Get Client Rect Offset

getClientRectOffsetY.js

function getClientRectOffsetY(elem, part, offset) {
  elem = ge(elem);
  offset = offset || 0;
  var ey = getXY(elem)[1],
      eh = getSize(elem)[1],
      w = window, de = document.documentElement,
      ch = Math.max(intval(w.innerHeight), intval(de.clientHeight)),
      fixed_head = ge('page_header_cont'),
      hh = getSize(fixed_head)[1],
      st = (de.scrollTop || bodyNode.scrollTop || window.scrollY || 0);
  if (!part) {
    if (ey < st + hh + offset) return (ey - st + hh - offset);
    if (ey + eh > st + ch - offset) return (ey + eh - st - ch + offset);
  } else {
    if (ey + eh < st + hh + offset) return (ey + eh - st - hh - offset);
    if (ey > st + ch - offset) return (ey - st - ch + offset);
  }
  return 0;
}

function getXYRect(obj, notBounding) {
  var rect;
  if (notBounding && getStyle(obj, 'display') == 'inline') {
    var rects = obj.getClientRects();
    rect = rects && rects[0] || obj.getBoundingClientRect();
  } else {
    rect = obj.getBoundingClientRect();
  }

  return rect;
}

function getXY(obj, forFixed) {
  obj = ge(obj);
  if (!obj) return [0,0];

  var docElem, win,
      rect = {top: 0, left: 0},
      doc = obj.ownerDocument;
  if (!doc) {
    return [0, 0];
  }
  docElem = doc.documentElement;

  if (boundingRectEnabled(obj)) {
    rect = getXYRect(obj, true);
  }
  win = doc == doc.window ? doc : (doc.nodeType === 9 ? doc.defaultView || doc.parentWindow : false);
  return [
    rect.left + (!forFixed ? win.pageXOffset || docElem.scrollLeft : 0) - (docElem.clientLeft || 0),
    rect.top + (!forFixed ? win.pageYOffset || docElem.scrollTop : 0) - (docElem.clientTop || 0)
  ];
}

function getSize(elem, withoutBounds, notBounding) {
  elem = ge(elem);
  var s = [0, 0], de = document.documentElement, rect;
  if (withoutBounds && getStyle(elem, 'boxSizing') === 'border-box') {
    withoutBounds = false;
  }
  if (elem == document) {
    s = [Math.max(
        de.clientWidth,
        bodyNode.scrollWidth, de.scrollWidth,
        bodyNode.offsetWidth, de.offsetWidth
      ), Math.max(
        de.clientHeight,
        bodyNode.scrollHeight, de.scrollHeight,
        bodyNode.offsetHeight, de.offsetHeight
      )];
  } else if (elem){
    function getWH() {
      if (boundingRectEnabled(elem) && (rect = getXYRect(elem, notBounding)) && rect.width !== undefined) {
        s = [rect.width, rect.height];
      } else {
        s = [elem.offsetWidth, elem.offsetHeight];
      }
      if (!withoutBounds) return;
      var padding = 0, border = 0;
      each(s, function(i, v) {
        var which = i ? ['Top', 'Bottom'] : ['Left', 'Right'];
        each(which, function(){
          s[i] -= parseFloat(getStyle(elem, 'padding' + this)) || 0;
          s[i] -= parseFloat(getStyle(elem, 'border' + this + 'Width')) || 0;
        });
      });
    }
    if (!isVisible(elem)) {
      var props = {position: 'absolute', visibility: 'hidden', display: 'block'};
      var old = {}, old_cssText = false;
      if (elem.style.cssText.indexOf('!important') > -1) {
        old_cssText = elem.style.cssText;
      }
      each(props, function(i, v) {
        old[i] = elem.style[i];
        elem.style[i] = v;
      });
      getWH();
      each(props, function(i, v) {
        elem.style[i] = old[i];
      });
      if (old_cssText) {
        elem.style.cssText = old_cssText;
      }
    } else getWH();

  }
  return s;
}

function getW(el) {
  return getSize(el)[0];
}

function getH(el) {
  return getSize(el)[1];
}

function ge(el) {
  return (typeof el == 'string' || typeof el == 'number') ? document.getElementById(el) : el;
}

function getStyle(elem, name, force) {
  elem = ge(elem);
  if (isArray(name)) { var res = {}; each(name, function(i,v){res[v] = getStyle(elem, v);}); return res; }
  if (!elem) return '';
  if (force === undefined) {
    force = true;
  }
  if (!force && name == 'opacity' && browser.msie) {
    var filter = elem.style['filter'];
    return filter ? (filter.indexOf('opacity=') >= 0 ?
      (parseFloat(filter.match(/opacity=([^)]*)/)[1] ) / 100) + '' : '1') : '';
  }
  if (!force && elem.style && (elem.style[name] || name == 'height')) {
    return elem.style[name];
  }

  var ret, defaultView = document.defaultView || window;
  if (defaultView.getComputedStyle) {
    name = name.replace(/([A-Z])/g, '-$1').toLowerCase();
    var computedStyle = defaultView.getComputedStyle(elem, null);
    if (computedStyle) {
      ret = computedStyle.getPropertyValue(name);
    }
  } else if (elem.currentStyle) {
    if (name == 'opacity' && browser.msie) {
      var filter = elem.currentStyle['filter'];
      return filter && filter.indexOf('opacity=') >= 0 ?
        (parseFloat(filter.match(/opacity=([^)]*)/)[1]) / 100) + '' : '1';
    }
    var camelCase = name.replace(/\-(\w)/g, function(all, letter){
      return letter.toUpperCase();
    });
    ret = elem.currentStyle[name] || elem.currentStyle[camelCase];
    //dummy fix for ie
    if (ret == 'auto') {
      ret = 0;
    }

    ret = (ret + '').split(' ');
    each(ret, function(i,v) {
      if (!/^\d+(px)?$/i.test(v) && /^\d/.test(v)) {
        var style = elem.style, left = style.left, rsLeft = elem.runtimeStyle.left;
        elem.runtimeStyle.left = elem.currentStyle.left;
        style.left = v || 0;
        ret[i] = style.pixelLeft + 'px';
        style.left = left;
        elem.runtimeStyle.left = rsLeft;
      }
    });
    ret = ret.join(' ');
  }

  if (force && (name == 'width' || name == 'height')) {
    var ret2 = getSize(elem, true)[({'width': 0, 'height': 1})[name]];
    ret = (intval(ret) ? Math.max(floatval(ret), ret2) : ret2) + 'px';
  }

  return ret;
}