How to create an irregular shaped imagebutton where transparent part of image is not clickable?

Question

I have an irregular shaped PNG image for example a round image where the corners are transparent.

How can I create an imagebutton of this image and not letting the corners being touchable?

If possible I may want to create other irregular shaped imagebuttons.

Mab

Answer 1

Check out the second answer to this question, I believe it's exactly what you need.

Later edit:

Quick summary:

1. Use a TouchListener instead of ClickListener

2. Inside the listener, if the event is MotionEvent.ACTION_DOWN, get the touch coordinates

3. Check the image's pixel at the coordinates you obtained earlier; if the pixel is not transparent, consider the button was clicked, otherwise ignore the event.

Lunation

By changing the "hot zone" or "clickable area" method? Let me try and see. Thanks mate. – Mab

Elaborate on this, please. "Couldn't get it work" could mean anything. The answer I pointed you to seems pretty straightforward. – Lunation

Sorry still new in Android, I'm not exactly sure how to use that snippet into my code. Currently I have an ImageButton listening an onClickEvent. How does that onTouch or MotionEvent fill in? – Mab

Yes I'm able to get the touched coordinates. How do I check whether the coordinates are belonged to which image? And how do I check the transparency using the pixel? The getPixels() method is for Bitmap. Perhaps I need to draw the buttons using Bitmap? – Mab

Get the bitmap by using Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.YOUR_IMAGE_ID);. Now you have the bitmap object and you can use getPixel to check for transparency. – Lunation

Using Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.id.myimageid); I get a null point exception for getPixel – Mab

If using Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.myimagename); I get java.lang.OutOfMemoryError: bitmap size exceeds VM budget – Mab

Now I'm able to getPixel from the image. My image is a round shaped image with corners of the image being transparent. But I'm still getting a touch event on the corners(transparent) part of the image. – Mab

If the pixel is non-transparent it means the touch is valid; you have to do your processing here and return true. – Lunation

Yes I got it working with another image below it! Thanks a lot Gabriel :) – Mab