offset.js

/* WIP */

var Position = {
tests: {},

basicOffsetTests = function() {
  var result = Position.tests;

  result.CLIENT_TOP_SUPPORTED = 'clientTop' in Fuse._docEl;
  result.TABLE_TAG = return /^h/.test(Fuse._docEl.tagName) ? "table" : "TABLE";

  Position.basicOffsetTests = emptyFunction;
},

offsetTests = function offsetTests(req) {
 
  var body = Fuse._body,
   result = Position.tests;
 
  result.ran = true;
 
  if (!body) return;
 
  var marginTop = "marginTop", position = "position", padding = "padding",
    stat = "static",
    border = "border", s = body.style,
    bv = '1px solid transparent',
    z = "0",
    one = "1px",
    offsetTop = "offsetTop",
    ds = Fuse._docEl.style,
    x = Fuse._doc.createElement('div'),
    xs = x.style,
    table = Fuse._doc.createElement(result.TABLE_TAG),
    bodyBackup = {padding: s.padding, marginTop: s.marginTop,
      'top': s.top, border: s.border, position: s.position},
    docBackup = {padding: ds.padding, marginTop: ds.marginTop,
      position: ds.position};
 
  table.cellSpacing = table.cellPadding = xs.margin =
    s[padding] = s[marginTop] = s.top = z;
  s[border] = bv;
 
  ds.position = stat;
 
  // Table test (relies on td not defaulting to 7px)
  table.innerHTML = "<tbody><tr><td>x</td></tr></tbody>";
  table.style[border] = "7px solid";
 
  body.insertBefore(table, body.firstChild);
  result.IS_TABLE_BORDER_INCLUDED_IN_TD_OFFSET =
    table.getElementsByTagName("td")[0].offsetLeft === 7;
 
  body.removeChild(table);
 
  // Relies on marginTop of 0
  s.top = one;
  result.IS_BODY_TOP_INHERITED = x[offsetTop] === 1;
 
  // Now add margin to determine if body offsetTop is inherited.
  s.top = z;
  s[marginTop] = one;
  s[position] = relative;
  result.IS_BODY_MARGIN_INHERITED = (x[offsetTop] === 1);
  result.IS_BODY_OFFSET_EXCLUDING_MARGIN = body[offsetTop] === 0;
  result.IS_BODY_OFFSET_IGNORED_WHEN_BODY_RELATIVE_AND_LAST_CHILD_POSITIONED = x[offsetTop] === 0;
 
  //IS_BODY_OFFSET_TOP_NO_OFFSETPARENT = body.offsetTop && !body.offsetParent;
 
  xs[position] = "absolute";
  s[position] = stat;
   if(x.offsetParent === body) {
    xs.top = "2px";
    // XXX Safari gets offsetParent wrong (says 'body' when body is static,
    // but then positions element from ICB and then subtracts body's clientWidth.
    // Safari is half wrong.
    //
    // XXX Mozilla says body is offsetParent but does NOT subtract EL's offsetLeft/Top.
    // Mozilla is completely wrong.
    result.IS_STATIC_BODY_OFFSET_PARENT_BUT_ABSOLUTE_CHILD_SUBTRACTS_BODY_BORDER_WIDTH = x[offsetTop] === 1;
    s[border] = z;
 
    xs[position] = relative;
    ds[padding] = one;
    s[marginTop] = z;
 
    result.IS_CONTAINER_BODY_STATIC_INCLUDING_HTML_PADDING = x[offsetTop] === 3;
 
    // Opera does not respect position: relative on BODY.
    s[position] = relative;
    result.IS_CONTAINER_BODY_RELATIVE_INCLUDING_HTML_PADDING_REL_CHILD = x[offsetTop] === 3;
 
    xs[position] = "absolute";
    result.IS_CONTAINER_BODY_RELATIVE_INCLUDING_HTML_PADDING_ABS_CHILD = x[offsetTop] === 3;
 
