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Re: [css-masking] 'mask: none' clear all masking operations

From: Dirk Schulze <dschulze@adobe.com>
Date: Sun, 9 Jun 2013 11:40:54 -0700
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: fantasai <fantasai.lists@inkedblade.net>, www-style list <www-style@w3.org>, "public-fx@w3.org" <public-fx@w3.org>
Message-ID: <0B5B377F-44A2-471B-AF09-F2CE36AD3218@adobe.com>

On Jun 9, 2013, at 11:26 AM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:

> On Sun, Jun 9, 2013 at 1:09 PM, Dirk Schulze <dschulze@adobe.com> wrote:
>> On Jun 9, 2013, at 1:04 PM, "Tab Atkins Jr." <jackalmage@gmail.com> wrote:
>>> On Sat, Jun 8, 2013 at 7:34 PM, Dirk Schulze <dschulze@adobe.com> wrote:
>>>> Hi,
>>>> 
>>>> I had a chance to discuss this topic with fantasai during the CSS F2F. fantasai suggested that the 'mask-*' properties get a new shorthand property (maybe 'mask-layer'?). 'mask' itself would reset the 'mask-layer' and 'mask-box-image' properties and would itself have a reasonable setting.
>>>> 
>>>> Based on this idea, a syntax proposal could look like this:
>>>> 
>>>> 'mask' = none | <url> [alpha | luminance]?
>>>> 
>>>> - 'none' is the initial value in current implementations
>>>> - If 'mask' is set all mask properties (including 'mask-box-image-*' and 'mask-*') are reset to the initial value.
>>>> - '<url>' can just be used to reference <mask> elements, as it is defined SVG 1.1 and implemented in all browsers.
>>>> - 'mask' will not be a shorthand
>>>> 
>>>> The old 'mask' shorthand will be renamed to 'mask-layer' and all 'mask-*' longhands to 'mask-layer-*' (or a better name if there is one).
>>>> - 'mask-layer-image's '<url>' will just support CSS Images, no references to <mask> elements possible.
>>> 
>>> I'm not entirely sure I understand.  'mask' isn't a shorthand?  What
>>> exactly does it do, then?  Is it just like 'mask-layer', but with a
>>> different value space for <url>, and only supporting one layer?
>> 
>> No layer at all. It is just the normal SVG Masking from SVG 1.1. But with setting the value to none, it resets all masks.(Including CSS Masking from WebKit.) This is similar to border, which resets all settings on border-image.
> 
> But "none" is the initial value.  If 'mask' isn't a shorthand, then
> it's *always* none by default, which under your described semantics
> would prevent any of the other mask-* properties from working.

I am not sure if I can follow you here. mask and mask-box-image are two different shorthands with separate long hands at the moment. The one does not affect the other. Even if the initial value is none. Fantasai asked to make mask:none reset all masking operations, which is different from the current specification and implementation in Blink and WebKit. For The rest of the proposal see the initial mail.

Dirk 

> 
> You can't get the shorthand behavior where it only has the reset
> effect if *specified* unless it's actually a shorthand.  Otherwise,
> you have to rely on computed-value-time transformations, which always
> apply.
> 
> ~TJ
Received on Sunday, 9 June 2013 18:41:25 UTC

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