Flex 4/Air setting bounds for WindowedApplication

Question

for some reason this flex 4 code gives me an error but I can't figure out why. In my WindowedApplication I have:

var prefs:Object = fs.readObject();
fs.close();
var rect:Rectangle = new Rectangle();
rect = prefs.bounds as Rectangle;
this.bounds = rect;  // error here

Error message: ArgumentError: Error #2007: Parameter rect must be non-null.

I originally also tried it without the rect object and just did:

this.bounds = prefs.bounds as Rectangle;

which gives me the following error:

TypeError: Error #1034: Type Coercion failed: cannot convert Object@1dbbe1f1 to flash.geom.Rectangle.

That seems like a bogus error since I can assign pref.bounds to rect without an error. I don't know why this isn't working. It works under flex 3 compatibility mode but that also breaks a lot of my spark components so I can't use it.

Answer 1

rect = prefs.bounds as Rectangle;

rect ends up as null because prefs.bounds is not an instance of Rectangle class. Casting with as keywords returns null if it fails.

Just give a trace(prefs.bounds); after the call to readObject to see what it contains.

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Update:

The fact that the value in prefs.bounds have x, y, width and height properties, doesn't make it a Rectangle object - it is just an object with those four properties. The easy solution is to create a Rectangle object from those values and use that:

var prefs:Object = fs.readObject();
var rect:Rectangle = new Rectangle(prefs.bounds.x, prefs.bounds.y, prefs.width, prefs.height);
this.bounds = rect;

If you call registerClassAlias before writing the rectangle object to the file stream, the readObject would return an object of appropriate type instead of a generic one.

registerClassAlias("flash.geom.Rectangle", Rectangle);
fs.writeObject(this.bounds);

//later...
//Casting with () will throw an error if the read object is not a Rectangle
var rect:Rectangle = Rectangle(fs.readObject());
trace(rect);