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Add the secon recipe to the Actors chapter

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The second recipe shows how to use the ::paint signal to override
the paint sequence of a pre-existing actor.
This commit is contained in:
Emmanuele Bassi 2008-12-11 17:02:05 +00:00
parent 26b35e657f
commit a7f7bfbc87
1 changed files with 122 additions and 31 deletions
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153
doc/cookbook/clutter-cookbook.xml
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@ -43,9 +43,9 @@
Cookbook</emphasis>: approaching a programming problem is oftentimes Cookbook</emphasis>: approaching a programming problem is oftentimes
similar to balancing Columbus's egg. The initial difficulties of dealing similar to balancing Columbus's egg. The initial difficulties of dealing
with, and more importantly solving, problems in the computer programming with, and more importantly solving, problems in the computer programming
field sometimes can sometimes only be overcome if somebody shows you how field sometimes can only be overcome if somebody shows you how to use a
to use a new tool. This is true for programming languages but also for new tool. This is true for programming languages but also for programming
programming libraries.</para> libraries.</para>
<para>This book has been written to try and give you a reference on <para>This book has been written to try and give you a reference on
how to solve common issues that you might have to face when using how to solve common issues that you might have to face when using
@ -65,16 +65,16 @@
<para>Above all, this is a book for learning <emphasis>more</emphasis> <para>Above all, this is a book for learning <emphasis>more</emphasis>
about Clutter, and about how to use it in the most efficient and easiest about Clutter, and about how to use it in the most efficient and easiest
way. It is meant to help you move past the basic usage of Clutter</para> way. It is meant to help you move past the basic usage of Clutter.</para>
<para>This book is divided into chapters. Each chapter is dedicated to <para>This book is divided into chapters. Each chapter is dedicated to
a specific class, or a specific area. Each chapter starts with a short a specific class, like ClutterTexture, or a specific area, like animations.
introduction, followed by different <emphasis>recipes</emphasis>. Each Each chapter starts with a short introduction, followed by different
recipe has a problem, as a short statement describing what we want to <emphasis>recipes</emphasis>. Each recipe starts with a problem, or a short
achieve; a solution, containing the source code; and a discussion statement describing what we want to achieve; a solution, containing the
section, where the code is explained, where alternative approaches might source code; and a discussion section, where the code is explained, where
be usefule, caveats and references to the Clutter API for furher alternative approaches might be useful, caveats and references to the
studying.</para> Clutter API for furher studying.</para>
<para>This book, in the cookbook spirit, can be accessed mostly at <para>This book, in the cookbook spirit, can be accessed mostly at
random.</para> random.</para>
@ -98,8 +98,10 @@
<section> <section>
<title>About this document</title> <title>About this document</title>
<para>This document is available in various formats like HTML, <para>This document is available in various formats like HTML, and
text and PDF. The latest version is always available at PDF.</para>
<para>The latest version is always available at
<ulink url="&docurl;">&docurl;</ulink>.</para> <ulink url="&docurl;">&docurl;</ulink>.</para>
</section> </section>
@ -107,18 +109,20 @@
<section> <section>
<title>Where to get Clutter</title> <title>Where to get Clutter</title>
<para>You can obtain Clutter from <ulink url="&appurl;">&appurl;</ulink> <para>You can obtain Clutter from <ulink url="&appurl;">&appurl;</ulink>.</para>
or perhaps from your distributor.</para>
<para>Clutter is also available on all major GNU/Linux distributions,
in various package formats.</para>
<para>On OSX, Clutter is available with both Fink and MacPorts.</para>
<para>Binaries for Microsoft Windows are also available.</para>
</section> </section>
<section> <section>
<title>License</title> <title>License</title>
<para>Clutter is distributed under the terms of the GNU Lesser General <para>FIXME</para>
Public License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version. A copy
of this license can be found in the file COPYING included with the
source code of this program.</para>
</section> </section>
