font(n)                      Tk Built-In Commands                      font(n)



NAME
       font - Create and inspect fonts.

SYNOPSIS
       (font option ?arg arg ...?)

DESCRIPTION
       The font procedure provides several facilities for dealing with fonts,
       such as defining named fonts and inspecting the actual attributes of a
       font.  The procedure has several different forms, determined by the
       first argument.  The following forms are currently supported:

       (font 'actual font ?displayof window? ?option?)
              Returns information about the the actual attributes that are
              obtained when font is used on window's display; the actual
              attributes obtained may differ from the attributes requested due
              to platform-dependant limitations, such as the availability of
              font families and pointsizes.  font is a font description; see
              FONT DESCRIPTIONS below.  If the window argument is omitted, it
              defaults to the main window.  If option is specified, returns
              the value of that attribute; if it is omitted, the return value
              is a list of all the attributes and their values.  See FONT
              OPTIONS below for a list of the possible attributes.

       (font 'configure fontname ?option? ?value option value ...?)
              Query or modify the desired attributes for the named font called
              fontname.  If no option is specified, returns a list describing
              all the options and their values for fontname.  If a single
              option is specified with no value, then returns the current
              value of that attribute.  If one or more option-value pairs are
              specified, then the procedure modifies the given named font to
              have the given values; in this case, all widgets using that font
              will redisplay themselves using the new attributes for the font.
              See FONT OPTIONS below for a list of the possible attributes.

       (font 'create ?fontname? ?option value ...?)
              Creates a new named font and returns its name.  fontname
              specifies the name for the font; if it is omitted, then Tk
              generates a new name of the form "fontx", where x is an integer.
              There may be any number of option-value pairs, which provide the
              desired attributes for the new named font.  See FONT OPTIONS
              below for a list of the possible attributes.

       (font 'delete fontname ?fontname ...?)
              Delete the specified named fonts.  If there are widgets using
              the named font, the named font won't actually be deleted until
              all the instances are released.  Those widgets will continue to
              display using the last known values for the named font.  If a
              deleted named font is subsequently recreated with another call
              to font create, the widgets will use the new named font and
              redisplay themselves using the new attributes of that font.

       (font 'families)

       (font 'families displayof window?)
              The return value is a list of the case-insensitive names of all
              font families that exist on window's display.  If the window
              argument is omitted, it defaults to the main window.

       (font 'measure font ?displayof window? text)
              Measures the amount of space the string text would use in the
              given font when displayed in window.  font is a font
              description; see FONT DESCRIPTIONS below.  If the window
              argument is omitted, it defaults to the main window.  The return
              value is the total width in pixels of text, not including the
              extra pixels used by highly exagerrated characters such as
              cursive ``f''.  If the string contains newlines or tabs, those
              characters are not expanded or treated specially when measuring
              the string.

       (font 'metrics font ?displayof window? ?option?)
              Returns information about the metrics (the font-specific data),
              for font when it is used on window's display.  font is a font
              description; see FONT DESCRIPTIONS below.  If the window
              argument is omitted, it defaults to the main window.  If option
              is specified, returns the value of that metric; if it is
              omitted, the return value is a list of all the metrics and their
              values.  See FONT METRICS below for a list of the possible
              metrics.

       (font 'names)
              The return value is a list of all the named fonts that are
              currently defined.

FONT DESCRIPTION
       The following formats are accepted as a font description anywhere font
       is specified as an argument above; these same forms are also permitted
       when specifying the :font option for widgets.

       [1] fontname
              The name of a named font, created using the font create
              procedure.  When a widget uses a named font, it is guaranteed
              that this will never cause an error, as long as the named font
              exists, no matter what potentially invalid or meaningless set of
              attributes the named font has.  If the named font cannot be
              displayed with exactly the specified attributes, some other
              close font will be substituted automatically.

       [2] systemfont
              The platform-specific name of a font, interpreted by the
              graphics server.  This also includes, under X, an XLFD (see [4])
              for which a single ``*'' character was used to elide more than
              one field in the middle of the name.  See PLATFORM-SPECIFIC
              issues for a list of the system fonts.

       [3] family ?size? ?style? ?style ...?
              A properly formed list whose first element is the desired font
              family and whose optional second element is the desired size.
              The interpretation of the size attribute follows the same rules
              described for :size in FONT OPTIONS below.  Any additional
              optional arguments following the size are font styles.  Possible
              values for the style arguments are as follows:
              normal      bold        roman      italic underline   overstrike

       [4] X-font names (XLFD)
              A Unix-centric font name of the form -foundry-family-weight-
              slant-setwidth-addstyle-pixel-point-resx-resy-spacing-width-
              charset-encoding.  The ``*'' character may be used to skip
              individual fields that the user does not care about.  There must
              be exactly one ``*'' for each field skipped, except that a ``*''
              at the end of the XLFD skips any remaining fields; the shortest
              valid XLFD is simply ``*'', signifying all fields as defaults.
              Any fields that were skipped are given default values.  For
              compatibility, an XLFD always chooses a font of the specified
              pixel size (not point size); although this interpretation is not
              strictly correct, all existing applications using XLFDs assumed
              that one ``point'' was in fact one pixel and would display
              incorrectly (generally larger) if the correct size font were
              actually used.

