Efeitos em imagens

package imageshow;

import javafx.scene.image.*;
import javafx.animation.*;
import javafx.scene.Scene;
import javafx.stage.Stage;

def width:Number = 300; def height:Number = 300;
var imgUrls: String[] = [
            "http://gabrielcorpse.files.wordpress.com/2009/06/javafx_big.jpg",
            "http://raphaelmarques.files.wordpress.com/2009/07/javafx_logo_color_1.jpg",
            "http://norberto3d.files.wordpress.com/2008/05/javafx.jpg",
            "http://www.victorinfo.com.br/system/imagens/logo_javafx.png"
        ];
var images: Image[] =
        for (url in imgUrls) Image { width: width height: height backgroundLoading: true url: url };
var i: Integer = 0 on replace {
            if (i >= sizeof images)
                i = 0;
        };
var j: Integer = 1 on replace {
            if (j >= sizeof images)
                j = 1;
        };
def imgView: ImageView =
        ImageView { fitHeight: width fitWidth: height image: bind images[i] };

def imgView2: ImageView =
        ImageView { fitHeight: width fitWidth: height image: bind images[j] opacity:0 };

Timeline {
    time: 4s; repeatCount: Timeline.INDEFINITE; rate: 2 
    keyFrames: [
        KeyFrame {
            time: 2s
            values: [
                imgView.opacity => 0,
                imgView2.opacity => 1
            ]
            action: function () {
                i+=2;                
            }
        }
        KeyFrame {
            time: 4s
            values: [
                imgView.opacity => 1,   
                imgView2.opacity => 0
            ]
            action: function () {
                j+=2;                
            }
        }
    ]
}.play();

Stage {
    width: width height: height
    scene: Scene {
        content: [imgView, imgView2];
    }
}