[Bug 20109] Permitted values for pressure

https://www.w3.org/Bugs/Public/show_bug.cgi?id=20109

Jacob Rossi [MSFT] <jrossi@microsoft.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|FIXED                       |---

--- Comment #2 from Jacob Rossi [MSFT] <jrossi@microsoft.com> ---
We took a second look at this issue and have a suggested tweak to the change we
made [1]. In most pen enabled applications, mouse generally emulates half the
maximum pressure of pen.  As an example, Paint provides half the stroke width
when using a mouse as compared with maximum pressure of a pen. This is
generally in line with guidance Microsoft has given for pen drawing for quite
some time: minimum pressure should be 50% stroke width, half-way pressure is
100% (e.g. what mouse should produce), and maximum pressure is 150% [2].

Given that, I reactivated this bug for us to consider making the value 0.5
rather than 1 when the device is in the active buttons state. 

Similar to the pressure issue, the spec currently allows implementations to
provide a width/height that’s “typical of the device type” when the hardware
doesn’t support contact geometry [3]. But it doesn’t require it. IE10  does not
simulate width/height for devices that do not provide geometry. But I think
we’d probably make IE do so in our next release, similar to emulating pressure.
I’d like to consider making the MAY (optional) a SHOULD (recommended) in the
spec for emulating width/height. I think the emulation we’d use in IE is:

Mouse, Pen – 1x1 width
Touch without hw support for geometry – about 40x40 CSS pixels ***

This “smart default” approach should also apply to tiltX/tiltY, but the
existing default of 0 seems appropriate for those (e.g. the stylus is normal to
the screen).

-Jacob

*** Adjusted for zoom. 40 CSS pixels is approximately 11mm, the average width
of a touch contact [4].

[1] http://dvcs.w3.org/hg/pointerevents/rev/47212a0ea91c
[2] http://msdn.microsoft.com/en-us/subscriptions/cc300776.aspx#S11 
[3]
https://dvcs.w3.org/hg/pointerevents/raw-file/tip/pointerEvents.html#widl-PointerEvent-width 
[4] http://bit.ly/win8touchguidance

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Received on Tuesday, 5 February 2013 04:52:44 UTC