Gtk2::Buildable(3) User Contributed Perl Documentation Gtk2::Buildable(3)NAMEGtk2::Buildable - Interface for objects that can be built by
Gtk2::Builder
SYNOPSIS
package Thing;
use Gtk2;
use Glib::Object::Subclass
Glib::Object::,
# The important bit -- add this GInterface to our class
interfaces => [ Gtk2::Buildable:: ],
# Some signals and properties on the object...
signals => {
exploderize => {},
},
properties => [
Glib::ParamSpec->int ('force', 'Force',
'Explosive force, in megatons',
0, 1000000, 5, ['readable', 'writable']),
],
;
sub exploderize {
my $self = shift;
$self->signal_emit ('exploderize');
}
# We can accept all defaults for Buildable; see the description
# for details on custom XML.
package main;
use Gtk2 -init;
my $builder = Gtk2::Builder->new ();
$builder->add_from_string ('<interface>
<object class="Thing" id="thing1">
<property name="force">50</property>
<signal name="exploderize" handler="do_explode" />
</object>
</interface>');
$builder->connect_signals ();
my $thing = $builder->get_object ('thing1');
$thing->exploderize ();
sub do_explode {
my $thing = shift;
printf "boom * %d!\n", $thing->get ('force');
}
# This program prints "boom * 50!" on stdout.
HIERARCHY
Glib::Interface
+----Gtk2::Buildable
DESCRIPTION
In order to allow construction from a Gtk2::Builder UI description
(http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-UI
<http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-
UI>), an object must implement the Gtk2::Buildable interface. The
interface includes methods for setting names and properties of objects,
parsing custom tags, and constructing child objects.
The Gtk2::Buildable interface is implemented by all widgets and many of
the non-widget objects that are provided by GTK+. The main user of
this interface is Gtk2::Builder, so there should be very little need
for applications to call any of the Gtk2::Buildable methods.
So, instead of focusing on how to call the methods of a
Gtk2::Buildable, this documentation deals with implementing a buildable
object.
WIDGETS
Since Gtk2::Widget implements the Gtk2::Buildable interface, all
widgets get buildability gratis. If your widget requires no special
markup syntax to express its configuration, and all properties can be
handled through the standard mechanisms, you can simply add the name of
your perl-derived Glib::Object types to the "object" tag in the builder
UI description. You don't even have to do anything special in your
class definition. For example, objects of this class:
package My::Frame;
use Gtk2;
use Glib::Object::Subclass
Gtk2::Frame::,
properties => [
Glib::ParamSpec->int ('foo', ...),
],
;
...
1;
could be expressed in a builder definition file like this:
<object class="My__Frame" id="myframe">
<property name="foo">15</property>
</object>
Notice that the '::' package separator has been replaced with '__' in
the "class" attribute; this is because the ':' character is not valid
for GType type names. The mapping from perl package names to GType
names should, in general, be as simple as transliterating the colons.
PLAIN OBJECTS
Glib::Object does not implement Gtk2::Buildable by itself, so to get a
builder UI file to create your custom Glib::Object subtypes, you'll
have add the Gtk2::Buildable interface to your class's interfaces list.
package My::Thing;
use Gtk2; # to get Gtk2::Buildable
use Glib::Object::Subclass
Glib::Object::,
interfaces => [ 'Gtk2::Buildable' ],
...
;
Again, if you have no special requirements, then that should be all you
need to do.
OVERRIDING BUILDABLE INTERFACE METHODS
In some cases, you need to override the default Buildable behavior.
Maybe your objects already store their names, or you need some special
markup tags to express configuration. In these cases, add the
Gtk2::Buildable interface to your object declaration, and implement the
following methods as necessary.
Note that in the current implementation the custom tags code doesn't
chain up to any buildable interfaces in superclasses. This means for
instance if you implement Gtk2::Buildable on a new widget subclass then
you lose the <accelerator> and <accessibility> tags normally available
from Gtk2::Widget. This will likely change in the future, probably by
chaining up by default for unhandled tags, maybe with a way to ask
deliberately not to chain.
SET_NAME ($self, $name)
· $name (string)
This method should store $name in $self somehow. For example,
Gtk2::Widget maps this to the Gtk2::Widget's "name" property. If
you don't implement this method, the name will be attached in
object data down in C code. Implement this method if your object
has some notion of "name" and it makes sense to map the XML name
attribute to that.
string = GET_NAME ($self)
If you implement "SET_NAME", you need to implement this method to
retrieve that name.
