如何解决Kivy:尝试从MDDropDownMenu捕获选项时出错
我是kivy的新手,正在尝试添加一个DropDown列表并尝试捕获在变量中单击的选项,但是这样做似乎会遇到很多错误。 这是我得到的错误:
这是我的main.py文件:
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.properties import NumericProperty,ReferenceListProperty
from kivy.vector import Vector
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager,Screen
from kivymd.uix.menu import MDDropdownMenu
from kivymd.uix.behaviors import RectangularElevationBehavior
from kivymd.uix.boxlayout import MDBoxLayout
from kivy.config import Config
from kivymd.app import MDApp
from kivy.lang import Builder
Config.set('graphics','resizable',False)
class CustomToolbar(ThemableBehavior,RectangularElevationBehavior,MDBoxLayout,):
def __init__(self,**kwargs):
super().__init__(**kwargs)
self.md_bg_color = self.theme_cls.primary_color
class MainApp(MDApp):
def __init__(self,**kwargs):
self.VARIABLE = ""
super().__init__(**kwargs)
self.screen = Builder.load_file("main.kv")
menu_items = [{"viewclass": "MDMenuItem","text": "Label1"},{"viewclass":
"MDMenuItem","text": "Label2"}]
self.menu = MDDropdownMenu(
caller=self.screen.ids.drop_item,items=self.menu_items,position="center",width_mult=3,)
self.menu.bind(on_release=self.menu_callback)
def change_variable(self,value):
print("\nvalue=",value)
self.VARIABLE = value
print("\tself.VARIABLE=",self.VARIABLE)
def menu_callback(self,instance_menu,instance_menu_item):
instance_menu.dismiss()
def build(self):
return self.screen
MainApp().run()
这是我的.kv文件:
<ScreenManagement>:
id: scr_mngr
MainAppScreen:
name: 'main'
id: main
<CustomToolbar>:
#some widgets here
BoxLayout:
#some widgets here
<MDMenuItem>:
on_release: app.root.change_variable(self.text)
Screen:
MDRaisedButton:
id: drop_item
text: "W"
pos_hint: {"center_x": .9,"center_y": .68}
on_release: app.menu.open()
我在这里停留了2天,请帮忙。在此先感谢:D
解决方法
我认为,如果您使用build()
方法构建GUI并使用Clock.schedule_once()
来设置菜单,您的代码将可以正常工作,如下所示:
class MainApp(MDApp):
def change_variable(self,value):
print("\nvalue=",value)
self.VARIABLE = value
print("\tself.VARIABLE=",self.VARIABLE)
def menu_callback(self,instance_menu,instance_menu_item):
instance_menu.dismiss()
def build(self):
self.VARIABLE = ""
self.screen = Builder.load_file("main.kv")
Clock.schedule_once(self.setup_menu)
return self.screen
def setup_menu(self,dt):
menu_items = [{"viewclass": "MDMenuItem","text": "Label1"},{"viewclass":
"MDMenuItem","text": "Label2"}]
self.menu = MDDropdownMenu(
caller=self.screen.ids.drop_item,items=menu_items,position="center",width_mult=3
)
self.menu.bind(on_release=self.menu_callback)
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