XLoadFont, XQueryFont, XLoadQueryFont, XFreeFont, XGet-
       FontProperty, XUnloadFont, XCharStruct, XFontProp,
       XChar2b, XFontStruct - load or unload fonts and font met-
       ric structures


SYNTAX

       Font XLoadFont(display, name)
             Display *display;
             char *name;

       XFontStruct *XQueryFont(display, font_ID)
             Display *display;
             XID font_ID;

       XFontStruct *XLoadQueryFont(display, name)
             Display *display;
             char *name;

       XFreeFont(display, font_struct)
             Display *display;
             XFontStruct *font_struct;

       Bool XGetFontProperty(font_struct, atom, value_return)
             XFontStruct *font_struct;
             Atom atom;
             unsigned long *value_return;

       XUnloadFont(display, font)
             Display *display;
             Font font;


ARGUMENTS

       atom      Specifies the atom for the property name you
                 want returned.

       display   Specifies the connection to the X server.

       font      Specifies the font.

       font_ID   Specifies the font ID or the GContext ID.

       font_struct
                 Specifies the storage associated with the font.

       gc        Specifies the GC.

       name      Specifies the name of the font, which is a null-
                 terminated string.

       value_return
                 Returns the value of the font property.

       particular screen and can be stored as a component of any
       GC.  When the font is no longer needed, call XUnloadFont.

       XLoadFont can generate BadAlloc and BadName errors.

       The XQueryFont function returns a pointer to the
       XFontStruct structure, which contains information associ-
       ated with the font.  You can query a font or the font
       stored in a GC.  The font ID stored in the XFontStruct
       structure will be the GContext ID, and you need to be
       careful when using this ID in other functions (see
       XGContextFromGC).  If the font does not exist, XQueryFont
       returns NULL.  To free this data, use XFreeFontInfo.

       XLoadQueryFont can generate a BadAlloc error.

       The XLoadQueryFont function provides the most common way
       for accessing a font.  XLoadQueryFont both opens (loads)
       the specified font and returns a pointer to the appropri-
       ate XFontStruct structure.  If the font name is not in the
       Host Portable Character Encoding, the result is implemen-
       tation-dependent.  If the font does not exist, XLoadQuery-
       Font returns NULL.

       The XFreeFont function deletes the association between the
       font resource ID and the specified font and frees the
       XFontStruct structure.  The font itself will be freed when
       no other resource references it.  The data and the font
       should not be referenced again.

       XFreeFont can generate a BadFont error.

       Given the atom for that property, the XGetFontProperty
       function returns the value of the specified font property.
       XGetFontProperty also returns False if the property was
       not defined or True if it was defined.  A set of prede-
       fined atoms exists for font properties, which can be found
       in <X11/Xatom.h>.  This set contains the standard proper-
       ties associated with a font.  Although it is not guaran-
       teed, it is likely that the predefined font properties
       will be present.

       The XUnloadFont function deletes the association between
       the font resource ID and the specified font.  The font
       itself will be freed when no other resource references it.
       The font should not be referenced again.

       XUnloadFont can generate a BadFont error.


STRUCTURES

       The XFontStruct structure contains all of the information
       for the font and consists of the font-specific information
       typedef struct {
            Atom name;
            unsigned long card32;
       } XFontProp;

       typedef struct {              /* normal 16 bit characters are two bytes */
           unsigned char byte1;
           unsigned char byte2;
       } XChar2b;

       typedef struct {
            XExtData *ext_data;      /* hook for extension to hang data */
            Font fid;                /* Font id for this font */
            unsigned direction;      /* hint about the direction font is painted */
            unsigned min_char_or_byte2;/* first character */
            unsigned max_char_or_byte2;/* last character */
            unsigned min_byte1;      /* first row that exists */
            unsigned max_byte1;      /* last row that exists */
            Bool all_chars_exist;    /* flag if all characters have nonzero size */
            unsigned default_char;   /* char to print for undefined character */
            int n_properties;        /* how many properties there are */
            XFontProp *properties;   /* pointer to array of additional properties */
            XCharStruct min_bounds;  /* minimum bounds over all existing char */
            XCharStruct max_bounds;  /* maximum bounds over all existing char */
            XCharStruct *per_char;   /* first_char to last_char information */
            int ascent;              /* logical extent above baseline for spacing */
            int descent;             /* logical decent below baseline for spacing */
       } XFontStruct;

