(Chapa 1)


Emacs Glyphs (and their bugs)

I probably shouldn't, but I like Emacs glyphs too much...
and I've been convincing some people to like them too, with some success.
This page is to explain some bugs in the rendering of some glyphs.
Click on the screenshots to enlarge.

Quick index:

1. The red star glyph

...is essential for eev, and it works very well - no bugs.
Here is an explanation of what are the red stars, taken from the tutorial for eepitch:

Red stars
Eepitch.el sets the glyph for the char 15 to a red star in the
standard display table. In layman's terms: eepitch.el tells Emacs
that the character 15 should be displayed as a red star. The
character 15 corresponds to control-O, whose default
representation on screen would be "^O".. You can enter a
literal ^O in a buffer by typing C-q C-o.

The best way to understand how these red stars are used is watch a video called "eepitch: a way to control shell-like programs from Emacs" (links here). The main ideas appear in these screenshots,

and in the eepitch tutorial.

2. Glyphs for formfeed, backspace, and friends

I used to set by default all these glyphs in the screenshot below - click to enlarge.

Note that there's one for formfeed, another for backspace, etc - then I realized that these are just cosmetic changes, that shouldn't be forced on users. Only two of them are important - the green guillemets, «».

3. The green guillemets (glyphs for anchors)

Almost all of my big files are indexed using "«»"s to mark anchors, and sexp hyperlinks like these to jump to anchors:

(find-angg ".emacs" "figlet")
(find-angg "LATEX/2010diags.tex" "pres-frob-bcc")
(find-blogme3 "anggdefs.lua" "eev_math_glyphs_edrx")

The idea of "anchors" is explained here,

and here is a test - but note that my htmlizer
also colors in green, for emphasis, the stuff
between "«" and "»":

  «upper-anchor»   (to "middle-anchor")
  «middle-anchor»  (to "lower-anchor")
  «lower-anchor»   (to "upper-anchor")

The screenshot at the left below shows how these green guillemets appear in a non-buggy Emacs (Emacs23); the one at the right shows a very weird bug in recent Emacsen - the guillemets only appear in green in the echo area! Note how the cursor is on a non-green "«", but the output of `C-x =' in the echo area shows a green "«"...

4. Glyphs for (La)TeX

I sometimes use glyphs - heavily! - to typeset maths. The screenshots below, taken on Emacs23 (i.e., non-buggy), show, from left to right, how 1) M-x eev-math-glyphs-edrx sets up lots of glyphs, how 2) one of the .sty files for Dednat4 defines a meaning in (La)TeX for each of the glyph characters, how 3) a .tex file uses those glyphs; the resulting PDF can be found here, 4) what M-x eev-math-glyphs-edrx does in a buggy Emacs; compare with (1).

(By the way, LuaTeX supports only unicode/utf-8, so to port these things to LuaTeX I'll have to make lots of changes on my Emacs code, on Dednat, and on my LaTeX style files... I'll have to stop using some 1-byte glyphs, and add support for 2-byte glyphs...)

5. Glyphs for ASCII maths

I have also added some support for glyphs to BlogMe - the source in the screenshot below becomes this, and, with the help of PrinceXML (which is gratis, but non-free), this PDF.

6. Modified fonts for Linux VTs

(This is just a curiosity - I haven't used this in ages). Until a few years ago I used to use Linux VTs almost all the time, and X just for a few applications... and I made tweaked fonts, with lots of special math chars. Screenshots,

and links:

(find-vtutil4 "")
(find-vtutil4 "README")
(find-vtutil4 "mathchars.lua")
(find-vtutil4 "Makefile")

7. A bug report

Here ("bug#13691", 2013feb11):
Its script is here: (find-angg "elisp/glyph-bug.el")