Layout lo;// Declare the object
Button overButton;
Button clickedButton;
Button releasedButton;

void setup() {

 size(300, 300);
 smooth();
 noStroke();
 lo = new Layout();
}

void draw() {
 background(0);
 lo.display();
}

class Layout {
  Spot sp1;
  Spot sp2;

Layout() {
 PImage BaseImage_01 = loadImage("keyboard_01_off.jpg"); //load "01_off"
 PImage PressImage_01 = loadImage("keyboard_01_hit.jpg"); //load "01_off"
 
 sp1 = new Spot(20,70,30);
 sp2 = new Spot(50,25,30);
 
 Button b = new Button(200, 200, 52, color(204), color(255), color(102),BaseImage_01,PressImage_01, 2);
 registerDraw(b);
 registerMouseEvent(b);
}



 void display() {
   sp1.display();
   sp2.display();
   if(overButton != null)
     println("Mouse is over " + overButton.id);
   if(clickedButton != null)
     println("Mouse has clicked " + clickedButton.id);
   if(releasedButton != null)
     println("Mouse has released " + releasedButton.id);

   // These must be last 2 lines in draw method
   overButton = null;  
   clickedButton = null;
   releasedButton = null;
 }
}



class Spot {
 float x, y, diameter;

 Spot(float xpos, float ypos, float dia) {
   x = xpos; // Assign 33 to x
   y = ypos; // Assign 50 to y
   diameter = dia; // Assign 30 to diameter
 }

 void display() {
   ellipse(x, y, diameter, diameter);
 }
}

public class Button {
 int x, y;
 int size;
 color baseGray;
 color overGray;
 color pressGray;
 boolean over = false;
 boolean pressed = false;
 boolean released = false;
 PImage baseImage;
 PImage pressImage;
 int id;

 Button(int xp, int yp, int s, color b, color o, color p,PImage bi, PImage pi,int ident) {
   x = xp;
   y = yp;
   size = s;
   id = ident;
   baseGray = b;
   overGray = o;
   pressGray = p;
   baseImage = bi;
   pressImage = pi;
 }


 void mouseEvent(MouseEvent event){
   if ((mouseX >= x) && (mouseX <= x+size) && (mouseY >= y) && (mouseY <= y+size)) {  
     over = true;
     overButton = this;
     switch(event.getID()){
     case MouseEvent.MOUSE_PRESSED:
	 pressed = true;
	 clickedButton = this;
	 break;
     case MouseEvent.MOUSE_RELEASED:
	 released = true;
	 pressed = false;
	 releasedButton = this;
	 break;
     }
   }
   else {
     over = false;
     pressed = false;
     released = false;
   }
 }

 void draw() {
   fill(baseGray);
   stroke(255);	
   rect(x, y, size, size);
   if (pressed) {  
     image(pressImage,x,y);
   }
   else {
     image(baseImage,x,y);
   }
 }
} 

Panel p = new Panel(); // Can add size, pos, or change afterward
Button b1 = new Button("Go!", 100, 20); // Dims
p.add(b1); // Default pos
Button b2 = new Button("Click me"); // Default dims
p.add(b2, 10, 50); // Abs. pos, or set it relative to first button 

Panel(int size,int pos){
mySize = size;
myPos = pos; 
}