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Re: unitless angles (and times and frequencies) [css3-2d-transforms][css3-3d-transforms][css3-images]

From: Simon Fraser <smfr@me.com>
Date: Thu, 05 Nov 2009 06:59:48 -0800
Cc: "L. David Baron" <dbaron@dbaron.org>, www-style@w3.org
Message-id: <4240BEE6-02FF-4540-90A4-3AD87C427CD6@me.com>
To: Giovanni Campagna <scampa.giovanni@gmail.com>
On Nov 5, 2009, at 5:42 am, Giovanni Campagna wrote:

>>
> Angles can be used only in rotate / skew.
> rotate(0), rotateX(0), rotateY(0), rotateZ(0), rotate3d(x,y,z,0),
> skewX(0) and skewY(0) are all identity transforms, so I guess they're
> not used much

Actually they are, to specify the initial state of transitions or  
animations
when you want the end state to have a matching list of transform  
functions
so that you don't fall into the "matrix decomposition" path for  
animations.

See
<http://www.w3.org/TR/2009/WD-css3-2d-transforms-20090320/#animation>

> the only difference is in skew(0,y) or skew(x,0), which could be
> replaced by appropriate skewX / skewY
>
> IHMO, allowing unit-less angles in transforms and only in transforms
> would introduce additional complexity on implementers without any
> clear advantage to authors, that would use 0rad or 0deg anyway, for
> consistency with the rest of CSS

I disagree; there's very little additional complexity (in WebKit at  
least).
The decision to allow unitless 0 is made per property.

Simon
Received on Thursday, 5 November 2009 15:00:35 GMT

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