Using Ant with Flash

An introduction to Ant, and how to use it with Mtasc to compile swfs.
2005-07-27

Ant for Flash Primer

So you're a Flash developer, and you've perhaps heard of Ant. And perhaps you've heard of Mtasc. And you're curious (or more probably need to know for work) what the heck Ant is, and what it can do for you.

Assumed knowledge: XML, ActionScript 2.0, and basic command line usage.

Ant is a 'build tool', which means its used to compile and build software. When you're working in Macromedia Flash MX2004, your build tool is Ctrl-Enter. But generally with larger software projects, you aren't working with compiling just one file, but many. Perhaps hundreds or thousands. On big projects, pressing Ctrl-Enter a thousand times is not an option. Perhaps you'd also like to zip the files, and notify someone via email that you've compiled. And so build tools like Ant were born.

Installing Ant

You can download Ant from Ant's web site.

You will also need Java.

After downloading, unzip the files to a directory. From now on, this directory will be called c:/ant

Next we need to set your 'environment variables'. On Windows go to Control Panel>System>Advanced>Environment Variables. You'll need to create two new variables by clicking New:

These point to your Java and Ant directories. You then need to edit the Path variable to include the ant executable.

Add:

;%ANT_HOME%\bin

To the end of the Variable value field.

Et voila! You should now be able to open up a command prompt and use Ant by typing 'ant'. Although this is one way of doing it, depending on your setup, you may be able to call Ant from within your text editor. jEdit's AntFarm plugin does exactly that, and Ant is also built into Eclipse. I have jEdit set to compile with Ant using Ctrl-Enter, works great.

So How Does Ant Work?

When you type 'ant' at the command prompt, ant looks for a file called 'build.xml' in the current directory and attempts to run the instructions inside it.

Lets look at a simple build.xml:

<project name="Hello World" default="compile" >
	<target name="compile">
		<echo message="Hello World!"/>
	</target>
</project>

You might have noticed that Ant's build files are XML. This is a Very Good Thing.

You can execute this build by typing 'ant' in the command prompt in the directory of the build.xml:

Z:\chris\ant_primer>ant
Buildfile: build.xml

compile:
         [echo] Hello World!

BUILD SUCCESSFUL
Total time: 0 seconds

This is a simple build file that contains one 'target' (something for ant to do) named 'compile'. This is the <project/>'s default target (default="compile") so when we run ant without any arguments it will be the target called. Inside our target we have an echo 'task' which simply echos out the text 'Hello World!'.

Ant could be really useful! So how do I use it with Flash?

Mtasc is an open source ActionScript compiler, freely downloadable off the web. Now we'll use Ant to automate building of a blank swf file with Mtasc. First Download and unzip Mtasc to a directory.

Then create this file as 'build.xml':

<project name="Blank swf with MTASC" default="compile" basedir=".">
	<description>How to create a swf with Ant and Mtasc</description>

	<property name="mtasc" location="C:\Program Files\mtasc-1.09\mtasc.exe"/>
	<property name="swfOut" location="blank.swf"/>
	
	<target name="compile">
	<echo message="Compiling ${swfOut}."/>
		<exec executable="${mtasc}" failonerror="true">
			<arg value="-swf"/>
			<arg value="${swfOut}"/>
			<arg value="-header"/>
			<arg value="800:600:20"/>
			<arg value="-main"/>
			<arg value="MainClass.as"/>
		</exec>
	</target>
</project>

Mtasc needs a class to compile, in this example we'll call it MainClass.as. Create this file in the same folder as build.xml with the following:

class MainClass.as{
	public static function main(){
		//nada
	}
}

Also make sure the location attrib of the mtasc <property/> points to the correct location of mtasc.

This is closer to a full Ant project, with a description, variables, and compilation. We assign two variables with the <property/> tag, the location of mtasc, and the name of the swf we want to build. Then the target named 'compile' echoes out the name of the file we're building, and then runs Mtasc via the <exec/> task. The <exec/> task has a list of <arg/> tags, that are different paramters Mtasc requires to run. ( Check Mtasc's site for more info on the parameters ).

Notice also that Ant's very smart when it comes to file locations. Ant was built to be a cross-platform build tool. Except for the location of mtasc which needs to be changed, this file will build on Linux, Mac and Windows without problem.

And those are the Ant basics! There is a plethora of Ant tasks available that can generate documentation, zip files, delete files, create directories, send email and more. Ant also has fantastic documentation, available online covering all the ant tasks, their arguments, and general usage.

Bigger And Better

As flash projects get bigger and better, Ant will most likely become the standard for building files with Flash. This should get you compiling flash with Ant, but barely touches upon the cool features. Ant has tons of 'tasks' to automate your coding experience. For more information I recommend Ant: The Definitive Guide.