(Screen):
pass
class TestApp(MDApp):
def build(self):
# Create the screen manager
sm = ScreenManager()
sm.add_widget(Screen_principal(name='Screen_principal'))
sm.add_widget(Login_screen(name='Login_screen'))
return sm
if __name__ == '__main__':
TestApp().run()
I tried a lot of things but nothing work, if someone could fix it I would be very grateful
答案1
得分: 0
在你的 kv 文件中，进行如下更改：
将：
left_action_items: [["arrow-left", lambda *args: setattr(screen_manager, "current", "Screen_principal")]]
更改为：
left_action_items: [["arrow-left", lambda *args: setattr(root.manager, "current", "Screen_principal")]]
这个更改通过引用 root.manager 来访问 ScreenManager，而在这个上下文中，root 是 Login_screen。
英文:
In your kv, change:
left_action_items: [["arrow-left", lambda *args : setattr(screen_manager, "current", "Screen_principal")]]
to:
left_action_items: [["arrow-left", lambda *args : setattr(root.manager, "current", "Screen_principal")]]
This change accesses the ScreenManager by referencing root.manager, and the root in that context is the Login_screen.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论