<page xmlns="http://projectmallard.org/1.0/" xmlns:its="http://www.w3.org/2005/11/its" type="topic" id="magic-mirror.vala" xml:lang="gl">

  <info>

  <title type="text">Magic mirror (Vala)</title>

    <link type="guide" xref="vala#examples"/>

    <desc>Use your webcam as a mirror using the GStreamer framework and GTK+</desc>

    <revision pkgversion="0.1" version="0.1" date="2011-03-19" status="review"/>

    <credit type="author">

      <name>Daniel G. Siegel</name>

      <email its:translate="no">dgsiegel@gnome.org</email>

    </credit>

    <credit type="author">

      <name>Johannes Schmid</name>

      <email its:translate="no">jhs@gnome.org</email>

    </credit>

    <credit type="editor">

      <name>Marta Maria Casetti</name>

      <email its:translate="no">mmcasetti@gmail.com</email>

      <years>2013</years>

    </credit>

    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">

      <mal:name>Fran Dieguez</mal:name>

      <mal:email>frandieguez@gnome.org</mal:email>

      <mal:years>2012-2013.</mal:years>

    </mal:credit>

  </info>

<title>Magic mirror</title>

<synopsis>

  
Your mirror just fell off the wall and broke into a thousand pieces — but you need a mirror to shave your beard off or add some makeup! You only have 15 minutes left before catching the bus to work. So what can you do?

  
In this tutorial, we're going to make a program which lets you use your webcam as a mirror. You will learn how to:

  <list>

    <item>
Crear un apliativo GTK+
</item>

    <item>
Acceda á súa cámara web usando GStreamer e incruste o resultado nunha xanela
</item>

    <item>
Obter as fotos da śua cámara web
</item>

  </list>

  
You'll need the following to be able to follow this tutorial:

  <list>

    <item>
An installed copy of the <link xref="getting-ready">Anjuta IDE</link>
</item>

    <item>
Copias instaladas de GTK, GStreamer e compilador de Vala
</item>

    <item>
Coñecemento básico dun linguaxe de programación orientado a obxectos
</item>

  </list>

</synopsis>

<media type="image" mime="image/png" src="media/magic-mirror.png"/>

<section id="anjuta">

  <title>Cree un proxecto de Anjuta</title>

  
Antes de comezar a programar, deberá configurar un proxecto novo en Anjuta. Isto creará todos os ficheiros que precise para construír e executar o código máis adiante. Tamén é útil para manter todo ordenado.

  <steps>

    <item>

    
Inicie Anjuta e prema <guiseq><gui>Ficheiro</gui><gui>Novo</gui><gui>Proxecto</gui></guiseq> para abrir o asistente de proxectos.

    </item>

    <item>

    
Choose <gui>GTK+ (simple)</gui> from the <gui>Vala</gui> tab, click <gui>Forward</gui>, and fill out your details on the next few pages. Use <file>magic-mirror</file> as project name and directory.

   	</item>

   	<item>

    
Disable <gui>Use GtkBuilder for user interface</gui> as we will

    create the UI manually in this tutorial. Check the <link xref="guitar-tuner.vala">Guitar-Tuner</link>

    tutorial using the interface builder.

    </item>

    <item>

    
Make sure that <gui>Configure external packages</gui> is selected. On the next page, select

       gstreamer-0.10 from the list to include the <app>GStreamer</app> library into your project.

    </item>

    <item>

    
Click <gui>Apply</gui> and the project will be created for you. Open <file>src/magic_mirror.vala</file> from the <gui>Project</gui> or <gui>File</gui> tabs. You should see some code which starts with the lines:

using GLib;

using Gtk;]]>

    </item>

  </steps>

</section>

<section id="build">

  <title>Construír o código por primeira vez</title>

  
The code loads an (empty) window and shows it. More details are given below; skip this list if you understand the basics:

  <list>

  <item>

    
The two using lines import namespaces so we don't have to name them explicitly.

   </item>

   <item>

    
The constructor of the Main class creates a new window and sets its title. Afterwards the window

    is shown and a signal is connected which quits the application if the window is closed. More on signals later on.

   </item>

   <item>

    
The static main function is run by default when you start a Vala application. It calls a few functions which create the Main class, set up and then run the application. The Gtk.Main function starts the GTK main loop, which runs the user interface and starts listening for events (like clicks and key presses).

   </item>

  </list>

  
This code is ready to be used, so you can compile it by clicking <guiseq><gui>Build</gui><gui>Build Project</gui></guiseq> (or press <keyseq><key>Shift</key><key>F7</key></keyseq>).

  
Change the <gui>Configuration</gui> to <gui>Default</gui> and then press <gui>Execute</gui> to configure the build directory. You only need to do this once, for the first build.

</section>

<section id="webcam">

 <title>Acceder ao fluxo de vídeo de cámara web con GStreamer</title>

 
O contorno multimedia de traballo de GStreamer é capaz de manexar vídeo desde cámara web. Engada GStreamer ao seu aplicativo e poderá acceder ao fluxo de vídeo.

using GLib;

using Gtk;

public class Main : Object

{

	private Gst.Element camerabin;

	public Main () {

		this.camerabin = Gst.ElementFactory.make ("camerabin", "camera");

		this.camerabin.set_state (Gst.State.PLAYING);

	}

	static int main (string[] args) {

		Gtk.init (ref args);

		Gst.init (ref args);

		var app = new Main ();

		Gtk.main ();

		return 0;

	}

}

]]>

 <steps>

 <item>
Primeiro quítase a xanela creada anteriormente, xa que GStreamer encargarase de mostrar a imaxe na pantalla.

 </item>

  <item>

  
Agora vaise crear un elemento de GStreamer que accede á cámara web. Vaise a usar o elemento «Camerabin», que é un elemento de cámara todo en un capaz de facer fotos, vídeos, aplicar efectos e moito máis. Perfecto para o noso caso de uso. Con this.camerabin.set_state (Gst.State.PLAYING) indícase á túbería de GStreamer que se acaba de crear que empece a reproducir. Sinxelo, non?

  
Of course it is also possible to integrate the video more tightly into other

  windows but that is an advanced topic that includes some details of the X Window

  System we will omit here.

  Compile and run it again. You will end up with two windows. In the next step

  we will integrate the video into the GTK+ window.

  </item>

 </steps>

</section>

<section id="impl">

 <title>Implementación de referencia</title>

 
Se ten problemas con este titorial, compare o seu código con este <link href="magic-mirror/magic-mirror.vala">código de referencia</link>. Tamén hai unha <link href="magic-mirror/magic-mirror-advanced.vala">implementación máis ampla</link> que incrusta a xanela nunha xanela GTK regular que implica algunhas técnicas avanzadas, e engade botóns para iniciar/deter a imaxe.

</section>

<section id="further">

<title>Lectura complementaria</title>

Para atopar máis información sobre a linguaxe de programación Vala pode visitar <link href="http://live.gnome.org/Vala/Tutorial">o titorial de Vala</link>.

</section>

<section id="conclusion">

<title>Conclusión</title>

  
Isto é todo, acaba de crear un aplicativo completo para sacar fotos coa cámara web en menos de 15 minutos. Agora xa pode afeitar a barba, maquillarse un pouco e ordenar o seu espazo de traballo para impresionar aos seus amigos e colegas con un aplicativo feito en 15 minutos.

</section>

</page>