Flex Bindings in AS3 Projects
Since 99.9% of the work we do is Flash, we pretty much use flex builder to develop Actionscript Projects. One of the things I really wanted to have was bindings. Here's how to use Flex Bindings in Actionscript only projects.
Remember that the Flash framework (textfields, movieclips, sprites, etc) doesn't dispatch the data-binding event. This means that pretty much the only things you can bind are variables.
Make sure you add the flex framework.swc to your project Library Path to have access to the mx.binding.util class.
ChangeWatcher:
Acts like the watch on AS2. It watches a variable for changes and when something happens fires an event. Make sure you call the canWatch to ensure that you can watch it!
There are 3 ways to specify the second parameter, the chain.
- A String containing the name of a public bindable property of the host object.
ChangeWatcher.watch(this, "myvar", handler) - An Object in the form: { name: property name, access: function(host) { return host[name] } }. The Object contains the name of a public bindable property, and a function which serves as a getter for that property.
ChangeWatcher.watch(this, { name:"myvar", getter: function():String { return "something" }}, handler); - A non-empty Array containing any combination of the first two options. This represents a chain of bindable properties accessible from the host. For example, to watch the property host.a.b.c, call the method as: watch(host, ["a","b","c"]
BindingUtils.bindProperty
Works pretty much the same way as the watch, but instead of having to handle and event it allows you to immediately bind two properties one-way.
The first two parameters are for the the target, the second parameters are the triggers.
BindingUtils.bindProperty( this, "va1", this, "var2");
you can also use the same syntax for the chain.
References:
Language References
Another Tutorial
July 29th, 2008 at 12:07 pm
Can you please give some example code to demo?
Cheers
July 29th, 2008 at 1:22 pm
Seconding the request to look at some working example code. Cheers!
July 29th, 2008 at 2:03 pm
Very interesting. I was wondering if there was a way to do this. Thanks for posting. Could you post an example using this code?
July 29th, 2008 at 3:23 pm
I needed to have an application that would change it’s language dynamically at runtime. This meant replacing all the textfields texts.
I developed a class that binds the strings (tokens) to the textfields. When the user switches the language button the binded variable points to another array of tokens and all the textfields change.
July 29th, 2008 at 4:00 pm
Will that add to the SWF size? Just wondering
July 29th, 2008 at 5:38 pm
I would say yes, because you are including a couple of function from the flex framework. It shouldn’t be much though
August 19th, 2008 at 8:56 pm
Great job, interesting interview. Thank you.
September 18th, 2008 at 9:50 am
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September 23rd, 2008 at 11:30 am
Thx james
December 16th, 2008 at 12:16 pm
It ´s very interesting and like Scott I was wondering if there was a way to do that.
I have to accept that I have many problems with applications and such a things. But it’s really nice to find any response to any problem we have in internet. These kind of blogs schould stay forever!!!
Thanks for the post!