NAME

Font::FreeType - read font files and render glyphs from Perl using FreeType2

SYNOPSIS

use Font::FreeType;

my $freetype = Font::FreeType->new;
my $face = $freetype->face('Vera.ttf');

$face->set_char_size(24, 24, 100, 100);
my $glyph = $face->glyph_from_char('A');

DESCRIPTION

This module allows Perl programs to conveniently read information from font files. All the font access is done through the FreeType2 library, which supports many formats. It can render images of characters with high-quality hinting and antialiasing, extract metrics information, and extract the outlines of characters in scalable formats like TrueType.

Warning: this module is currently in 'beta' stage. It'll be another release or two before it stabilizes. The API may change in ways that break programs based on it, but I don't think it will change much. Some of the values returned may be wrong, or not scaled correctly. See the TODO file to get a handle on how far along this work is. Contributions welcome, particularly if you know more than I do (which isn't much) about fonts and the FreeType2 library.

The Font::FreeType API is not intended to replicate the C API of the FreeType library -- it offers a much more Perl-friendly interface.

The quickest way to get started with this library is to look at the examples in the examples directory of the distribution. Full details of the API are contained in this documentation, and (more importantly) the documentation for the Font::FreeType::Face and Font::FreeType::Glyph classes.

To use the library, first create a Font::FreeType object. This can be used to load faces from files, for example:

my $freetype = Font::FreeType->new;
my $face = $freetype->face('Vera.ttf');

If your font is scalable (i.e., not a bitmapped font) then set the size and resolution you want to see it at, for example 24pt at 100dpi:

$face->set_char_size(24, 24, 100, 100);

Then load a particular glyph (an image of a character), either by character code (in Unicode) or the actual character:

my $glyph = $face->glyph_from_char_code(65);
my $glyph = $face->glyph_from_char('A');

Glyphs can be rendered to bitmap images, among other things:

my $bitmap = $glyph->bitmap;

See the documentation for Font::FreeType::Glyph for details of the format of the bitmap array reference that returns, and for other ways to get information about a glyph.

METHODS

Unless otherwise stated, all methods will die if there is an error.

new()

Create a new 'instance' of the freetype library and return the object. This is a class method, which doesn't take any arguments. If you only want to load one face, then it's probably not even worth saving the object to a variable:

my $face = Font::FreeType->new->face('Vera.ttf');

face(filename, %options)

Return a Font::FreeType::Face object representing a font face from the specified file.

The index option specifies which face to load from the file. It defaults to 0, and since most fonts only contain one face it rarely needs to be provided.

The load_flags option takes various flags which alter the way glyphs are loaded. The default is usually OK for rendering fonts to bitmap images. When extracting outlines from fonts, be sure to set the FT_LOAD_NO_HINTING flag.

The following load flags are available. They can be combined with the bitwise OR operator (|). The symbols are exported by the module and so will be available once you do use Font::FreeType.

FT_LOAD_DEFAULT

The same as doing nothing special.

FT_LOAD_COMPUTE_METRICS

Compute glyph metrics from the glyph data, without the use of bundled metrics tables (for example, the 'hdmx' table in TrueType fonts). This flag is mainly used by font validating or font editing applications, which need to ignore, verify, or edit those tables.

This option is only available with FreeType 2.6.1 or newer.

FT_LOAD_CROP_BITMAP

Remove extraneous black bits round the edges of bitmaps when loading embedded bitmaps.

FT_LOAD_FORCE_AUTOHINT

Use FreeType's own automatic hinting algorithm rather than the normal TrueType one. Probably only useful for testing the FreeType library.

FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH

Probably only useful for loading fonts with wrong metrics.

FT_LOAD_IGNORE_TRANSFORM

Don't transform glyphs. This module doesn't yet have support for transformations.

FT_LOAD_LINEAR_DESIGN

Don't scale the metrics.

FT_LOAD_NO_AUTOHINT

Don't use the FreeType autohinting algorithm. Hinting with other algorithms (such as the TrueType one) will still be done if possible. Apparently some fonts look worse with the autohinter than without any hinting.

This option is only available with FreeType 2.1.3 or newer.

FT_LOAD_NO_BITMAP

Don't load embedded bitmaps provided with scalable fonts. Bitmap fonts are still loaded normally. This probably doesn't make much difference in the current version of this module, as embedded bitmaps aren't deliberately used.

FT_LOAD_NO_HINTING

Prevents the coordinates of the outline from being adjusted ('grid fitted') to the current size. Hinting should be turned on when rendering bitmap images of glyphs, and off when extracting the outline information if you don't know at what resolution it will be rendered. For example, when converting glyphs to PostScript or PDF, use this to turn the hinting off.

FT_LOAD_NO_SCALE

Don't scale the font's outline or metrics to the right size. This will currently generate bad numbers. To be fixed in a later version.

FT_LOAD_PEDANTIC

Raise errors when a font file is broken, rather than trying to work around it.

FT_LOAD_VERTICAL_LAYOUT

Return metrics and glyphs suitable for vertical layout. This module doesn't yet provide any intentional support for vertical layout, so this probably won't be much use.

version()

Returns the version number of the underlying FreeType library being used. If called in scalar context returns a string containing three numbers in the format "major.minor.patch". In list context returns the three numbers as separate values.

SEE ALSO

Font::FreeType::Face, Font::FreeType::Glyph

AUTHOR

Geoff Richards <qef@laxan.com>

COPYRIGHT

Copyright 2004, Geoff Richards.

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