From 5ac8c19826a51d2780e4ab2e1822b521b36b41b1 Mon Sep 17 00:00:00 2001 From: Po Lu Date: Tue, 22 Aug 2023 21:42:06 +0800 Subject: [PATCH] Illustrate more font problems * etc/PROBLEMS (Runtime problems specific to Android): Mention problems with three other fonts users have inquired into. --- etc/PROBLEMS | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/etc/PROBLEMS b/etc/PROBLEMS index 131f8740845..c139f25e086 100644 --- a/etc/PROBLEMS +++ b/etc/PROBLEMS @@ -3453,6 +3453,47 @@ Then, reassemble the font from the modified XML: which should produce a modified font by the name of Anonymous_Pro#1.ttf. +** The "IBM Plex Mono" font displays incorrectly. + +This problem is precipitated by an attempt to exploit the undocumented +feature of the MS font scaler explicated within the previous heading. + +Its remedy is also unsurprisingly alike the fix described there: both +patching the preprogram to reset the point movement vectors and +replacing the instruction code with code generated by "ttfautohint" +will adequately resolve the problem. + +** Glyphs are missing within the "Arial" font or it does not load. + +On account of its origins at Microsoft, instruction code included +within this font is awash with references to behavior specific to the +MS scaler. It is incorrigibly broken, to a degree that even +"ttfautohint" cannot repair; your only recourse is to select some +other font. + +This issue may extend beyond Arial to encompass a larger selection of +fonts designed by Microsoft. + +** Some TrueType test fonts don't work. + +It is unlikely that any of these fonts will really prove useful for +text editing tasks, since they are designed for the express purpose of +testing a TrueType font scaler. The following explanation is present +only to satisfy a cat-like curiosity. + +Most TrueType test fonts "hide" points by moving them to a +preposterous location outside the confines of the glyph bounding box. +The Microsoft scaler and FreeType promptly disregard such points. + +Nothing in the TrueType specifications implies that points "hidden" in +this fashion should be afforded any special treatment, and thus Emacs +eschews doing so. Consequentially, black streaks are displayed as +Emacs interpolates glyph edges between points within the glyph and +points the test font attempts to hide. + +Since this behavior does not influence the display of real fonts, no +action will be taken to address this problem. + ** CJK text does not display in Emacs, but does in other programs. When inserting CJK text into a buffer or visiting a file containing -- 2.39.2