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Re: [css-masking] 'mask-source-type' and 'mask-type'

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 11 Dec 2013 09:46:37 -0800
Message-ID: <52A8A4FD.6040108@inkedblade.net>
To: www-style@w3.org
On 12/11/2013 08:12 AM, Dirk Schulze wrote:
>
> On Dec 11, 2013, at 11:46 AM, fantasai <fantasai.lists@inkedblade.net> wrote:
>
>>    8. Does 'mask-source-type' apply to 'mask-box-image-source'?
>>       It's not clear from the spec. (See editorial issue #8, of
>>       which this seems to be a symptom.)
>
> No, it does not. That is one reason why it is not mask-box-image-type.
> mask-box-image just supports alpha masking at the moment. Since you
> can apply mask-box-image and mask-image on an element, it wouldn’t
> make sense to have the same property set the mask type for both.

I don't disagree with you, but please make sure this is clear when you
fix editorial issue #8.

>>     If it doesn't:
>>       8.A.1 Having its name match mask-x-type per issue #1 would
>>             help clarify that relationship.
>>       8.A.2 This raises the issue of whether we need a mask-y-type.
>
> This will not part of the discussion in this thread. (See [css-masking]
> Comments.)

I don't think 8.A.2 was covered in that other thread.

>>     If it does:
>>       8.B.1 I should be pulled out into the same section as the
>>             'mask' shorthand, since they both apply to both types
>>             of masking.
>>       8.B.2 Also, in this case, I'd like to reraise the question of
>>             whether mask-source-type and mask-type should be merged.
>>             I think it would be less confusing if there was just one
>>             property and its value at the point of application overrode
>>             its value at the point of source definition, the same way
>>             the 'width' property does.
>
> I take the question to merge 'mask-source-type' and 'mask-type’.
>
> Both properties apply to different element. ‘mask-source-type’ applies
> to SVG graphical element, SVG containers and HTML elements. mask-type
> applies to SVG mask elements exclusively.
>
> In the following I describe the reasons why they are separate properties:
> * mask-type defines the type (luminance|alpha) of the <mask> element.
>   The author of the mask defines the preferred type for the created mask.
> * mask-source-type interacts with mask-type: a preference from the author
>   of the mask element can be overruled by the author of the document. The
>   spec has an example where this can make sense. Note: the mask can be in
>   a different document, written by a different author.
> * mask-source-type has a value auto to chose the preferred masking type
>   of the SVG mask.

Fwiw, this is pretty much exactly the relationship between the 'width'
property on a replaced element and the 'width' property on an <svg>
root. That is, you get the same interaction as I was proposing for
'mask-type' on an element referencing a <mask> and the <mask> itself
as you do for 'width' on an element referencing an external SVG and
the <svg> itself.

However, we're in the wrong if-clause here. anyway. :)

> * mask and its longhands do not apply to the mask element. A special
>   casing of mask-source-type seems strange.
> * mask-type stays a single item property. mask-source-type is designed
>   for a layer based mask, which will happen eventually - in the next
>   version of the spec.

[These two reasons I'd accept as valid.]

~fantasai
Received on Wednesday, 11 December 2013 17:47:06 UTC

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