       [5] option value ?option value ...?
              A properly formed list of option-value pairs that specify the
              desired attributes of the font, in the same format used when
              defining a named font; see FONT OPTIONS below.

       When font description font is used, the system attempts to parse the
       description according to each of the above five rules, in the order
       specified.  Cases [1] and [2] must match the name of an existing named
       font or of a system font.  Cases [3], [4], and [5] are accepted on all
       platforms and the closest available font will be used.  In some
       situations it may not be possible to find any close font (e.g., the
       font family was a garbage value); in that case, some system-dependant
       default font is chosen.  If the font description does not match any of
       the above patterns, an error is generated.

FONT METRICS
       The following options are used by the font metrics procedure to query
       font-specific data determined when the font was created.  These
       properties are for the whole font itself and not for individual
       characters drawn in that font.  In the following definitions, the
       ``baseline'' of a font is the horizontal line where the bottom of most
       letters line up; certain letters, such as lower-case ``g'' stick below
       the baseline.

       :ascent
              The amount in pixels that the tallest letter sticks up above the
              baseline of the font, plus any extra blank space added by the
              designer of the font.

       :descent
              The largest amount in pixels that any letter sticks down below
              the baseline of the font, plus any extra blank space added by
              the designer of the font.

       :linespace
              Returns how far apart vertically in pixels two lines of text
              using the same font should be placed so that none of the
              characters in one line overlap any of the characters in the
              other line.  This is generally the sum of the ascent above the
              baseline line plus the descent below the baseline.

       :fixed
              Returns a boolean flag that is ``#t'' if this is a fixed-width
              font, where each normal character is the the same width as all
              the other characters, or is ``#f'' if this is a proportionally-
              spaced font, where individual characters have different widths.
              The widths of control characters, tab characters, and other non-
              printing characters are not included when calculating this
              value.

FONT OPTIONS
       The following options are supported on all platforms, and are used when
       constructing a named font or when specifying a font using style [5] as
       above:

       :family name
              The case-insensitive font family name.  Tk guarantees to support
              the font families named Courier (a monospaced ``typewriter''
              font), Times (a serifed ``newspaper'' font), and Helvetica (a
              sans-serif ``European'' font).  The most closely matching native
              font family will automatically be substituted when one of the
              above font families is used.  The name may also be the name of a
              native, platform-specific font family; in that case it will work
              as desired on one platform but may not display correctly on
              other platforms.  If the family is unspecified or unrecognized,
              a platform-specific default font will be chosen.

       :size size
              The desired size of the font.  If the size argument is a
              positive number, it is interpreted as a size in points.  If size
              is a negative number, its absolute value is interpreted as a
              size in pixels.  If a font cannot be displayed at the specified
              size, a nearby size will be chosen.  If size is unspecified or
              zero, a platform-dependent default size will be chosen.

              Sizes should normally be specified in points so the application
              will remain the same ruler size on the screen, even when
              changing screen resolutions or moving scripts across platforms.
              However, specifying pixels is useful in certain circumstances
              such as when a piece of text must line up with respect to a
              fixed-size bitmap.  The mapping between points and pixels is set
              when the application starts, based on properties of the
              installed monitor, but it can be overridden by calling  (tk-
              state 'scaling).

       :weight weight
              The nominal thickness of the characters in the font.  The value
              normal specifies a normal weight font, while bold specifies a
              bold font.  The closest available weight to the one specified
              will be chosen.  The default weight is normal.

       :slant slant
              The amount the characters in the font are slanted away from the
              vertical.  Valid values for slant are roman and italic.  A roman
              font is the normal, upright appearance of a font, while an
              italic font is one that is tilted some number of degrees from
              upright.  The closest available slant to the one specified will
              be chosen.  The default slant is roman.

       :underline boolean
              The value is a boolean flag that specifies whether characters in
              this font should be underlined.  The default value for underline
              is #f.

       :overstrike boolean
              The value is a boolean flag that specifies whether a horizontal
              line should be drawn through the middle of characters in this
              font.  The default value for overstrike is #f.


PLATFORM-SPECIFIC ISSUES
       The following named system fonts are supported:

              X Windows:
                     All valid X font names, including those listed by
                     xlsfonts(1), are available.

              MS Windows:
                     system      ansi        device
                     systemfixed ansifixed   oemfixed

              Macintosh:
                     system      application



Tk                                    4.0                              font(n)
