CreateJS is a JavaScript framework that makes use of the HTML5 Canvas, rather than the HTML DOM, to make graphic-based objects, such as shapes, buttons, and text. The integration of CreateJS with FlexJS lets CreateJS developers take advantage of coding in ActionScript (a cousin of JavaScript, with true classes and strong data typing). Further, CreateJS applications can use MXML for layout and definition.

The examples on this page require the installation of the Apache Flex SDK which can be found on the Getting Started With FlexJS page in order to run.

This section mimics the tutorial found on the聽Getting Started Guide聽on the CreateJS site. The example below uses a command line approach and can easily be adapted to a FlexJS-compatible IDE.聽

Create a new directory for your FlexJS project and in the directory make a sub-directory called src. Change to the src directory and create a file called, Demo.mxml. Open the file and add the following Application tag and content:

Notice that the namespace for the Application tag is cjs and the cjs namespace is defined to bring in all of the FlexJS CreateJS component framework. You will identify FlexJS CreateJS elements using the cjs namespace. The FlexJS CreateJS Application tag creates the HTML5 Canvas automatically.

Within the cjs:View聽element, add the following MXML tags to create a CreateJS circle.

Save the file and compile it:

${FLEXJS_INSTALLDIR}/js/bin/mxmlc Demo.mxml

Once the compilation is complete, you will find a bin directory parallel to the src directory. Open ../bin/js-debug/index.html in a browser. You should see a blue circle.

Continue with the previous example where you already have a circle to work with. You will add some MXML declarations for the tweens and a bit of ActionScript code to trigger them. Copy the following MXML declarations and fx:Script block into the Demo.mxml file, above the聽js:initialView聽definition:

The fx:Declarations tag in MXML is where you put non-visual items that are referenced in the app. Here, a set of Tweens is declared for the circle and surrounded by the Sequence聽tween which forces the individual Tweens to play in the order specified. Note that the easing function on some of the Tweens is specified using binding to an expression.

In order for the Sequence to happen however, the Sequence's play() function, needs to be triggered by an event. Modify the cjs:Application tag with an applicationComplete event handler to call the play() function:

Save the file and compile it:

${FLEXJS_INSTALLDIR}/js/bin/mxmlc Demo.mxml

Open the ../bin/js-debug/index.html file in a browser. You will see the circle move and fade across the screen. The loop option on the Sequence will make it run continuously.

You can see the complete code below.

This section examines the demonstration code (above) in more detail and compares it with the original CreateJS demo code.聽The example looks like this:

聽聽The original CreateJS example is an HTML page with a Canvas in the body of the page. A JavaScript function is used to programmatically create the circle and insert it onto the Stage (the CreateJS root of its own DOM structure or display list). The corresponding FlexJS MXML file looks like this:

Unlike the original HTML, the MXML elements (or tags) define the size, placement, and color of the circle without using any code.聽

Beneath the covers, the FlexJS application creates an HTML5 Canvas and sets up the drawing Stage; FlexJS has wrapper classes for the CreateJS and EaselJS constructs (note that today only a few exist but the pattern to add more has been established). Using either ActionScript or MXML, the CreateJS components can be added to the stage and displayed.

An advantage to using the FlexJS MXML approach is that the compiler (or an IDE if you use one) can catch errors before you need to run the code. For instance, in the original JavaScript you could accidentally write, circle.c = 100 and the page would load fine and even execute, except the circle would not be where you thought it would be. Using FlexJS, if you mistyped "c" for "x" in the cjs:Circle tag, the compiler would immediately spot the problem. If you use an IDE with FlexJS, you have code-completion in addition to syntax checking which will also help avoid errors.聽

In addition to EaselJS, the FlexJS CreateJS framework also includes a bit of TweenJS, the animation package. There is a small TweenJS example on the CreateJS page which looks like this:

The corresponding FlexJS MXML file looks like this:

The Tweens are declared in an fx:Declarations block and correspond to the CreateJS tween.to()聽functions written in JavaScript. You specify exactly the same things: target, duration, x position, y position, alpha value, and even easing functions. Once again, you can quickly declare your Tweens and given them parameters, any of which can be specified using data binding.

FlexJS is a "pay as you go" system. The use of binding for the easing functions on the Tweens necessitates the including of the js:ApplicationDataBinding bead. Without the bead the data binding will not happen and should only be included in applications that use data binding to reduce their final footprint and runtime overhead.

At this time the FlexJS CreateJS framework is far from complete. CreateJS has a lot to offer and this foray into it via FlexJS just touches upon it and lays the foundation to extend it.

Components from the FlexJS Basic framework cannot be used with components from the FlexJS CreateJS framework. This is due to the fact that CreateJS uses the HTML5 Canvas as its drawing space and maintains its own DOM; the FlexJS Basic framework uses the HTML DOM.

If you look at the flex-asjs repository, specifically the frameworks/projects/CreateJS directory, you'll see how the 聽FlexJS wrapper classes are composed. There is an Application class which provides the injection of the necessary CreateJS JavaScript downloads as well as creating the Canvas and the CreateJS Stage object.

From there, components use org.apache.flex.createjs.core.CreateJSBase as their foundation class. Other "higher level" components such as Circle, Rect, Label, and TextButton build from there. The key part is the createElement function. You can see how the CheckBox, for example, is composed from several different EaselJS elements. You would add any new components following this pattern.

Since CreateJS is an JavaScript-only framework, you can see that many of the classes use the COMPILE::JS compiler tag to identify the code that only belongs on the JavaScript side (code that gets cross-compiled to JavaScript and does not have any relevance to the SWF). Any additional CreateJS structures or code should be wrapped in the COMPILE::JS tag.

Keep in mind however, that when you specify an API (public functions or properties) these items should not be limited to COMPILE::JS blocks but be universally visible. This is so the properties and functions are available in MXML tags.

Once components are added, if they can be used from MXML, they must appear in the createjs-manifest.xml file. Classes should also appear in the CreateJSClasses.as file if they are not MXML components and can be used from ActionScript.

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