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X11R7.4 - man page for xquerytextextents (x11r4 section 3)

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XTextExtents(3) 			  XLIB FUNCTIONS			  XTextExtents(3)

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

SYNTAX
       int XTextExtents(XFontStruct *font_struct, char *string, int nchars, int *direc-
	      tion_return, int *font_ascent_return, int *font_descent_return, XCharStruct *over-
	      all_return);

       int XTextExtents16(XFontStruct *font_struct, XChar2b *string, int nchars, int *direc-
	      tion_return, int *font_ascent_return, int *font_descent_return, XCharStruct *over-
	      all_return);

       int XQueryTextExtents(Display *display, XID font_ID, char *string, int nchars, int *direc-
	      tion_return, int *font_ascent_return, int *font_descent_return, XCharStruct *over-
	      all_return);

       int XQueryTextExtents16(Display *display, XID font_ID, XChar2b *string, int nchars, int
	      *direction_return, int *font_ascent_return, int *font_descent_return, XCharStruct
	      *overall_return);

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

       display	 Specifies the connection to the X server.

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

       font_ascent_return
		 Returns the font ascent.

       font_descent_return
		 Returns the font descent.

       font_struct
		 Specifies the XFontStruct structure.

       nchars	 Specifies the number of characters in the character string.

       string	 Specifies the character string.

       overall_return
		 Returns the overall size in the specified XCharStruct structure.

DESCRIPTION
       The XTextExtents and XTextExtents16 functions perform the size computation locally and,
       thereby, avoid the round-trip overhead of XQueryTextExtents 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 mem-
       ber is set to the sum of the character-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 char-
       acters 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 indexing, 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 functions 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 mem-
       ber is set to the sum of the character-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 char-
       acters 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 indexing, 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 default_char,
       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 GContext.

SEE ALSO
       XLoadFont(3X11), XTextWidth(3X11)
       Xlib - C Language X Interface

X Version 11				   libX11 1.2.1 			  XTextExtents(3)
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