jquery.ba-resize.js

/*!
 * jQuery resize event - v1.1 - 3/14/2010
 * http://benalman.com/projects/jquery-resize-plugin/
 * 
 * Copyright (c) 2010 "Cowboy" Ben Alman
 * Dual licensed under the MIT and GPL licenses.
 * http://benalman.com/about/license/
 */

// Script: jQuery resize event
//
// *Version: 1.1, Last updated: 3/14/2010*
// 
// Project Home - http://benalman.com/projects/jquery-resize-plugin/
// GitHub       - http://github.com/cowboy/jquery-resize/
// Source       - http://github.com/cowboy/jquery-resize/raw/master/jquery.ba-resize.js
// (Minified)   - http://github.com/cowboy/jquery-resize/raw/master/jquery.ba-resize.min.js (1.0kb)
// 
// About: License
// 
// Copyright (c) 2010 "Cowboy" Ben Alman,
// Dual licensed under the MIT and GPL licenses.
// http://benalman.com/about/license/
// 
// About: Examples
// 
// This working example, complete with fully commented code, illustrates a few
// ways in which this plugin can be used.
// 
// resize event - http://benalman.com/code/projects/jquery-resize/examples/resize/
// 
// About: Support and Testing
// 
// Information about what version or versions of jQuery this plugin has been
// tested with, what browsers it has been tested in, and where the unit tests
// reside (so you can test it yourself).
// 
// jQuery Versions - 1.3.2, 1.4.1, 1.4.2
// Browsers Tested - Internet Explorer 6-8, Firefox 2-3.6, Safari 3-4, Chrome, Opera 9.6-10.1.
// Unit Tests      - http://benalman.com/code/projects/jquery-resize/unit/
// 
// About: Release History
// 
// 1.1 - (3/14/2010) Fixed a minor bug that was causing the event to trigger
//       immediately after bind in some circumstances. Also changed $.fn.data
//       to $.data to improve performance.
// 1.0 - (2/10/2010) Initial release

(function($,window,undefined){
  '$:nomunge'; // Used by YUI compressor.
  
  // A jQuery object containing all non-window elements to which the resize
  // event is bound.
  var elems = $([]),
    
    // Extend $.resize if it already exists, otherwise create it.
    jq_resize = $.resize = $.extend( $.resize, {} ),
    
    timeout_id,
    
    // Reused strings.
    str_setTimeout = 'setTimeout',
    str_resize = 'resize',
    str_data = str_resize + '-special-event',
    str_delay = 'delay',
    str_pendingDelay = 'pendingDelay',
    str_activeDelay = 'activeDelay',
    str_throttle = 'throttleWindow';
  
  // Property: jQuery.resize.delay
  // 
  // The numeric interval (in milliseconds) at which the resize event polling
  // loop executes. Defaults to 250.
  
  jq_resize[ str_pendingDelay ] = 250;
  jq_resize[ str_activeDelay ] = 20;
  jq_resize[ str_delay ] = jq_resize[ str_pendingDelay ];
  
  // Property: jQuery.resize.throttleWindow
  // 
  // Throttle the native window object resize event to fire no more than once
  // every <jQuery.resize.delay> milliseconds. Defaults to true.
  // 
  // Because the window object has its own resize event, it doesn't need to be
  // provided by this plugin, and its execution can be left entirely up to the
  // browser. However, since certain browsers fire the resize event continuously
  // while others do not, enabling this will throttle the window resize event,
  // making event behavior consistent across all elements in all browsers.
  // 
  // While setting this property to false will disable window object resize
  // event throttling, please note that this property must be changed before any
  // window object resize event callbacks are bound.
  
  jq_resize[ str_throttle ] = true;
  
  // Event: resize event
  // 
  // Fired when an element's width or height changes. Because browsers only
  // provide this event for the window element, for other elements a polling
  // loop is initialized, running every <jQuery.resize.delay> milliseconds
  // to see if elements' dimensions have changed. You may bind with either
  // .resize( fn ) or .bind( "resize", fn ), and unbind with .unbind( "resize" ).
  // 
  // Usage:
  // 
  // > jQuery('selector').bind( 'resize', function(e) {
  // >   // element's width or height has changed!
  // >   ...
  // > });
  // 
  // Additional Notes:
  // 
  // * The polling loop is not created until at least one callback is actually
  //   bound to the 'resize' event, and this single polling loop is shared
  //   across all elements.
  // 
  // Double firing issue in jQuery 1.3.2:
  // 
  // While this plugin works in jQuery 1.3.2, if an element's event callbacks
  // are manually triggered via .trigger( 'resize' ) or .resize() those
  // callbacks may double-fire, due to limitations in the jQuery 1.3.2 special
  // events system. This is not an issue when using jQuery 1.4+.
  // 
  // > // While this works in jQuery 1.4+
  // > $(elem).css({ width: new_w, height: new_h }).resize();
  // > 
  // > // In jQuery 1.3.2, you need to do this:
  // > var elem = $(elem);
  // > elem.css({ width: new_w, height: new_h });
  // > elem.data( 'resize-special-event', { width: elem.width(), height: elem.height() } );
  // > elem.resize();
      
