Flash Pixel Transition Effect Tutorial

Open a new flash 8 professional document & set the desired background color, width and height of the document. Keep the frame rate at 12fps.
Import all the images (I have considered only 3 images for this tutorial) required for animation to the library.(Library panel shortcut key => ctrl+l) Let all the images be of the same dimensions. Right click on the 1st image in library panel and click on 'linkage…'. In the linkage properties window enter the 'Identifier' as 'img1' and check the 'Export for ActionScript' & 'Export in first frame' boxes. Similarly enter the linkage properties for 2nd image as 'img2' and for 3rd image as 'img3'.
Drag the 1st image to the stage at frame1 and align it to the left and top edge. This can be done by pressing ctrl+alt+1 and ctrl+alt+4. Rename this layer to 'stage'.
While the playhead is still at frame1 press F8. This opens a 'Convert to Symbol' window. Enter the name as 'Photo' and select Type as 'Movie clip'. Choose the top left corner point for Registration. Click on OK.
Create a new layer above the 'stage' layer and name it 'functions'. Enter the following code in this layer at frame1 in the actions panel.

import flash.display.*
import flash.geom.*	
var effects:Array = new Array({label:"Pixels", data:"pixels"})
myCombo.dataProvider = effects
effectListener = {}
effectListener.ref = this
effectListener.change = function(evt:Object){
	var action:String = evt.target.selectedItem.data
	this.ref.transition = action //set transition
	clearInterval(run) //re-create set Interval
	}
myCombo.addEventListener("change", effectListener)
//Gallery array, bitmaps on library
var images:Array = new Array("img1", "img2", "img3")
var current:Number = 0 //image counter
//general holder
a = BitmapData.loadBitmap(images[current])
w = a.width
h = a.height
container = this.createEmptyMovieClip("container", 1)
container.createEmptyMovieClip("holder", 1)
container.holder.attachBitmap(a, new Matrix())
container.holder._x = 0
container.holder._y = 0
//default transition
transition = "pixels";
//Begin gallery showcase
run = setInterval(nextImg, 3000, this)	
function nextImg(where){
	where.current = ((where.current+1)>where.images.length-1)?0 : where.current+1
	where[where.transition](where.current)
}
 
//Transition	**************************************************************
 
function pixels(nr){
	//Bitmap data for next image 
	trans = BitmapData.loadBitmap(images[nr])
	//capture data for pixelDisolve method
	var area = trans.rectangle
	var p = area.topLeft
	percent = 0	
	transarea = w*h
	//change mixing pixels
	this.onEnterFrame = function(){
		//percentage of pixels to mix
		var numPixels=( ( w * h ) / 100 ) * percent;
		percent+=5 //increment percentage
		a.pixelDissolve(trans , area , p , 0, numPixels);
		//clear onEnterFrame when finish
		if(numPixels>=(w*h)) {
			delete this.onEnterFrame 
			//copy next image
			a.draw(container.holder)
			//release memory
			trans.dispose()	
		}
	}
}

Create a new layer above 'functions' layer & name it as 'prototypes'. Enter the following code at frame1 in this layer in the actions panel.

stop()
MovieClip.prototype.linearMove = function(dist:Number){
	this.walked = 0
	this.onEnterFrame = function(){
		this._x+=this.velx
		this._y+=this.vely
		this.walked+=int(this.vel)
		if(this.walked>dist) {
			delete this.onEnterFrame
			this.removeMovieClip()
		}
	}
}
MovieClip.prototype.turnOut = function(dir){
	this.counter = 0
	this.onEnterFrame = function(){
		this._rotation+=dir
		this.counter+=Math.abs(dir)
		if(this.counter>=100) {
			delete this.onEnterFrame
			this.removeMovieClip()
		}
	}
}

Save and test the movie.

Notes