Font::TTF::Glyph - Holds a single glyph's information


Font::TTF::Glyph - Holds a single glyph's information


This is a single glyph description as held in a TT font. On creation only its header is read. Thus you can get the bounding box of each glyph without having to read all the other information.


In addition to the named variables in a glyph header (xMin etc.), there are also all capital instance variables for holding working information, mostly from the location table.

The standard attributes each glyph has are:


There are also other, derived, instance variables for each glyph which are read when the whole glyph is read (via read_dat):

Number of bytes in the hinting instructions (Warning this variable is deprecated, use length($g-{'hints'})> instead).

The string containing the hinting code for the glyph

In addition there are other attribute like instance variables for simple glyphs:

For each contour there is:

An array of endpoints for each contour in the glyph. There are numberOfContours contours in a glyph. The number of points in a glyph is equal to the highest endpoint of a contour.

There are also a number of arrays indexed by point number

The flags associated with reading this point. The flags for a point are recalculated for a point when it is updated. Thus the flags are not very useful. The only important bit is bit 0 which indicates whether the point is an 'on' curve point, or an 'off' curve point.

The absolute x co-ordinate of the point.

The absolute y co-ordinate of the point

For composite glyphs there are other variables

This holds the component number (not its glyph number) of the component from which the metrics for this glyph should be taken.

This is an array of hashes for each component. Each hash has a number of elements:
The glyph number of the glyph which comprises this component of the composite.

An array of two arguments which may be an x, y co-ordinate or two attachment points (one on the base glyph the other on the component). See flags for details.

The flag for this component

A 4 number array for component scaling. This allows stretching, rotating, etc. Note that scaling applies to placement co-ordinates (rather than attachment points) before locating rather than after.

This is a generated value which contains the number of components read in for this compound glyph.

The private instance variables are:

The input file form which to read any information

Location relative to the start of the glyf table in the read file

The location of the glyf table in the read file

This is the number of bytes required by the glyph. It should be kept up to date by calling the update method whenever any of the glyph content changes.

Location relative to the start of the glyf table. This variable is only active whilst the output process is going on. It is used to inform the location table where the glyph's location is, since the glyf table is output before the loca table due to alphabetical ordering.

This indicates the length of the glyph data when it is output. This more accurately reflects the internal memory form than the LEN variable which only reflects the read file length. The OUTLEN variable is only set after calling out or out_dat.


If you want to edit a glyph in some way, then you should read_dat the glyph, then make your changes and then update the glyph or set the $g->{' isdirty'} variable. It is the application's duty to ensure that the following instance variables are correct, from which update will calculate the rest, including the bounding box information.

    x, y, flags         (only flags bit 0)

For components, the numPoints, x, y, endPoints & flags are not required but the following information is required for each component.

    flag                (bits 2, 10, 11, 12)
    metric              (glyph instance variable)



Creates a new glyph setting various instance variables


Reads the header component of the glyph (bounding box, etc.) and also the glyph content, but into a data field rather than breaking it down into its constituent structures. Use read_dat for this.


Reads the contents of the glyph (components and curves, etc.) from the memory store DAT into structures within the object. Then, to indicate where the master form of the data is, it deletes the DAT instance variable.


Writes the glyph data to outfile

$g->out_xml($context, $depth)

Outputs an XML description of the glyph


Generates a $self-{'DAT'}> from the internal structures, if the data has been read into structures in the first place. If you are building a glyph from scratch you will need to set the instance variable ' read' to 2 (or something > 1) for the update to work.


Updates the bounding box for this glyph according to the points in the glyph


Empties the glyph of all information to the level of not having been read. Useful for saving memory in apps with many glyphs being read


This method creates point information for a compound glyph. The information is stored in the same place as if the glyph was not a compound, but since numberOfContours is negative, the glyph is still marked as being a compound


Returns an array of all the glyph ids that are used to make up this glyph. That is all the compounds and their references and so on. If this glyph is not a compound, then returns an empty array



Martin Hosken See the Font::TTF::Font manpage for copyright and licensing.

 Font::TTF::Glyph - Holds a single glyph's information