</chapter> <!-- introduction }}} --> </chapter> <!-- introduction }}} -->
@ -156,7 +160,7 @@
</section> </section>
<section id="actors-recipe-1"> <!-- recipe 1 {{{ --> <section id="actors-allocation-notify"> <!-- {{{ -->
<title>Knowing when an actor position or size change</title> <title>Knowing when an actor position or size change</title>
<section> <section>
@ -177,11 +181,14 @@
<informalexample> <informalexample>
<programlisting> <programlisting>
g_signal_connect (actor, "notify::x", g_signal_connect (actor, "notify::x",
G_CALLBACK (on_x_changed), NULL); G_CALLBACK (on_x_changed),
NULL);
g_signal_connect (actor, "notify::height", g_signal_connect (actor, "notify::height",
G_CALLBACK (on_height_changed), NULL); G_CALLBACK (on_height_changed),
NULL);
g_signal_connect (actor, "notify::depth", g_signal_connect (actor, "notify::depth",
G_CALLBACK (on_depth_changed), NULL); G_CALLBACK (on_depth_changed),
NULL);
</programlisting> </programlisting>
</informalexample> </informalexample>
@ -193,7 +200,8 @@ g_signal_connect (actor, "notify::depth",
<informalexample> <informalexample>
<programlisting> <programlisting>
g_signal_connect (actor, "notify::allocation", g_signal_connect (actor, "notify::allocation",
G_CALLBACK (on_allocation_changed), NULL); G_CALLBACK (on_allocation_changed),
NULL);
</programlisting> </programlisting>
</informalexample> </informalexample>
@ -229,7 +237,7 @@ on_x_changed (GObject *gobject,
{ {
gint x_value = 0; gint x_value = 0;
g_object_get (gobject, pspec->name, &amp;x_value, NULL); g_object_get (gobject, pspec-&gt;name, &amp;x_value, NULL);
g_print ("The new X coordinate is '%d' pixels\n", x_value); g_print ("The new X coordinate is '%d' pixels\n", x_value);
} }
@ -273,6 +281,63 @@ on_allocation_changed (GObject *gobject,
</section> <!-- recipe 1 }}} --> </section> <!-- recipe 1 }}} -->
<section id="actors-paint-wrappers"> <!-- {{{ -->
<title>Overriding the paint sequence</title>
<section>
<title>Problem</title>
<para>You want to override the way an actor paints itself
without creating a subclass.</para>
</section>
<section>
<title>Solution</title>
<para>You can use the <emphasis>paint</emphasis> signal to
invoke a callback that will be executed before the actor's
paint implementation:</para>
<informalexample>
<programlisting>
g_signal_connect (actor, "paint",
G_CALLBACK (on_paint),
NULL);
</programlisting>
</informalexample>
<para>You can paint something after the actor's paint implementation
by using the <function>g_signal_connect_after()</function> function
instead of <function>g_signal_connect()</function>:</para>
<informalexample>
<programlisting>
g_signal_connect_after (actor, "paint",
G_CALLBACK (on_paint_after),
NULL);
</programlisting>
</informalexample>
<para>The signature for the handler of the "paint" signal is:</para>
<informalexample>
<programlisting>
void
on_paint (ClutterActor *actor,
gpointer user_data);
</programlisting>
</informalexample>
</section>
<section>
<title>Discussion</title>
<para>...</para>
</section>
</section> <!-- }}} -->
</chapter> <!-- actors }}} --> </chapter> <!-- actors }}} -->
<chapter id="textures"> <!-- textures {{{ --> <chapter id="textures"> <!-- textures {{{ -->
@ -289,13 +354,13 @@ on_allocation_changed (GObject *gobject,
<para>introduction</para> <para>introduction</para>
</section> </section>
<section> <!-- recipe 1 {{{ --> <section id="textures-aspect-ratio">
<title>Maintaining the aspect ratio when loading a texture</title> <title>Maintaining the aspect ratio when loading a texture</title>
<section> <section>
<title>Problem</title> <title>Problem</title>
<para></para> <para>You want to maintain the aspect ratio of a texture.</para>
</section> </section>
<section> <section>
@ -334,19 +399,20 @@ on_allocation_changed (GObject *gobject,
<section> <section>
<title>Problem</title> <title>Problem</title>
<para></para> <para>You want to have an animation exactly mirroring another one
that you just played.</para>
</section> </section>
<section> <section>
<title>Solution</title> <title>Solution</title>
<para></para> <para>...</para>
</section> </section>
<section> <section>
<title>Discussion</title> <title>Discussion</title>
<para></para> <para>...</para>
</section> </section>
</section> <!-- recipe 1 }}} --> </section> <!-- recipe 1 }}} -->
@ -361,4 +427,29 @@ on_allocation_changed (GObject *gobject,
directory of Clutter.</para> directory of Clutter.</para>
</appendix> <!-- contributing }}} --> </appendix> <!-- contributing }}} -->
<!--
<section id="recipe">
<title>Recipe</title>
<section>
<title>Problem</title>
<para>...</para>
</section>
<section>
<title>Solution</title>
<para>...</para>
</section>
<section>
<title>Discussion</title>
<para>...</para>
</section>
</section>
-->
</book> </book>