preview.js

function Preview() {
  grabBag = this.gen();
}
Preview.prototype.init = function() {
  //XXX fix ugly code lolwut
  while (1) {
    this.grabBag = this.gen();
    if ([3, 4, 6].indexOf(this.grabBag[0]) === -1) break;
  }
  this.grabBag.push.apply(this.grabBag, this.gen());
  this.draw();
};
Preview.prototype.next = function() {
  var next;
  next = this.grabBag.shift();
  if (this.grabBag.length === 7) {
    this.grabBag.push.apply(this.grabBag, this.gen());
  }
  this.draw();
  return next;
  //TODO Maybe return the next piece?
};
/**
 * Creates a "grab bag" of the 7 tetrominos.
 */
Preview.prototype.gen = function() {
  var pieceList = [0, 1, 2, 3, 4, 5, 6];
  return pieceList.sort(function() {
    return 0.5 - rng.next();
  });
};
/**
 * Draws the piece preview.
 */
Preview.prototype.draw = function() {
  clear(previewCtx);
  for (var i = 0; i < 6; i++) {
    if (this.grabBag[i] === 0 || this.grabBag[i] === 3) {
      draw(
        pieces[this.grabBag[i]].tetro,
        pieces[this.grabBag[i]].x - 3,
        pieces[this.grabBag[i]].y + 2 + i * 3,
        previewCtx,
      );
    } else {
      draw(
        pieces[this.grabBag[i]].tetro,
        pieces[this.grabBag[i]].x - 2.5,
        pieces[this.grabBag[i]].y + 2 + i * 3,
        previewCtx,
      );
    }
  }
};
var preview = new Preview();