       X supports single byte/character, two bytes/character
       matrix, and 16-bit character text operations.  Note that
       any of these forms can be used with a font, but a single
       byte/character text request can only specify a single byte
       (that is, the first row of a 2-byte font).  You should
       view 2-byte fonts as a two-dimensional matrix of defined
       characters: byte1 specifies the range of defined rows and
       byte2 defines the range of defined columns of the font.
       Single byte/character fonts have one row defined, and the
       byte2 range specified in the structure defines a range of
       characters.

       The bounding box of a character is defined by the
       XCharStruct of that character.  When characters are absent
       from a font, the default_char is used.  When fonts have
       all characters of the same size, only the information in
       the XFontStruct min and max bounds are used.

       The members of the XFontStruct have the following seman-
       tics:

       o    The direction member can be either FontLeftToRight or
            FontRightToLeft.  It is just a hint as to whether
            sponding to the per_char array element N (counting
            from 0) are:

                 byte1 = N/D + min_byte1
                 byte2 = N\D + min_char_or_byte2

            where:

                    D = max_char_or_byte2 - min_char_or_byte2 + 1
                    / = integer division
                    \ = integer modulus

       o    If the per_char pointer is NULL, all glyphs between
            the first and last character indexes inclusive have
            the same information, as given by both min_bounds and
            max_bounds.

       o    If all_chars_exist is True, all characters in the
            per_char array have nonzero bounding boxes.

       o    The default_char member specifies the character that
            will be used when an undefined or nonexistent charac-
            ter is printed.  The default_char is a 16-bit charac-
            ter (not a 2-byte character).  For a font using
            2-byte matrix format, the default_char has byte1 in
            the most-significant byte and byte2 in the least sig-
            nificant byte.  If the default_char itself specifies
            an undefined or nonexistent character, no printing is
            performed for an undefined or nonexistent character.

       o    The min_bounds and max_bounds members contain the
            most extreme values of each individual XCharStruct
            component over all elements of this array (and ignore
            nonexistent characters).  The bounding box of the
            font (the smallest rectangle enclosing the shape
            obtained by superimposing all of the characters at
            the same origin [x,y]) has its upper-left coordinate
            at:
                 [x + min_bounds.lbearing, y - max_bounds.ascent]

            Its width is:
                 max_bounds.rbearing - min_bounds.lbearing

            Its height is:
                 max_bounds.ascent + max_bounds.descent

       o    The ascent member is the logical extent of the font
            above the baseline that is used for determining line
            spacing.  Specific characters may extend beyond this.

       o    The descent member is the logical extent of the font
            at or below the baseline that is used for determining

       [x + lbearing, y - ascent]

       Its width is:

       rbearing - lbearing

       Its height is:

       ascent + descent

       The origin for the next character is defined to be:

       [x + width, y]

       The lbearing member defines the extent of the left edge of
       the character ink from the origin.  The rbearing member
       defines the extent of the right edge of the character ink
       from the origin.  The ascent member defines the extent of
       the top edge of the character ink from the origin.  The
       descent member defines the extent of the bottom edge of
       the character ink from the origin.  The width member
       defines the logical width of the character.


DIAGNOSTICS

       BadAlloc  The server failed to allocate the requested
                 resource or server memory.

       BadFont   A value for a Font or GContext argument does not
                 name a defined Font.

       BadName   A font or color of the specified name does not
                 exist.


SEE ALSO

       XCreateGC(3X11), XListFonts(3X11), XSetFontPath(3X11)
       Xlib - C Language X Interface



X Version 11               Release 6.4                          1