package { import com.bit101.components.PushButton; import flash.display.Bitmap; import flash.display.BitmapData; import flash.display.Loader; import flash.display.Sprite; import flash.events.Event; import flash.geom.Point; import flash.net.FileFilter; import flash.net.FileReference; /** * This marching squares alg uses 2x2 window * and has deadlock problem, as described at * http://www.sakri.net/blog/2009/05/28/detecting-edge-pixels-with-marching-squares-algorithm/ * * Please come up with simplest possible fix :) */ public class MarchingSquares extends Sprite { public var file:FileReference, loader:Loader; public var image:BitmapData, image2:BitmapData; public function MarchingSquares () { file = new FileReference; file.addEventListener (Event.SELECT, onFileSelected); file.addEventListener (Event.COMPLETE, onFileLoaded); new PushButton (this, 0, 0, "LOAD IMAGE", onButtonClicked); } public function onButtonClicked (e:Event):void { file.browse ([new FileFilter ("Black'n'white image, please", "*.gif;*.png")]); } public function onFileSelected (e:Event):void { file.load (); } public function onFileLoaded (e:Event):void { loader = new Loader; loader.contentLoaderInfo.addEventListener (Event.COMPLETE, onImageReady); loader.loadBytes (file.data); } public function onImageReady(e:Event):void { if (loader.content) { loader.contentLoaderInfo.removeEventListener (Event.COMPLETE, onImageReady); image = loader.content ["bitmapData"]; removeChildAt (0); addChild (new Bitmap (image)); // threshold it just in case image.threshold (image, image.rect, image.rect.topLeft, ">=", 127, 0xFFFFFFFF, 0xFF); image.threshold (image, image.rect, image.rect.topLeft, "<", 127, 0xFF000000, 0xFF); image2 = new BitmapData (image.width, image.height, true, 0); addChild (new Bitmap (image2)); w = image.width; at = new Point (0, image.height >> 1); imageData = image.getVector (image.rect); addEventListener (Event.ENTER_FRAME, marchingSquares); } } public var at:Point, w:int, imageData:Vector.<uint>; public function marchingSquares (e:Event):void { var nw:uint = imageData [w * at.y + at.x] & 1; var ne:uint = imageData [w * at.y + at.x + 1] & 1; if ((ne == 1) && (nw == 0)) { // we go up at.y--; } else { var sw:uint = imageData [w * (at.y + 1) + at.x] & 1; if ((nw == 1) && (sw == 0)) { // we go left at.x--; } else { var se:uint = imageData [w * (at.y + 1) + at.x + 1] & 1; if ((sw == 1) && (se == 0)) { // we go down at.y++; } else { // we go right at.x++; } } } image2.setPixel32 (at.x, at.y, 0xFFFF0000); } } }