// Dart has a habit of using double-inclusive bounds,
// and I strongly prefer half-open bounds
//
// So: Here's a reimplementation of the geometry I need
class Size {
  final int dx;
  final int dy;

  Size(this.dx, this.dy) {
    assert(dx >= 0);
    assert(dy >= 0);
  }
}

class Offset {
  final int x;
  final int y;

  const Offset(this.x, this.y);
}

class Rect {
  final int x0;
  final int y0;
  final int dx;
  final int dy;

  int get x1 => x0 + dx;
  int get y1 => y0 + dy;

  Rect(this.x0, this.y0, this.dx, this.dy) {
    assert(dx >= 0);
    assert(dy >= 0);
  }

  bool contains(int x, int y) {
    return x0 <= x && x < x1 && y0 <= y && y < y1;
  }

  bool containsPoint(Offset xy) {
    return contains(xy.x, xy.y);
  }

  bool containsRect(Rect rect) {
    return x0 <= rect.x0 && y0 <= rect.y0 && rect.x1 <= x1 && rect.y1 <= y1;
  }
}