Re: [svgwg] Replace <opacity-value> with <alpha-value> (#403)

The SVG Working Group just discussed `Percentages for alpha values`, and agreed to the following:

* ``RESOLVED: Define syntax of SVG `*-opacity` properties by reference to the `opacity` property``

<details><summary>The full IRC log of that discussion</summary>
&lt;AmeliaBR> Topic: Percentages for alpha values<br>
&lt;AmeliaBR> github: https://github.com/w3c/svgwg/issues/403<br>
&lt;AmeliaBR> Eric: This was added, but no one has implemented it. Only numbers are accepted.<br>
&lt;AmeliaBR> Chris: The complication is that it isn't SVG-only. Also want to keep coordinated with the rest of CSS.<br>
&lt;AmeliaBR> Dirk: We used to define the value in our own data type; now we reference the CSS type, but that includes the unimplemented value.<br>
&lt;AmeliaBR> Eric: Can we follow up with implementers and see if they're interested in adding this?<br>
&lt;AmeliaBR> Myles: I think we could implement it, but not a high priority.<br>
&lt;AmeliaBR> Amelia: We're currently referencing a CSS-defined data type, correct? Can we do it in a way that defers to CSS to update the allowed values when the implementations are there?<br>
&lt;AmeliaBR> Dirk: I don't think so. CSS Level 3 didn't have a single name for that.<br>
&lt;AmeliaBR> Eric: It shouldn't be hard to implement.<br>
&lt;AmeliaBR> Dirk: Then please do so in Blink, and we won't have to have as much discussion!<br>
&lt;AmeliaBR> Dirk: Tav, what about Inkscape?<br>
&lt;AmeliaBR> Tav: I'm currently looking up how hard it would be.<br>
&lt;AmeliaBR> Amelia: My only opinion is that the allowed values should stay consistent with CSS for the opacity property. Whatever we need to do to make that happen.<br>
&lt;AmeliaBR> Dirk: Could we make normative text that just refers to whatever is valid for the opacity property?<br>
&lt;ericwilligers> See https://drafts.fxtf.org/fill-stroke/#fill-opacity<br>
&lt;AmeliaBR> Eric: Yes, that syntax exists. I think it's just `&lt;opacity>` meaning, use the syntax for the opacity property.<br>
&lt;AmeliaBR> ... (pastes link above) that's what fill-opacity is defined as in Fill and Stroke module.<br>
&lt;AmeliaBR> RESOLVED: Define syntax of SVG `*-opacity` properties by reference to the `opacity` property<br>
&lt;AmeliaBR> Tav: What's the status of the opacity spec?<br>
&lt;AmeliaBR> Chris: It's in CSS Color. Parts of Color 4 are supported, but it's not expected to go to PR this year.<br>
&lt;AmeliaBR> Amelia: But important detail is that `opacity` already exists, with the more limited syntax (number only).<br>
&lt;AmeliaBR> Chris: Yes, so percentage support would hold up CSS Color advancing to rec, but not SVG.<br>
</details>


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Received on Monday, 3 December 2018 21:51:37 UTC