Question

I’m trying to write a class that its constructor takes as argument a String ( which is an image in my directory ie: jpg ) and load the corresponding image via a loader object in memory. I also provide function getBitmapFromLoader() to get the bitmap of the loader in order to use it from another class.

public class LoadImage extends Loader
{
    private var bitmap:Bitmap;
    private var ldr:Loader;

    public function LoadImage(nameURL:String):void
    {
        trace("LoadImage constructor");
        ldr = new Loader();
        ldr.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);
        ldr.contentLoaderInfo.addEventListener(IOErrorEvent.IO_ERROR, ioErrorEventHandler);
        var request:URLRequest = new URLRequest(nameURL);
        ldr.load(request);
    }

    /* methods */
    public function getBitmapFromLoader():Bitmap
    {
        return bitmap;
    }

    public function toSprite():Sprite
    {
        trace("toSprite method");
        var sprite:Sprite = new Sprite();
        sprite.addChild(bitmap);
        return sprite;
    }

    public function toMovieClip():MovieClip
    {
        trace("toMovieClip method");
        var mvc:MovieClip = new MovieClip();
        mvc.addChild(bitmap);
        return mvc;
    }

    private function completeHandler(event:Event):void
    {
        trace("completeHandler " + event.currentTarget);
        bitmap = new Bitmap();
        bitmap = Bitmap(event.currentTarget.content);
    }

    private function ioErrorEventHandler(event:IOErrorEvent):void
    {
        trace("ioErrorEventHandler " + event.currentTarget);
        trace("error on loading image: " + event.currentTarget.url);
        bitmap = null;
    }
}
}

but it does not work.
This is what flash outputs:

Main constructor
LoadImage constructor
toSprite method
TypeError: Error #2007: Parameter child must be non-null.
at flash.display::DisplayObjectContainer/addChild()
at loader::LoadImage/toSprite()
at Main()
completeHandler [object LoaderInfo]


This is how i use it from a main class:

package
{
import loader.*;

import flash.display.MovieClip;
import flash.display.Sprite;

public class Main extends MovieClip
{
    /* properties */

    /* constructor */
    public function Main():void
    {
        trace("Main constructor");
        var imgLdr:LoadImage = new LoadImage("smile_bg.jpg");
        var spr1:Sprite = imgLdr.toSprite();
        //this.width = spr1.width;
        //this.height = spr1.height;
        this.addChild(spr1);
    }

    /* methods */

}

}


Answer 1

Well, a Loader is itself a DisplayObject – so you could just addChild(event.currentTarget) and it’ll show up just fine. It extends DisplayObjectContainer just like Sprite does.

If you literally need a Bitmap, then you can do something like:

var bmd:BitmapData = new BitmapData(event.currentTarget.width, event.currentTarget.height);
bmd.draw(event.currentTarget);
bitmap = new Bitmap(bmd);

And do it that way. You might have to tweak that a bit I’m going from memory.

If you’re ever having issues with the Display API, this is a very good chart to summarize what lives where and how the various display object children are connected: http://accad.osu.edu/~pgerstma/class/pca/resources/as3API/AS3API-flash.display.png