Implement 'align' attribute for <div> elements

[frewsxcv]

[highfive]

Warning

• These commits modify unsafe code. Please review it carefully!

[frewsxcv]

So I need a little help with this.

At the time of writing, this test fails after this pull request:
tests/wpt/metadata/html/rendering/non-replaced-elements/flow-content-0/div-align.html

I'm actually not even sure how it was passing prior to this getting implemented. I'm guessing it fails now because this isn't implemented? If anyone has any thoughts, please let me know, thanks.

[eefriedman]

See

servo/resources/presentational-hints.css

Line 10 in ab42ca4

div[align=left i] { text-align: -servo-left; }

. See also #7825.

I don't think there's any reason to move the rendering rule from presentational-hints.css to synthesize_presentational_hints_for_legacy_attributes.

[nox]

I don't think there's any reason to move the rendering rule from presentational-hints.css to synthesize_presentational_hints_for_legacy_attributes.

Not all presentational hints can be expressed through CSS, though.

[frewsxcv]

Will those CSS hints work correctly with the IDL/content getters/setters? Also, align=center is not part of the spec

[nox]

@frewsxcv You sure?

The center element, and the div element when it has an align attribute whose value is an ASCII case-insensitive match for either the string "center" or the string "middle", are expected to center text within themselves, as if they had their 'text-align' property set to 'center' in a presentational hint, and to align descendants to the center.

[nox]

@frewsxcv I'm pretty sure you can just implement reflecting IDL getters and setters and consider that attribute to hold onto a plain old string.

[nox]

@frewsxcv For other presentational hints, like the one related to the non-zero table border, or fancy color attributes that need to be parsed, we can't avoid going through the synthesis machinery, but I'm pretty sure we prefer going through CSS for the simpler one, as mentioned by @eefriedman.

[frewsxcv]

You're right. I totally glossed over that first paragraph because I thought it only applied to center elements

[frewsxcv]

Thanks all for the help, very helpful information to know :)

Force push incoming...

[frewsxcv]

Ready for review

[mbrubeck]

Reviewed 4 of 4 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks pending.

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Comments from the review on Reviewable.io

[mbrubeck]

@bors-servo r+

[bors-servo]

📌 Commit 55c65d3 has been approved by mbrubeck

[bors-servo]

⌛ Testing commit 55c65d3 with merge 0dd6556...

[bors-servo]

💔 Test failed - mac-rel-wpt

[frewsxcv]

@bors-servo retry

• #7731

[bors-servo]

⌛ Testing commit 55c65d3 with merge babeed9...

[bors-servo]

☀️ Test successful - android, gonk, linux-dev, linux-rel, mac-dev-ref-unit, mac-rel-css, mac-rel-wpt