Major refactoring: refer to "direct manipulation" rather than "touch"

[patrickhlauke]

This is admittedly slightly awkward, but necessary - as touch-action does not simply apply to touch, but any other situation where an input serves to directly scroll/zoom (e.g. stylus on touchscreen). Before, it was just a non-normative note, but if we want to make this normative and require (for web compat) that UAs do this, it's probably the least-bad approach. (still leaves a bit of cognitive dissonance with the fact that the CSS property is called touch-action, but hey...)

Closes #202

Please take your time reviewing this, as it's probably quite a fundamental decision here. We should discuss this in the upcoming call(s).

---

Preview | Diff

[patrickhlauke]

Setting this to draft, as we likely need to wordsmith this / discuss this a bit more than other changes, so avoiding accidental merging.

[patrickhlauke]

/cc @RByers (if he's still interested in this, as he originally filed #202)

[mustaqahmed]

This are my first pass comments. I am still not done with the whole PR, will complete next week.

[patrickhlauke]

any more thoughts on this?

[patrickhlauke]

tl;dr now wondering if instead of talking about things like direct manipulation behaviors (such as panning or zooming) it should be more direct manipulation behaviors *for* panning or zooming. this would aknowledge that there are different types of "direct manipulation", including the definition that also covers GUIs where a user can drag/drop elements with a mouse pointer, and hones in specifically on the direct manipulation for panning/zooming which is unique to the types of scenarios we mean (finger / stylus that is used to pan/zoom)

[patrickhlauke]

Took another stab at making the language more comprehensible. Maybe went a bit overboard, but:

• to simplify matters, just settled on talking about "scrolling" rather than always clarifying it's "panning/scrolling". we do still have a note that says we're intending "pan" to mean the same as "scroll"
• as discussed in our call, instead of just saying "direct manipulation", specified, where necessary, that we're talking about "direct manipulation for scroll/zoom" or similar. this bridges the weird gap of having "direct manipulation" mean different things to different people (touch/stylus only for us, but in some quarters even a mouse GUI is called a "direct manipulation" interface ... for the latter though, scrolling/zooming is generally NOT done via this direct manipulation, so by being specific this now makes sense regardless of which way you interpret "direct manipulation")

this will still need a refactor/rebase/potential more work once #349 lands

[patrickhlauke]

Did a rebase, tweaked some things along the way, and turned out I needed to force-push and rewrite history on this. Apologies. This should now however be in line with the recently merged stuff from the other PR.

[smaug----]

Minor nit and the question about scrolling or panning.

[patrickhlauke]

Made some further changes based on today's PEWG call - changed most instances of "scrolling" to "panning", and turned a few sentences around a bit to make them easier to read (hopefully without introducing any substantially new interpretations)

[patrickhlauke]

Sorry, one more tweak (and now i'll leave this alone to give sufficient time to review) - after @mustaqahmed's comment in today's call, I revisited the glossary definition for "direct manipulation". I think I see what you meant now ... so turned it around a bit.