UIImageView subclass that ignores touches on transparent pixels, based on OBShapedButton by Ole Begemann.
RMShapedImageView does it magic by overriding
pointInside:withEvent:. This method is called to determine if a touch is inside the view. In our case, we only want to return
YES if the corresponding pixels are not transparent (
alpha > 0).
RMShapedImageView.mto your project.
RMShapedImageVieweither in code or Interface Builder (by setting the Class of your
Touches are inexact things and querying the alpha value of a single pixel might be too strict, even more so if the image is scaled down. Furthermore, if the image has shadows you might also want to ignore touches on them.
RMShapedImageView has two configuration options to work around these problems:
shapedTransparentMaxAlpha: maximum alpha value that will be considered transparent. 0 by default.
shapedPixelTolerance: number of pixels around the point that will be examined. If at least one of them has alpha bigger than
YES. 0 by default.
Copyright 2013 Robot Media SL
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