W3C home > Mailing lists > Public > public-fx@w3.org > April to June 2012

Re: [css3-transforms] 7.2. Syntax of the SVG ‘transform’ attribute

From: Dirk Schulze <dschulze@adobe.com>
Date: Sat, 21 Apr 2012 07:51:50 -0700
To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
CC: "www-style@w3.org" <www-style@w3.org>, "public-fx@w3.org" <public-fx@w3.org>
Message-ID: <8B2F9296-446A-4FCD-BD7F-455C3DC83DF4@adobe.com>
Hi,

On Apr 21, 2012, at 7:30 AM, "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de> wrote:

> Hello,
> 
> this is about 
> http://www.w3.org/TR/2012/WD-css3-transforms-20120403/#svg-syntax

> 
> It notes:
> [To provide backwards compatibility, the syntax of the ‘transform’ 
> presentation attribute differs from the syntax of the ‘transform’ style 
> property as shown in the example above. However, the syntax used for 
> the ‘transform’ style property can be used for a ‘transform’ presentation 
> attribute value. Authors are advised to follow the rules of CSS Values and 
> Units Module. Therefore an author should write ‘transform="translate(200px, 
> 200px)"’ instead of ‘transform="translate (200 200)"’ because the second 
> example with the spaces before the ‘(’, the missing comma between the 
> arguments and the values without the explicit unit notation would be valid 
> for the attribute only.]
> 
> Because in SVG 1.1 and SVG tiny 1.2 all numeric values for transform
> are numbers, it is obviously for backwards compatibility a bad idea to
> add any units, because this will/should not work in proper older/curent
> viewers.


This specification wants to provide backwards compatibility to SVG 1.1, not to older viewers. If we consider that new content must work on older Viewers, we can't include any new feature at all. 

Dirk

> And typically it is widely recommended best practice for SVG anyway to 
> use no units at all within the content to avoid confusion and problems.
> 
> Therefore I suggest to change this section to something like this:
> [To provide backwards compatibility, the syntax for the ‘transform’ 
> presentation attribute and the syntax for the ‘transform’ style property
> differ from each other as shown in the example above. 
> However, the syntax used for the ‘transform’ style property can be used 
> for a ‘transform’ presentation attribute value, if backwards compatibility 
> does not matter. 
> 
> Authors are recommended to avoid any units for the transform
> attribute, if backwards compatibility matters. To be on the safe side an
> author should write ‘transform="translate(200, 200)"’ instead 
> of ‘transform="translate(200px, 200px)"’ or ‘transform="translate (200 
> 200)"’, because the third example with the spaces before the ‘(’, the missing 
> comma between the arguments and the values without the explicit unit notation 
> would be valid for the attribute only. The second example with units however 
> does not fit to the definition of transform in previous SVG recommendations 
> and should be avoided for backward compatibility.
> Note that for the attribute scientic notation is available as well:
> ‘transform="translate(1e6, 3e5)"’. ]
> 
> Additionally one could add the precise Backus-Naur Form (BNF)
> to decribe precisely, what is correct for the attribute.
> 
> 
> Best wishes
> 
> Olaf
> 
Received on Saturday, 21 April 2012 14:52:23 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 21 April 2012 14:52:23 GMT