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 possible 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 corresponding 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 $context->{'tree'}[-1]) or during
XML_end of a child element, 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.
METHODS¶
