python - 带参数的 Kivy 按钮绑定(bind)函数

Question

我正在尝试学习如何在 Kivy 中创建应用程序，但我在向函数发送参数时遇到了问题。我想将文本从输入发送到函数并打印出来。有人可以告诉我该怎么做吗？

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput
from kivy.uix.button import Button


class TutorialApp(App):
    def gratulation(self, *args):
        print args

    def build(self):
        boxLayout = BoxLayout(spacing=10,orientation='vertical')
        g = TextInput(text='Enter gratulation', 
                      multiline=False,
                      font_size=20,
                      height=100)
        button = Button(text='Send')
        button.bind(on_press=self.gratulation)  

        boxLayout.add_widget(g)
        boxLayout.add_widget(button)
        return boxLayout

if __name__ == "__main__":
    TutorialApp().run()

Answer 1

你必须从“g”中获取文本，然后将其发送到按钮回调，有两种方法可以做到这一点，通过 lambda 函数，或者调用你的类方法来应用它。

Lambda 版本:

from __future__ import print_function ##Need to import this for calling print inside lambda

def build(self):
    boxLayout = BoxLayout(spacing=10,orientation='vertical')
    g = TextInput(text='Enter gratulation', 
                  multiline=False,
                  font_size=20,
                  height=100)
    button = Button(text='Send')
    buttoncallback = lambda:print(g.text)
    button.bind(on_press=buttoncallback)  
    ...

部分版本:

from functools import partial ##import partial, wich allows to apply arguments to functions returning a funtion with that arguments by default.
def build(self):
    boxLayout = BoxLayout(spacing=10,orientation='vertical')
    g = TextInput(text='Enter gratulation', 
                  multiline=False,
                  font_size=20,
                  height=100)
    button = Button(text='Send')
    buttoncallback = partial(self.gratulation, g.text)
    button.bind(on_press=buttoncallback)  
    ...