[svgwg] Issue: Alignment point for text should not depend on “script” (#629) marked as Text chapter

dirkschulze has just labeled an issue for https://github.com/w3c/svgwg as "Text chapter":

== Alignment point for text should not depend on “script” ==
> alignment point
>    The point on a typographic character that should be aligned with the current text position. It is determined by the glyph cell metrics and may depend on the script and inline-base direction. 

> Glyphs are positioned relative to a particular point on each glyph known as the alignment point. For horizontal writing-modes, the glyphs' alignment points are vertically aligned while for vertical writing-modes, they are horizontally aligned. The position of the alignment point depends on the script. For example, Western glyphs are aligned at the bottom of capital letters, northern indic glyphs are aligned at the top of a horizontal stroke near the top of the glyphs, and far-eastern glyphs are aligned either at the bottom or center of the glyph. 

That last sentence in particular is complete nonsense. It would mean that for a text with a given y position, Latin characters would sit on the baseline, CJK characters would be pushed up a bit higher, and indic glyphs would be dropped below the baseline. Luckily that doesn't seem to actually happen in implementations. (Also, how is the spec expecting the UA to determine the "script" of a glyph? Sure letters can belong to a specific writing system, but punctuation doesn't.)

The alignment point in the block axis should be based on the `alignment-baseline` and `dominant-baseline` properties. That's what they're for.

See https://github.com/w3c/svgwg/issues/629

Received on Monday, 21 January 2019 18:06:26 UTC