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2007-06-16 Emmanuele Bassi <ebassi@openedhand.com>

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* subclassing-ClutterActor.sgml: Add a chapter about how to
	correctly subclass the actor base class.

	* clutter-docs.sgml: Include the new chapter about subclassing
	ClutterActor; add a description for some of the API reference
	parts.
This commit is contained in:
Emmanuele Bassi 2007-06-16 20:56:40 +00:00
parent 46baa44daf
commit 31efd346bd
4 changed files with 164 additions and 2 deletions
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9
doc/reference/ChangeLog
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@ -1,3 +1,12 @@
2007-06-16 Emmanuele Bassi <ebassi@openedhand.com>
* subclassing-ClutterActor.sgml: Add a chapter about how to
correctly subclass the actor base class.
* clutter-docs.sgml: Include the new chapter about subclassing
ClutterActor; add a description for some of the API reference
parts.
2007-06-14 Emmanuele Bassi <ebassi@openedhand.com>
* clutter-sections.txt:

7
doc/reference/Makefile.am
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@ -71,12 +71,15 @@ HTML_IMAGES=
# Extra SGML files that are included by $(DOC_MAIN_SGML_FILE).
# e.g. content_files=running.sgml building.sgml changes-2.0.sgml
content_files= version.xml
content_files= \
subclassing-ClutterActor.sgml \
version.xml
# SGML files where gtk-doc abbrevations (#GtkWidget) are expanded
# These files must be listed here *and* in content_files
# e.g. expand_content_files=running.sgml
expand_content_files=
expand_content_files= \
subclassing-ClutterActor.sgml
# CFLAGS and LDFLAGS for compiling gtkdoc-scangobj with your library.
# Only needed if you are using gtkdoc-scangobj to dynamically query widget

38
doc/reference/clutter-docs.sgml
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@ -2,6 +2,7 @@
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
<!ENTITY version SYSTEM "version.xml">
<!ENTITY clutter-SubclassingActor SYSTEM "xml/subclassing-ClutterActor.sgml">
]>
<book id="index" xmlns:xi="http://www.w3.org/2003/XInclude">
@ -93,6 +94,10 @@
<chapter>
<title>Container Actors</title>
<partintro>
<para>Actors containing other actors.</para>
</partintro>
<xi:include href="xml/clutter-group.xml"/>
<xi:include href="xml/clutter-hbox.xml"/>
<xi:include href="xml/clutter-vbox.xml"/>
@ -105,6 +110,11 @@
<chapter>
<title>Base Classes</title>
<partintro>
<para>Clutter base animation objects</para>
</partintro>
<xi:include href="xml/clutter-timeline.xml"/>
<xi:include href="xml/clutter-alpha.xml"/>
<xi:include href="xml/clutter-behaviour.xml"/>
@ -112,6 +122,11 @@
<chapter>
<title>Clutter Behaviours</title>
<partintro>
<para>Classes implementing ClutterBehaviour</para>
</partintro>
<xi:include href="xml/clutter-behaviour-bspline.xml"/>
<xi:include href="xml/clutter-behaviour-ellipse.xml"/>
<xi:include href="xml/clutter-behaviour-opacity.xml"/>
@ -122,6 +137,11 @@
<chapter>
<title>Simple Effects</title>
<partintro>
<para>Simple animation API</para>
</partintro>
<xi:include href="xml/clutter-effects.xml"/>
</chapter>
@ -141,12 +161,30 @@
<part>
<title>Clutter Backends</title>
<partintro>
<para>Clutter is usually compiled against a specific drawing backend.
All backends have a common API for querying the underlying platform,
and some of them might have specific API exposed by Clutter.</para>
</partintro>
<xi:include href="xml/clutter-backend.xml"/>
<xi:include href="xml/clutter-glx.xml"/>
</part>
<part>
<title>Additional Documentation</title>
<partintro>
<para>This section contains additional useful documentation for
developing with Clutter.</para>
</partintro>
&clutter-SubclassingActor;
</part>
<index>
<title>Index</title>
</index>

112
doc/reference/subclassing-ClutterActor.sgml Normal file
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@ -0,0 +1,112 @@
<chapter id="clutter-subclassing-ClutterActor">
<chapterinfo>
<author>
<firstname>Emmanuele</firstname>
<surname>Bassi</surname>
<affiliation>
<address>
<email>ebassi@openedhand.com</email>
</address>
</affiliation>
</author>
</chapterinfo>
<title>Implementing a new actor</title>
<para>In order to implement a new #ClutterActor subclass the usual
machinery for subclassing a GObject should be used. After that, the
ClutterActor::query_coords() and ClutterActor::request_coords() virtual
functions should be overidden. Optionally, also the ClutterActor::paint()
virtual functions should be overridden.</para>
<para>The ClutterActor::query_coords() method of a #ClutterActor is
invoked when clutter_actor_query_coords() is called on an instance
of that actor class. It is used to return a #ClutterActorBox containing
the coordinates of the bounding box for the actor (the coordinates
of the top left corner and of the bottom right corner of the rectangle
that fully contains the actor). Container actors, or composite actors
with internal children, should call clutter_actor_query_coords() on
each visible child. Remember: the returned coordinates must be relative
to the parent actor.</para>
<example id="clutter-actor-query-coords-example">
<para>This example shows how an actor class should override the
query_coords() virtual function of #ClutterActor. In this case,
the returned bounding box is the sum of the bounding boxes of all
the <structname>FooActor</structname> children.</para>
<programlisting>
static void
foo_actor_query_coords (ClutterActor *actor,
ClutterActorBox *box)
{
FooActor *foo_actor = FOO_ACTOR (actor);
GList *child;
guint width, height;
/* initialize our size */
width = height = 0;
for (l = foo_actor-&gt;children; l != NULL; l = l-&gt;next)
{
ClutterActor *child_actor = child-&gt;data;
/* we return only visible actors */
if (CLUTTER_ACTOR_IS_VISIBLE (child_actor))
{
ClutterActorBox child_box;
clutter_actor_query_coords (child_actor, &amp;child_box);
width += child_box.x2 - child_box.x2;
height += child_box.y2 - child_box.y1;
}
}
/* internally, the coordinates are all expressed in generic
* "units", but the public API converts them into pixels,
* so we need to juggle around with conversions
*/
box-&gt;x2 = box-&gt;x1 + CLUTTER_UNITS_FROM_INT (width);
box-&gt;y2 = box-&gt;y1 + CLUTTER_UNITS_FROM_INT (height);
}
</programlisting>
</example>
<para>The ClutterActor::request_coords() method of a #ClutterActor
is invoked when clutter_actor_request_coords() is called on an instance
of that actor class. It is used to set the coordinates of the bounding
box for the actor. Container actors, or composite actors with internal
children, should call clutter_actor_request_coords() on each visible
child.</para>
<para>The ClutterActor::paint() method should be overridden if the
actor needs to control its drawing process, by using the GL API
directly. Actors performing transformations should push the GL matrix
first and then pop the GL matrix before returning. Container actors
or composite actors with internal children should do the same, and call
clutter_actor_paint() on every visible child:</para>
<example id="clutter-actor-paint-example">
<programlisting>
static void
foo_actor_paint (ClutterActor *actor)
{
FooActor *foo_actor = FOO_ACTOR (actor);
GList *child;
glPushMatrix ();
for (child = foo_actor-&gt;children; child != NULL; child = child-&gt;next)
{
ClutterActor *child_actor = child-&gt;data;
clutter_actor_paint (child_actor);
}
glPopMatrix ();
}
</programlisting>
</example>
</chapter>