How to dynamically load a progressive jpeg/jpg in ActionScript 3 using Flash and know it's width/height before it is fully loaded

Question

I am trying to dynamically load a progressive jpeg using ActionScript 3. To do so, I have created a class called Progressiveloader that creates a URLStream and uses it to streamload the progressive jpeg bytes into a byteArray. Every time the byteArray grows, I use a Loader to loadBytes the byteArray. This works, to some extent, because if I addChild the Loader, I am able to see the jpeg as it is streamed, but I am unable to access the Loader's content and most importantly, I can not change the width and height of the Loader. After a lot of testing, I seem to have figured out the cause of the problem is that until the Loader has completely loaded the jpg, meaning until he actually sees the end byte of the jpg, he does not know the width and height and he does not create a content DisplayObject to be associated with the Loader's content. My question is, would there be a way to actually know the width and height of the jpeg before it is loaded? P.S.: I would believe this would be possibl…

Accepted Answer

I think your problem is that loadBytes is asyncronous... that means that you need to wait until the "complete" event before you retrieve (or change) its width and height... I mean:

```
var loader:Loader=new Loader();
loader.loadBytes(myBytes);
trace(loader.width, loader.contentLoaderInfo.width); //will always output zero
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, imgLoaded);
function imgLoaded(e) {
   trace(loader.width, loader.height); //will output the loader dimensions
   trace(loader.contentLoaderInfo.width, loader.contentLoaderInfo.height); //will always output the original JPEG dimensions
}
```

How to dynamically load a progressive jpeg/jpg in ActionScript 3 using Flash and know it's width/height before it is fully loaded

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