discussion about touch events

Pavel Safrata pavel.safrata at oracle.com
Thu Dec 12 12:29:09 PST 2013

Hello all,
I'm sorry for the long delay on my side.

Daniel, the only remaining point of our discussion that I feel deserves  
a comment:

>>> We could reasonably limit the algorithm to dealing with convex shapes.
>> Can we? What about paths, polygons etc?
> I realize that it is possible to describe touch sensitive concave 
> shapes, but I am not sure they matter for this. If developers are 
> going to go to the trouble of defining a concave shape that they want 
> to be touch sensitive within its area but not in all of its bounding 
> box, are they really then going to want that area to be extended? I’d 
> consider a concave touch shape with extended capture zone to be 
> sufficiently unlikely that we could treat it as concave. Which, I 
> realize is not quite what my proposed algorithm does.

I can imagine, for instance, an application showing a graph - a set of 
vertices connected by edges. The edges are not straight lines, but are 
e.g. QuadCurves. I can touch an edge and drag it to change its shape 
(the control point). Now to be able to touch the curve, I certainly want 
it to have the extended capture zone (it's thin). But if an edge circles 
around the graph, I don't want it to be picked everywhere in between. 
I'm not sure if this is compelling enough, but to me it sounds like a 
reasonable use-case that needs concave extended capture zones..


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