/*====================================================================================================
//////////////////////////////////////////////////////////////////////////////////////////////////////

 Author : http://www.yomotsu.net
 created: 2007/03/13
 update : 2007/11/01 IE6 のアルファチャンネル付き png も対象になるよう変更
 Licensed under the GNU Lesser General Public License version 2.1
 
 画像のロールオーバーをするためのスクリプト

//////////////////////////////////////////////////////////////////////////////////////////////////////
====================================================================================================*/
var yomotsuRollover = {
  
  preLoad : {},
  main : function() {
    var img = document.images, i, preLoadImg;
    
    for (i = 0; i <img.length; i++) {
      if ((img[i].src.match(/.*_off\./))||(img[i].style.filter)){
        
        var preLoadImg = new Image;
        preLoadImg.src = img[i].src.replace('_off.', '_on.');
        yomotsuRollover.preLoad[img[i].src] = preLoadImg.src;

        img[i].onmouseover = yomotsuRollover.over;
        img[i].onmouseout  = yomotsuRollover.out;
      }
    }
  },
  
  over : function() {
    var imgSrc, preLoadImgSrc;
    if((this.style.filter)&&(this.style.filter.match(/_off\.png/))){//(IE5.5-6 && png)
      imgSrc = (this.style.filter.match(/src=.*\)/)+"").slice(5,-2);
      preLoadImgSrc = yomotsuRollover.preLoad[imgSrc];
      this.style.filter = this.style.filter.replace(imgSrc, preLoadImgSrc);
    }
    else{
      this.src = yomotsuRollover.preLoad[this.src];
    }
  },

  out : function(){
    if((this.style.filter)&&(this.style.filter.match(/_on\.png/))){//(IE5.5-6 && png)
      this.style.filter = this.style.filter.replace('_on.png', '_off.png');
    }
    else{
      this.src = this.src.replace('_on.', '_off.');
    }
  },

  addEvent : function(){
    try {
      window.addEventListener('load', this.main, false);
    } catch (e) {
      window.attachEvent('onload', this.main);
    }
  }
}

yomotsuRollover.addEvent();