MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH

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Creating bitmaps with the BitmapData class 535

■ On the Macintosh, browse to Macintosh HD/Applications/Macromedia Flash 8/Samples

and Tutorials/Samples/ActionScript/BitmapData.

The following procedure dynamically loads a JPEG image onto the Stage, and uses the

BitmapData class to create a noise effect, similar to static on a television. The noise effect is

redrawn with a random pattern every 100 milliseconds (1/10 of a second). Moving the mouse

pointer along the x-axis and y-axis affects how much static is drawn at every interval.

To create a noise effect with the BitmapData class:

1. Create a new Flash document and save it as noise.fla.

2. Add the following ActionScript to Frame 1 of the Timeline:

import flash.display.BitmapData;

this.createTextField("status_txt", 90, 0, 0, 100, 20);

status_txt.selectable = false;

status_txt.background = 0xFFFFFF;

status_txt.autoSize = "left";

function onMouseMove() {

status_txt._x = _xmouse;

status_txt._y = _ymouse-20;

updateAfterEvent();

}

this.createEmptyMovieClip("img_mc", 10);

img_mc.loadMovie("http://www.helpexamples.com/flash/images/image1.jpg");

var noiseBmp:BitmapData = new BitmapData(Stage.width, Stage.height,

true);

this.attachBitmap(noiseBmp, 20);

setInterval(updateNoise, 100);

var grayScale:Boolean = true;

function updateNoise():Void {

var low:Number = 30 * _xmouse / Stage.width;

var high:Number = 200 * _ymouse / Stage.height;

status_txt.text = "low:" + Math.round(low) + ", high:" +

Math.round(high);

noiseBmp.noise(Math.round(Math.random() * 100000), low, high, 8,

true);

}

This code creates a text field with the instance name status_txt, which follows the

mouse pointer and displays the current values for the

high and low parameters for the

noise() method. The setInterval() function changes the noise effect, which is

updated every 100 milliseconds (1/10 of a second), by continuously calling the

updateNoise() function. The high and low parameters for the noise() method are

determined by calculating the pointer’s current position on the Stage.

MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH - Page 535