Waiting for Embedded Image to Load? - actionscript-3

Question

So I'm trying to load a sprite sheet. I've embedded it into the .swf, but when I instantiate a class and call a function that starts clipping from the sprite sheet, I get the error:
"Parameter sourceBitmapData must be non-null."
I know that what is happening is that the code is being called before the sprite sheet image is actually loaded, but I'm not sure how to solve this problem since I'm embedding rather than using a loader. I assume I'll need to use event listeners, but how do I make that work with the embedding? Here's my code so far:
In the Main public class:
private var currentSprite:SpriteSheet;
[Embed(source='../assets/images/sprite_sheet_1.png')]
private var sheetClass:Class;
private var sheet:Bitmap = new sheetClass();
Then in the Main function:
currentSprite = new SpriteSheet( sheet, 25, 25 );
addChild(currentSprite);
The SpriteSheet function is set up like so:
public function SpriteSheet(tileSheetBitmap:Bitmap, width:Number = 25, height:Number = 25) {
tileSheetBitmapData = tileSheetBitmap.bitmapData;
tileWidth = width;
tileHeight = height;
rowLength = int(tileSheetBitmap.width / width );
tileRectangle = new Rectangle( 0, 0, tileWidth, tileHeight );
tilePoint = new Point( 0, 0 );
canvasBitmapData = new BitmapData( tileWidth, tileHeight, true );
var canvasBitmap:Bitmap = new Bitmap(canvasBitmapData);
addChild(canvasBitmap);
drawTile(0);
addEventListener(Event.REMOVED_FROM_STAGE, remove);
}
In my SpriteSheet class, I call a drawTile function which calls copyPixels(), where the error is originating from:
canvasBitmapData.copyPixels(tileSheetBitmapData, tileRectangle, tilePoint);
I know that's a lot of code, but I feel there's probably a simple solution. Any feedback would be greatly appreciated. Thanks!
Edit: Here is the SpriteSheet class:
package
{
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Sprite;
import flash.geom.Point;
import flash.geom.Rectangle;
import flash.events.Event;
public class SpriteSheet extends Sprite {
public var tileSheetBitmapData:BitmapData;
private var canvasBitmapData:BitmapData;
private var tileWidth:int;
private var tileHeight:int;
private var rowLength:int;
private var tileRectangle:Rectangle;
private var tilePoint:Point;
public function SpriteSheet(tileSheetBitmap:Bitmap, width:Number = 25, height:Number = 25) {
tileSheetBitmapData = tileSheetBitmap.bitmapData;
if(tileSheetBitmap != null ) {
trace("tileSheetBitmap is not null in SpriteSheet");
}
if( tileSheetBitmapData != null ){
trace("tileSheetBitmapData is not null in SpriteSheet");
}
tileWidth = width;
tileHeight = height;
rowLength = int(tileSheetBitmap.width / width );
tileRectangle = new Rectangle( 0, 0, tileWidth, tileHeight );
tilePoint = new Point( 0, 0 );
canvasBitmapData = new BitmapData( tileWidth, tileHeight, true );
var canvasBitmap:Bitmap = new Bitmap(canvasBitmapData);
addChild(canvasBitmap);
drawTile(0);
addEventListener(Event.REMOVED_FROM_STAGE, remove);
} //end of SpriteSheet
public function drawTile(tileNumber:int):BitmapData {
trace("Reached drawTile");
tileRectangle.x = int( (tileNumber % rowLength) ) * tileWidth;
tileRectangle.y = int( (tileNumber / rowLength) ) * tileHeight;
canvasBitmapData.copyPixels(tileSheetBitmapData, tileRectangle, tilePoint);
trace("Reached past copyPixels");
return canvasBitmapData.clone();
} //end of drawTile
public function tileBoard(boardIndex:Array):BitmapData {
var wide:int = boardIndex[0].length;
var tall:int = boardIndex.length;
canvasBitmapData = new BitmapData( (tileWidth * wide), (tileHeight * tall), true);
var boardCanvas:Bitmap = Bitmap(getChildAt(0));
boardCanvas.bitmapData = canvasBitmapData;
tileRectangle = new Rectangle( 0, 0, (tileWidth * wide), (tileHeight * tall) );
for( var i:int = 0; i < wide; i++ ) {
for( var j:int = 0; j < tall; j++ ) {
tilePoint = new Point((tileWidth * i), (tileHeight * j) );
drawTile(boardIndex[j][i]);
}
}
return canvasBitmapData.clone();
} //end tileBoard
public function remove(e:Event):void {
tileSheetBitmapData.dispose();
canvasBitmapData.dispose();
} //end remove
} //end class SpriteSheet
} //end package

Answer 1

This isn't a loading issue, since you're embedding the png file into your swf, all the image loading is done while the swf is loaded.
this is a problem with the Flash IDE compiler only... With Flex compiler this is not necessary...
try:
private var sheet:BitmapData = new sheetClass(0,0);
change your SpriteSheet class to accept the bitmapData directly