Re: [fxtf-drafts] [motion] contain should modify percentages, not path

The spec currently has
"Defining a path with \<angle\>, the element can be positioned with 
the used of polar coordinates. "

The suggestions in #61 and #73 would each prevent polar positioning: 
the distance that a given percentage translates to would depend on the
 direction.

Here is a server-side implementation of CSS Motion Path for rays, 
based on my understanding of the current spec:  https://goo.gl/32E9Vq
Example without contain: https://goo.gl/1IpMxH
Example with contain: https://goo.gl/sE0yvA

The examples use
`offset: ray(45deg) 100% 0deg OR ray(45deg contain) 100% 0deg`
`offset: ray(180deg) 100% 0deg OR ray(180deg contain) 100% 0deg`
`offset: ray(120deg) -120% 0deg OR ray(120deg contain) -120% 0deg`

The clamping for 'contain' happens at the last possible moment, and 
takes into account the offset-rotation and the offset-anchor. Whenever
 offset-distance is sufficiently small, 'contain' has no effect on the
 interpretation of percentages, and we achieve polar coordinates.




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Received on Tuesday, 8 November 2016 06:37:49 UTC