Kivy在拖动小部件时执行函数

Question

我在这里有一个小演示：

来自DemoApp.py:

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.behaviors import DragBehavior
from kivy.core.window import Window

class DraggableButton(DragBehavior, Button):
def on_drag(self, *args):
...

class DemoLayout(FloatLayout):
def __init__(self, **kwargs):
super(DemoLayout, self).__init__(**kwargs)
self.add_widget(DraggableButton(text='Drag Me'))

class DemoApp(App):
def build(self):
self.button= DraggableButton(text='Drag Me')
Window.bind(mouse_pos=lambda w, p: setattr(self.button, "mouse_pos", p))
return self.button

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

来自demo.kv:

<DraggableButton>:
drag_rectangle: self.x, self.y, self.width, self.height
drag_timeout: 10000000
drag_distance: 0

问题是，我想在拖动DraggableButton时调用我的on_drag方法。

此外，我只想要在功能中的鼠标位置，因此我可以删除
Window.bind(mouse_pos=lambda w, p: setattr(self.button, "mouse_pos", p))行

有什么解决办法吗？

Answer 1

它使用DragBehavior，所以我找到了DragBehavior的源代码
，并且我看到它有方法on_touch_move(touch)。

我在DraggableButton()中替换了这个方法，当按钮被移动时，它会得到MouseMotionEvent和pos，这似乎是鼠标的位置。

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.behaviors import DragBehavior
from kivy.core.window import Window

class DraggableButton(DragBehavior, Button):
def on_touch_move(self, touch):  
super().on_touch_move(touch)  # run original `on_touch_move()`

print('[on_drag] touch:', touch)

#print('[on_drag] touch.dpos:', touch.dpos)
#print('[on_drag] touch.spos:', touch.spos)
print('[on_drag] touch.pos:', touch.pos)
print('---')

class DemoApp(App):
def build(self):
self.button = DraggableButton(text='Drag Me')
return self.button

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

结果：

[on_drag] touch: <MouseMotionEvent spos=(0.36, 0.5766666666666667) pos=(288.0, 346.0)>
[on_drag] touch.pos: (288.0, 346.0)
---
[on_drag] touch: <MouseMotionEvent spos=(0.35875, 0.5783333333333334) pos=(287.0, 347.0)>
[on_drag] touch.pos: (287.0, 347.0)
---
[on_drag] touch: <MouseMotionEvent spos=(0.35875, 0.5783333333333334) pos=(287.0, 347.0)>
[on_drag] touch.pos: (287.0, 347.0)
---