ADD_CHILD ($self, $builder, $child, $type)
· $builder (Gtk2::Builder)
· $child (Glib::Object or undef)
· $type (string)
"ADD_CHILD" will be called to add $child to $self. $type can be
used to determine the kind of child. For example, Gtk2::Container
implements this method to add a child widget to the container, and
Gtk2::Notebook uses $type to distinguish between "page-label" and
normal children. The value of $type comes directly from the "type"
attribute of the XML "child" tag.
SET_BUILDABLE_PROPERTY ($self, $builder, $name, $value)
· $builder (Gtk2::Builder)
· $name (string)
· $value (scalar)
This will be called to set the object property $name on $self,
directly from the "property" XML tag. It is not normally necessary
to implement this method, as the fallback simply calls
"Glib::Object::set()". Gtk2::Window implements this method to
delay showing itself (i.e., setting the "visible" property) until
the whole interface is created. You can also use this to handle
properties that are not wired up through the Glib::Object property
system (though simply creating the property is easier).
parser or undef = CUSTOM_TAG_START ($self, $builder, $child, $tagname)
· $builder (Gtk2::Builder)
· $child (Glib::Object or undef)
· $tagname (string)
When Gtk2::Builder encounters an unknown tag while parsing the
definition of $self, it will call "CUSTOM_TAG_START" to give your
code a chance to do something with it. If $tagname was encountered
inside a "child" tag, the corresponding object will be passed in
$child; otherwise, $child will be "undef".
Your "CUSTOM_TAG_START" method should decide whether it supports
$tagname. If not, return "undef". If you do support it, return a
blessed perl object that implements three special methods to be
used to parse that tag. (These methods are defined by GLib's
GMarkupParser, which is a simple SAX-style setup.)
START_ELEMENT ($self, $context, $element_name, $attributes)
· $context (Gtk2::Buildable::ParseContext)
· $element_name (string)
· $attributes (hash reference) Dictionary of all attributes
of this tag.
TEXT ($self, $context, $text)
· $context (Gtk2::Buildable::ParseContext)
· $text (string) The text contained in the tag.
END_ELEMENT ($self, $context, $element_name)
· $context (Gtk2::Buildable::ParseContext)
· $element_name (string)
Any blessed perl object that implements these methods is valid as a
parser. (Ain't duck-typing great?) Gtk2::Builder will hang on to
this object until the parsing is complete, and will pass it to
"CUSTOM_TAG_END" and "CUSTOM_FINISHED", so you shouldn't have to
worry about its lifetime.
CUSTOM_TAG_END ($self, $builder, $child, $tagname, $parser)
· $builder (Gtk2::Builder)
· $child (Glib::Object or undef)
· $tagname (string)
· $parser (some perl object) as returned from "CUSTOM_TAG_START"
This method will be called (if it exists) when the close tag for
$tagname is encountered. $parser will be the object you returned
from "CUSTOM_TAG_START". $child is the same object-or-undef as
passed to "CUSTOM_TAG_START".
CUSTOM_FINISHED ($self, $builder, $child, $tagname, $parser)
· $builder (Gtk2::Builder)
· $child (Glib::Object or undef)
· $tagname (string)
· $parser (some perl object) as returned from "CUSTOM_TAG_START"
This method will be called (if it exists) when the parser finishes
dealing with the custom tag $tagname. $parser will be the object
you returned from "CUSTOM_TAG_START". $child is the same object-
or-undef as passed to "CUSTOM_TAG_START".
PARSER_FINISHED ($self, $builder)
· $builder (Gtk2::Builder)
If this method exists, it will be invoked when the builder finishes
parsing the description data. This method is handy if you need to
defer any object initialization until all of the rest of the input
is parsed, most likely because you need to refer to an object that
is declared after $self or you need to perform special cleanup
actions. It is not normally necessary to implement this method.
object or undef = GET_INTERNAL_CHILD ($self, $builder, $childname)
· $builder (Gtk2::Builder)
· $childname (string)
This will be called to fetch an internal child of $self. Implement
this method if your buildable has internal children that need to be
accessed from a UI definition. For example, Gtk2::Dialog
implements this to give access to its internal vbox child.
SEE ALSO
Gtk2, Glib::Interface,
http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-UI
<http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-
UI>, Gtk2::Buildable::ParseContext
COPYRIGHT
Copyright (C) 2003-2011 by the gtk2-perl team.
This software is licensed under the LGPL. See Gtk2 for a full notice.
perl v5.14.1 2011-08-30 Gtk2::Buildable(3)
