Re: [Linuxwacom-devel] RFC: Back to the tablet buttons representation (aimed at making an OSD window for the Expresskeys)

[Olivier F. <ofo...@re...>]

Hi Jason,

Jason Gerecke said the following on 09/28/2012 12:19 AM:
> On Thu, Sep 27, 2012 at 2:32 AM, Olivier Fourdan<ofo...@re...>  wrote:
>> [...]
>>
>> Question:
>>
>> * Does any of the above makes sense? ;-)
> Seems logical enough. There's some hand-waving going on regarding the
> tablet definition language that needs to be sorted out though.
> Describing where and how large physical elements are sounds awfully
> like UI layout, so it may make sense to make use of languages that
> already exist for that purpose.
>
>> * Is it simple enough? Or too simplistic?
> For the moment, I don't see any problems. But don't underestimate the
> flexibility requirements. For example, the Cintiq 21UX2 has its touch
> strips located on the *back* of the tablet. You may run into problems
> describing the 3D position of elements with most 2D layout languages.

Good point. But I have a bit of the same issue representing a 3D 
layout on a 2D window...

>
>> * Is SVG appropriate for that? Do we actually need an accurate image of the
>> buttons?
> We probably don't need accurate button images and could get away with
> simplified representations created "directly" from the tablet
> definition. I wouldn't be against having something a little less
> symbolic though :)

That's the point of having optional SVG images, usage would not be 
mandatory.

But then it's worth asking if SVG is worth it in this case. I guess 
possibly not.

>> * Assuming it makes sense, what unit should be used for the position/size of
>> elements?
> This kinda gets at the tablet definition language issues I was
> mentioning. Using a flat file with real-world units (e.g. centimeters)
> would be adequate to describe most anything, but would probably be
> hard to quickly write. Using an XML file could allow you to quickly
> describe things in relative terms, but would probably be more verbose
> when trying to get the layout "perfect".
>> * Should the representation be per tablet, or per side of tablet, ie one
>> description for the left buttons with their relative position, same for
>> right, top, etc?
>>
> I would probably represent the whole tablet. The symmetries are there,
> but I don't know if it'd be worth the programming work necessary to
> allow their description. It'd be more worth it to allow partial
> descriptions to be "included" into tablet definitions (e.g. describe
> the Intuos3 button layout once, and then include it twice in a
> half-dozen files), but I still don't know if it'd be enough.

Well there are two problems really, one is the external interface, ie 
what do apps get when querying libwacom for a layout, the other one 
being how it's imimplemented within the libwacom database.

For the former, a list of named buttons with their size and position 
(and optional SVG representation) would be enough imho, whereas for 
the later we can think of anything really, including XML and external 
file inclusion.

Cheers,
Olivier.