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I've currently been thinking about how I could register only touch events on the visible (non-transparent) parts of a .PNG image.

-I've been testing around with AndEngine and it seems they have multiple options: I've tried any I could find to no avail.

-I could very possibly create my own method of checking a given touched area's transparency I suppose, but not sure how much work/overhead that might create with 15-20 objects on screen being able to be touched..

Any help is much appreciated!

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One simple way to do it would be to grab the the pixel color at the touch location. Then you can check if the pixel is transparent:

int color = Bitmap.getPixel(x,y); // x and y are the location of the touch event in Bitmap space int alpha = Color.getAlpha(color); boolean isTransparent = (alpha==0);

Note: Depending on how you implement your touch listener will might need to convert the x,y location of the touch event to the x,y coordinates of the image view.

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4 Comments

Haha, I just edited to ask how this works. Thanks for the quick reply! I'll definitely try it in hopes that it's not too costly!
If you attach a onTouchListener to each object then you only have to check the all the objects only the object that was touched.
Very true, very helpful. This should work, I just have to find a way to traverse back from a TiledTextureRegion in andEngine to get the actual color attributes of a given Bitmap.pixel()
slayton, just realized getAlpha() should be alpha() I think :-D

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