Ubuntu Manpage: Tk_MeasureChars, Tk_TextWidth, Tk_DrawChars, Tk_UnderlineChars

Provided by: tk8.6-doc_8.6.14-1build1_all

NAME

       Tk_MeasureChars,  Tk_TextWidth,  Tk_DrawChars, Tk_UnderlineChars - routines to measure and
       display simple single-line strings.

SYNOPSIS

       #include <tk.h>

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

       int
       Tk_TextWidth(tkfont, string, numBytes)

       Tk_DrawChars(display, drawable, gc, tkfont, string, numBytes, x, y)

       Tk_UnderlineChars(display, drawable, gc, tkfont, string, x, y, firstByte, lastByte)

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 numBytes (in) The maximum number of bytes to consider when measuring
or drawing string. Must be greater than or equal to 0.

int maxPixels (in) If maxPixels is >= 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 character as long as any part of it fits in
the length given by maxPixels; otherwise, a character
must fit completely 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 letters
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_MeasureChars.

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 characters. 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 displaying string.

int firstByte (in) The index of the first byte of the first character to
underline in the string. Underlining begins at the
left edge of this character.

int lastByte (in) The index of the first byte of the last character up to
which the underline will be drawn. The character
specified by lastByte will not itself be underlined.
_________________________________________________________________________________________________

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.  Note that the interfaces described here are byte-oriented not  character-
       oriented,  so  index  values  coming from Tcl scripts need to be converted to byte offsets
       using the Tcl_UtfAtIndex and related routines.

       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.  Characters 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  bytes  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  numBytes.
       *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 drawable.

       Tk_UnderlineChars  underlines  the given range of characters in the given string.  It does
       not 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, measurement

NAME

SYNOPSIS

ARGUMENTS

DESCRIPTION

SEE ALSO

KEYWORDS