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<section id="building-a-nacl-app">
<h1 id="building-a-nacl-app">Building a NaCl App</h1>
<section id="in-the-browser">
<h2 id="in-the-browser">In the browser!</h2>
<p>Follow along with Brad Nelson’s Google I/O 2014 talk.
Explore our new in-browser development environment and debugger.</p>
<p>Learn how easy it is to edit, build, and debug NaCl application
all in your desktop web browser or on a Chromebook.
Work either on-line or off-line!</p>
<iframe class="video" width="500" height="281"
src="//www.youtube.com/embed/MvKEomoiKBA?rel=0" frameborder="0"></iframe><section id="installation">
<h3 id="installation">Installation</h3>
<p>The setup process currently requires several steps.
We’re working to reduce the number of steps in future releases.
As the process gets easier, we’ll update this page.</p>
<p>You currently need to:</p>
<ul class="small-gap">
<li><p class="first">Navigate to: chrome://flags and:</p>
<ul class="small-gap">
<li>Enable <strong>Native Client</strong>.</li>
<li>Enable <strong>Native Client GDB-based debugging</strong>. (For the debugger)</li>
</ul>
</li>
<li><p class="first">Install the NaCl in-browser debugger.</p>
<ul class="small-gap">
<li>Install the <a class="reference external" href="https://chrome.google.com/webstore/detail/nacl-debugger/ncpkkhabohglmhjibnloicgdfjmojkfd">NaCl Debugger Extension</a>.</li>
<li>Install <a class="reference external" href="https://chrome.google.com/webstore/detail/gdb/gkjoooooiaohiceibmdleokniplmbahe">GDB</a>.</li>
</ul>
</li>
<li><p class="first">Install the <a class="reference external" href="https://chrome.google.com/webstore/detail/nacl-development-environm/aljpgkjeipgnmdpikaajmnepbcfkglfa">NaCl Development Environment</a>.</p>
<ul class="small-gap">
<li>First run is slow (as it downloads and installs packages).</li>
</ul>
</li>
</ul>
</section><section id="editor">
<h3 id="editor">Editor</h3>
<p>To follow along in this tutorial, you’ll need to use a text editor to modify
various files in our development environment.
There are currently two editor options, nano or vim.
Emacs is coming soon...
If you’re unsure what to pick, nano is simpler to start with and has on-screen
help.</p>
<ul class="small-gap">
<li><p class="first">You can open <strong>nano</strong> like this:</p>
<pre class="prettyprint">
$ nano <filename>
</pre>
<p>Here’s an online <a class="reference external" href="http://mintaka.sdsu.edu/reu/nano.html">nano tutorial</a>.</p>
</li>
<li><p class="first">You can open <strong>vim</strong> like this:</p>
<pre class="prettyprint">
$ vim <filename>
</pre>
<p>Here’s an online <a class="reference external" href="http://www.openvim.com/tutorial.html">vim tutorial</a>.</p>
</li>
</ul>
</section><section id="git-setup">
<h3 id="git-setup">Git Setup</h3>
<p>This tutorial also uses a revision control program called
<a class="reference external" href="http://en.wikipedia.org/wiki/Git_(software)">git</a>.
In order to commit to a git repository,
you need to setup your environment to with your identity.</p>
<p>You’ll need to add these lines to <cite>~/.bashrc</cite> to cause them to be invoked each
time you start the development environment.</p>
<pre class="prettyprint">
git config --global user.name "John Doe"
git config --global user.email johndoe@example.com
</pre>
</section><section id="tour-follow-the-video">
<h3 id="tour-follow-the-video">Tour (follow the video)</h3>
<p>Create a working directory and go into it:</p>
<pre class="prettyprint">
$ mkdir work
$ cd work
</pre>
<p>Download a zip file containing our sample:</p>
<pre class="prettyprint">
$ curl http://nacltools.storage.googleapis.com/io2014/voronoi.zip -O
$ ls -l
</pre>
<p>Unzip the sample:</p>
<pre class="prettyprint">
$ unzip voronoi.zip
</pre>
<p>Go into the sample and take a look at the files inside:</p>
<pre class="prettyprint">
$ cd voronoi
$ ls
</pre>
<p>Our project combines voronoi.cc with several C++ libraries to produce a NEXE
(or Native Client Executable).</p>
<img alt="/native-client/images/voronoi1.png" src="/native-client/images/voronoi1.png" />
<p>The resulting application combines the NEXE with some Javascript to load
the NaCl module, producing the complete application.</p>
<img alt="/native-client/images/voronoi2.png" src="/native-client/images/voronoi2.png" />
<p>Let’s use git (a revision control program) to track our changes.</p>
<p>First, create a new repository:</p>
<pre class="prettyprint">
$ git init
</pre>
<p>Add everything here:</p>
<pre class="prettyprint">
$ git add .
</pre>
<p>Then commit our starting state:</p>
<pre class="prettyprint">
$ git commit -m "imported voronoi demo"
</pre>
<p>Now, likes run <strong>make</strong> to compile our program (NOTE: Changed since video,
we’ve got Makefiles!):</p>
<pre class="prettyprint">
$ make
</pre>
<p>Oops, we get this error:</p>
<pre class="prettyprint">
voronoi.cc: In member function 'void Voronoi::Update()':
voronoi.cc:506: error: 'struct PSContext2D_t' has no member named 'hieght'
</pre>
<p>We’ll need to start an editor to fix this.
You’ll want to change <em>hieght</em> to <em>height</em> on line 506.
Then rebuild:</p>
<pre class="prettyprint">
$ make
</pre>
<p>Lets look at the diff:</p>
<pre class="prettyprint">
$ git diff
</pre>
<p>And commit our fix:</p>
<pre class="prettyprint">
$ git commit -am "fixed build error"
</pre>
<p>To test our application, we run a local web server, written in python.
Run the server with this command (NOTE: Running through a Makefile
now):</p>
<pre class="prettyprint">
$ make serve
</pre>
<p>Then, navigate to <a class="reference external" href="http://localhost:5103/">http://localhost:5103/</a> to test the demo.</p>
<p>If you follow along with the demo video, you will discover the sample crashes
when you change the thread count.</p>
<p><em>Debugger walk-thru coming soon.</em></p>
<p>Once you’ve identified the problem. You’ll want to stop the test server.
Press enter to halt it.</p>
<p>Open your editor again, navigate to line 485 and change <em>valu</em> to <em>value</em>.</p>
<p>Then rebuild:</p>
<pre class="prettyprint">
$ make
</pre>
<p>Check the diff and commit our fix:</p>
<pre class="prettyprint">
$ git diff
$ git commit -am "fixed thread ui bug"
</pre>
<p>Now look at your commit history:</p>
<pre class="prettyprint">
$ git log
</pre>
<p>Run the demo again. And everything now works:</p>
<pre class="prettyprint">
$ make serve
</pre>
</section></section></section>
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