[Raku PDF Project] / [Font-FreeType Module] / Font::FreeType :: Face

class Font::FreeType::Face

Font typefaces loaded from Font::FreeType

multi method forall-chars

multi method forall-chars(
    &code,
    :$flags = Code.new
) returns Mu

iterate all char-mapped glyphs

Synopsis

use Font::FreeType;
use Font::FreeType::Face;

my Font::FreeType $freetype .= new;
my Font::Freetype::Face $vera = $freetype.face('Vera.ttf');

Description

This class represents a font face (or typeface) loaded from a font file. Usually a face represents all the information in the font file (such as a TTF file), although it is possible to have multiple faces in a single file.

This class is loaded automatically from Font::FreeType. Use the Font::FreeType.face() method to create a new Font::FreeType::Face object from a filename and then use the forall-chars(), or forall-glyphs() methods.

Methods

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

ascender()

The height above the baseline of the ‘top’ of the font’s glyphs.

attach-file(filename)

Informs FreeType of an ancillary file needed for reading the font.

In particular an *.afm (font metrics) file needs to accompany a Type-1 *.pfa or *.pfb file to obtain kerning and other font metrics.

font-format()

Return a string describing the format of a given face. Possible values are ‘TrueType’, ‘Type 1’, ‘BDF’, ‘PCF’, ‘Type 42’, ‘CID Type 1’, ‘CFF’, ‘PFR’, and ‘Windows FNT’.

face-index()

The index number of the current font face. Usually this will be zero, which is the default. See Font::FreeType.face() for how to load other faces from the same file.

descender()

The depth below the baseline of the ‘bottom’ of the font’s glyphs. Actually represents the distance moving up from the baseline, so usually negative.

family-name()

A string containing the name of the family this font claims to be from.

fixed-sizes()

Returns an array of Font::FreeType::BitMap::Size objects which detail sizes. Each object has the following available methods:

size

Size of the glyphs in points. Only available with Freetype 2.1.5 or newer.
height

Height of the bitmaps in pixels.
width

Width of the bitmaps in pixels.
x-res(:dpi), y-res(:dpi)

Resolution the bitmaps were designed for, in dots per inch. Only available with Freetype 2.1.5 or newer.
x-res(:ppem), y-res(:ppem)

Resolution the bitmaps were designed for, in pixels per em. Only available with Freetype 2.1.5 or newer.

cmap

say $face.cmap.head(3).map({.key => .value.chr}).raku; # e.g. (3 => " ", 4 => "!", 5 => "\"")

Iterates the fonts character map, returning character mappings from glyphs-indexes to characters-codes. Any glyphs that don’t have character mapping are ommitted. It is also possible for a single glyph-index to map to multiple characters.

glyph-images(str)

Returns an array of Font::FreeType::GlyphImage objects for the Unicode string.

For example, to load particular glyphs (character images):

for $face.glyph-images('ABC') {
    # Glyphs can be rendered to bitmap images, among other things:
    my $bitmap = .bitmap;
    say $bitmap.Str;
}`

forall-chars($text, &code)

$face.forall-chars: "Raku", -> Font::FreeType::Glyph $glyph { ... }

Iterates through all the characters in the text, and passes the corresponding Font::FreeType::Glyph object for each of them in turn. Glyphs which don’t correspond to Unicode characters are ignored.

Each time your callback code is called, a object is passed for the current glyph. The object is only valid for the duration of the call.

If there was an error loading the glyph, then the glyph’s, stat method will return non-zero and the error method will return an exception object.

If $text is ommitted, all Unicode mapped characters in the font are iterated.

forall-glyphs()

$face.forall-glyphs: -> Font::FreeType::Glyph $glyph { ... }

Iterates through all the glyphs in the font, and passes Font::FreeType::Glyph objects.

If there was an error loading the glyph, then the glyph’s, stat method will return non-zero and the error method will return an exception object.

forall-char-images($text, &code)

$face.forall-char-images: "Raku", -> Font::FreeType::GlyphImage $glyph-image { ... }

Iterates through all the characters in the text, and passes the corresponding Font::FreeType::GlyphImage object for each of them in turn. Glyphs which don’t correspond to Unicode characters are ignored.

Each time your callback code is called, a object is passed for the current glyph.

If there was an error loading the glyph image, then the glyph-image’s, stat method will return non-zero and the error method will return an exception object.

If $text is ommitted, all Unicode mapped characters in the font are iterated.

forall-glyph-images()

$face.forall-glyph-images: -> Font::FreeType::GlyphImage $glyph-image { ... }

Similar to forall-glyphs, except that detachable Font::FreeType::GlyphImage are returned

If there was an error loading the glyph, then the glyph-images’s, stat method will return non-zero and the error method will return an exception object.

glyph-image()

Returns a single Font::FreeType::GlyphImage object for a code-point.

has-glyph-names()

True if individual glyphs have names. If so, the names can be retrieved with the name() method on Font::FreeType::Glyph objects.

