2

I have this function within a class that creates a bitmap of any DisplayObject I pass in. As you will see, each time I create a new bitmap I am creating a new BitmapData object and a new Bitmap Object.

Is there a way to tweak this function so I no longer have to recreate these two objects each time I run the function?

private var bitmapData:BitmapData;
private var bm:Bitmap; 

crop(someSprite.width, someSprite.height, someSprite);

private function crop(_width:Number, _height:Number, displayObject:DisplayObject):void {

bitmapData.dispose();
bitmapData = new BitmapData( _width, _height, false, 0xFFFFFFFF );  
bitmapData.draw(displayObject);

bm = null;
bm = new Bitmap(bitmapData, PixelSnapping.ALWAYS, true);
bm.smoothing = true;
bm.alpha = 0;

}

Thanks,

Mark

crooksy88
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2 Answers2

3

If the display object dimensions change every time, you will have to recreate a BitmapData every time.

For the Bitmap object, you don't need to recreate it. You can simply set the bitmap data directly:

bm.bitmapData = bitmapData;
laurent
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2

If you want to avoid creating a new BitmapData every time you just create one BitmapData in the biggest dimensions you expect once and in your crop method you first clear that map using yourMap.fillRect(yourMap.rect,0) and then do the draw in the upper right corner using a clip rect with the crop dimensions. For an additional tiny performance boost you could then set the ScrollRect property of the Bitmap object that displays it to the cropped dimensions.

Quasimondo
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  • Thanks for the info. I'm a bit lost though. What is the yourMap object and how would that apply to the example above? – crooksy88 Jun 29 '12 at 11:50
  • yourMap would be the one bitmapdata in the maximum expected dimensions that you create once and then reuse all the time. The only issue is that if you are using your crop() method more like a utility for general bitmapdatas this approach will not work since if you only have one instance of yourMap it will change the view for all bitmaps that are using it whenever you call crop. – Quasimondo Jun 30 '12 at 10:44