Clear font cache.

Close FONT-OBJECT.

Return a font-entity matching with FONT-SPEC on the current frame.
Optional 2nd argument FRAME, if non-nil, specifies the target frame.

Return a font-object for displaying a character at POSITION.
Optional second arg WINDOW, if non-nil, is a window displaying
the current buffer.  It defaults to the currently selected window.

List available font families on the current frame.
Optional argument FRAME, if non-nil, specifies the target frame.

Return the value of FONT's property KEY.
FONT is a font-spec, a font-entity, or a font-object.
KEY is any symbol, but these are reserved for specific meanings:
  :family, :weight, :slant, :width, :foundry, :adstyle, :registry,
  :size, :name, :script, :otf
See the documentation of `font-spec' for their meanings.
In addition, if FONT is a font-entity or a font-object, values of
:script and :otf are different from those of a font-spec as below:

The value of :script may be a list of scripts that are supported by the font.

The value of :otf is a cons (GSUB . GPOS) where GSUB and GPOS are lists
representing the OpenType features supported by the font by this form:
  ((SCRIPT (LANGSYS FEATURE ...) ...) ...)
SCRIPT, LANGSYS, and FEATURE are all symbols representing OpenType
Layout tags.

Return a vector of FONT-OBJECT's glyphs for the specified characters.
FROM and TO are positions (integers or markers) specifying a region
of the current buffer.
If the optional fourth arg OBJECT is not nil, it is a string or a
vector containing the target characters.

Each element is a vector containing information of a glyph in this format:
  [FROM-IDX TO-IDX C CODE WIDTH LBEARING RBEARING ASCENT DESCENT ADJUSTMENT]
where
  FROM is an index numbers of a character the glyph corresponds to.
  TO is the same as FROM.
  C is the character of the glyph.
  CODE is the glyph-code of C in FONT-OBJECT.
  WIDTH thru DESCENT are the metrics (in pixels) of the glyph.
  ADJUSTMENT is always nil.
If FONT-OBJECT doesn't have a glyph for a character,
the corresponding element is nil.

Return t if and only if font-spec SPEC matches with FONT.
FONT is a font-spec, font-entity, or font-object.

Set one property of FONT: give property KEY value VAL.
FONT is a font-spec, a font-entity, or a font-object.

If FONT is a font-spec, KEY can be any symbol.  But if KEY is the one
accepted by the function `font-spec' (which see), VAL must be what
allowed in `font-spec'.

If FONT is a font-entity or a font-object, KEY must not be the one
accepted by `font-spec'.

Shape the glyph-string GSTRING.
Shaping means substituting glyphs and/or adjusting positions of glyphs
to get the correct visual image of character sequences set in the
header of the glyph-string.

If the shaping was successful, the value is GSTRING itself or a newly
created glyph-string.  Otherwise, the value is nil.

Return a newly created font-spec with arguments as properties.

ARGS must come in pairs KEY VALUE of font properties.  KEY must be a
valid font property name listed below:

`:family', `:weight', `:slant', `:width'

They are the same as face attributes of the same name.  See
`set-face-attribute'.

`:foundry'

VALUE must be a string or a symbol specifying the font foundry, e.g. ``misc''.

`:adstyle'

VALUE must be a string or a symbol specifying the additional
typographic style information of a font, e.g. ``sans''.

`:registry'

VALUE must be a string or a symbol specifying the charset registry and
encoding of a font, e.g. ``iso8859-1''.

`:size'

VALUE must be a non-negative integer or a floating point number
specifying the font size.  It specifies the font size in pixels (if
VALUE is an integer), or in points (if VALUE is a float).

`:name'

VALUE must be a string of XLFD-style or fontconfig-style font name.

`:script'

VALUE must be a symbol representing a script that the font must
support.  It may be a symbol representing a subgroup of a script
listed in the variable `script-representative-chars'.

`:lang'

VALUE must be a symbol of two-letter ISO-639 language names,
e.g. `ja'.

`:otf'

VALUE must be a list (SCRIPT-TAG LANGSYS-TAG GSUB [ GPOS ]) to specify
required OpenType features.

  SCRIPT-TAG: OpenType script tag symbol (e.g. `deva').
  LANGSYS-TAG: OpenType language system tag symbol,
     or nil for the default language system.
  GSUB: List of OpenType GSUB feature tag symbols, or nil if none required.
  GPOS: List of OpenType GPOS feature tag symbols, or nil if none required.

GSUB and GPOS may contain `nil' element.  In such a case, the font
must not have any of the remaining elements.

For instance, if the VALUE is `(thai nil nil (mark))', the font must
be an OpenType font whose GPOS table of `thai' script's default
language system must contain `mark' feature.

Return a list of variation glyphs for CHAR in FONT-OBJECT.
Each element of the value is a cons (VARIATION-SELECTOR . GLYPH-ID),
where
  VARIATION-SELECTOR is a character code of variation selection
    (#xFE00..#xFE0F or #xE0100..#xE01EF)
  GLYPH-ID is a glyph code of the corresponding variation glyph.

Return XLFD name of FONT.
FONT is a font-spec, font-entity, or font-object.
If the name is too long for XLFD (maximum 255 chars), return nil.
If the 2nd optional arg FOLD-WILDCARDS is non-nil,
the consecutive wildcards are folded into one.

Return t if OBJECT is a font-spec, font-entity, or font-object.
Return nil otherwise.
Optional 2nd argument EXTRA-TYPE, if non-nil, specifies to check
which kind of font it is.  It must be one of `font-spec', `font-entity',
`font-object'.

List available fonts matching FONT-SPEC on the current frame.
Optional 2nd argument FRAME specifies the target frame.
Optional 3rd argument NUM, if non-nil, limits the number of returned fonts.
Optional 4th argument PREFER, if non-nil, is a font-spec to
control the order of the returned list.  Fonts are sorted by
how close they are to PREFER.

Open FONT-ENTITY.

Return information about FONT-OBJECT.
The value is a vector:
  [ NAME FILENAME PIXEL-SIZE SIZE ASCENT DESCENT SPACE-WIDTH AVERAGE-WIDTH
    CAPABILITY ]

NAME is the font name, a string (or nil if the font backend doesn't
provide a name).

FILENAME is the font file name, a string (or nil if the font backend
doesn't provide a file name).

PIXEL-SIZE is a pixel size by which the font is opened.

SIZE is a maximum advance width of the font in pixels.

ASCENT, DESCENT, SPACE-WIDTH, AVERAGE-WIDTH are metrics of the font in
pixels.

CAPABILITY is a list whose first element is a symbol representing the
font format (x, opentype, truetype, type1, pcf, or bdf) and the
remaining elements describe the details of the font capability.

If the font is OpenType font, the form of the list is
  (opentype GSUB GPOS)
where GSUB shows which "GSUB" features the font supports, and GPOS
shows which "GPOS" features the font supports.  Both GSUB and GPOS are
lists of the format:
  ((SCRIPT (LANGSYS FEATURE ...) ...) ...)

If the font is not OpenType font, currently the length of the form is
one.

SCRIPT is a symbol representing OpenType script tag.

LANGSYS is a symbol representing OpenType langsys tag, or nil
representing the default langsys.

FEATURE is a symbol representing OpenType feature tag.

If the font is not OpenType font, CAPABILITY is nil.