    // Opera inherits HTML margin when body is relative and child is relative or absolute.
    ds[padding] = z;
    ds[marginTop] = one;
    result.IS_CONTAINER_BODY_INCLUDING_HTML_MARGIN = x[offsetTop] === 3;
  }
 
  // xs.position = "fixed";
  // FIXED_HAS_OFFSETPARENT = x.offsetParent != null;
 
  body.removeChild(x);
  Fuse.Element.Methods(body).setStyle(bodyBackup);
  Fuse.Element.Methods(ds).setStyle(docBackup);
}
 
};

Position.toFloat = function toFloat(val) { return parseFloat(val) || 0 };

if (Feature('ELEMENT_BOUNDING_CLIENT_RECT')) {
  Position.getOffsets = function getOffsets(el, container) {
    if (!el || !el.ownerDocument) { return null }
    Position.basicOffsetTests();

    var toFloat = Position.toFloat
     doc        = el.ownerDocument,
     docEl      = doc.documentElement,
     body       = doc.body,
     tests      = Position.tests,
     box        = el.getBoundingClientRect(),
     rootEl     = Bug('BODY_ACTING_AS_ROOT') ? body : docEl,
     clientTop  = rootEl.clientTop || 0,
     clientLeft = rootEl.clientLeft || 0,
     x = box.left + max(docEl.scrollLeft, body.scrollLeft),
     y = box.top + max(docEl.scrollTop, body.scrollTop),
     bodyCurStyle;

     container = container || doc;

    if (tests.CLIENT_TOP_SUPPORTED) {
      x -= clientTop;
      y -= clientLeft;
    }

    if (container !== doc) {
      box = Position.getOffsets(container, null);
      x -= box.x;
      y -= box.y;
      if (Bug('BODY_ACTING_AS_ROOT') &&
          container === body &&
          tests.CLIENT_TOP_SUPPORTED) {
        x -= borderLeft;
        y -= borderTop;
      }
      else if (Bug('BODY_ACTING_AS_ROOT') &&
          Feature('ELEMENT_CURRENT_STYLE') &&
          container !== body) {
        bodyCurStyle = body.currentStyle;
        x += toFloat(bodyCurStyle.marginLeft) + toFloat(bodyCurStyle.left);
        y += toFloat(bodyCurStyle.marginTop) + toFloat(bodyCurStyle.top);
      }
    }

    return {left: x, top: y};
  };
}
else {
  Position.getOffsets = function getOffsets(el, container, coords) {
    if (!el || !el.ownerDocument) { return null }
    Position.offsetTests();

    var toFloat = Position.toFloat
     doc        = el.ownerDocument,
     docEl      = doc.documentElement,
     body       = doc.body,
     tests      = Position.tests;

    container = container || doc;
    if (!coords) coords = {};
    else coords = {left: toFloat(coords.left), top: toFloat(coords.left)};
 
    if (el === container)
      return (coords.x = coords.y = 0) && coords;
 
  // Crawling up the tree.
    if (Feature('ELEMENT_COMPUTED_STYLE')) {
 
      var offsetLeft = el.offsetLeft,
        offsetTop = el.offsetTop,
        defaultView = doc.defaultView,
        cs = defaultView.getComputedStyle(el, '');
      if (cs.position == "fixed") {
        coords.x = offsetLeft + documentElement.scrollLeft;
        coords.y = offsetTop + documentElement.scrollTop;
        return coords;
      }
      var bcs = defaultView.getComputedStyle(body,''),
        isBodyStatic = !positionedExp.test(bcs.position),
        lastOffsetParent = el,
        parent = el.parentNode,
        offsetParent = el.offsetParent;
 
    // Main loop -----------------------------------------------------------------------
      // Loop up, gathering scroll offsets on parentNodes.
      // when we get to a parent that's an offsetParent, update
      // the current offsetParent marker.
      for( ; parent && parent !== container; parent = parent.parentNode) {
        if (parent !== body && parent !== documentElement) {
          offsetLeft -= parent.scrollLeft;
          offsetTop -= parent.scrollTop;
        }
        if (parent === offsetParent) {
          // If we get to BODY and have static position, skip it.
          if (parent === body && isBodyStatic);
          else {
 
