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Transformed Pointer Coordinates?

From: Doug Schepers <schepers@w3.org>
Date: Tue, 29 Jan 2013 12:28:56 -0500
Message-ID: <510806D8.5050403@w3.org>
To: public-pointer-events@w3.org, public-fx@w3.org, www-style@w3.org
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
[2] http://www.w3.org/2009/09/16-webapps-minutes.html#item09
[3] http://www.w3.org/2010/10/13-webapps-minutes.html#item01

Regards-
-Doug
Received on Tuesday, 29 January 2013 17:29:08 GMT

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