Kivy Screen Manager参考语言(KV语言) [英] Kivy Screen manager reference in kv language

问题描述

我正在尝试创建一个主菜单，该菜单使我可以在单击按钮时切换屏幕，但是我不知道如何从该按钮引用管理器.

I'm trying to make a main menu that lets me switch Screens when I click a button, but I can't figure out how to reference the manager from the button.

我有一个用于主菜单页面的设置(在kv文件中):

I have a setup for a main menu page (in kv file):

<MainMenu>:  #AnchorLayout
     BoxLayout:
         Button:
             text: "button 1"
         Button:
             text: "change screen"
             on_release: root.manager.current = "OtherPage"

<MainWidget>:
    screen_manger: screen_manager
    ScreenManger:
        id: screen_manger
        Screen:
            name: "MainMenu"
            MainMenu
        Screen:
            name: "OtherPage"
            OtherPage    #this is defined in the kv file, just lazy to type it.

当我点击按钮Change Screen时，我得到:

When I click on the Button Change Screen, i get:

AttributeError: 'MainMenu' object has no attribute 'manager'

说实话，这并不令我惊讶.我想我可以通过以下方式解决此问题:在python代码中编写所有布局，并在BoxLayout或MainMenu小部件中添加对屏幕管理器的引用，但是我不知道如何在kv文件中执行此操作.

which, in all honesty doesn't supprise me. I figure I can work around this by writing all the layout in python code and adding a reference to the screen manager in the BoxLayout or MainMenu widgets, but I have no idea how to do this in the kv file.

推荐答案

在更好地理解问题后重新做答案:

Re-doing the answer after understanding the issue better:

您的MainWidget实例不知道screen_manager引用，它不会传递给它(并且在其规则root中引用MainWidget实例，而不是ScreenManager实例.

Your MainWidget instance doesn't know about the screen_manager reference, it's not passed to it (and in its rule root refer to the MainWidget instance, not the ScreenManager one.

如果将manager: screen_manager放在MainWidget实例的声明下(第15行)，并将manager ObjectProperty添加到MainWidget的python声明中，则绑定将起作用.

If you put manager: screen_manager under the declaration of MainWidget instance (line 15), and you add a manager ObjectProperty to the python declaration of MainWidget, then your binding will work.

python:

class MainWidget(Widget):
    manager = ObjectProperty(None)

kv:

<MainWidget>:
    screen_manger: screen_manager
    ScreenManger:
        id: screen_manger
        Screen:
            name: "MainMenu"
            MainMenu:
                manager: screen_manager
        Screen:
            name: "OtherPage"

然后它应该可以按您想要的方式工作.

then it should work as you want it.

此外，qua-non的此Wiki条目可能很有帮助 https://github.com/kivy/kivy/wiki/Linking-ScreenManager-to-a-different-Widget

edit: also, this wiki entry by qua-non could be helpful https://github.com/kivy/kivy/wiki/Linking-ScreenManager-to-a-different-Widget

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