Re: Wacom Airbrush and tangentialPressure - always reports zero

Some further information on this "finger wheel": note that there is no 
specific "meaning" to what the wheel itself does in applications, and it 
can generally be remapped (for instance, in Photoshop, the default 
mapping is for opacity, which is then different from the default mapping 
for pressure which generally relates to how thick/wide a brush stroke is 
... but users often remap the wheel to control brush size instead).

There seems to be some confusion (or rather, a lack of detail) what this 
"finger wheel" should map to? I initially was convinced this would be 
tangentialPressure/barrel pressure, as that's what we say in our spec. 
This came about from Dave Fleck (at Wacom) telling us that that's what 
the wheel maps to tangential pressure (aka barrel pressure) in the HID 
definition 
https://github.com/w3c/pointerevents/issues/25#issuecomment-152013055 / 
https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf

The name tangentialPressure for this property is perhaps a bit 
misleading, but we adopted it because that's what Apple map this as 
https://developer.apple.com/documentation/appkit/nsevent/1525959-tangentialpressure 
... but perhaps we should clarify somewhere that in practice this value 
may be used for other things that are not really "pressure" related/that 
a user/apps often remap this to something else.

P
-- 
Patrick H. Lauke

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Received on Thursday, 2 March 2023 10:55:42 UTC