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Opening on behalf of François Remy. Current spec text defines pressure as a normalized value where 0 is no pressure and 1 is maximum pressure. This creates a potential issue where more capable devices are penalized such to work on the same range of values, meaning a user may have to apply more pressure on one device to achieve the same result as another. Detailed discussion: http://lists.w3.org/Archives/Public/public-pointer-events/2012OctDec/0018.html
12/4 telecon resolution: -For devices that do not support pressure (e.g. a mouse), pressure must be 1 when in the active buttons state and 0 otherwise. -Pressure will remain normalized (e.g. in the range of [0,1]) (no change) http://lists.w3.org/Archives/Public/public-pointer-events/2012OctDec/0091.html Change: http://dvcs.w3.org/hg/pointerevents/rev/47212a0ea91c
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
Making change as suggested per 2/5 telecon. https://dvcs.w3.org/hg/pointerevents/rev/f8d79fb0835c RESOLUTION:http://lists.w3.org/Archives/Public/public-pointer-events/2013JanMar/0084.html http://www.w3.org/2013/02/05-pointerevents-minutes.html