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

Re: opacity, animate and mask

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sat, 4 Aug 2007 19:47:10 +0200
To: j.chetwynd@btinternet.com, www-svg@w3.org
Message-Id: <200708041947.10097.Dr.O.Hoffmann@gmx.de>


Lets try this simple example,
I think it is not easy to manage it, 
if elements with opacity 0 cannot 
receive events, because this has 
side effects on the interpretation 
of the content.

I need the following circle receiving always 
events to begin or end animations:


<?xml version="1.0" encoding="iso-8859-1" ?> 
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" 
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg width="100%" height="100%" viewBox="-50 -50 100 100" 
    xmlns="http://www.w3.org/2000/svg" version="1.1"
    xmlns:xlink="http://www.w3.org/1999/xlink">
<title>Creating the Light - Abstraction</title>
<desc>centered mouseup for dawn and mousedown for nemesis</desc>

<g>
<title>Tohu Va-Vohu</title>
<rect x="-1000" y="-1000" width="2000" height="2000" />

<circle opacity="0" cx="0" cy="0" r="40" fill="#fc0">
<title>The Light</title>
<animate attributeName="opacity" dur="10s"
   begin="mouseup" end="mousedown; indefinite" to="1" fill="freeze"
   id="dawn" />
<animate attributeName="opacity" dur="10s"
   begin="mousedown" end="mouseup; indefinite" to="0" fill="freeze"
   id="nemesis" />
</circle>
</g>
</svg>


Now what to do if the circle cannot receive events, if
opacity is 0? The animation cannot begin (or end if started
with a hyperlink activation), if opacity is 0.
Because pointer-events does not care about opacity, even
if I set it to 'painted' or 'all' following your idea this will not 
influence the event behaviour.
With your interpretation you need another element 
recieving events instead of the circle, but this 
changes the 'philosophical' meaning of this somehow 
religious art work - you have to 'touch' the emptiness to 
let go the big bang or to 'create' the light, not yet to
activate it with another element - this is somehow 
'creatio ex nihilo' ;o) 
Therefore events on elements with opacity 0 gives the 
opportunity for: 'Eritis sicut Deus, scientes bonum et malum' ;o)
Note that you have to be careful with a second 'touch' -
this is 'philosophical' intended ;o)
Received on Saturday, 4 August 2007 18:50:52 GMT

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