694834 - CSS Transition from 'normal' to a length not working for letter-spacing property

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[nick]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1
Build ID: 20110928134238

Steps to reproduce:

CSS styling as follows (FYI was on a H2 tag)

-moz-transition: letter-spacing 0.3s ease-in-out, color 0.3s ease-in-out, text-shadow 0.3s ease-in-out;


Actual results:

color and text-shadow transitions occur as expected, letter-spacing doesn't (jumps directly to new CSS property with no animation)


Expected results:

In this case the letter-spacing is set to increase so the text should have gradually got wider rather than immediately jumping to the final value.

Comment 1

[j.j.]

Should work but we have bug 585831.
Please provide a URL or attach a testcase (use the "Add an attachment" link above).

Comment 2

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

letter-spacing should transition correctly between two length values, but we don't support transitions betweeen 'normal' and lengths.

(For 'letter-spacing', 'normal' and '0' are not quite the same thing; for 'word-spacing' it turns out they are, but we still treat them differently for purposes of animation... which does match the spec, I think.)

Comment 3

[Boris Zbarsky [:bzbarsky]]

Confirming, but it's not clear to me that there's a good way to define this to work...

Comment 4

[nick]

Confirmed that this works fine once an initial letter-spacing property is set (in this instance both 0em and 0.1em work).  This is fine for my purposes but may want documenting.  J.j - still need me to file a test case ?

Comment 5

[j.j.]

Why isn't this just a dup of bug 585831?

Comment 6

[nick]

I think it is, I just wasn't aware of that bug when I filed this (my initial search criteria were "css transitions letter spacing" - I actually wasn't aware that no value == normal).  Apologies if I've caused extra work but the MDN transitions page does state that letter-spacing is fully supported.

Comment 7

[Jean-Yves Perrier [:teoli]]

I've fixed the MDN documentation on that page: https://developer.mozilla.org/en/CSS/CSS_transitions (for the 4 concerned properties).

Comment 8

[nick]

Cheers for this and sorry to quibble, but it should specifically say that those properties should be set (to 0, or indeed anything) initially, for transitioning to occur - 585831 makes no reference to this and you shouldn't expect people who haven't read the spec to know that 'normal' is the actual default value - as I said, I didn't and I've been doing this for a couple of years.

Comment 9

[j.j.]

>> Why isn't this just a dup of bug 585831?
> I think it is
This was a question for Boris.

> Apologies if I've caused extra work
Absolutely no reason to apologize. Thank you for your bug report! 

> I actually wasn't aware that no value == normal)
See  https://developer.mozilla.org/en/CSS/letter-spacing
(second information on this page :-)

> but it should specifically say that those properties should be set
I updated  https://developer.mozilla.org/en/CSS/CSS_transitions
BTW, MDN docs are a wiki and everybody can improve it. Feel free!

Comment 10

[nick]

Doh! RTFM! ;-)

TBH I didn't feel qualified to, but perhaps I can add value so I'll potentially reconsider.

Many thanks again for the prompt and successful resolution :)