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(elisp)Glyphs

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Glyphs
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   A "glyph" is a generalization of a character; it stands for an image
that takes up a single character position on the screen.  Glyphs are
represented in Lisp as integers, just as characters are.

   The meaning of each integer, as a glyph, is defined by the glyph
table, which is the value of the variable `glyph-table'.

 - Variable: glyph-table
     The value of this variable is the current glyph table.  It should
     be a vector; the Gth element defines glyph code G.  If the value
     is `nil' instead of a vector, then all glyphs are simple (see
     below).  The glyph table is not used on windowed displays.

   Here are the possible types of elements in the glyph table:

STRING
     Send the characters in STRING to the terminal to output this
     glyph.  This alternative is available on character terminals, but
     not under a window system.

INTEGER
     Define this glyph code as an alias for glyph code INTEGER.  You
     can use an alias to specify a face code for the glyph; see below.

`nil'
     This glyph is simple.  On an ordinary terminal, the glyph code mod
     524288 is the character to output.  In a window system, the glyph
     code mod 524288 is the character to output, and the glyph code
     divided by 524288 specifies the face number (Note: Face
     Functions) to use while outputting it.  (524288 is 2**19.)
     Note: Faces.

   If a glyph code is greater than or equal to the length of the glyph
table, that code is automatically simple.

 - Function: create-glyph string
     This function returns a newly-allocated glyph code which is set up
     to display by sending STRING to the terminal.