WebkitForce property of touch event: Finger feedback. Documentation Search

Question

I am running some tests on my Chrome browser Nexus 7 and found a curious webkitForce property in the touch object provided by touch events.

Of course, it looks like a scalar, which is usually set between about 0.05 and about 1.2, which seems to scale with finger pressure on a capacitive touch screen. It works with multiple simultaneous touches; I have a test page that extends circles scaled to this value, and it correlates well with finger pressure / position, providing a three-dimensional amount for every touch.

There is some slight inconsistency that can occur when the pressure changes on one finger, affecting the readings provided for the other finger, which is close to it on any axis. This looks like the result of restrictions, either from the actual capacitive touch equipment, or from the software that processes it.

I searched for it and found nothing. It is strange that Google does not have any site (which I can find through a search engine) that documents this.

So my question is, where can I find more information about this neat little function? Why iOS devices (with more flexible and capable touch screens) do not provide anything like this? What Android devices and OS / Browser combinations provide this feature?

Answer 1

.force is part of the Touch Events v2 specification: http://dvcs.w3.org/hg/webevents/raw-file/default/touchevents.html#widl-Touch-force

the relative value of the applied pressure in the range from 0 to 1, where 0 is equal to no pressure, and 1 is the highest level of pressure the sensor device can perceive; 0 if the value is not known. In environments where force is known, the absolute pressure, the attribute represented by the force, and the sensitivity in pressure levels can vary.