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RE: when do transitions occur?

From: Brian Manthos <brianman@microsoft.com>
Date: Fri, 16 Sep 2011 10:29:07 +0000
To: Øyvind Stenhaug <oyvinds@opera.com>, Tab Atkins Jr. <jackalmage@gmail.com>
CC: "L. David Baron" <dbaron@dbaron.org>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <9710FCC2E88860489239BE0308AC5D17162EE7@TK5EX14MBXC266.redmond.corp.microsoft.com>
Øyvind:
> On Thu, 15 Sep 2011 21:48:43 +0200, Tab Atkins Jr.
> <jackalmage@gmail.com>
> wrote:
> 
> > On Thu, Sep 15, 2011 at 2:41 AM, Brian Manthos
> <brianman@microsoft.com>
> > wrote:
> 
> >> Example D (CSS3)
> >>        from    { text-shadow: 1px 2px 3px red; }
> >>        to      { text-shadow: 1px 2px 3px blue; }
> >>
> >> Example E (CSSn, where n > 3)
> >>        from    { text-shadow: 1px 2px 3px pink; text-shadow-color:
> red;
> >> }
> >>        to      { text-shadow: 1px 2px 3px cyan; text-shadow-color:
> >> blue; }
> 
> >> CSS3 browser - Example D
> >> 1. text-shadow event ("1px 2px 3px red" -> "1px 2px 3px blue")
> >>
> >> CSS3 browser - Example E
> >> 1. text-shadow event ("1px 2px 3px pink" -> "1px 2px 3px cyan")
> >>
> >> CSSn browser - Example D
> >> 1. text-shadow event ("1px 2px 3px red" -> "1px 2px 3px blue")
> >> 2. text-shadow-color event ("red" -> "blue")
> >>
> >> CSSn browser - Example E
> >> 1. text-shadow event ("1px 2px 3px red" -> "1px 2px 3px blue")
> >> 2. text-shadow-color event ("red" -> "blue")
> >
> > Agreed with all of these - this is the only way I can see it working
> > sanely with the possibility of turning properties into shorthands in
> > the future.
> 
> So a shorthand value is constructed based on the cascaded longhand
> values
> (or something like that). What if that's not possible? No event?

Definitely not "No event".

Look back at my examples.  BOTH the shorthand and the longhand should be sent in CSSn D & E.


> E.g.
> 	from	{ border: solid; }
> 	to	{ border: dotted; border-left-style: none; }

Let's call this Example F.  Some shorthand values *can* be constructed in this case, just not the border shorthand.  And even though you can't construct a border shorthand, an event should fire for it.

CSS3 browser - Example F:
1. border event ("solid" -> "")
2. border-top event ("solid" -> "dotted")
3. border-right event ("solid" -> "dotted")
4. border-bottom event ("solid" -> "dotted")
5. border-left event ("solid" -> "none")
6. border-style event ("solid" -> "dotted dotted dotted none")
7. border-top-style event ("solid" -> "dotted")
8. border-right-style event ("solid" -> "dotted")
9. border-bottom-style event ("solid" -> "dotted")
10. border-left-style event ("solid" -> "none")

Again, note that the first event's end state of "" is because the shorthand cannot be represented.


I think of it in somewhat simple terms.

Conceptually...
1. Query all CSS properties (including shorthands) @ the from state
2. Query all CSS properties (including shorthands) @ the to state
3. Diff the results of 1 and 2
4. Any properties (including shorthands) that show differences from step 3 should have an event fire


A somewhat simpler border example might make it clearer.

Example G
	from	{ border: solid; }
	to	{ border: solid; border-left-style: none; }

CSS3 browser - Example G:
1. border event ("solid" -> "")
2. border-left event ("solid" -> "none")
3. border-style event ("solid" -> "solid solid solid none")
4. border-left-style event ("solid" -> "none")


So the most concise form that strikes me at the moment is, events should fire for both:
A. longhand properties that change
B. all shorthand properties that contain entries from A



Received on Friday, 16 September 2011 10:29:47 GMT

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