ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Filtering display objects
import flash.display.BitmapData;
import flash.display.Loader;
import flash.events.MouseEvent;
import flash.filters.DisplacementMapFilter;
import flash.geom.Point;
import flash.net.URLRequest;
// Load an image onto the Stage.
var loader:Loader = new Loader();
var url:URLRequest = new URLRequest("http://www.helpexamples.com/flash/images/image3.jpg");
loader.load(url);
this.addChild(loader);
var mapImage:BitmapData;
var displacementMap:DisplacementMapFilter;
// This function is called when the image finishes loading.
function setupStage(event:Event):void
{
// Center the loaded image on the Stage.
loader.x = (stage.stageWidth - loader.width) / 2;
loader.y = (stage.stageHeight - loader.height) / 2;
}
// Create the displacement map image.
mapImage = new BitmapData(loader.width, loader.height, false, 0xFF0000);
// Create the displacement filter.
displacementMap = new DisplacementMapFilter();
displacementMap.mapBitmap = mapImage;
displacementMap.mapPoint = new Point(0, 0);
displacementMap.componentX = BitmapDataChannel.RED;
displacementMap.scaleX = 250;
loader.filters = [displacementMap];
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, setupStage);
The properties used to define the displacement are as follows:
Map bitmap: The displacement bitmap is a new BitmapData instance created by the code. Its dimensions match the
dimensions of the loaded image (so the displacement is applied to the entire image). It is filled with solid red pixels.
Map point: This value is set to the point 0, 0—again, causing the displacement to be applied to the entire image.
X component: This value is set to the constant BitmapDataChannel.RED, meaning the red value of the map bitmap
will determine how much the pixels are displaced (how much they move) along the x axis.
X scale: This value is set to 250. The full amount of displacement (from the map image being completely red) only
displaces the image by a small amount (roughly one-half of a pixel), so if this value was set to 1 the image would
only shift .5 pixels horizontally. By setting it to 250, the image shifts by approximately 125 pixels.
Last updated 6/6/2012
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