XTextExtents(XS)  X Version 11 (Release 5) 6 January 1993   XTextExtents(XS)


 Name

    XTextExtents - compute or query text extents

 Syntax


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

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

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

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


 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 con-
                   tains 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
                   structure.

 Description

    The XTextExtents and XTextExtents16 functions perform the size computa-
    tion locally and, thereby, avoid the round-trip overhead of XQueryTextEx-
    tents 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 char-
    acter 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 mini-
    mum 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 charac-
    ter, undefined characters in the string are taken to have all zero
    metrics.

    The XQueryTextExtents and XQueryTextExtents16 functions return the bound-
    ing box of the specified 8-bit and 16-bit character string in the speci-
    fied 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 char-
    acter 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 mini-
    mum 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 charac-
    ter, 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(XS), XTextWidth(XS)
    Xlib - C Language X Interface