W3C home > Mailing lists > Public > www-svg@w3.org > March 2007

SVGZoomEvent errata - screenX et. al.

From: Jonathan Watt <jwatt@jwatt.org>
Date: Wed, 07 Mar 2007 18:40:40 +0100
Message-ID: <45EEF918.2030806@jwatt.org>
To: www-svg@w3.org

Hi all,

When I implemented SVGZoomEvent for Mozilla I did not implement:

   screenX, screenY, clientX, clientY, altKey, ctrlKey, shiftKey,
   metaKey or relatedNode [1]

because SVG 1.1 says SVGZoomEvent inherits from events::UIEvent so there's no 
inherited interface that defines these properties. Even if they could somehow be 
implemented, screenX, screenY, clientX and clientY wouldn't really provide you 
with the information you want. When reacting to a zoom event you want to be able 
to reposition the children of the target <svg> element relative to the edges of 
the <svg> element. To do that you want to know the coordinates in user space 
(the user space established _by_ the target <svg> element) of the top-left-most 
and bottom-right-most points still visible in the <svg> element after the zoom. 
With that information (which you'd have as an SVGRect if my previous email [2] 
is accepted) you could also easily obtain the center point making any 
information screenX, screenY, clientX and clientY might provide redundant. 
Besides that the text "center of the zoom area" is unclear, and having 
coordinates in "screen" or viewport coordinates is not useful.

As for altKey, ctrlKey, shiftKey and metaKey they don't seem to belong on an 
SVGZoom event.

Finally, relatedNode is the same as event.target so it's redundant.

I suggest that an errata item remove (or as close to remove as possible) any 
mention of the MouseEvent properties screenX et. al. from text pertaining to 
SVGZoomEvent.

Regards,
Jonathan


[1] http://www.w3.org/TR/SVG11/script.html#InterfaceSVGZoomEvent
[2] http://lists.w3.org/Archives/Public/www-svg/2007Mar/0002.html
Received on Wednesday, 7 March 2007 17:41:45 GMT

This archive was generated by hypermail 2.3.1 : Friday, 8 March 2013 15:54:36 GMT