ParticeLib v1.3 [Java] (c) xerpi 2011

import java.util.ArrayList;
import java.util.ListIterator;
import java.util.Random;

import android.graphics.Bitmap;
import android.graphics.Canvas;

public class Particles {
    Random random = new Random();
    private float speed1,speed2,initX,initY;
    int screenW,screenH;
    boolean run = false;
    ArrayList <Particle> particles = new ArrayList<Particle>();

    public Particles(int screenW,int screenH,int total,double speed1,double speed2){
        this.speed1 = (float) speed1;
        this.speed2 = (float) speed2;
        for (int i =0; i<total;i++){
            this.add(speed1,speed2);
        }
        this.screenW = screenW;
        this.screenH = screenH;
    }
    public class Particle{
        double x,y,inc_x,inc_y,w,h,angle,speed;
        public Particle(){
            this.angle = random.nextFloat() * 6.28;
            this.inc_x = Math.cos(this.angle);
            this.inc_y = Math.sin(this.angle);
            this.speed = getSpeedValue(speed1,speed2);
        }
    }
    public boolean outOfScreen(Particle particle){
        if (this.initX+particle.x > this.screenW  || this.initX+particle.x< 0  || this.initY+particle.y < 0 || this.initY+particle.y > this.screenH){
            return true;
        }
        return false;
    }
    public void blit(Bitmap img,Canvas canvas){
        if (this.run){
            ListIterator<Particle> a = particles.listIterator();
            float fX,fY;
            while(a.hasNext()) {
                Particle i = (Particle) a.next();
                fX = (float) (this.initX+i.x);
                fY = (float) (this.initY+i.y);
                canvas.save();
                canvas.rotate((float) Math.toDegrees(i.angle),fX,fY);
                canvas.drawBitmap(img, fX,fY,null);
                canvas.restore();
            }
        }
    }

    public boolean move() {
        if (this.run){
            ListIterator<Particle> a = particles.listIterator();
            while(a.hasNext()) {
                Particle i = (Particle) a.next();
                i.y += i.inc_y * i.speed;
                i.x += i.inc_x * i.speed;
                if (outOfScreen(i)){
                    a.remove();
                }
            }
            return (a.nextIndex()<1);
        }
        return false;
    }

    public void reset() {
        for (int i = 0; i < this.particles.size(); i++) {
            this.particles.set(i,new Particle());
        }
    }
    public void init( float x, float y){
        this.initX = x;
        this.initY = y;
        this.run = true;
    }
    public void resume(){
        this.run = true;
    }
    public void pause(){
        this.run = false;
    }
    public void changeXY( float x, float y){
        this.initX = x;
        this.initY = y;
    }

    public void add(double speed1,double speed2){
        this.particles.add(new Particle());
    }
    public double getSpeedValue(double num1,double num2){
        return num1 + ((num2-num1)*this.random.nextDouble());
    }
}