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Re: [css3-transitions] Interpolating images

From: David Singer <singer@apple.com>
Date: Tue, 30 Nov 2010 14:26:49 -0800
Cc: www-style list <www-style@w3.org>
Message-Id: <B05CD571-21A4-4915-B6AD-4475E394F13D@apple.com>
To: Tab Atkins Jr. <jackalmage@gmail.com>
Um, wouldn't it work by deciding what the appearance would be for the initial image, and what the appearance would be for the final image (and this decides all the scaling, cropping, replicating, etc. that might occur), and then the transition would happen between those two appearances?  We shouldn't have to make 'new' decisions about scaling etc., should we?

And should there be some way to suggest that the transition is other than a crossfade?

On Nov 30, 2010, at 12:44 , Tab Atkins Jr. wrote:

> Currently, images in general can't be transitioned.  It's been
> suggested before that we allow such transitions, implementing them as
> a cross-fade between the two images.  Would it be acceptable for me to
> specify this behavior in Image Values, or is it something we'd rather
> put off until Transitions 4?  Either decision is acceptable to me; I
> just want to put a note into Image Values if we decide on the latter.
> 
> There is an obvious issue with transitioning between images of
> different sizes, with a few different solutions:
> 
> 1) In addition to crossfading, scale the images between the starting
> and ending size, so they always match in size.  This is probably
> expensive.  As a benefit, it's clear what the size of the cross-faded
> image is, for the purpose of background-repeat, background-size, etc.
> 
> 2) Treat it as transitioning between two infinite layers.  Sections
> outside of each image would just be transparent pixels.  You'd then
> just do a naive pixel-based cross-fade.  This doesn't give us a clear
> answer about the image's size, though.
> 
> I don't know if there are any further issues or not here.
> 
> So, should I add a note to Image Values saying "general <image>
> interpolation will be specified in a later version of Transitions", or
> should I try and define it here?
> 
> ~TJ
> 

David Singer
Multimedia and Software Standards, Apple Inc.
Received on Tuesday, 30 November 2010 22:27:23 GMT

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