ADOBE® FLEX® 3: PROGRAMMING ACTIONSCRIPT™ 3.0

ADOBE FLEX 3

Developer Guide

383

// Create a red square.

var redSquare1:Bitmap = new Bitmap(bmd2);

this.addChild(redSquare1);

redSquare1.x = 0;

// Create a second red square.

var redSquare2:Bitmap = new Bitmap(bmd2);

this.addChild(redSquare2);

redSquare2.x = 150;

redSquare2.y = 150;

// Define the point at the top-left corner of the bitmap.

var pt1:Point = new Point(0, 0);

// Define the point at the center of redSquare1.

var pt2:Point = new Point(20, 20);

// Define the point at the center of redSquare2.

var pt3:Point = new Point(160, 160);

trace(bmd1.hitTest(pt1, 0xFF, pt2)); // true

trace(bmd1.hitTest(pt1, 0xFF, pt3)); // false

Copying bitmap data

To copy bitmap data from one image to another, you can use several methods: clone(), copyPixels(),

copyChannel(), and draw().

As its name suggests, the

clone() method lets you clone, or sample, bitmap data from one BitmapData object to

another. When called, the method returns a new BitmapData object that is an exact clone of the original instance it

was copied from.

The following example clones a copy of an orange (parent) square and places the clone beside the original parent

square:

import flash.display.Bitmap;

import flash.display.BitmapData;

var myParentSquareBitmap:BitmapData = new BitmapData(100, 100, false, 0x00ff3300);

var myClonedChild:BitmapData = myParentSquareBitmap.clone();

var myParentSquareContainer:Bitmap = new Bitmap(myParentSquareBitmap);

this.addChild(myParentSquareContainer);

var myClonedChildContainer:Bitmap = new Bitmap(myClonedChild);

this.addChild(myClonedChildContainer);

myClonedChildContainer.x = 110;

The copyPixels() method is a quick and easy way of copying pixels from one BitmapData object to another. The

method takes a rectangular snapshot (defined by the

sourceRect parameter) of the source image and copies it to

another rectangular area (of equal size). The location of the newly “pasted” rectangle is defined within the

destPoint parameter.

The

copyChannel() method samples a predefined color channel value (alpha, red, green, or blue) from a source

BitmapData object and copies it into a channel of a destination BitmapData object. Calling this method does not

affect the other channels in the destination BitmapData object.