XCreateFontSet, XFreeFontSet - create and free an international text
drawing font set
XFontSet XCreateFontSet(Display *display, char *base_font_name_list,
char ***missing_charset_list_return, int
*missing_charset_count_return, char **def_string_return);
void XFreeFontSet(Display *display, XFontSet font_set);
display Specifies the connection to the X server.
Specifies the base font names.
Returns the string drawn for missing charsets.
font_set Specifies the font set.
Returns the number of missing charsets.
Returns the missing charsets.
The XCreateFontSet function creates a font set for the specified
display. The font set is bound to the current locale when
XCreateFontSet is called. The font set may be used in subsequent calls
to obtain font and character information and to image text in the
locale of the font set.
The base_font_name_list argument is a list of base font names that Xlib
uses to load the fonts needed for the locale. The base font names are
a comma-separated list. The string is null-terminated and is assumed
to be in the Host Portable Character Encoding; otherwise, the result is
implementation-dependent. White space immediately on either side of a
separating comma is ignored.
Use of XLFD font names permits Xlib to obtain the fonts needed for a
variety of locales from a single locale-independent base font name.
The single base font name should name a family of fonts whose members
are encoded in the various charsets needed by the locales of interest.
An XLFD base font name can explicitly name a charset needed for the
locale. This allows the user to specify an exact font for use with a
charset required by a locale, fully controlling the font selection.
If a base font name is not an XLFD name, Xlib will attempt to obtain an
XLFD name from the font properties for the font. If this action is
successful in obtaining an XLFD name, the XBaseFontNameListOfFontSet
function will return this XLFD name instead of the client-supplied
Xlib uses the following algorithm to select the fonts that will be used
to display text with the XFontSet.
For each font charset required by the locale, the base font name list
is searched for the first appearance of one of the following cases that
names a set of fonts that exist at the server:
· The first XLFD-conforming base font name that specifies the
required charset or a superset of the required charset in its
CharSetRegistry and CharSetEncoding fields. The implementation
may use a base font name whose specified charset is a superset of
the required charset, for example, an ISO8859-1 font for an ASCII
· The first set of one or more XLFD-conforming base font names that
specify one or more charsets that can be remapped to support the
required charset. The Xlib implementation may recognize various
mappings from a required charset to one or more other charsets and
use the fonts for those charsets. For example, JIS Roman is ASCII
with tilde and backslash replaced by yen and overbar; Xlib may
load an ISO8859-1 font to support this character set if a JIS
Roman font is not available.
· The first XLFD-conforming font name or the first non-XLFD font
name for which an XLFD font name can be obtained, combined with
the required charset (replacing the CharSetRegistry and
CharSetEncoding fields in the XLFD font name). As in case 1, the
implementation may use a charset that is a superset of the
· The first font name that can be mapped in some implementation-
dependent manner to one or more fonts that support imaging text in
For example, assume that a locale required the charsets:
The user could supply a base_font_name_list that explicitly specifies
the charsets, ensuring that specific fonts are used if they exist. For
Alternatively, the user could supply a base_font_name_list that omits
the charsets, letting Xlib select font charsets required for the
locale. For example:
Alternatively, the user could simply supply a single base font name
that allows Xlib to select from all available fonts that meet certain
minimum XLFD property requirements. For example:
If XCreateFontSet is unable to create the font set, either because
there is insufficient memory or because the current locale is not
supported, XCreateFontSet returns NULL, missing_charset_list_return is
set to NULL, and missing_charset_count_return is set to zero. If fonts
exist for all of the charsets required by the current locale,
XCreateFontSet returns a valid XFontSet, missing_charset_list_return is
set to NULL, and missing_charset_count_return is set to zero.
If no font exists for one or more of the required charsets,
XCreateFontSet sets missing_charset_list_return to a list of one or
more null-terminated charset names for which no font exists and sets
missing_charset_count_return to the number of missing fonts. The
charsets are from the list of the required charsets for the encoding of
the locale and do not include any charsets to which Xlib may be able to
remap a required charset.
If no font exists for any of the required charsets or if the locale
definition in Xlib requires that a font exist for a particular charset
and a font is not found for that charset, XCreateFontSet returns NULL.
Otherwise, XCreateFontSet returns a valid XFontSet to font_set.
When an Xmb/wc drawing or measuring function is called with an XFontSet
that has missing charsets, some characters in the locale will not be
drawable. If def_string_return is non-NULL, XCreateFontSet returns a
pointer to a string that represents the glyphs that are drawn with this
XFontSet when the charsets of the available fonts do not include all
font glyphs required to draw a codepoint. The string does not
necessarily consist of valid characters in the current locale and is
not necessarily drawn with the fonts loaded for the font set, but the
client can draw and measure the default glyphs by including this string
in a string being drawn or measured with the XFontSet.
If the string returned to def_string_return is the empty string (""),
no glyphs are drawn, and the escapement is zero. The returned string
is null-terminated. It is owned by Xlib and should not be modified or
freed by the client. It will be freed by a call to XFreeFontSet with
the associated XFontSet. Until freed, its contents will not be
modified by Xlib.
The client is responsible for constructing an error message from the
missing charset and default string information and may choose to
continue operation in the case that some fonts did not exist.
The returned XFontSet and missing charset list should be freed with
XFreeFontSet and XFreeStringList, respectively. The client-supplied
base_font_name_list may be freed by the client after calling
The XFreeFontSet function frees the specified font set. The associated
base font name list, font name list, XFontStruct list, and
XFontSetExtents, if any, are freed.
XExtentsofFontSet(3), XFontsOfFontSet(3), XFontSetExtents(3)
Xlib - C Language X Interface