NEW210484
Ascent/descent of SVG Fonts converted using SVGToOTFFontConversion is wrong, breaking text selection 
https://bugs.webkit.org/show_bug.cgi?id=210484
Summary Ascent/descent of SVG Fonts converted using SVGToOTFFontConversion is wrong, ...
Nikolas Zimmermann
Reported 2020-04-14 02:34:52 PDT
Created attachment 396391 [details] Patch When comparing SVG Fonts converted to OTF using FontForge and using WebKits builtin SVGToOTFFontConversion it is evident that the HHEA table is incorrect. The ascent/descent (HheaAscent/HheaDescent) stored in the HHEA table is currently equivalent to the typographic ascent/descent, as specified in the SVGFontFaceElement. This is not correct, it should be computed as unite of the individual glyph bounding boxes. Currently this wrong behavior leads to broken text seleciton when using SVG Fonts. The text selection highlight is placed incorrectly. This is easiy visible when converting the SVG Font to OTF using e.g. FontForge and comparing the text selection rects.
Attachments
Patch (731.35 KB, patch)
2020-04-14 02:34 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (740.11 KB, patch)
2020-04-14 02:40 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (1.54 MB, patch)
2020-04-15 02:42 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (1.78 MB, patch)
2020-04-15 03:57 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (1.91 MB, patch)
2020-04-16 14:48 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (1.99 MB, patch)
2020-04-20 00:22 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (2.21 MB, patch)
2020-04-20 02:36 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (2.21 MB, patch)
2020-04-22 00:20 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Patch (2.21 MB, patch)
2020-04-22 08:44 PDT, Nikolas Zimmermann 		no flags
DetailsFormatted DiffDiff
Show Obsolete (9) View All Add attachment proposed patch, testcase, etc.
Nikolas Zimmermann
Comment 1 2020-04-14 02:40:17 PDT
Created attachment 396392 [details] Patch
Nikolas Zimmermann
Comment 2 2020-04-14 02:41:32 PDT
TODO: - Missing one reftest to compare SVG Fonts->OTF on-the-fly conversion vs. FontForge converted SVG Fonts - Expecations for mac (going through EWS to obtain them)
Nikolas Zimmermann
Comment 3 2020-04-15 02:42:00 PDT
Created attachment 396517 [details] Patch
Nikolas Zimmermann
Comment 4 2020-04-15 03:57:11 PDT
Created attachment 396519 [details] Patch
Nikolas Zimmermann
Comment 5 2020-04-16 14:48:21 PDT
Created attachment 396700 [details] Patch
Nikolas Zimmermann
Comment 6 2020-04-20 00:22:04 PDT
Created attachment 396956 [details] Patch
Nikolas Zimmermann
Comment 7 2020-04-20 02:36:42 PDT
Created attachment 396961 [details] Patch
Nikolas Zimmermann
Comment 8 2020-04-22 00:20:22 PDT
Created attachment 397176 [details] Patch
Nikolas Zimmermann
Comment 9 2020-04-22 08:44:35 PDT
Created attachment 397195 [details] Patch
Nikolas Zimmermann
Comment 10 2020-04-22 14:09:49 PDT
*sigh* I need access to a local Mac :-) This patch works flawlessly on Gtk/WPE (FreeType based font rendering) but shows issues on macOS, most noticeable on svg/text/kerning.svg, which is broken with the patch. Will investigate, no need to review until I get this sorted out.
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