W3C home > Mailing lists > Public > public-css-bugzilla@w3.org > February 2012

[Bug 16016] New: Place some constraints on when computed values must be deemed to change

From: <bugzilla@jessica.w3.org>
Date: Fri, 17 Feb 2012 17:16:35 +0000
To: public-css-bugzilla@w3.org
Message-ID: <bug-16016-5148@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=16016

           Summary: Place some constraints on when computed values must be
                    deemed to change
           Product: CSS
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Transitions
        AssignedTo: dino@apple.com
        ReportedBy: ayg@aryeh.name
         QAContact: public-css-bugzilla@w3.org
                CC: cmarrin@apple.com, eoconnor@apple.com, smfr@me.com


"""
Since this specification does not define when computed values change, and thus
what changes to computed values are considered simultaneous, authors should be
aware that changing any of the transition properties a small amount of time
after making a change that might transition can result in behavior that varies
between implementations, since the changes might be considered simultaneous in
some implementations but not others.
"""
http://dev.w3.org/csswg/css3-transitions/#starting

I understand that we don't want to spec this precisely, but can we at least
place some constraints?  It's not possible to test transitions if browsers are
allowed to say that changes after setTimeout(..., 10000) are considered
simultaneous by their implementation.  :)

Basic test script:

data:text/html,<!doctype html>
<body>
<script>
var div = document.createElement("div");
div.textContent = "The quick brown fox jumped over the lazy dog";
div.style.transition = "5s color";
document.body.appendChild(div);
div.style.color = "green";
</script>

Tested browsers: IE10 Developer Preview, mozilla-central build from 2012-02-17,
Chrome 18 dev, Opera Next 12.00 alpha.

* No transition in any browser for the basic test.
* Adding "getComputedStyle(div);" before the last line: still no transition in
any browser tested.
* Adding "getComputedStyle(div).color;" before the last line: IE still does not
transition.  Other browsers transition.
* Adding "</script><script>" before the last line: no transition in any browser
tested.
* Wrapping the last line with "setTimeout(function(){" ... "}, 0)": transition
in every browser tested.
* Wrapping the last line with "onload = function(){" ... "}": IE does not
transition.  Other browsers transition.

Can we at least require that if you make a change, then a setTimeout() function
makes another change, they can't be simultaneous?  There should be at least one
way for authors to change styles and know it's not simultaneous.

-- 
Configure bugmail: https://www.w3.org/Bugs/Public/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
Received on Friday, 17 February 2012 17:16:42 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 17 February 2012 17:16:42 GMT