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

Re: opacity, animate and mask

From: ~:'' ありがとうございました。 <j.chetwynd@btinternet.com>
Date: Sat, 4 Aug 2007 07:56:03 +0100
Message-Id: <A85D77C5-F46B-4FD1-B847-42C43899562C@btinternet.com>
Cc: Jeff Schiller <codedread@gmail.com>, "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
To: SVG List <www-svg@w3.org>

Jeff and Olaf,

I take your points, however it seems to me you may be imagining this  
issue from a developer and implementer viewpoint rather than a naive  
coder or someone using a design or drawing tool.

In this instance the naive user might well discover the suggested  
special significance of zero or "none".
(other values such as 0.000001 providing for current use cases)

However it's a significant hurdle for the naive user to add an extra  
attribute, even when they understand this is necessary.

Perhaps you are aware of how easy it is to set up a slideshow with  
how is this done with inkscape or another SVG tool?

This issue isn't even raised in the generally excellent "SVG  
Essentials" neither indeed is pointer-events afaik

I'm concerned by the lack of usability testing with naive users, when  
creating W3 specifications.
in particular I'd like to see an SVG specification designed around a  
simple to use authoring tool for ordinary people, currently known as  


Jonathan Chetwynd

On 3 Aug 2007, at 15:26, Jeff Schiller wrote:


Ok, here's a use case:  I want to implement a modal dialog type
functionality in a web app.  When somebody clicks on something, I'm
going to display a tiny modal message box.  While that message box is
displayed, I don't want to accept any clicks on other visible
entities.  In other words, I want a completely transparent rectangle
to sit on top of my UI and "block" any mouse clicks until the message
box has been closed, rather than have a variable to track whether the
message box is displayed or not - or temporarily turn off my event
handlers, etc.

Maybe I'm missing where the problem lies, but why can't you just
animate your display to "none" along with opacity to "remove" a faded
element?  Why do you deem your suggested behavior "essential"?


On 8/3/07, "~:'' ありがとうございました。"  
<j.chetwynd@btinternet.com> wrote:
> Olaf,
> there are many possible similes but why chose the opacity of a glass
> plate?
> why not it's thickness for instance?
> No one has so far contributed a use case, where this behaviour is
> essential or even desirable, whereas the uses of the contrary
> position seem natural, as for instance fading linked images...
> regards
> Jonathan Chetwynd
> apologies, I made an error with respect to Opera, it may have been
> Amaya which allows one to select and click through some holes.
> On 3 Aug 2007, at 10:13, Dr. Olaf Hoffmann wrote:
> Hello,
> if pointer-events is not explicitly noted, the initial
> value 'visiblePainted' is used.
> I looked in my test case(s) related to this and could
> not find any problem with Opera 9.
> The relation of opacity and events is maybe comparable
> to an opaque glass plate - no matter how opaque it is,
> you cannot grab through it, even if you cannot see it.
> This is different if you set for example display to none
> or visibility not to visible or pointer-events to none, then
> it is possible to 'grab' through to an object below it.
> I think in SMIL 3 they want to offer a value for opacity
> related attributes or properties, to allow authors to
> define, how opaque something has to be to recieve
> an event, but this is not the case for SVG (or SMIL 2).
> User agents I know to support animation of opacity:
> Opera 8 and 9, adobe plugin.
> KSVG1 and Amaya with some specific simple animation types
> can animate it too, but they do not care about events.
Received on Saturday, 4 August 2007 06:56:24 UTC

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