Android Question Sprite Auto Snap in when near to canvas

[herryj]

I already create a polygon out of canvas , and form it a kind of object (object I mean is like boat, book, candle, etc.) out of it. And now what I want to do next is. I have this piece of shape(example a triangle) which the sprite then, when I drag this triangle shape on the triangle part in (image attached) those red area. This triangle shape will automatically fill in or snap in the triangle part of the image attach.

Thus, I don't have any idea.

Can you give some,

Looking forward to you response

Sincerely,
H