如何使用kivy从python文件中的按钮中使用*args调用函数

Question

我试图让按钮调用一个函数，在kivy文件中，我可以在括号中有*args。如何让函数在python文件中工作?

main.py

from kivy.config import Config
Config.set('input', 'mouse', 'mouse,disable_multitouch')
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import Button
from kivy.uix.bubble import Bubble
class MainWidget(FloatLayout):
clicked = False
def __init__(self, **kwargs):
b = Button(text="A")
b.bind(self.onpressed)
def onpressed(self, widget, touch):
if touch.button == 'left':
print("LEFT")
if self.clicked:
self.remove_widget(self.ccp)
self.clicked = False
elif touch.button == 'right':
print("RIGHT")
if self.clicked:
self.remove_widget(self.ccp)
self.ccp = CutCopyPaste()
self.add_widget(self.ccp)
self.clicked = True
class CutCopyPaste(Bubble):
pass
class RightClickApp(App):
pass
if __name__ == "__main__":
RightClickApp().run()

rightclick.kv

MainWidget:
<MainWidget>:
#Button:
#    text: "A"
#    on_touch_down: root.onpressed(*args)
<CutCopyPaste>:
size_hint: (None, None)
size: (160, 160)
pos_hint: {'center_x': .5, 'y': .6}
BubbleButton:
text: 'Cut'
BubbleButton:
text: 'Copy'
BubbleButton:
text: 'Paste'

我找到的所有方法都不起作用。请帮助。

Answer 1

如果您希望将Button实例和touch对象传递给您的onpressed()方法，那么将其绑定到提供这些参数的on_touch_down。这样的:

def __init__(self, **kwargs):
super().__init__(**kwargs)   # added missing call
b = Button(text="A")
b.bind(on_touch_down = self.onpressed)
self.add_widget(b)  # added

此外，无论何时重写super()__init__()方法，都必须调用它。您的代码没有将Button添加到MainWidget。

Answer 2

正确的绑定语法是:

widget_instance.bind(widget_kvprop_or_event = callback_method_or_function)

这里，你可以这样做，

def __init__(self, **kwargs):
super().__init__(**kwargs)
b = Button(text="A")
# Bind the event 'on_touch_down' to a method 'onpressed'.
b.bind(on_touch_down = self.onpressed)
# Don't forget to add the widget.
self.add_widget(b)