Defoma::Subst(3pm)Defoma::Subst(3pm)NAMEDefoma::Subst - Defoma module to handle Subst cache/rule.
SYNOPSIS
use Defoma::Subst;
$Sb = defoma_subst_open(
rulename => rulename,
threshold => threshold,
idobject => id_object,
private => private_flag );
defoma_subst_close( subst_object );
defoma_subst_register( subst_object, font, realname );
defoma_subst_unregister( subst_object, font realname );
defoma_subst_add_rule( subst_object, required_id, rule... );
defoma_subst_remove_rule( subst_object, required_id, rule... );
DESCRIPTIONDefoma::Subst is a Defoma module to handle subst-cache and subst-rule.
When a certain id is required but not provided as RealName or Alias by
any font, fonts which have similar appearance and the same characters
should substitute for such a font. Required ids and their information
about appearance and charset things (called *rule*) are described in a
subst-rule. Defoma::Subst compares such a rule of a certain required
id with hints of a substitutive font and calculates the degree of simi‐
larity in percentage, and registers the required id and the font with
the value as its priority as 'Substituted' type to an id-cache through
Defoma::Id module.
subst-rule is mainly edittable by users, which means users edit sub‐
st-rule file to add/remove/modify the required ids and their informa‐
tion, but sometimes unedittable by them and modified by a Defoma-con‐
figuration script. The former is called public subst-rule and the lat‐
ter is called private subst-rule.
subst-cache holds fonts which are candidacies for substituting for re‐
quired ids. As mentioned above, a rule of a required id and hints of
such a font are compared. Hints are not recorded in a subst-cache so
retrieved from an id-cache. In addition a required id and its rule are
recorded in an subst-rule, so subst-cache, subst-rule and id-cache are
strongly linked up. Especially subst-cache and subst-rule are not sepa‐
ratable and Defoma::Subst handles these two through a single united ob‐
ject.
defoma_subst_open is a function used to open a subst-cache and sub‐
st-rule specified by rulename and private_flag and returns the sub‐
st_object used for further operation. If the subst-rule is private
one, set private_flag to non-zero. Otherwise it can be omitted. The
subst-rule becomes public. id_object must be specified because sub‐
st-cache and subst-rule are strongly linked up to id-cache as mentioned
above. Hints of a substitutive font are retrieved from the id-cache
specified by the id_object, and required ids described in the sub‐
st-rule are registered to the id-cache. threshold prevents fonts that
have less degree of similarity from being registered. If a required id
is already registered in the id-cache, substitutive fonts whose degree
of similarity are less than this threshold are not registered to an
id-cache.
defoma_subst_close is a function used to close a subst-cache and sub‐
st-rule specified by subst_object. Internally it writes the content of
cache and rule stored in a memory to files.
defoma_subst_register is a function used to register a font which is
candidate for substituting for required ids to the subst-cache speci‐
fied by subst_object. RealName of the font must be specified.
defoma_subst_unregister is a function used to unregister a font from
the subst-cache specified by subst_object. RealName can be omitted.
defoma_subst_add_rule is a function used to add a required id and its
rule to the subst-rule specified by subst_object.
defoma_subst_remove_rule is a function used to remove a required id and
its rule from the subst-rule specified by sbst_object. If rule is
omitted, all the rules describing the required_id are removed from the
subst-rule. Otherwise only one rule specified by rule and required_id
is removed.
EXAMPLES
1. Open private subst-rule and subst-rule.
$Id = defoma_id_open();
$Sb = defoma_subst_open(rulename => 'subst1',
idobject => $Id);
2. Register a substitutive font.
defoma_id_register($Id, type => 'real',
font => $font,
id => $realname,
priority => $priority,
hints => join(' ', @_));
defoma_subst_register($Sb, $font, $realname);
3. Unregister.
defoma_subst_unregister($Id, $font);
defoma_id_unregister($Id, 'real', $font);
4. Add a rule.
defoma_subst_add_rule($Sb, 'Helvetica', @hints);
5. Remove all rules for Helvetica.
defoma_subst_remove_rule($Sb, 'Helvetica');
SEE ALSOdefoma(1). Defoma::Id(1).
March 4, 2001 Defoma::Subst(3pm)
