// my sprite class
class Sprite {
  int x, y, top, bottom, left, right;
  PImage img;
  
  Sprite(String i, int ix, int iy) {
    img = loadImage(i);
    // self centering, since Moblie Processing lacks imageMode(CENTER); ?
    update_edges();
    x = ix;
    y = iy;
  }
  
  // alternate constructor with default x, y
  Sprite(String i) {
    img = loadImage(i);
    x = 0;
    y = 0;
  }
  
  void update_edges() {
    top = y;
    bottom = top + img.height;
    left = x;
    right = x + img.width;
  }
  
  void xy(int ix, int iy) {
    x = ix;
    y = iy;
  }
  
  void draw() {
    update_edges();
    image(img, x - img.width/2, y - img.height/2);
  }
}