            // XXX Mozilla; Exclude static body; if static, it's offsetTop will be wrong.
            // Include parent border widths. This matches behavior of clientRect approach.
            // XXX Opera <= 9.2 includes parent border widths.
            // See Bug('BODY_OFFSETS_INHERIT_ITS_MARGINS') below.
            if ( !Bug('BODY_OFFSETS_INHERIT_ITS_MARGINS') &&
              ! (parent.tagName === tests.TABLE_TAG && tests.IS_TABLE_BORDER_INCLUDED_IN_TD_OFFSET)) {
                var pcs = defaultView.getComputedStyle(parent, "");
                // Mozilla doesn't support clientTop. Add borderWidth to the sum.
                offsetLeft += parseFloat(pcs[borderLeftWidth]) || 0;
                offsetTop += parseFloat(pcs[borderTopWidth]) || 0;
            }
            if (parent !== body) {
              offsetLeft += offsetParent.offsetLeft;
              offsetTop += offsetParent.offsetTop;
              lastOffsetParent = offsetParent;
              offsetParent = parent.offsetParent; // next marker to check for offsetParent.
            }
          }
        }
      }
 
      //--------Post - loop, body adjustments----------------------------------------------
      // Complications due to CSSOM Views - the browsers try to implement a contradictory
      // spec: http://www.w3.org/TR/cssom-view/#offset-attributes
 
      // XXX Mozilla, Safari 3, Opera: body margin is never
      // included in body offsetLeft/offsetTop.
      // This is wrong. Body's offsetTop should work like any other element.
      // In Safari 2.0.4, BODY can have offsetParent, and even
      // if it doesn't, it can still have offsetTop.
      // But Safari 2.0.4 doubles offsetTop for relatively positioned elements
      // and this script does not account for that.
 
      // XXX Mozilla: When body has a border, body's offsetTop === negative borderWidth;
      // Don't use body.offsetTop.
      var bodyOffsetLeft = 0,
        bodyOffsetTop = 0,
        isLastElementAbsolute,
        isLastOffsetElementPositioned,
        isContainerDocOrDocEl = container === doc || container === documentElement,
        dcs,
        lastOffsetPosition;
 
      // If the lastOffsetParent is document,
      // it is not positioned (and hence, not absolute).
      if (lastOffsetParent != doc) {
        lastOffsetPosition = defaultView.getComputedStyle(lastOffsetParent,'').position;
        isLastElementAbsolute = absoluteExp.test(lastOffsetPosition);
        isLastOffsetElementPositioned = isLastElementAbsolute ||
          positionedExp.test(lastOffsetPosition);
      }
 
      // do we need to add margin?
      if (
        (lastOffsetParent === el && el.offsetParent === body && !tests.IS_BODY_MARGIN_INHERITED
        && container !== body && !(isBodyStatic && tests.IS_BODY_OFFSET_EXCLUDING_MARGIN))
        || (tests.IS_BODY_MARGIN_INHERITED && lastOffsetParent === el && !isLastOffsetElementPositioned)
        || !isBodyStatic
        && isLastOffsetElementPositioned
        && tests.IS_BODY_OFFSET_IGNORED_WHEN_BODY_RELATIVE_AND_LAST_CHILD_POSITIONED
        && isContainerDocOrDocEl) {
          bodyOffsetTop += parseFloat(bcs.marginTop) || 0;
          bodyOffsetLeft += parseFloat(bcs.marginLeft) || 0;
      }
 