  $.event.special[ str_resize ] = {
    
    // Called only when the first 'resize' event callback is bound per element.
    setup: function() {
      // Since window has its own native 'resize' event, return false so that
      // jQuery will bind the event using DOM methods. Since only 'window'
      // objects have a .setTimeout method, this should be a sufficient test.
      // Unless, of course, we're throttling the 'resize' event for window.
      if ( !jq_resize[ str_throttle ] && this[ str_setTimeout ] ) { return false; }
      
      var elem = $(this);
      
      // Add this element to the list of internal elements to monitor.
      elems = elems.add( elem );
      
      // Initialize data store on the element.
      $.data( this, str_data, { w: elem.width(), h: elem.height() } );
      
      // If this is the first element added, start the polling loop.
      if ( elems.length === 1 ) {
        loopy();
      }
    },
    
    // Called only when the last 'resize' event callback is unbound per element.
    teardown: function() {
      // Since window has its own native 'resize' event, return false so that
      // jQuery will unbind the event using DOM methods. Since only 'window'
      // objects have a .setTimeout method, this should be a sufficient test.
      // Unless, of course, we're throttling the 'resize' event for window.
      if ( !jq_resize[ str_throttle ] && this[ str_setTimeout ] ) { return false; }
      
      var elem = $(this);
      
      // Remove this element from the list of internal elements to monitor.
      elems = elems.not( elem );
      
      // Remove any data stored on the element.
      elem.removeData( str_data );
      
      // If this is the last element removed, stop the polling loop.
      if ( !elems.length ) {
        clearTimeout( timeout_id );
      }
    },
    
    // Called every time a 'resize' event callback is bound per element (new in
    // jQuery 1.4).
    add: function( handleObj ) {
      // Since window has its own native 'resize' event, return false so that
      // jQuery doesn't modify the event object. Unless, of course, we're
      // throttling the 'resize' event for window.
      if ( !jq_resize[ str_throttle ] && this[ str_setTimeout ] ) { return false; }
      
      var old_handler;
      
      // The new_handler function is executed every time the event is triggered.
      // This is used to update the internal element data store with the width
      // and height when the event is triggered manually, to avoid double-firing
      // of the event callback. See the "Double firing issue in jQuery 1.3.2"
      // comments above for more information.
      
      function new_handler( e, w, h ) {
        var elem = $(this),
          data = $.data( this, str_data );
        
        // If called from the polling loop, w and h will be passed in as
        // arguments. If called manually, via .trigger( 'resize' ) or .resize(),
        // those values will need to be computed.
        data.w = w !== undefined ? w : elem.width();
        data.h = h !== undefined ? h : elem.height();
        
        old_handler.apply( this, arguments );
      };
      
      // This may seem a little complicated, but it normalizes the special event
      // .add method between jQuery 1.4/1.4.1 and 1.4.2+
      if ( $.isFunction( handleObj ) ) {
        // 1.4, 1.4.1
        old_handler = handleObj;
        return new_handler;
      } else {
        // 1.4.2+
        old_handler = handleObj.handler;
        handleObj.handler = new_handler;
      }
    }
    
  };
  
  function loopy() {
    
    // Start the polling loop, asynchronously.
    timeout_id = window[ str_setTimeout ](function(){
      
      // Iterate over all elements to which the 'resize' event is bound.
      elems.each(function(){
        var elem = $(this),
          width = elem.width(),
          height = elem.height(),
          data = $.data( this, str_data );
        
        // If element size has changed since the last time, update the element
        // data store and trigger the 'resize' event.
        if ( width !== data.w || height !== data.h ) {
          jq_resize[ str_delay ] = jq_resize[ str_activeDelay ];
          elem.trigger( str_resize, [ data.w = width, data.h = height ] );
        } else {
          jq_resize[ str_delay ] = jq_resize[ str_pendingDelay ];
        }
        
      });
      
      // Loop.
      loopy();
      
    }, jq_resize[ str_delay ] );
    
  };
  
})(jQuery,this);