Christopher J. Madsen > PostScript-File > PostScript::File::Metrics

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Module Version: 2.11   Source  

NAME ^

PostScript::File::Metrics - Metrics for PostScript fonts

VERSION ^

This document describes version 2.11 of PostScript::File::Metrics, released February 11, 2012 as part of PostScript-File version 2.20.

SYNOPSIS ^

  use PostScript::File;

  my $ps = PostScript::File->new(reencode => 'cp1252');

  my $metrics = $ps->get_metrics('Helvetica-iso', 9);

  my $upos = $metrics->underline_position;

  my $width = $metrics->width('Hello, World!');

  my @lines = $metrics->wrap( 72, # wrap it into 1 inch lines
    'This is a long string that will not fit on just one line of text.'
  );

DESCRIPTION ^

PostScript::File::Metrics provides a subset of the metrics available from Font::AFM. Its reason for existence is that it allows you to pre-compile the AFM files into Perl modules. This makes loading them more efficient, but more importantly, it means you don't have to install (or configure) Font::AFM. That's important because the locations and filenames of AFM files are not very standardized, which makes configuring Font::AFM quite difficult.

PostScript::File::Metrics includes pre-compiled metrics for the 13 standard PostScript fonts:

  Courier              Helvetica              Times-Roman
  Courier-Bold         Helvetica-Bold         Times-Bold
  Courier-BoldOblique  Helvetica-BoldOblique  Times-BoldItalic
  Courier-Oblique      Helvetica-Oblique      Times-Italic
                       Symbol

If you need metrics for a font not in that list, you'll need to have Font::AFM installed and configured. (You can modify examples/generate_metrics.pl to create additional pre-compiled modules, but you'll still have to get Font::AFM working on one system.)

ATTRIBUTES ^

All attributes are read-only, except for auto_hyphen and size, which can be set using the corresponding set_ methods.

size

The current font size in points. This is not an attribute of the font, but of this Metrics object. The attributes that describe the font's dimensions are adjusted according to this value.

auto_hyphen

If true, the width and wrap methods will do hyphen-minus processing as described in "Hyphens and Minus Signs" in PostScript::File, but only if the encoding is cp1252 or iso-8859-1.

full_name

Unique, human-readable name for an individual font, for instance "Times Roman".

family

Human-readable name for a group of fonts that are stylistic variants of a single design. All fonts that are members of such a group should have exactly the same family. Example of a family name is "Times".

weight

Human-readable name for the weight, or "boldness", attribute of a font. Examples are Roman, Bold, Medium.

italic_angle

Angle in degrees counterclockwise from the vertical of the dominant vertical strokes of the font. (This is normally <= 0.)

fixed_pitch

1 if the font is a fixed-pitch (monospaced) font. 0 otherwise.

font_bbox

An arrayref of four numbers giving the lower-left x, lower-left y, upper-right x, and upper-right y of the font bounding box. The font bounding box is the smallest rectangle enclosing the shape that would result if all the characters of the font were placed with their origins coincident at (0,0), and then painted. You must not modify the returned arrayref.

cap_height

Usually the y-value of the top of the capital H. Some fonts, like Symbol, may not define this attribute.

x_height

Typically the y-value of the top of the lowercase x. Some fonts, like Symbol, may not define this attribute.

ascender

Typically the y-value of the top of the lowercase d. Some fonts, like Symbol, may not define this attribute.

descender

Typically the y-value of the bottom of the lowercase p. Some fonts, like Symbol, may not define this attribute.

underline_position

Recommended distance from the baseline for positioning underline strokes. This number is the y coordinate of the center of the stroke.

underline_thickness

Recommended stroke width for underlining.

version

Version number of the font.

METHODS ^

new

  $metrics = PostScript::File::Metrics->new($font, [$size, [$encoding]])

You would normally use "get_metrics" in PostScript::File to construct a Metrics object (because it can get the $encoding from the document), but it is possible to construct one directly.

$size is the font size in points, and defaults to 1000.

$encoding is the character encoding used by "width" and "wrap". Valid choices are std, sym, cp1252, and iso-8859-1. The default is std, meaning PostScript's StandardEncoding (unless the $font is Symbol, which uses sym, meaning PostScript's SymbolEncoding). Neither std nor sym does any character set translation.

The auto_hyphen attribute is always set to true when character translation is enabled.

set_auto_hyphen( translate )

If translate is a true value, then width and wrap will do automatic hyphen-minus translation as described in "Hyphens and Minus Signs" in PostScript::File.

set_size

  $metrics->set_size($new_size)

This method sets the font size (in points). This influences the attributes that concern dimensions and the string width calculations. It returns the Metrics object, so you can chain to the next method.

set_wrap_chars

  $metrics->set_wrap_chars($new_chars)

This method (introduced in version 2.11) sets the characters after which a word can be wrapped. A line can wrap after any character in $new_chars, which should not include whitespace. Whitespace is always a valid breakpoint. If $new_chars is omitted or undef, restores the default wrap characters, which means -/ and (if using cp1252) both en and em dashes. It returns the Metrics object, so you can chain to the next method.

width

  $width = $metrics->width($string, [$already_encoded])

This calculates the width of $string (in points) when displayed in this font at the current size. If $string has the UTF8 flag set, it is translated into the font's encoding. Otherwise, the $string is expected to be in the correct character set already. $string should not contain newlines.

If optional parameter $already_encoded is true, then $string is assumed to be already encoded in the document's character set. This also prevents any hyphen-minus processing.

wrap

  @lines = $metrics->wrap($width, $text, [\%param])

This wraps $text into lines of no more than $width points. If $text contains newlines, they will also cause line breaks. If $text has the UTF8 flag set, it is translated into the font's encoding. Otherwise, the $text is expected to be in the correct character set already.

If the auto_hyphen attribute is true, then any HYPHEN-MINUS (U+002D) characters in $text will be converted to either HYPHEN (U+2010) or MINUS SIGN (U+2212) in the returned strings.

The characters after which a line can wrap (other than space and tab, which are always valid line breaks) can be set with the set_wrap_chars method. In addition, $text may contain ZERO WIDTH SPACE (U+200B) characters to indicate potential line breaks. All ZWSP characters and CRs will be removed from the returned strings. $text may also contain NO-BREAK SPACE (U+00A0) characters, which indicate whitespace without a potential line break.

The optional \%param (introduced in version 2.11) allows additional control over the wrapping. It may contain the following keys:

chars

This overrides the line-breaking characters normally set by the set_wrap_chars method. The value has the same meaning as for set_wrap_chars.

maxlines

The maximum number of lines to return. The final line will contain all the remaining text, even if that exceeds $width or contains newline characters.

quiet

If true, do not warn about words that are too wide to fit in the specified $width.

warnings

If present, must be an arrayref. Warning messages about words that are too wide to fit in the specified $width will be pushed onto the array. You should also pass quiet => 1 if you don't want the warnings printed to STDERR.

CONFIGURATION AND ENVIRONMENT ^

PostScript::File::Metrics requires no configuration files or environment variables.

INCOMPATIBILITIES ^

None reported.

BUGS AND LIMITATIONS ^

No bugs have been reported.

AUTHOR ^

Christopher J. Madsen <perl AT cjmweb.net>

Please report any bugs or feature requests to <bug-PostScript-File AT rt.cpan.org> or through the web interface at http://rt.cpan.org/Public/Bug/Report.html?Queue=PostScript-File.

You can follow or contribute to PostScript-File's development at http://github.com/madsen/postscript-file.

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2012 by Christopher J. Madsen.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTY ^

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENSE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

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