Kivy - 将标签文本绑定到变量(仅限 Python) [英] Kivy - Bind Label Text To Variable (Python Only)

问题描述

我已经尝试让我的标签自动更新很长一段时间了，我已经阅读了十几个 StackOverflow 问题，但无济于事.

I have been trying to get my labels to auto-update themselves for quite a while now and I have read over a dozen StackOverflow questions but to no avail.

我有一个全局对象，其中包含一个整数值，我希望在其中一个小部件类中显示该值并带有标签.

I have an global object that contains an integer value that I want to be displayed with a label inside of one of my widget classes.

小部件类如下所示:

class Battle(Widget):

    def __init__(self, **kwargs):
        super(Battle, self).__init__(**kwargs)

        #Enemy Stats
        self.enemyBar = BoxLayout(orientation="horizontal", size=(Window.width, Window.height/8), center_y = Window.height - self.height/2)
        self.enemyBar.add_widget(Label(text=enemy.name))

        #Enemy Health Label
        health_label = Label(text=str(enemy.health))
        self.enemyBar.add_widget(health_label)
        self.add_widget(self.enemyBar)


    def update_health(instance, value):
        health_label.text = str(enemy.health) #<-- Error happens here

    enemy.bind(health=update_health)

当 enemy.health 的值在程序中改变时，我希望我的标签也改变.我不想使用任何 kivy 语言，因为我更喜欢只有一个主 python 文件.

When the value of enemy.health is changed in the program, I want my label to change as well. I do not want to use any of the kivy language because I prefer having just one main python file.

敌人对象是使用实体类创建的.这是实体代码:

The enemy object is created with an entity class. Here is the entity code:

class entity(Widget):
    #entity creation
    health = NumericProperty() 

    def __init__(self, health):
        self.health = health

当我运行代码时，我按下一个按钮，该按钮调用一个改变敌人生命值的函数，然后我得到一个错误:

When I run the code I press a button that calls a function that changes the enemy health and then I get an error:

未定义全局名称health_label"

不知何故，当调用 update_health 函数时，程序看不到在 init 中创建的 health_label 变量.

Somehow, when the update_health function is called, the program doesn't see the health_label variable that was created in the init.

推荐答案

需要使用bind方法，类似如下

You need to use the bind method, something like the following

health_label = Label(text=enemy.health)
self.enemyBar.add_widget(health_label)
def update_health(instance, value):
    health_label.text = str(enemy.health)
enemy.bind(health=update_health)

这只是我脑海中的一个基本示例，它可以根据您的程序结构变得更简洁.如果enemy.health 是一个字符串，你可以这样做 enemy.bind(health=health_label.setter('text')).

This is just a basic example off the top of my head, it can be made neater depending on the structure of your program. If enemy.health is a string, you can just do enemy.bind(health=health_label.setter('text')).

为此，health 属性必须是 kivy 属性:

For this to work, the health attribute must be a kivy property:

class Enemy(Something):
    health = StringProperty('')

在您的代码中，敌人似乎是一个全局对象.很可能有更好的方法来做到这一点.另外，我建议使用 kv 语言 - 将代码放在一个文件中并没有任何特殊价值(事实上，一旦它变得不平凡，它通常被认为是不好的做法)，并且 kv 使很多事情变得更容易，而 python 只是'不适合某些任务.

In your code it seems that enemy is a global object. There is quite likely a better way to do that. Also, I recommend using kv language - there is not really any special value in putting your code in one file (indeed, it's commonly considered bad practice once it gets non-trivial), and kv makes a lot of things easier where python just isn't suited to certain tasks.

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