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Tk_MeasureChars(3)	     Tk Library Procedures	    Tk_MeasureChars(3)

______________________________________________________________________________

NAME
       Tk_MeasureChars,	 Tk_TextWidth,	Tk_DrawChars, Tk_UnderlineChars - rou‐
       tines to measure and display simple single-line strings.

SYNOPSIS
       #include <tk.h>

       int
       Tk_MeasureChars(tkfont, string, maxChars, maxPixels, flags, lengthPtr)

       int
       Tk_TextWidth(tkfont, string, numChars)

       void
       Tk_DrawChars(display, drawable, gc, tkfont, string, numChars, x, y)

       void
       Tk_UnderlineChars(display, drawable, gc, tkfont, string, x, y, firstChar, lastChar)

ARGUMENTS
       Tk_Font	    tkfont	(in)	  Token for font in which text	is  to
					  be  drawn  or	 measured.   Must have
					  been returned by a previous call  to
					  Tk_GetFont.

       const char   *string	(in)	  Text	to  be	measured or displayed.
					  Need not be  null  terminated.   Any
					  non-printing	meta-characters in the
					  string (such as tabs, newlines,  and
					  other	 control  characters)  will be
					  measured or displayed in a platform-
					  dependent manner.

       int	    maxChars	(in)	  The  maximum number of characters to
					  consider  when   measuring   string.
					  Must be greater than or equal to 0.

       int	    maxPixels	(in)	  If  maxPixels	 is greater than 0, it
					  specifies  the  longest  permissible
					  line	length	in pixels.  Characters
					  from string are processed only until
					  this	many pixels have been covered.
					  If maxPixels is <= 0, then the  line
					  length  is  unbounded	 and the flags
					  argument is ignored.

       int	    flags	(in)	  Various flag	bits  OR-ed  together:
					  TK_PARTIAL_OK	 means include a char‐
					  acter as long as any part of it fits
					  in  the  length  given by maxPixels;
					  otherwise, a character must fit com‐
					  pletely     to     be	   considered.
					  TK_WHOLE_WORDS means stop on a  word
					  boundary,	if    possible.	    If
					  TK_AT_LEAST_ONE  is  set,  it	 means
					  return  at  least one character even
					  if no characters could  fit  in  the
					  length   given   by  maxPixels.   If
					  TK_AT_LEAST_ONE    is	   set	   and
					  TK_WHOLE_WORDS is also set, it means
					  that if not even one	word  fits  on
					  the  line, return the first few let‐
					  ters of the word that	 did  fit;  if
					  not even one letter of the word fit,
					  then the first letter will still  be
					  returned.

       int	    *lengthPtr	(out)	  Filled  with	the  number  of pixels
					  occupied by the number of characters
					  returned  as	the  result of Tk_Mea‐
					  sureChars.

       int	    numChars	(in)	  The total number  of	characters  to
					  measure  or  draw from string.  Must
					  be greater than or equal to 0.

       Display	    *display	(in)	  Display on which to draw.

       Drawable	    drawable	(in)	  Window or pixmap in which to draw.

       GC	    gc		(in)	  Graphics context for drawing charac‐
					  ters.	  The  font selected into this
					  GC must be the same as the tkfont.

       int	    x, y	(in)	  Coordinates at which	to  place  the
					  left	edge of the baseline when dis‐
					  playing string.

       int	    firstChar	(in)	  The index of the first character  to
					  underline  in the string.  Underlin‐
					  ing begins at the left edge of  this
					  character.

       int	    lastChar	(in)	  The  index  of the last character up
					  to  which  the  underline  will   be
					  drawn.   The	character specified by
					  lastChar will not itself  be	under‐
					  lined.
_________________________________________________________________

DESCRIPTION
       These  routines	are  for  measuring and displaying simple single-font,
       single-line, strings.  To measure and display single-font,  multi-line,
       justified  text,	 refer	to the documentation for Tk_ComputeTextLayout.
       There is no programming interface in  the  core	of  Tk	that  supports
       multi-font, multi-line text; support for that behavior must be built on
       top of simpler layers.

       A glyph is the displayable picture of a letter, number, or  some	 other
       symbol.	Not all character codes in a given font have a glyph.  Charac‐
       ters such as tabs, newlines/returns, and control characters  that  have
       no  glyph are measured and displayed by these procedures in a platform-
       dependent manner; under X, they are replaced  with  backslashed	escape
       sequences,  while under Windows and Macintosh hollow or solid boxes may
       be substituted.	Refer to the  documentation  for  Tk_ComputeTextLayout
       for  a  programming  interface  that  supports the platform-independent
       expansion of tab characters  into  columns  and	newlines/returns  into
       multi-line text.

       Tk_MeasureChars	is  used  both to compute the length of a given string
       and to compute how many characters from a string fit in a given	amount
       of  space.   The	 return	 value is the number of characters from string
       that fit in the space specified by maxPixels subject to the  conditions
       described  by  flags.   If all characters fit, the return value will be
       maxChars.  *lengthPtr is filled with the computed width, in pixels,  of
       the  portion  of	 the  string  that  was measured.  For example, if the
       return value is 5, then *lengthPtr is filled with the distance  between
       the left edge of string[0] and the right edge of string[4].

       Tk_TextWidth is a wrapper function that provides a simpler interface to
       the Tk_MeasureChars function.  The return value is how  much  space  in
       pixels the given string needs.

       Tk_DrawChars  draws the string at the given location in the given draw‐
       able.

       Tk_UnderlineChars underlines the given range of characters in the given
       string.	It doesn't draw the characters (which are assumed to have been
       displayed previously by Tk_DrawChars); it  just	draws  the  underline.
       This  procedure is used to underline a few characters without having to
       construct an underlined font.  To produce natively underlined text, the
       appropriate underlined font should be constructed and used.

KEYWORDS
       font

Tk							    Tk_MeasureChars(3)
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