NAME

       Font::TTF::Glyph - Holds a information for a single glyph

DESCRIPTION

       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.

INSTANCE VARIABLES

       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.

   Variables for all glyphs:
       The standard attributes each glyph has are:

       numberOfContours
           For simple glyphs this will be the count of contours. For compound glyphs this will be -1.

       xMin
       yMin
       xMax
       yMax
           These identify the bounding box of the glyph.

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

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

       hints
           The string containing the hinting code for the glyph

   Variables for simple glyphs (numberOfContours >= 0):
       endPoints
           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.

       numPoints
           This is a generated value which contains the total number of points for this simple glyph.

       There are also a number of arrays indexed by point number:

       flags
           The flags associated with reading this point. The flags for a point are recalculated for a point when
           it is "update"d. 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.

       x   The absolute x co-ordinate of the point.

       y   The absolute y co-ordinate of the point

   Variables for compound glyphs (numberOfContours == -1):
       metric
           This holds the component number (not its glyph number) of the component from which the metrics for
           this glyph should be taken.

       comps
           This is an array of hashes for each component. Each hash has a number of elements:

           glyph
               The glyph number of the glyph which comprises this component of the composite.  NOTE: In some
               badly generated fonts, "glyph" may contain a numerical value but that glyph might not actually
               exist in the font file.  This could occur in any glyph, but is particularly likely for glyphs
               that have no strokes, such as SPACE, U+00A0 NO-BREAK SPACE, or U+200B ZERO WIDTH SPACE.

           args
               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.

           flag
               The flag for this component

           scale
               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.

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

   Private instance variables:
       INFILE (P)
           The input file form which to read any information

       LOC (P)
           Location relative to the start of the glyf table in the read file

       BASE (P)
           The location of the glyf table in the read file

       LEN (P)
           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.

       OUTLOC (P)
           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 is located, since the
           glyf table is output before the loca table due to alphabetical ordering.

       OUTLEN (P)
           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".

   Editing
       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.  The application must ensure that the
       following instance variables are correct, from which update will calculate the rest, including the
       bounding box information.

           numPoints
           numberOfContours
           endPoints
           x, y, flags         (only flags bit 0)
           instLen
           hints

       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)
           glyph
           args
           scale
           metric              (glyph instance variable)

METHODS

Font::TTF::Glyph->new(%parms)

       Creates a new glyph setting various instance variables

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

   $g->read_dat
       Reads the contents of the glyph (components and curves, etc.) from the memory store "DAT" into structures
       within the object.

   $g->out($fh)
       Writes the glyph data to outfile

   $g->out_xml($context, $depth)
       Outputs an XML description of the glyph

   $g->dirty($val)
       This sets the dirty flag to the given value or 1 if no given value. It returns the value of the flag

   $g->update
       Generates a "$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 '
       isDirty'.

   $g->update_bbox
       Updates the bounding box for this glyph according to the points in the glyph

   $g->maxInfo
       Returns lots of information about a glyph so that the "maxp" table can update itself. Returns array
       containing contributions of this glyph to maxPoints, maxContours, maxCompositePoints,
       maxCompositeContours, maxSizeOfInstructions, maxComponentElements, and maxComponentDepth.

   $g->empty
       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

   $g->get_points
       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

   $g->get_refs
       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.

       Please note the warning about bad fonts that reference nonexistent glyphs under INSTANCE VARIABLES above.
       This function will not attempt to filter out nonexistent glyph numbers.

BUGS

       •   The instance variables used here are somewhat clunky and inconsistent with the other tables.

       •   "update" doesn't re-calculate the bounding box or "numberOfContours".

AUTHOR

       Martin Hosken <http://scripts.sil.org/FontUtils>.

LICENSING

       Copyright (c) 1998-2016, SIL International (http://www.sil.org)

       This module is released under the terms of the Artistic License 2.0.  For details, see the full text of
       the license in the file LICENSE.