Re: transform as a presentation attribute [was: Re: [whatwg] SVG cloning elements from HTML5]

Dear Dirk Schulze, hello world,

Dirk Schulze wrote:
>> Tab Atkins Jr. wrote:
>>> On Mon, Jun 23, 2014 at 9:35 PM, Dirk Schulze <dschulze@adobe.com> wrote:
>>>> On Jun 24, 2014, at 5:25 AM, Robert O'Callahan <robert@ocallahan.org> wrote:
>>>>> 4) Add a "transform" attribute to HTMLElement and have it map to the
>>>>> "transform" CSS property.
>>>> In this case we should think about making transform a presentation attribute in general for HTML and SVG.
>>> That's effectively what it would do, yes.
>> Hey, that's a nice proposal - transform as a presentation attribute in SVG! Why? What would that mean?
> 
> This is not a proposal anymore. It is already specced for SVG elements and partly implemented in WebKit, Blink and Firefox. The relevant spec is CSS Transforms[1]. The discussion here is about extending it to all HTMLElements as well. It seems unlikely that content uses the ítransformí attribute in HTML today.
> 
> [...]
> 
> [1] http://dev.w3.org/csswg/css-transforms/

Probably I did not read your former EMail carefully enough, so I did not 
pay attention to the following statement:
> It is already specced for SVG elements and [...]

Poooh, really? What's the status of the "spec"? It's "Editorís Draft, 28 
May 2014" ... what does that mean? In my understanding, this is _not_ a 
"standard" (whatever might be called "standard", these days), at least. 
And may new drafts easily change existing standards without mentioning 
the changed status in the "old", but now implicitely altered standard? 
Since in the relevant SVG standard, I do not see any mentioning of that 
change in the respective chapters, not even in the errata 
[http://www.w3.org/2011/08/REC-SVG11-20110816-errata].

And from the quoted statements above ...
>>>> In this case we should think about making transform a presentation attribute in general for HTML and SVG.
>>> That's effectively what it would do, yes.
... I read at least that transform is not a presentation attribute in 
some cases of HTML and SVG. In which cases is it not a presentation 
attribute? For HTML, where you would probably use transform as a pure 
means of presentation, it is not a presentation attribute, but for SVG, 
where you need transform essenatially for its functionality, e.g. in 
order to paint an ellipse which axis' are not aligned 
horizontally/vertically, it is just "presentation"? Who thought about 
that, and what is the reason?

And if I read further in that "spec", I even see other passages which 
make me freeze (13.2):
> Therefore an author should write "transform="translate(200px, 200px)" instead of transform="translate (200 200)" because [...]

But translation in SVG is not a simple modification of a position on a 
screen (wherever this might be, finally), but it is a specific change of 
the object's position in the coordinate system, and the latter is not 
measured in pixels at all! I may make 1 (one) coordinate system unit be 
of size 1px, 42px, 4711px, or even just 0.0815px, dependent on the 
viewbox, scaling of containing elements, and resolution of the output 
device. And now I get told that I should use a unit "pixel" for that? 
Incredible!

Please, tell me that this "spec" will never become a recommendation!

Juergen Roethig

Received on Tuesday, 24 June 2014 16:01:24 UTC