MirOS Manual: XQueryTextExtents(3), XQueryTextExtents16(3), XTextExtents(3), XTextExtents16(3)


XTextExtents(3X11)       XLIB FUNCTIONS        XTextExtents(3X11)

NAME

     XTextExtents, XTextExtents16, XQueryTextExtents, XQueryTex-
     tExtents16 - compute or query text extents

SYNTAX

     int XTextExtents(XFontStruct *font_struct, char *string, int
          nchars, int *direction_return, int *font_ascent_return,
          int *font_descent_return, XCharStruct *overall_return);

     int XTextExtents16(XFontStruct *font_struct, XChar2b
          *string, int nchars, int *direction_return, int
          *font_ascent_return, int *font_descent_return, XChar-
          Struct *overall_return);

     int XQueryTextExtents(Display *display, XID font_ID, char
          *string, int nchars, int *direction_return, int
          *font_ascent_return, int *font_descent_return, XChar-
          Struct *overall_return);

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

ARGUMENTS

     direction_return
               Returns the value of the direction hint (FontLeft-
               ToRight 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 charac-
               ter string.

     string    Specifies the character string.

     overall_return
               Returns the overall size in the specified XChar-
               Struct structure.

XFree86                   Version 4.5.0                         1

XTextExtents(3X11)       XLIB FUNCTIONS        XTextExtents(3X11)

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
     member 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 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 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 charac-
     ters 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
     member 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 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 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 charac-
     ters in the string are taken to have all zero metrics.

XFree86                   Version 4.5.0                         2

XTextExtents(3X11)       XLIB FUNCTIONS        XTextExtents(3X11)

     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 Bad-
     Font 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

XFree86                   Version 4.5.0                         3

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