See also has-reliable-glyph-names() below.

has-horizontal-metrics()

has-vertical-metrics()

These return true if the font contains metrics for the corresponding directional layout. Most fonts will contain horizontal metrics, describing (for example) how the characters should be spaced out across a page when being written horizontally like English. Some fonts, such as Chinese ones, may contain vertical metrics as well, allowing typesetting down the page.

has-kerning()

True if the font provides kerning information. See the kerning() method below.

has-reliable-glyph-names()

True if the font contains reliable PostScript glyph names. Some Some fonts contain bad glyph names.

height()

The line-height of the text, i.e. distance between baselines of two lines of text.

is-bold()

True if the font claims to be in a bold style.

is-fixed-width()

True if all the characters in the font are the same width. Will be true for mono-spaced fonts like Courier.

is-italic()

Returns true if the font claims to be in an italic style.

is-scalable()

True if the font has a scalable outline, meaning it can be rendered nicely at virtually any size. Returns false for bitmap fonts.

is-sfnt()

True if the font file is in the ‘sfnt’ format, meaning it is either TrueType or OpenType. This isn’t much use yet, but future versions of this library might provide access to extra information about sfnt fonts.

kerning(left-char, right-char, :$mode)

Returns a vector for the the suggested kerning adjustment between two glyphs.

For example:

my $kern = $face.kerning('A', 'V');
my $kern-distance = $kern.x;

The mode option controls how the kerning is calculated, with the following options available:

FT_KERNING_UNSCALED

Leave the measurements in font units, without scaling, and without hinting.
FT_KERNING_DEFAULT

Grid-fitting (hinting) and scaling are done. Use this when rendering glyphs to bitmaps to make the kerning take the resolution of the output in to account.
FT_KERNING_UNFITTED

Scaling is done, but not hinting. Use this when extracting the outlines of glyphs. If you used the FT_LOAD_NO_HINTING option when creating the face then use this when calculating the kerning.

num-faces()

The number of faces contained in the file from which this one was created. Usually there is only one. See Font::FreeType.face() for how to load the others if there are more.

num-glyphs()

The number of glyphs in the font face.

postscript-name()

A string containing the PostScript name of the font, or Str:U if it doesn’t have one.

glyph-name(char)

Returns the name for the given character, where char can be a string or code-point number

glyph-index(char)

Returns the glyph index in the font, or 0 if the character does not exist. char can be a string or code-point number

glyph-name-from-index(index)

Returns the name for the given character.

index-from-glyph-name(name)

Returns the glyph index for the given glyph name.

set-font-size(width, height, x-res, y-res)

Set the size at which glyphs should be rendered. The width and height will usually be the same, and are in points. The resolution is in dots-per-inch.

The height and resolution may be omitted. The height defaults to the width and the reslution defaults to 72 (dpi).

When generating PostScript or PDF outlines a resolution of 72 will scale to PostScript points.

Font metrics and metrics for individual glyphs are also scaled to match.

set-char-size(width, height, x-res, y-res)

Older alternative to set-font-size. Font metrics are scaled for individual glyphs, but are not scaled for font metrics. The scaled-metrics method may be called to get the scaled metrics.

set-pixel-sizes(width, height, :$scale-font)

Set the size at which bit-mapped fonts will be loaded. Bitmap fonts are automatically set to the first available standard size, so this usually isn’t needed.

Font metrics are scaled for individual glyphs. The :scale-font option will also cause scaling of font metrics:

use Font::FreeType;

my Font::FreeType $ft .= new;
my $vera = $ft.face: 't/fonts/Vera.ttf';

$vera.set-pixel-sizes(24,24,);

$vera.for-glyphs: "T", { say .width; } # 16 (scaled)
say $vera.height;               # 2384 (unscaled)
say $vera.kerning('T', '.').x;  # -243 (scaled)

$vera.set-pixel-sizes(24,24, :scale-font);

$vera.for-glyphs: "T", { say .width; } # 16
say $vera.height;               # 5.25
say $vera.kerning('T', '.').x;  # -1.421875

scaled-metrics()

This method can be called after calling set-char-size() or set-pixel-sizes() without the :scale-font option to get a Font::FreeType::SizeMetrics object that returns scaled font metrics.

style-name()

A string describing the style of the font, such as ‘Roman’ or ‘Demi Bold’. Most TrueType fonts are just ‘Regular’.

underline-position()

underline-thickness()

The suggested position and thickness of underlining for the font. Int:U is returned if the information isn’t available.

units-per-EM()

The size of the em square used by the font designer. This can be used to scale font-specific measurements to the right size, although that’s usually done for you by FreeType. Usually this is 2048 for TrueType fonts.

charmap()

The current active Font::FreeType::CharMap object for this face.

charmaps()

An array of the available Font::FreeType::CharMap objects for the face.

num-charmaps()

The number of charmaps for this face.

set-charmap(n)

Select a charmap, where n is in the range 1 .. $.num-charmaps.

index-to-unicode()

Returns an array[uint32] of glyph-index to unicode code-point mappings. Unmapped glyphs are set to zero.

bounding-box() [or bbox()]

The outline’s bounding box returned as a Font::FreeType::BBox array: ($x-min, $y-min, $x-max, $y-max).

raw()

use Font::FreeType::Raw;
use Cairo;
my FT_Face $ft-face-raw = $face.raw;
$ft-face-raw.FT_Reference_Face;
my Cairo::Font $font .= create(
     $ft-face-raw, :free-type,
);
# some time later...
$ft-face.FT_Done_Face;
$ft-face = Nil;

This method provides access to the underlying raw FT_Face native struct; for example, for integration with the Cairo graphics library.

The FT_Reference_Face and FT_Done_Face methods will need to be called if the struct outlives the parent $face object.

protect()

This method should only be needed if the low level native freetype bindings are being use directly. See Font::FreeType::Raw.

Author

Geoff Richards qef@laxan.com

Ivan Baidakou dmol@cpan.org

David Warring david.warring@gmail.com (Raku Port)

COPYRIGHT

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