Bug 58140

Summary: Support transitions to and from 'auto' values of left, top, width, height, etc.
Product: WebKit Reporter: gossi <mail>
Component: CSSAssignee: Nobody <webkit-unassigned>
Severity: Normal CC: davidbarr, david.b.calhoun, shanestephens
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: PC   
OS: OS X 10.5   

Description gossi 2011-04-08 06:25:51 PDT
Please support transitions to auto values. Like a transition from height: 0; to height: auto;

I attached such a non-yet-working example.

See also Mozilla's Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=571344

Comment 1 David Calhoun 2011-10-03 13:41:29 PDT
The way this works now seems like a bug.

Current behavior:
A transition from a specific height to height:auto will result in the element animating to height:0 and only then jumping down immediately to height:auto.

Expected behavior:
A transition from a specific height to height:auto should result in a smooth transition to the value calculated by height:auto.  The height:auto calculation shouldn't occur after the transition.
Comment 2 David Barr 2011-10-12 21:07:48 PDT
Tested with WebKit nightly (r97312) and test suite,

The 5th test, which corresponds to this bug report:
...the initial value of an animated property is 'auto'
I expect the property to be animated properly."
passed, so this bug is resolved at or before r97312.
Comment 3 Shane Stephens 2012-01-04 19:54:49 PST
Marking this as resolved. Although the current behaviour may not seem ideal, the specification (http://dev.w3.org/csswg/css3-transitions/) doesn't deal with what happens when animating to/from auto at all. It's better to discuss this issue on www-style@w3.org and wait for a specified behaviour to exist than to debate in this bug.