Re: Transformed Pointer Coordinates?

I've started hacking this up for Gecko[1]. The DOMPoint IDL source
currently looks like this:

[Constructor(optional float x = 0, optional float y =
0),Pref="layout.css.dompoint.enabled"]
dictionary DOMPoint {
  float x = 0;
  float y = 0;
};

I'd like to ratify the IDL in the appropriate spec before moving on to the
coord-space-conversion methods. Do we have consensus?

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=850805

--Jet

On Tue, Jan 29, 2013 at 9:28 AM, Doug Schepers <schepers@w3.org> wrote:

> Hi, folks-
>
> When elements are transformed (shifted X/y through translate, larger or
> smaller through scale, etc.) using CSS transforms or SVG, dealing with
> pointer events becomes more complicated and unintuitive... things just
> aren't where they appear to be.
>
> This leads to all sorts of confusion for authors in positioning things...
> dragging, repositioning, or creating elements based on pointer position.
> (To a lesser extent, this is a general problem with positioning relative to
> transformed elements, but nesting context takes care of most
> non-pointer-position cases.)
>
> Jonathan Watt (Mozilla) has a handy script library [1] that helps authors
> solve this in SVG, but unless someone knows about that script, it is
> frustrating. I think this should be solved in a spec, perhaps as a method
> to get the relative transformed coordinates in the appropriate coordinate
> space.
>
> I started to address this in DOM3 Events [2][3], but we decided to defer
> it, or to address it in CSSOM or the CSS Transforms spec.
>
> I'm raising this here to ask where it is most appropriate to address this:
> the Pointer Events v2 spec (still in the future), the CSS Transforms spec,
> or the CSSOM spec?
>
> [1] http://jwatt.org/svg/tmp/**mouse-relative-positioning.svg<http://jwatt.org/svg/tmp/mouse-relative-positioning.svg>
> [2] http://www.w3.org/2009/09/16-**webapps-minutes.html#item09<http://www.w3.org/2009/09/16-webapps-minutes.html#item09>
> [3] http://www.w3.org/2010/10/13-**webapps-minutes.html#item01<http://www.w3.org/2010/10/13-webapps-minutes.html#item01>
>
> Regards-
> -Doug
>
>