Kivy: Access MouseMotionEvent information from Button on_release/on_press

Question

I want to create a button widget with Kivy that uses information from the touch event when clicked, i.e. The mouse position and the mouse button used for clicking.

If I re-implement on_release or on_press like this:

from kivy.uix.button import Button

class myBtn(Button):
    def on_release(touch=None):
        print('Touch:', touch) # Touch: None (always)

Touch will always be None. If I re-implement on_touch_up or on_touch_down I can access the touch information:

from kivy.uix.button import Button

class myBtn(Button):
    def on_touch_up(touch=None):
        print('Touch:', touch)
        # Touch: <MouseMotionEvent spos=(..., ...) pos=(..., ...)

        print('Button:', touch.button) # Button: left

The problem with this version is that the button press/release animation will remain as if pressed even after I release the mouse button, also the function is called 2 times instead of only once.

If I do the same with on_touch_down the function executes only once but the button animation doesn't change at all when clicked.

How can I recover the MouseMotionEvent avoiding the problems I found with on_touch_down and on_touch_up?

Answer 1

If you want to use on_release or on_press you can access the MouseMotionEvent like this:

from kivy.uix.button import Button

class myBtn(Button):
    def on_release():
        print('Touch:', self.last_touch)
        print('Button:', self.last_touch.button)

If you want to use on_touch_down or on_touch_up you just need to make sure to call the super() implementation:

from kivy.uix.button import Button

class myBtn(Button):
    def on_touch_up(touch):
        print('Touch:', touch)
        print('Button:', touch.button)    
        super(myBtn, self).on_touch_up(touch) 

But it will still be executed more than once.