float x,y,w,h;

float ox, oy, ow, oh;

void setup(){
  size(1000,600);
  rectMode(RADIUS);
  colorMode(HSB,360,100,100);
  
  x = width / 2;
  y = height / 2;
  w = width / 20;
  h = height / 5;
  
  ox = width / 2;
  oy = height / 2;
  ow = width / 2 - 120;
  oh = height / 2 - 120;
}

void draw(){
  background(0);
  noStroke();
  fill(30,20,90);
  rect(ox,oy,ow,oh);
  fill(240,30,60);
  rect(x,y,w,h);
}

void mouseDragged(){
  if( ox - ow <= mouseX - w && mouseX + w <= ox + ow ) {
    x = mouseX;
  }
  if( oy - oh <= mouseY - h && mouseY + h <= oy + oh ) {
    y = mouseY;
  }
  
  if( mouseX - w < ox - ow ) {
    x = ox - ow + w;
  } else if( ox + ow < mouseX + w ) {
    x = ox + ow - w;
  }
  if( mouseY - h < oy - oh ) {
    y = oy - oh + h;
  } else if( oy + oh < mouseY + h ) {
    y = oy + oh - h;
  }
}