W3C home > Mailing lists > Public > www-style@w3.org > March 2009

Re: [css3-transitions]

From: Brad Kemper <brad.kemper@gmail.com>
Date: Mon, 30 Mar 2009 17:29:06 -0700
Message-ID: <7e1f93760903301729g12f3f460l1ddee2736be75bc0@mail.gmail.com>
To: Dean Jackson <dino@apple.com>
Cc: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>, www-style@w3.org
On Mon, Mar 30, 2009 at 4:27 PM, Dean Jackson <dino@apple.com> wrote:

>  5. in section 4. it is not noted, how to animate
>> between keywords (they are mentioned
>> in 5. too). This will be the same as for
>> 'visibility'? Or are the keywords always
>> converted into numbers for the current
>> animatable properties (seems to apply
>> only to vertical-align).
> We'll have to define this for every keyword-based property. I'm not a big
> fan of these properties being animated anyway.
>  About paint-server - how to interpolate
>> between a radial and linear gradient?
>> Is the direction vector for linear gradients
>> interpolated too if different? Respectively
>> the cx, cy, fx, fy, r for a radial gradient?
>> What about gradientUnits, gradientTransform,
>> spreadMethod, xlink:href? Or is the interpolation
>> done for each pixel of the output separately?
>> I think, it needs some more explanations
>> how this should work.
> It's still up in the air how gradients should transition. For regular
> images, like background, they should probably crossfade (with the opacity
> used in the transition calculated by the timing function.. and the reverse
> for the outgoing image).

Or other transition effects, such as checkerboard, barn-door, shape-zoom,

> For gradients, in some cases it might be possible to animate - if they are
> similar enough. They would have to be the same type and have the same number
> of stops. However, some people think they should just be treated like images
> and crossfade.
>  6. in section 5. Animatable properties
>> the transform property seems to miss,
>> but in 4. it is noted, that this is animatable too.
>> Why not animation for 'display'? This is already
>> now quite popular to be changed with :hover,
>> I think more than for example 'visibility'
> Because it is unclear what the animation actually means. It isn't fadin?
> out like opacity. Also, what values do you use as a starting state when
> display was none.

If images can fade from one to the other to represent multiple states that
wouldn't normally wouldn't be represented in CSS (a list item marker would
normally only have one url() at a time), then let's go hog wild with how to
represent the midway states of other binary properties:

Visibility could fade as though it represented opacity of 0 or 100%.

'display:none' could be treated as though it was equivalent to 'width:0;
height:0; opacity:0;'.

To transition between 'position:static' and 'position:relative', you could
immediately switch the static to 'position:relative; left:0; right:0; top:0;
bottom:0; z-index:0;'.

> If people really want this, we can add it. For now, it's probably ok to
> fade out with an opacity transition then turn display off.
> Dean
Received on Tuesday, 31 March 2009 00:29:43 UTC

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