Python 中 Kivy 小部件之间的交互 [英] Interaction between Kivy widgets in Python

问题描述

我正在使用 kivy 做一个项目，但我的复选框有问题.起初，我正在尝试使用 python 编码之类的程序(我知道它不干净，但我了解更多)而且我有一个带有此编码的第一个屏幕:

I'm doing a proyect using kivy but i have a problem with the checkboxes. At first I'm trying to do the program like python coding (I know it is'nt clean, but I understand more) And i have a first screen with this coding:

from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.gridlayout import GridLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.textinput import TextInput
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
from kivy.uix.checkbox import CheckBox




class MainScreen(GridLayout):
    def __init__(self,**kwargs):
        e=[]
        super(MainScreen, self).__init__(**kwargs)
        self.cols=2
        def on_checkbox_active(checkbox, value):
            if value:
                e.append(value)
                print e
            else:
                print('The checkbox', checkbox, 'is inactive')

        self.add_widget(Label(text='Inserta assignatures desitjades',font_size=35))
        self.add_widget(Label(text=''))
        ch1 = CheckBox()
        self.add_widget(ch1)
        self.add_widget(Label(text='Termotecnia'))
        ch2 = CheckBox()
        self.add_widget(ch2)
        self.add_widget(Label(text='Termotecnia'))
        ch3 = CheckBox()
        self.add_widget(ch3)
        self.add_widget(Label(text='Termotecnia'))
        ch4 = CheckBox()
        self.add_widget(ch4)
        self.add_widget(Label(text='Termotecnia'))
        b1=Button(text='Exit',background_color=[0.7,0.7,1,1],font_size=24)  
        self.add_widget(b1)
        b2=Button(text='Next',font_size=24,font_color=[1,3,4,0],background_color=[1,2,3,6]) 
        self.add_widget(b2)
        ch1.bind(active=on_checkbox_active)
        ch2.bind(active=on_checkbox_active)
        b1.bind(on_press=exit)
        b2.bind(on_press=reloaded)
...

class SimpleKivy(App):
    def build(self):
        return MainScreen()


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

例如，我想选择两个或三个选项，并将其保存到下一个屏幕，就像一种选择.如果有人知道如何做并为下一个屏幕保存信息，它会对我有很大帮助，因为我有所有选项的下一个屏幕的代码，但我想在第一个屏幕中预选，然后只使用我选择了.另外，如果有人可以帮助我，我想知道如何在按下下一步"按钮时转换到另一个类(屏幕).我知道这个问题很简单，但我是 kivy 编程的新手，有些概念非常困难.谢谢.

I want to select two or three options for example, and save it for the next screen, like a type of selection. If anyone knows how to do it and save information for the next screen it woul help me a lot, because i have the code of the next screen for all the options, but i want to preselect in the first screen and then only use which i have selected. Also if anyone can help me, i want to know hoy to do the transition to another class (screen) when the button "Next" is pressed. I know this question are pretty simple but I'm new in kivy programming and some concepts are pretty difficult. Thanks.

推荐答案

您想要的是访问其他类中的变量.有时这可能很烦人，你可以用所有 __init__() 和其他东西来做这件事，或者……一个更简单的方法来了:它是 get_running_app().

What you want is accessing variables in other classes. Sometimes this can be annoying and you can do it either hard way with all __init__() and stuff, or... a simplier way comes along: it's get_running_app().

您可以创建字典或其他东西，您可以在其中存储其他类需要访问的任何值.它类似于使用 globals 并且花费更少的代码行.例如，在您的情况下，您可以使用字典(或嵌套字典、json、...)来存储例如 'checkboxes':'<names of checksed>' 并在每个初始化中可以遍历这些值以使复选框 active

You can create a dictionary or something else, where you can store any value your other classes need to access. It's similar to using globals and it costs you less lines of code. For example in your case you could use a dictionary(or nested dictionaries, json, ...) to store for example 'checkboxes':'<names of checked ones>' and in each init you can loop over these values to make checkboxes active

基本上所有你需要的是 a = App.get_running_app() 某处和一些可以在 main - App - 类中访问的东西.

Basically all you need is a = App.get_running_app() somewhere and something to access in main - App - class.

示例:

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
Builder.load_string('''
<Root>:
    MainScreen:
        name: 'main'
    AnotherScreen:
        name: 'another'
<MainScreen>:
    BoxLayout:
        Button:
            text: 'next screen'
            on_release: root.parent.current='another'
        Button:
            text: 'ping!'
            on_release: root.ping()
<AnotherScreen>:
    BoxLayout:
        Button:
            text: 'previous screen'
            on_release: root.parent.current='main'
        Button:
            text: 'ping!'
            on_release: root.ping()
''')

class MainScreen(Screen):
    def __init__(self, **kw):
        super(MainScreen, self).__init__(**kw)
        self.a = App.get_running_app()
    def ping(self):
        print self.a.big_dict['hi']

class AnotherScreen(Screen):
    def ping(self):
        b = App.get_running_app()
        print b.big_dict['hi']

class Root(ScreenManager):
    pass
class SimpleKivy(App):
    big_dict={'hi':'hi there!'}
    def build(self):
        return Root()
SimpleKivy().run()

你可以看到不需要调用__init__()，如果你真的不需要，也不需要写更多的代码行.

You can see there's no need to call __init__(), no need to write more lines of code if you really don't need to.

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