font(3tk) Tk Built-In Commands font(3tk)
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NAME
font - Create and inspect fonts.
SYNOPSIS
font option ?arg arg ...?
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DESCRIPTION
The font command provides several facilities for dealing with fonts,
such as defining named fonts and inspecting the actual attributes of a
font. The command has several different forms, determined by the first
argument. The following forms are currently supported:
font actual font ?-displayof window? ?option? ?--? ?char?
Returns information about the actual attributes that are ob-
tained when font is used on window's display; the actual at-
tributes obtained may differ from the attributes requested due
to platform-dependent limitations, such as the availability of
font families and point sizes. 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 OP-
TIONS below for a list of the possible attributes. If the char
argument is supplied, it must be a single character. The font
attributes returned will be those of the specific font used to
render that character, which will be different from the base
font if the base font does not contain the given character. If
char may be a hyphen, it should be preceded by -- to distinguish
it from a misspelled option.
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 op-
tion is specified with no value, then returns the current value
of that attribute. If one or more option-value pairs are speci-
fied, then the command modifies the given named font to have the
given values; in this case, all widgets using that font will re-
display themselves using the new attributes for the font. See
FONT OPTIONS below for a list of the possible attributes.
Note that on Aqua/Mac OS X, the system fonts (see PLATFORM SPE-
CIFIC FONTS below) may not be actually altered because they are
implemented by the system theme. To achieve the effect of modi-
fication, use font actual to get their configuration and font
create to synthesize a copy of the font which can be modified.
font create ?fontname? ?option value ...?
Creates a new named font and returns its name. fontname speci-
fies 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 will not actually be deleted un-
til 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 re-
display themselves using the new attributes of that font.
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 ar-
gument 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 descrip-
tion; 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 pix-
els used by highly exaggerated 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 argu-
ment 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 cur-
rently defined.
FONT DESCRIPTIONS
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 command.
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 mat-
ter 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 graph-
ics 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 FONTS
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 op-
tional 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-fam-
ily-weight-slant-setwidth-addstyle-pixel-point-resx-resy-spac-
ing-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 de-
faults. Any fields that were skipped are given default values.
For compatibility, an XLFD always chooses a font of the speci-
fied 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 ac-
tually 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 situa-
tions it may not be possible to find any close font (e.g., the font
family was a garbage value); in that case, some system-dependent de-
fault 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 command to query
font-specific data determined when the font was created. These proper-
ties 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 us-
ing the same font should be placed so that none of the charac-
ters in one line overlap any of the characters in the other
line. This is generally the sum of the ascent above the base-
line line plus the descent below the baseline.
-fixed
Returns a boolean flag that is “1” if this is a fixed-width
font, where each normal character is the same width as all the
other characters, or is “0” 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 posi-
tive 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 chang-
ing screen resolutions or moving scripts across platforms. How-
ever, 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 the tk scaling com-
mand.
-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 false.
-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 false.
STANDARD FONTS
The following named fonts are supported on all systems, and default to
values that match appropriate system defaults.
TkDefaultFont
This font is the default for all GUI items not otherwise speci-
fied.
TkTextFont
This font should be used for user text in entry widgets, list-
boxes etc.
TkFixedFont
This font is the standard fixed-width font.
TkMenuFont
This font is used for menu items.
TkHeadingFont
This font should be used for column headings in lists and ta-
bles.
TkCaptionFont
This font should be used for window and dialog caption bars.
TkSmallCaptionFont
This font should be used for captions on contained windows or
tool dialogs.
TkIconFont
This font should be used for icon captions.
TkTooltipFont
This font should be used for tooltip windows (transient informa-
tion windows).
It is not advised to change these fonts, as they may be modified by Tk
itself in response to system changes. Instead, make a copy of the font
and modify that.
PLATFORM SPECIFIC FONTS
The following system fonts are supported:
X Windows
All valid X font names, including those listed by xlsfonts(1),
are available.
MS Windows
The following fonts are supported, and are mapped to the user's
style defaults.
system ansi device
systemfixed ansifixed oemfixed
Mac OS X
The following fonts are supported, and are mapped to the user's
style defaults.
system application menu
Additionally, the following named fonts provide access to the
Aqua theme fonts:
systemSystemFont systemEmphasizedSystemFont
systemSmallSystemFontsystemSmallEmphasizedSystemFont
systemApplicationFontsystemLabelFont
systemViewsFont systemMenuTitleFont
systemMenuItemFont systemMenuItemMarkFont
systemMenuItemCmdKeyFontsystemWindowTitleFont
systemPushButtonFontsystemUtilityWindowTitleFont
systemAlertHeaderFontsystemToolbarFont
systemMiniSystemFontsystemDetailSystemFont
systemDetailEmphasizedSystemFont
EXAMPLE
Fill a text widget with lots of font demonstrators, one for every font
family installed on your system:
pack [text .t -wrap none] -fill both -expand 1
set count 0
set tabwidth 0
foreach family [lsort -dictionary [font families]] {
.t tag configure f[incr count] -font [list $family 10]
.t insert end ${family}:\t {} \
"This is a simple sampler\n" f$count
set w [font measure [.t cget -font] ${family}:]
if {$w+5 > $tabwidth} {
set tabwidth [expr {$w+5}]
.t configure -tabs $tabwidth
}
}
SEE ALSO
options(3tk)
KEYWORDS
font
Tk 8.0 font(3tk)
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