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

NAME

       font - Create and inspect fonts.

SYNOPSIS

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

	   $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.

       [3] 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 v5.14.2							    2010-05-29								 Font(3pm)