NAME¶
Gtk2::Buildable - Interface for objects that can be built by Gtk2::Builder
SYNOPSIS¶
package Thing;
use Gtk2;
use Glib::Object::Subclass
Glib::Object::,
# 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", $thing->get ('force');
}
# This program prints "boom * 50!" on stdout.
HIERARCHY¶
Glib::Interface
+----Gtk2::Buildable
DESCRIPTION¶
The Gtk2::Buildable interface allows objects and widgets to have
"<child>" objects, special property settings, or extra custom
tags in a Gtk2::Builder UI description
(
http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-UI
<
http://library.gnome.org/devel/gtk/unstable/GtkBuilder.html#BUILDER-UI>).
The main user of the Gtk2::Buildable interface is Gtk2::Builder, so there should
be very little need for applications to call any of the Gtk2::Buildable
methods. So this documentation deals with implementing a buildable object.
Gtk2::Builder already supports plain Glib::Object or Gtk2::Widget with
"<object>" construction and "<property>"
settings, so often the "Gtk2::Buildable" interface is not needed.
The only thing to note is that an object or widget implemented in Perl must be
loaded before building.
OVERRIDING BUILDABLE INTERFACE METHODS¶
The buildable interface can be added to a Perl code object or widget subclass by
putting "Gtk2::Buildable" in the interfaces list and implementing
the following methods.
In current Gtk2-Perl the custom tags code doesn't chain up to any buildable
interfaces in superclasses. This means for instance if you implement
Gtk2::Buildable on a new widget subclass then you lose the <accelerator>
and <accessibility> tags normally available from Gtk2::Widget. This will
likely change in the future, probably by chaining up by default for unhandled
tags, maybe with a way to ask deliberately not to chain.
- SET_NAME ($self, $name)
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.
If
$childname is unknown then return "undef".
(The builder will then generally report a GError for the UI description
referring to an unknown 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.