Crop whitespace from PNG image

Sunday, February 1st, 2009

Yesterday, I’ve posted about interesting AS3 Class InteractivePNG, and now I’m adding new addition for solving other problem with transparent Bitmaps. If you have transparent bitmap with whitespace around image and you want to crop whitespace around “real” image, you can use this function…

public static function getBitmapCroppedOutWhitespace(bd:BitmapData):Bitmap
{
	var bmd:BitmapData = new BitmapData(bd.width, bd.height, true, 0x00000000);
	bmd.draw(bd);
 
	var rect:Rectangle = bmd.getColorBoundsRect(0xFFFFFF, 0x00000000, false);
	var bmd2:BitmapData = new BitmapData(rect.width, rect.height, true, 0x00000000);
	bmd2.draw(bmd, new Matrix(1,0,0,1, -rect.x, -rect.y));
 
	var bmp:Bitmap = new Bitmap(bmd2);
 
	return bmp;
}

From BitmapData it creates Bitmap without whitespace. It will find whitespace automaticaly and removes it. If you want to insert Bitmap data instead of BitmapData, just edit this function slightly. This is just idea how to do such cropping. Enjoy, I hope it will be useful for someone.

tagged under: ActionScript.AS3 Tip.Flash

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2 Comments

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February 3rd, 2009

Ya there is alot to know about the web development industry. And sometimes it’s hard to find good information on the web. Thanks for the good input.
Jos Faber
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February 9th, 2009

Cool use of getColorBoundsRect. I was looking into this one as well. Made an AIR app that crops en entire dir with png’s and outputs a textfile with coordinates as well. Your script to get the whitespace out is better. It’s less code. I should implement it into mine

here’s the source and compiled app: http://www.nrg3.nl/blog/?p=673

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