- From: jdaw1 via GitHub <noreply@w3.org>
- Date: Mon, 16 Mar 2026 20:27:33 +0000
- To: public-svg-issues@w3.org
jdaw1 has just created a new issue for https://github.com/w3c/svgwg: == `baseline-y` in SVG == ## Whereas ## Assume a set of [beautiful chart markers](https://github.com/jdaw1/chart_markers/blob/main/Documentation/ChartMarkers_Gallery.md), hand‑coded in SVG. So far, so fabulous. These are to be used on charts. Hence the centre of each bounding‑box must equal the optical centre of the marker. Hence for an odd‑number‑pointed star in usual orientation, such as , there must be some empty space at the bottom ([explanatory images](https://github.com/jdaw1/chart_markers/blob/main/Documentation/ChartMarkers_Code.md#centres)). <div align="center">  </div> ## Problem ## But that means that when used as an item in text, it seems to sit above the line. So each marker has an alternate SVG, with a ‘tight’ bounding box. Compare the previous and the tight‑box versions:  ,  ,  ,  . But even they are imperfect. In a typical font, flat‑bottomed characters (e.g., H, L, M, N, R, X, Z) sit on the baseline, but round‑bottomed characters (C, G, J, O, S, U) slightly [underhang](https://typetype.org/typography-terms/#wd_overhang) beneath the baseline, such that the intersection with the baseline is of non‑zero length. A five‑pointed star should likewise sit slightly below the baseline. This is not currently achievable. ## Suggestion ## The natural solution is for the svg container, with which an SVG starts, to allow an optional element `baseline-y`, being the viewport *y* position of the baseline on which the SVG is to sit when used in text as if a glyph. This would allow one SVG to do both my tasks, and to do the second task more beautifully. And it would fail elegantly: if not understood by the renderer, the image would show as now: slightly mis-positioned, but showing. ## CJKV variation ## This suggestion could have a variant — but I lack relevant expertise. From the [PostScript Language Reference Manual third edition](https://www.adobe.com/jp/print/postscript/pdfs/PLRM.pdf#page=346) (1999), p332: > In some writing systems, text is frequently aligned in two different directions. For example, it is common to write Japanese and Chinese glyphs either horizontally or vertically. To handle this, a font can optionally contain a second set of metrics for each glyph. So perhaps also allowed should be `baseline-x`, being the viewport *x* position of the baseline for when used as a glyph in vertical writing. But this is not in my parish: I have no expertise in CJKV Asian writing systems. <div align="right"> <i>— [JDAW](https://www.jdawiseman.com/author.html), London<br/>16<small><sup>th</sup></small> March 2026</i> </div> Please view or discuss this issue at https://github.com/w3c/svgwg/issues/1075 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Monday, 16 March 2026 20:27:34 UTC