      // Case for padding on documentElement.
      if (container === body) {
        dcs = defaultView.getComputedStyle(documentElement,'');
        if (
          (!isBodyStatic &&
            ((tests.IS_CONTAINER_BODY_RELATIVE_INCLUDING_HTML_PADDING_REL_CHILD && !isLastElementAbsolute)
            ||
            (tests.IS_CONTAINER_BODY_RELATIVE_INCLUDING_HTML_PADDING_ABS_CHILD && isLastElementAbsolute))
          )
          || isBodyStatic && tests.IS_CONTAINER_BODY_STATIC_INCLUDING_HTML_PADDING
          ) {
          bodyOffsetTop -= parseFloat(dcs.paddingTop) || 0;
          bodyOffsetLeft -= parseFloat(dcs.paddingLeft) || 0;
        }
 
        if (tests.IS_CONTAINER_BODY_INCLUDING_HTML_MARGIN){
          if (!isLastOffsetElementPositioned
            || isLastOffsetElementPositioned && !isBodyStatic)
          bodyOffsetTop -= parseFloat(dcs.marginTop) || 0;
          bodyOffsetLeft -= parseFloat(dcs.marginLeft) || 0;
        }
      }
      if (isBodyStatic) {
        // XXX Safari subtracts border width of body from element's offsetTop (opera does it, too)
        if (tests.IS_STATIC_BODY_OFFSET_PARENT_BUT_ABSOLUTE_CHILD_SUBTRACTS_BODY_BORDER_WIDTH
        // XXX: Safari will use HTML for containing block (CSS),
        // but will subtract the body's border from the body's absolutely positioned
        // child.offsetTop. Safari reports the child's offsetParent is BODY, but
        // doesn't treat it that way (Safari bug).
          || (!isLastElementAbsolute && !Bug('BODY_OFFSETS_INHERIT_ITS_MARGINS')
            && isContainerDocOrDocEl)) {
               bodyOffsetTop += parseFloat(bcs[borderTopWidth]);
               bodyOffsetLeft += parseFloat(bcs[borderLeftWidth]);
        }
      }
 
      // body is positioned, and if it excludes margin,
      // it's probably partly using the AVK-CSSOM disaster.
      else if (tests.IS_BODY_OFFSET_EXCLUDING_MARGIN) {
        if (isContainerDocOrDocEl) {
          if (!tests.IS_BODY_TOP_INHERITED) {
 
            // If the body is positioned, add its left and top value.
             bodyOffsetTop += parseFloat(bcs.top) || 0;
             bodyOffsetLeft += parseFloat(bcs.left) || 0;
 
            // XXX: Opera normally include the parentBorder in offsetTop.
            // We have a preventative measure in the loop above.
            if (isLastElementAbsolute && Bug('BODY_OFFSETS_INHERIT_ITS_MARGINS')) {
              bodyOffsetTop += parseFloat(bcs[borderTopWidth]);
              bodyOffsetLeft += parseFloat(bcs[borderLeftWidth]);
            }
          }
 
          // Padding on documentElement is not included,
          // but in this case, we're searching to documentElement, so we
          // have to add it back in.
          if (container === doc && !isBodyStatic
            && !tests.IS_CONTAINER_BODY_RELATIVE_INCLUDING_HTML_PADDING_REL_CHILD) {
            if (!dcs) dcs = defaultView.getComputedStyle(documentElement,'');
            bodyOffsetTop += parseFloat(dcs.paddingTop) || 0;
            bodyOffsetLeft += parseFloat(dcs.paddingLeft) || 0;
          }
        }
        else if (tests.IS_BODY_TOP_INHERITED) {
          bodyOffsetTop -= parseFloat(bcs.top);
          bodyOffsetLeft -= parseFloat(bcs.left);
        }
        if (tests.IS_BODY_MARGIN_INHERITED && (!isLastOffsetElementPositioned || container === body)) {
          bodyOffsetTop -= parseFloat(bcs.marginTop) || 0;
          bodyOffsetLeft -= parseFloat(bcs.marginLeft) || 0;
        }
      }
      coords.x = round(offsetLeft + bodyOffsetLeft);
      coords.y = round(offsetTop + bodyOffsetTop);
 
      return coords;
    }
  };
}