Re: animation in SVG-in-OT glyphs

On Sun, Nov 18, 2018 at 1:29 AM Myles C. Maxfield <mmaxfield@apple.com>
wrote:

> The trouble with animation is it requires a retained-mode drawing model
> like an HTML DOM or a UIKit view hierarchy. These systems are built on top
> of text engines, which are usually immediate-mode.
>
> Currently, people describe font animations as using a higher-level
> framework to animate a variation axis/axes. I wonder what use cases this
> approach doesn’t satisfy. Adding variations in OT-SVG, rather than
> animation, would likely fit the bill, would would also be compatible with
> existing immediate-mode graphics APIs.
>

I think there are some fairly reasonable use cases it wouldn't cover such
as allowing a different animation duration based on the glyph. At least I
can see the animated emoji in Skype have different durations.

If the font author wants to define an animation for a glyph 'a' that has a
cycle of 1s, and an animation for a glyph 'b' that has a cycle of 2s, then
in order to achieve that with variation axes, I imagine the content author
would need to do a reverse mapping from glyphs to code points (likely
breaking ligatures etc. along the way) and then wrap each character in a
<span> with the appropriate class. (And if the text is editable such as for
emoji in a messaging app then it would become a contenteditable nightmare.)


> I’m not quite sure what you mean by “typographically sound.” All animation
> systems that I know of (CSS animations, SMIL, CoreAnimation, etc.) are all
> designed such that the object graph at any point in the animation is
> representable outside of an animation. Are you suggesting flipbook-style
> animations with cross-fades?
>

That's not quite true, but it probably should be. (For example, we have
special internal notation for representing the intermediate state of
interpolating 'currentColor' with something else, or mismatched transform
lists when percentages are involved.)

Brian

>