font::ttf::xmlparse(3)
NAME
Font::TTF::XMLparse - provides support for XML parsing.
Requires Expat module XML::Parser::Expat
SYNOPSIS
use Font::TTF::Font; use Font::TTF::XMLparse; $f = Font::TTF::Font->new; read_xml($f, $ARGV[0]); $f->out($ARGV[1]);
DESCRIPTION
This module contains the support routines for parsing XML
and generating the Truetype font structures as a result.
The module has been separated from the rest of the package
in order to reduce the dependency that this would bring,
of the whole package on XML::Parser. This way, people
without the XML::Parser can still use the rest of the
package.
The package interacts with another package through the use
of a context containing and element 'receiver' which is an
object which can possibly receive one of the following
messages:
- XML_start
- This message is called when an open tag occurs. It is
called with the context, tag name and the attributes.
The return value has no meaning. - XML_end
- This messages is called when a close tag occurs. It is
called with the context, tag name and attributes (held
over from when the tag was opened). There are 3 possi
ble return values from such a message: - undef This is the default return value indicating
that default processing should occur in which
either the current element on the tree, or the
text of this element should be stored in the
parent object. - $context
- This magic value marks that the element should
be deleted from the parent. Nothing is stored
in the parent. (This rather than '' is used to
allow 0 returns.) - anything
- Anything else is taken as the element content
to be stored in the parent. - In addition, the context hash passed to these messages
contains the following keys: - xml This is the expat xml object. The context is also
- available as $context->{'xml'}{' mycontext'}. But that
is a long winded way of not saying much! - font
- This is the base object that was passed in for XML
parsing. - receiver
- This holds the current receiver of parsing events. It
may be set in associated application to adjust which
objects should receive messages when. It is also
stored in the parsing stack to ensure that where an
object changes it during XML_start, that that same
object that received XML_start will receive the corre
sponding XML_end - stack
- This is the parsing stack, used internally to hold the
current receiver and attributes for each element open,
as a complete hierarchy back to the root element. - tree
- This element contains the storage tree corresponding
to the parent of each element in the stack. The
default action is to push undef onto this stack during
XML_start and then to resolve this, either in the
associated application (by changing $con
text->{'tree'}[-1]) or during XML_end of a child ele
ment, by which time we know whether we are dealing
with an array or a hash or what. - text
- Character processing is to insert all the characters
into the text element of the context for available use
later.