SVG.Line = function Line() {
  this.constructor.call(this, SVG.create('line'));
};

// Inherit from SVG.Shape
SVG.Line.prototype = new SVG.Shape();

// Add required methods
SVG.extend(SVG.Line, {
  // Move line
  move: function(x, y) {
    var bbox = this.bbox();
    
    return this.attr({
      x1: this.attr('x1') - bbox.x + x,
      y1: this.attr('y1') - bbox.y + y,
      x2: this.attr('x2') - bbox.x + x,
      y2: this.attr('y2') - bbox.y + y
    });
  },
  // Move element by its center
  center: function(x, y) {
    var bbox = this.bbox();
    
    return this.move(x - bbox.width / 2, y - bbox.height / 2);
  },
  // Set line size by width and height
  size: function(width, height) {
    var bbox = this.bbox();
    
    this.attr(this.attr('x1') < this.attr('x2') ? 'x2' : 'x1', bbox.x + width);
    return this.attr(this.attr('y1') < this.attr('y2') ? 'y2' : 'y1', bbox.y + height);
  }
});

// Extend all container modules
SVG.extend(SVG.Container, {
  line: function(x1, y1, x2, y2) {
    return this.put(new SVG.Line().attr({
      x1: x1,
      y1: y1,
      x2: x2,
      y2: y2
    }));
  }
});