packery/js/rect.js

bin-packing layout library

/**
 * Rect
 * low-level utility class for basic geometry
 */

( function( window ) {

"use strict";

// -------------------------- Packery -------------------------- //

// global namespace
var Packery = window.Packery = function() {};

function rectDefinition() {

// -------------------------- Rect -------------------------- //

function Rect( props ) {
  // extend properties from defaults
  for ( var prop in Rect.defaults ) {
    this[ prop ] = Rect.defaults[ prop ];
  }

  for ( prop in props ) {
    this[ prop ] = props[ prop ];
  }

}

// make available
Packery.Rect = Rect;

Rect.defaults = {
  x: 0,
  y: 0,
  width: 0,
  height: 0
};

/**
 * Determines whether or not this rectangle wholly encloses another rectangle or point.
 * @param {Rect} rect
 * @returns {Boolean}
**/
Rect.prototype.contains = function( rect ) {
  // points don't have width or height
  var otherWidth = rect.width || 0;
  var otherHeight = rect.height || 0;
  return this.x <= rect.x &&
    this.y <= rect.y &&
    this.x + this.width >= rect.x + otherWidth &&
    this.y + this.height >= rect.y + otherHeight;
};

/**
 * Determines whether or not the rectangle intersects with another.
 * @param {Rect} rect
 * @returns {Boolean}
**/
Rect.prototype.overlaps = function( rect ) {
  var thisRight = this.x + this.width;
  var thisBottom = this.y + this.height;
  var rectRight = rect.x + rect.width;
  var rectBottom = rect.y + rect.height;

  // http://stackoverflow.com/a/306332
  return this.x < rectRight &&
    thisRight > rect.x &&
    this.y < rectBottom &&
    thisBottom > rect.y;
};

/**
 * @param {Rect} rect - the overlapping rect
 * @returns {Array} freeRects - rects representing the area around the rect
**/
Rect.prototype.getMaximalFreeRects = function( rect ) {

  // if no intersection, return false
  if ( !this.overlaps( rect ) ) {
    return false;
  }

  var freeRects = [];
  var freeRect;

  var thisRight = this.x + this.width;
  var thisBottom = this.y + this.height;
  var rectRight = rect.x + rect.width;
  var rectBottom = rect.y + rect.height;

  // top
  if ( this.y < rect.y ) {
    freeRect = new Rect({
      x: this.x,
      y: this.y,
      width: this.width,
      height: rect.y - this.y
    });
    freeRects.push( freeRect );
  }

  // right
  if ( thisRight > rectRight ) {
    freeRect = new Rect({
      x: rectRight,
      y: this.y,
      width: thisRight - rectRight,
      height: this.height
    });
    freeRects.push( freeRect );
  }

  // bottom
  if ( thisBottom > rectBottom ) {
    freeRect = new Rect({
      x: this.x,
      y: rectBottom,
      width: this.width,
      height: thisBottom - rectBottom
    });
    freeRects.push( freeRect );
  }

  // left
  if ( this.x < rect.x ) {
    freeRect = new Rect({
      x: this.x,
      y: this.y,
      width: rect.x - this.x,
      height: this.height
    });
    freeRects.push( freeRect );
  }

  return freeRects;
};

Rect.prototype.canFit = function( rect ) {
  return this.width >= rect.width && this.height >= rect.height;
};

return Rect;

}

// -------------------------- transport -------------------------- //

if ( typeof define === 'function' && define.amd ) {
  // AMD
  define( rectDefinition );
} else if ( typeof exports === 'object' ) {
  // CommonJS
  module.exports = rectDefinition();
} else {
  // browser global
  window.Packery = window.Packery || {};
  window.Packery.Rect = rectDefinition();
}

})( window );