// Mouse Functions 
// by REAS <http://reas.com> 

float bx; 
float by; 
int bs = 20; 
boolean bover = false; 
boolean locked = false; 
float bdifx = 0.0; 
float bdify = 0.0; 
 
 
void setup() 
{ 
  size(200, 200); 
  bx = width/2.0; 
  by = height/2.0; 
  rectMode(CENTER_RADIUS);  
} 
 
void draw() 
{ 
  background(0); 
  
  // Test if the cursor is over the box 
  if (mouseX > bx-bs && mouseX < bx+bs && 
      mouseY > by-bs && mouseY < by+bs) { 
    bover = true;  
    if(!locked) { 
      stroke(255); 
      fill(153); 
    } 
  } else { 
    stroke(153); 
    fill(153); 
    bover = false; 
  } 
  
  // Draw the box 
  rect(bx, by, bs, bs); 
} 
 
void mousePressed() { 
  if(bover) { 
    locked = true; 
    fill(255, 255, 255); 
  } else { 
    locked = false; 
  } 
  bdifx = mouseX-bx; 
  bdify = mouseY-by; 
 
} 
 
void mouseDragged() { 
  if(locked) { 
    bx = mouseX-bdifx; 
    by = mouseY-bdify; 
  } 
} 
 
void mouseReleased() { 
  locked = false; 
}