Question

我的程序在一个屏幕上输入，然后将其显示在另一个屏幕中。我想提出一个条件，即只有当数值大于0时屏幕才会改变。我的屏幕管理器在kivy文件中定义。我的问题是如何在我的条件下使用这个“root.manager.current =”SecondScreen“”命令。我不知道如何引用它。或者也许有办法在.kv文件中创建条件？

main.py

    from kivy.app import App
    from kivy.properties import StringProperty, NumericProperty, ObjectProperty
    from kivy.uix.floatlayout import FloatLayout
    from kivy.uix.screenmanager import ScreenManager, Screen
    from kivy.uix.textinput import TextInput
    from kivy.properties import StringProperty, NumericProperty, ObjectProperty

    global var
    global pp
    pp = '0'
    class FirstScreen(Screen):
        global pp
        ppp = StringProperty('')
        def g(self, text):
            global pp
            if text.isdigit() and int(text) > 0:
                pp = text

我的test.kv文件

ScreenManager:
    id: screen_manager
    FirstScreen:
        id: screen1
        name: "FirstScreen"
        manager: screen_manager
    SecondScreen:
        id: screen2
        name: "SecondScreen"
        manager: screen_manager
<FirstScreen>:
    text_input: text_input
    FloatLayout:
        id: fl1
        canvas.before:
            Color:
                rgba: 0.1, 0.1, 0.1, 1
            Rectangle:
                # self here refers to the widget i.e BoxLayout
                pos: self.pos
                size: self.size
        TextInput:
            id: text_input
            text: root.ppp
            multiline: False
            size_hint_x: .4
            size_hint_y: .1
            pos_hint: {'x': .1, 'y': .20}
        Button:
            background_color: 0.2, 0.7, 1, 1,
            font_size: root.width / 15
            id: btn1
            text: "Next"
            on_press:
                root.g(text_input.text)
                root.manager.current = 'SecondScreen'
            size_hint_x: .4
            size_hint_y: .1
            pos_hint: {'x': .5, 'y': .20}
<SecondScreen>:
    on_enter: root.f()
    FloatLayout:
        id: fl2
        canvas.before:
            Color:
                rgba: 0.1, 0.1, 0.1, 1
            Rectangle:
                # self here refers to the widget i.e BoxLayout
                pos: self.pos
                size: self.size
        Label:
            color: 0.2, 0.7, 1, 1,
            font_size: 15
            id: lb1
            text: root.idf
            size_hint_y: .2
            pos_hint: {'x': .1, 'y': .8}

Answer 1

kvlang中的方法：

app.root.current = 'screen_name_you_want_to_switch_to'

可以在屏幕类中使用self.parent在python中完成：

self.parent.current = 'screen_name_you_want_to_switch_to'

self.parent指自身对象（屏幕）的父对象（screenmanager）

显示两者的示例如下所示，首先是文本输入的旁注：我认为您可以直接使用self.ids['text_input'].text来访问该值，您可以尝试。

import kivy
kivy.require('1.9.0') 
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager,Screen

kvlang = '''
<ScreenManagement>:
    ScreenOne:
    ScreenTwo:

<ScreenOne>:
    name: 'First'
    id: screen1
    Button:
        text: 'screen 1, press me to switch to screen 2, defined in python'
        on_press: root.switch()

<ScreenTwo>:
    name: 'Second'
    id: screen2
    Button:
        text: 'screen 2, press me to switch to screen 1, defined in kvlang'
        on_press: app.root.current = 'First'
'''

class ScreenManagement(ScreenManager):
    pass

class ScreenOne(Screen):
    def switch(self):
        #here you can insert any python logic you like 
        self.parent.current = 'Second'

class ScreenTwo(Screen):
    pass


class MyApp(App):
    def build(self):
        Builder.load_string(kvlang)
        return ScreenManagement()

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

Answer 2

执行此操作的一种方法是在python文件中交换屏幕。首先将屏幕管理器简单地定义为没有属性或子项（添加屏幕将在python中完成）

<ScreenManager>:

将ScreenManager类与FirstScreen和SecondScreen的类一起添加到python文件中。给ScreenManager（）方法交换FirstScreen和SecondScreen

class ScreenManager(widget):
    def __init__(self):
        self.show_FirstScreen()

    def show_FirstScreen(self):
        firstscreen = FirstScreen()
        self.clear_widgets()
        self.add_widget(firstscreen)

    def show_SecondScreen(self):
        secondscreen = SecondScreen()
        self.clear_widgets()
        self.add_widget(secondscreen)

然后添加一个on_press按钮事件调用的方法，在显示不同的屏幕之前执行某些逻辑，例如

    def handle_button(self):
        if <some logic>:
            self.show_SecondScreen()

按下.kv文件中的按钮必须到达ScreenManager类才能获得handle_button方法，类似于root.parent.handle_button，具体取决于结构的深度

如果在kivy文件中定义了Screen Manager，如何在Python中更改屏幕？

2 个答案: