AS3/FLEX - how to convert Sprite graphics into bytes - actionscript-3

Question

I wrote application that lets people paint together via internet (using Adobe cirrus). Everything works great but when for example I run my application and paint something before my friend connects, he dont see that what I have painted. So I'm looking for the method, that would let me convert my canvas into something(object) that it is possible to send by internet (I cant send whole Sprite, it's not possible to copy its graphics on the friend's application, it's null).
So let's get this clear. The main question is: How to convert graphic's of Sprite into object, that would let me convert it back to Sprite and copy its canvas.
ANSWER:
I used DisplayConverter library from "www.Flextras.com" post with his mod to convert Sprite to BitmapData and then to ByteArray and it works. I couldn't receive BitmapData on the friend's app, but It worked with ByteArray.
Sprite -> BitmapData -> ByteArray;
ByteArray -> BitmapData -> Sprite;
//TO SEND
var bitmapdata:BitmapData = DisplayConverter.spriteToBitmapData(palette);
var bytearr:ByteArray = bitmapdata.getPixels(bitmapdata.rect);
//TO RECEIVE
var bmd:BitmapData = new BitmapData(530,430);
bmd.setPixels(bmd.rect, bytearr);
mysprite.graphics.beginBitmapFill(bmd);
mysprite.graphics.drawRect(0,0,530,430);
mysprite.graphics.endFill();
Hope this will help someone

Answer 1

I think you want to convert your Canvas into a BitMap or BitMapData (and back). A Flex Canvas extends Sprite, so you can use a library like this one. To copy the relevant code, this will convert a Sprite to a BitMap:
public static function spriteToBitmap(sprite:Sprite, smoothing:Boolean = false):Bitmap
{
var bitmapData:BitmapData = new BitmapData(sprite.width, sprite.height, true, 0x00FFFFFF);
bitmapData.draw(sprite);
return new Bitmap(bitmapData, "auto", smoothing);
} // END FUNCTION spriteToBitmap
This will convert a Bit Map to a Sprite:
public static function bitmapToSprite(bitmap:Bitmap, smoothing:Boolean = false):Sprite
{
var sprite:Sprite = new Sprite();
sprite.addChild( new Bitmap(bitmap.bitmapData.clone(), "auto", smoothing) );
return sprite;
} // END FUNCTION bitmapToSprite
In my own development, I have a mod to this library, which allows me to get the BitMapData instead of an actual BitMap. So, this will turn a Sprite into BitMapData:
public static function spriteToBitmapData(sprite:Sprite):BitmapData
{
var bitmapData:BitmapData = new BitmapData(sprite.width, sprite.height, true, 0x00FFFFFF);
bitmapData.draw(sprite);
return bitmapData;
} // END FUNCTION spriteToBitmapData
This will take BitMapData and turn it back into a Sprite:
public static function bitmapDataToSprite(bitmapData:BitmapData, smoothing:Boolean = false):Sprite
{
var sprite:Sprite = new Sprite();
sprite.addChild( new Bitmap(bitmapData.clone(), "auto", smoothing) );
return sprite;
} // END FUNCTION bitmapToSprite
You do want to keep in mind that when converting the BitMap or BitMapData back into a Sprite you will probably not be able to cast it as a Canvas. For information on sending BitMapData to a server; look at this question.

Answer 2

A better approach is, instead of going directly to pixels, have the user gestures create data, then reflect that data as a drawing on your canvas. Transmit the same data to the other user and he/she will get the same drawing.