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XCreateFontSet(3X11)
X11R6
NAME
XCreateFontSet, XFreeFontSet - create and free an international text
drawing font set
SYNOPSIS
XFontSet XCreateFontSet(display, base_font_name_list,
missing_charset_list_return, missing_charset_count_return,
def_string_return)
Display *display;
char *base_font_name_list;
char ***missing_charset_list_return;
int *missing_charset_count_return;
char **def_string_return;
void XFreeFontSet(display, font_set)
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:
1. 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.
2. 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.
3. 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.
4. 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 get 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.
SEE ALSO
XExtentsOfFontSet(3X11), XFontsOfFontSet(3X11), XFontSetExtents(3X11)
Xlib -- C Language X Interface
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