[Python] Avoid having my custom button bound to multiple instances of that button when pressed

My example seems to pass self in the button object (based on printing my_id to debug and it matching the my_id for each button, but when I click on "Option A" all 3 buttons animate. When I click on "Option B", B and C animate.

Why is the on_touch_down event trigging other buttons of the same RoundedButton class on the same page? (these are in a screen manager, not shown in code).

<RoundedButton@Button>:
style: "elevated"
background_color: (0, 0, 0, 0)
background_normal: ""
background_down: ""

canvas.before:
Color:
rgba: (0.72, 0.68, 0.92, 1) if self.state == 'normal' else (0.33, 0.48, 0.92, 1)
RoundedRectangle:
size: self.size
pos: self.pos
radius: [20]
Color:
rgba: (0.72, 0.68, 0.92, 1)
Line:
rounded_rectangle: (self.pos[0], self.pos[1], self.size[0], self.size[1], 20)
width: 1 if self.state == 'normal' else 5


...


MDBoxLayout:
orientation: 'horizontal'

RoundedButton:
my_id: 'optionA'
text: 'Option A'
size_hint: 0.15, 0.35
on_touch_down: app.animate_darken(self)

RoundedButton:
my_id: 'optionB'
text: 'Option B'
size_hint: 0.15, 0.35
on_touch_down: app.animate_darken(self)

RoundedButton:
my_id: 'optionC'
text: 'Option C'
size_hint: 0.15, 0.35
on_touch_down: app.animate_darken(self)


And elsewhere, that animate_darken function:

def animate_darken(self, widget, fade_length=0.5, *args):
print(widget.my_id)
BG_color = widget.background_color
A = Animation(
background_color=(0,0,0,1),
duration=fade_length #seconds
)
A += Animation(x=0, y=0, duration=0.3)
A += Animation(background_color=BG_color) # reset it
A.start(widget)


Q: How do I bind each RoundeButton only to that button, and animate it without affecting other buttons on the screen?

Continue reading...