Finding where the top of the page view is

[fesh]

This is sort of a hard question to describe, but here it goes:

I'm trying to completely center an element on a page (this means both horizontal and vertically). However, what I'm wondering is if there is a way, via the DOM functionality to make it so if, say, you've scrolled X-distance down the page it centers it in the current view of the page, not to the original view of the page.

Like I said, I'm not sure how to describe this very well, hope I conveyed my information.

[Kravvitz]

Here's a function that I wrote to find the coordinates of the center of the page.

function findVisiblePageCenter() {
var x1,y1,x2,y2,d=document,coords={};

  // function by Dynamic Site Solutions -- http://www.dynamicsitesolutions.com/
  // much of the code in this function came from
  // http://www.quirksmode.org/viewport/compatibility.html

  if(self.innerHeight) { // all except Explorer
    x1 = self.innerWidth;
    y1 = self.innerHeight;
  }
  else if(d.documentElement && d.documentElement.clientHeight) {
    // Explorer 6 Strict Mode
    x1 = d.documentElement.clientWidth;
    y1 = d.documentElement.clientHeight;
  }
  else if(d.body) { // other Explorers
    x1 = d.body.clientWidth;
    y1 = d.body.clientHeight;
  }

  if(self.pageYOffset) { // all except Explorer
    x2 = self.pageXOffset;
    y2 = self.pageYOffset;
  }
  else if(d.documentElement && d.documentElement.scrollTop) {
    // Explorer 6 Strict
    x2 = d.documentElement.scrollLeft;
    y2 = d.documentElement.scrollTop;
  }
  else if(d.body) { // all other Explorers
    x2 = d.body.scrollLeft;
    y2 = d.body.scrollTop;
  }

  if(!isNaN(y2) && !isNaN(x2)) {
    coords.x = Math.floor(x1/2 + x2);
    coords.y = Math.floor(y1/2 + y2);
  } else {
    coords.x = Math.floor(x1/2);
    coords.y = Math.floor(y1/2);
  }

  return coords;
}

[Janakar]

I remember that Mike had something like this in his CBE-libary
http://www.cross-browser.com/cbe/

You have to add an
window.cbe.addEventListener('scroll', scrollListener,false);

function scrollListener(e) {
var st = document.cbe.scrollTop();
myContainer.moveTo(document.cbe.width()/2, document.cbe.height()/2+st);

}

But perhaps there something in his new libary.
I wasn't very busy during the last time.

[fesh]

Kravvitz. Thank you very much, that helped a ton (I hope you don't mind me using the code in my page, cited of course?).

[Kravvitz]

You're welcome

I wouldn't have posted it if I didn't want other people to use it.