CODEWITHSUNDEEP
objective-ciosuiimageviewhittest
Simon
Simon

Reputation: 25984

How do I restrict touches on a UIImageView to the opaque parts of its UIImage?

I have a UIImageView with userInteractionEnabled set to YES, and a few gesture recognizers on it which let the user interact with it. The view's image is of a shape, with the rest transparent, and I only want the opaque parts of the image to accept touches (the superview is also interactive).

I'm guessing I need to override a hit testing method, but which one and how?

Upvotes: 1

Views: 308

Answers (2)

cocoakomali
cocoakomali

Reputation: 1356

You can obtain the the pixel color information on the touched point ( How to get the RGB values for a pixel on an image on the iphone ). May be you can test for its alpha value to determine whether it is opaque.

Upvotes: 2

JFoulkes
JFoulkes

Reputation: 2429

Although this isn't the exact answer you're after, this should give you an idea of one way of achieving this. This blog entry is using the Cocoas2D framework.

http://abitofcode.com/2011/07/irregular-touch-detection-when-cgrect-is-not-enough-part-1/

Upvotes: 0

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