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Font(3)		      User Contributed Perl Documentation	       Font(3)

NAME
       Tk::Font	- Create and inspect fonts.

SYNOPSIS
       A A A A $widget->Font(option?, arg, arg,	...?)

       A A A A $font->Option?(arg, arg,	...)?

DESCRIPTION
       The Font	method 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(-option?)
       $widget->fontActual(font?, -option?)
	   Returns information about the actual	attributes that	are obtained
	   when	font is	used on	$font'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 DESCRIPTION"
	   below.  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(-option??=>value, -option=>value, ...?)
	   Query or modify the desired attributes for $font.  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 method 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.

	   Note: the above behaviour differs in	detail to configure on
	   widgets, images etc.

       $font = $widget->Font(-option=>value, ...>?)
       $font = $widget->fontCreate(?fontname??,	-option=>value,	...>?)
	   Creates a new font object and returns a reference to	it.  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.

	   Note: the created font is not shared	between	widgets	of different
	   MainWindows.

       $font->delete
       $widget->fontDelete(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 fontCreate, the
	   widgets will	use the	new named font and redisplay themselves	using
	   the new attributes of that font.

       $widget->fontFamilies
	   The return value is a list of the case-insensitive names of all
	   font	families that exist on $widget's display.

       $font->measure(text)
       $widget->fontMeasure(font, text)
	   Measures the	amount of space	the string text	would use in the given
	   font	when displayed in $widget.  font is a font description;	see
	   "FONT DESCRIPTION" below.  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(-option?)
       $widget->fontMetrics(font?, -option?)
	   Returns information about the metrics (the font-specific data), for
	   font	when it	is used	on $widget's display.  font is a font
	   description;	see "FONT DESCRIPTION" below.  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.

       $widget->fontNames
	   The return value is a list of all font objects that are currently
	   defined for $widget's MainWindow.

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 fontCreate method.
	   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.

       [1a] $font
	   A font object created using the Font	method.	This is	essentially
	   the same as using a named font. The object is a reference to	the
	   name, and carries additional	information e.g. which MainWindow it
	   relates to in an manner peculiar to perl/Tk.

       [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 metrics/fontMetrics method	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.  ($font->ascent is provided for
	   compatibility.)

       -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.  ($font->descent is provided for
	   compatibility.)

       -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 ``1''	if this	is a fixed-width font,
	   where each normal character is the 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 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.

	   The original	Tcl/Tk authors believe 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. While this	is an admirable	goal it	does
	   not work as well in practice	as they	hoped.	The mapping between
	   points and  pixels is set when the application starts, based	on
	   alleged properties of the installed monitor,	but it can be
	   overridden by calling the  scaling command. However this can	be
	   problematic when system has no way of telling if (say) an 11" or
	   22" monitor is attached, also if it can tell	then some monitor
	   sizes may result in poorer quality scaled fonts being used rather
	   than	a "tuned" bitmap font.	In addition specifying pixels is
	   useful in certain circumstances such	as when	a piece	of text	must
	   line	up with	respect	to a fixed-size	bitmap.

	   At present the Tcl/Tk scheme	is used	unchanged, with	"point"	size
	   being returned by actual (as	an integer), and used internally.
	   Suggestions for work-rounds to undesirable behaviour	welcome.

       -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.

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

COMPATIBILITY WITH PREVIOUS VERSIONS
       In prior	versions of perl/Tk the	$widget->Font method was a perl
       wrapper on the original "[4] X-font names (XLFD)" style as described
       above (which was	the only form supported	by versions of core tk prior
       to version tk8.0).  This	module is provided in its original form	(it
       has just	been renamed) via:

	use Tk::X11Font;
	I<$widget>-E<gt>B<X11Font>(...)

       However the methods of the old scheme have been mimiced as closely as
       possible	with the new scheme. It	is intended that code should work
       without modification, except for	the case of using :

	 @names	= $font->Name;

       i.e. the	Name method in an array/list context. This now returns one
       element on all platforms	(as it did on Win32), while previously on X
       systems it returned a list of fonts that	matched	an under-specified
       pattern.

       Briefly the methods supported for compatibilty are as follows:

       $newfont	= $font->Clone(-option=>value, ...>?)
	   Returns a new font object $newfont related to the original $font by
	   changing the	values of the specified	-options.

       $font->Family - maps to -family
       $font->Weight - maps to -weight
       $font->Slant - maps to -slant
       $font->Pixel and	Point -	map to -size

       New code	should use $font->configure to achieve same effect as last
       four items above.

       Foundry,	Swidth,	Adstyle, Xres, Yres, Space, Avgwidth, Registry,
       Encoding
	   Are all ignored if set, and return '*' if queried.

       $font->Name
	   Returns the name of a named font, or	a string representation	of an
	   unnamed font. Using $font in	a scalar context does the same.	Note
	   this	is distinctly different	from behaviour of X11Font's Name in a
	   list	context.

       $font->Pattern
	   Returns a XLFD string for the font based on actual values, and some
	   heuristics to map Tk's forms	to the "standard" X conventions.

SEE ALSO
       Tk::options

       Tk::X11Font

KEYWORDS
       font

perl v5.24.1			  2013-11-15			       Font(3)

NAME | SYNOPSIS | DESCRIPTION | FONT DESCRIPTION | FONT METRICS | FONT OPTIONS | PLATFORM-SPECIFIC ISSUES | COMPATIBILITY WITH PREVIOUS VERSIONS | SEE ALSO | KEYWORDS

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