XTextExtents(3) XLIB FUNCTIONS XTextExtents(3)

NAME
       XTextExtents, XTextExtents16, XQueryTextExtents, XQueryTextExtents16 -
       compute or query text extents

SYNTAX
       int XTextExtents(XFontStruct *fontstruct, char *string, int nchars,
              int *directionreturn, int *fontascentreturn, int
              *fontdescentreturn, XCharStruct *overallreturn);

       int XTextExtents16(XFontStruct *fontstruct, XChar2b *string, int
              nchars, int *directionreturn, int *fontascentreturn, int
              *fontdescentreturn, XCharStruct *overallreturn);

       int XQueryTextExtents(Display *display, XID fontID, char *string, int
              nchars, int *directionreturn, int *fontascentreturn, int
              *fontdescentreturn, XCharStruct *overallreturn);

       int XQueryTextExtents16(Display *display, XID fontID, XChar2b *string,
              int nchars, int *directionreturn, int *fontascentreturn, int
              *fontdescentreturn, XCharStruct *overallreturn);

ARGUMENTS
       directionreturn
                 Returns the value of the direction hint (FontLeftToRight or
                 FontRightToLeft).

       display   Specifies the connection to the X server.

       fontID   Specifies either the font ID or the GContext ID that contains
                 the font.

       fontascentreturn
                 Returns the font ascent.

       fontdescentreturn
                 Returns the font descent.

       fontstruct
                 Specifies the XFontStruct structure.

       nchars    Specifies the number of characters in the character string.

       string    Specifies the character string.

       overallreturn
                 Returns the overall size in the specified XCharStruct struc‐
                 ture.

DESCRIPTION
       The XTextExtents and XTextExtents16 functions perform the size computa‐
       tion locally and, thereby, avoid the round-trip overhead of XQueryTex‐
       tExtents and XQueryTextExtents16.  Both functions return an XCharStruct
       structure, whose members are set to the values as follows.

       The ascent member is set to the maximum of the ascent metrics of all
       characters in the string.  The descent member is set to the maximum of
       the descent metrics.  The width member is set to the sum of the charac‐
       ter-width metrics of all characters in the string.  For each character
       in the string, let W be the sum of the character-width metrics of all
       characters preceding it in the string.  Let L be the left-side-bearing
       metric of the character plus W.  Let R be the right-side-bearing metric
       of the character plus W.  The lbearing member is set to the minimum L
       of all characters in the string.  The rbearing member is set to the
       maximum R.

       For fonts defined with linear indexing rather than 2-byte matrix index‐
       ing, each XChar2b structure is interpreted as a 16-bit number with
       byte1 as the most significant byte.  If the font has no defined default
       character, undefined characters in the string are taken to have all
       zero metrics.

       The XQueryTextExtents and XQueryTextExtents16 functions return the
       bounding box of the specified 8-bit and 16-bit character string in the
       specified font or the font contained in the specified GC.  These func‐
       tions query the X server and, therefore, suffer the round-trip overhead
       that is avoided by XTextExtents and XTextExtents16.  Both functions
       return a XCharStruct structure, whose members are set to the values as
       follows.

       The ascent member is set to the maximum of the ascent metrics of all
       characters in the string.  The descent member is set to the maximum of
       the descent metrics.  The width member is set to the sum of the charac‐
       ter-width metrics of all characters in the string.  For each character
       in the string, let W be the sum of the character-width metrics of all
       characters preceding it in the string.  Let L be the left-side-bearing
       metric of the character plus W.  Let R be the right-side-bearing metric
       of the character plus W.  The lbearing member is set to the minimum L
       of all characters in the string.  The rbearing member is set to the
       maximum R.

       For fonts defined with linear indexing rather than 2-byte matrix index‐
       ing, each XChar2b structure is interpreted as a 16-bit number with
       byte1 as the most significant byte.  If the font has no defined default
       character, undefined characters in the string are taken to have all
       zero metrics.

       Characters with all zero metrics are ignored.  If the font has no
       defined defaultchar, the undefined characters in the string are also
       ignored.

       XQueryTextExtents and XQueryTextExtents16 can generate BadFont and
       BadGC errors.

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

       BadGC     A value for a GContext argument does not name a defined GCon‐
                 text.

SEE ALSO
       XLoadFont(3), XTextWidth(3)
       Xlib - C Language X Interface



X Version 11                     libX11 1.6.5                  XTextExtents(3)