Applying touch events to irregular shape element

I am learning Corona SDK and so far I found it faster to develop than other framework i found. I have followed a simple tutorial on creating draggable objects. The object I created is an irregular shape, in fact it looks like a huge letter ‘T’ png object. The function that handles the touch and drag event works fine but I noticed that the hotspot of the touch covers the entire rectangular are of the object. So when I pressed on the transparent part of the object it will still select it and thereby the drag function is applied.

How can I change this in such a way that the touch will only be applied to the non-transparent section of the png image?

Ironically, your photo holds the answer:  masks.

http://docs.coronalabs.com/api/library/graphics/newMask.html

Touch events will fall through the masked (transparent) area.

Ironically, your photo holds the answer:  masks.

http://docs.coronalabs.com/api/library/graphics/newMask.html

Touch events will fall through the masked (transparent) area.