Re: [css3-animation] why content property not animatable?

On Thu, Oct 2, 2014 at 3:43 AM, Tim Larson <> wrote:
> Background: I had the idea recently to implement a simple "busy spinner" using text. Cycling through a sequence like the characters U+25F0 through U+25F3, or even 0 through 9, seems like a good way to convey this idea. Using text eliminates the need for downloading an image, and this would also theoretically be possible in a console UA.
> So after I'd whipped up the @keyframes declaration to try it out, I was surprised to notice that the content property is not animatable. Why is that? Of course, one could code it up in JS, but it would be so much simpler to do it declaratively, this ought to be a CSS solution.
> I've been trying to find the answer to why some properties can be animated but others cannot. Perhaps some just wouldn't make sense, but this one does.

Originally we only made properties animatable if they lived in a
reasonable metric space - we needed some way to compute distance and
represent intermediate values at all points of the animation.  This
covers everything whose value is a number or number-like things (such
as colors).

We've planned for some time to allow all properties to be animatable,
even when they don't have a metric.  Instead, they'd just switch from
their start to end value halfway through the timing-function progress.
This is still the plan of record, but nobody's tried out the
implementation yet to see if there are any compat issues that we'd
have to address.


Received on Wednesday, 8 October 2014 17:36:15 UTC