Tribblix: manual page: XCreateFontSet.3

XCreateFontSet(3) XLIB FUNCTIONS XCreateFontSet(3)

NAME

XCreateFontSet, XFreeFontSet - create and free an international text
drawing font set

SYNTAX

XFontSet XCreateFontSet(Display *display, _Xconst 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);

ARGUMENTS

display Specifies the connection to the X server.

base_font_name_list
Specifies the base font names.

def_string_return
Returns the string drawn for missing charsets.

font_set Specifies the font set.

missing_charset_count_return
Returns the number of missing charsets.

missing_charset_list_return
Returns the missing charsets.

DESCRIPTION

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 name.

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:

+o 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 charset.

+o 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.

+o 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
required charset.

+o The first font name that can be mapped in some implementation-
dependent manner to one or more fonts that support imaging text
in the charset.

For example, assume that a locale required the charsets:

ISO8859-1
JISX0208.1983
JISX0201.1976
GB2312-1980.0

The user could supply a base_font_name_list that explicitly specifies
the charsets, ensuring that specific fonts are used if they exist.
For example:

"-JIS-Fixed-Medium-R-Normal--26-180-100-100-C-240-JISX0208.1983-0,\
-JIS-Fixed-Medium-R-Normal--26-180-100-100-C-120-JISX0201.1976-0,\
-GB-Fixed-Medium-R-Normal--26-180-100-100-C-240-GB2312-1980.0,\
-Adobe-Courier-Bold-R-Normal--25-180-75-75-M-150-ISO8859-1"

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:

"-JIS-Fixed-Medium-R-Normal--26-180-100-100-C-240,\
-JIS-Fixed-Medium-R-Normal--26-180-100-100-C-120,\
-GB-Fixed-Medium-R-Normal--26-180-100-100-C-240,\
-Adobe-Courier-Bold-R-Normal--25-180-100-100-M-150"

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:

"-*-*-*-R-Normal--*-180-100-100-*-*"

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
XCreateFontSet.

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.

NAME

SYNTAX

ARGUMENTS

DESCRIPTION

SEE ALSO