// BlendTrans script by Des
// http://www.brainerror.net/scripts_js_blendtrans.php
// MRV: added use of IE blendTrans filter if available (smoother transition)

function opacity(id, opacStart, opacEnd, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;

	//determine the direction for the blending, if start and end are the same nothing happens
	if(opacStart > opacEnd) {
		for(i = opacStart; i >= opacEnd; i--) {
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	} else if(opacStart < opacEnd) {
		for(i = opacStart; i <= opacEnd; i++)
			{
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
	var object = document.getElementById(id).style; 
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}

function shiftOpacity(id, millisec) {
	//if an element is invisible, make it visible, else make it ivisible
	if(document.getElementById(id).style.opacity == 0) {
		opacity(id, 0, 100, millisec);
	} else {
		opacity(id, 100, 0, millisec);
	}
}

function playBlendTrans() {
  this.filters.blendTrans.Play();
}

function unblendimage(divid, imageid) {
  // Setting opacity to 100% causes the background image to be briefly
  // visible on Win/Firefox. As a workaround, we set the background
  // equal to the foreground before setting opacity to 100%.
    var el = document.getElementById(divid);
    var el2 = document.getElementById(imageid);
    el.style.backgroundImage = "url(" + el2.src + ")";
    changeOpac(100, imageid);
}

function blendimage(divid, imageid, imagefile, millisec) {
    var el = document.getElementById(divid);
    var el2 = document.getElementById(imageid);
    if (!millisec) {
	  el2.src = imagefile;
      el.style.backgroundImage = "url(" + imagefile + ")";
    } else if (document.all) {
      // Use MSIE blendtrans filter
      el.style.backgroundImage='';
      el2.style.filter = 'blendTrans(duration='+(millisec/1000)+')';
      el2.filters.blendTrans.Apply();
      el2.onload = playBlendTrans;
      el2.src = imagefile;
    } else {
      // Use Des' blendtrans
      //set the current image as background
      el.style.backgroundImage = "url(" + el2.src + ")";
      //make image transparent
	  changeOpac(0, imageid);
      //make new image
	  el2.src = imagefile;
      //fade in image
      var i;
	  for(i = 0; i <= 99; i++) {
		setTimeout("changeOpac(" + i + ",'" + imageid + "')",(i*millisec/100));
	  }
      setTimeout("unblendimage('"+divid+"','"+imageid+"')", millisec);
    }
}

function currentOpac(id, opacEnd, millisec) {
	//standard opacity is 100
	var currentOpac = 100;
	
	//if the element has an opacity set, get it
	if(document.getElementById(id).style.opacity < 100) {
		currentOpac = document.getElementById(id).style.opacity * 100;
	}

	//call for the function that changes the opacity
	opacity(id, currentOpac, opacEnd, millisec)
}