jquery/src/offset.js

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// The Offset Method
// Originally By Brandon Aaron, part of the Dimension Plugin
// http://jquery.com/plugins/project/dimensions
jQuery.fn.offset = function() {
var left = 0, top = 0, elem = this[0], results;
if ( elem ) with ( jQuery.browser ) {
var parent = elem.parentNode,
offsetChild = elem,
offsetParent = elem.offsetParent,
doc = elem.ownerDocument,
safari2 = safari && parseInt(version) < 522 && !/adobeair/i.test(userAgent),
css = jQuery.curCSS,
fixed = css(elem, "position") == "fixed";
// Use getBoundingClientRect if available
if ( !(mozilla && elem == document.body) && elem.getBoundingClientRect ) {
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var box = elem.getBoundingClientRect();
// Add the document scroll offsets
add(box.left + Math.max(doc.documentElement.scrollLeft, doc.body.scrollLeft),
box.top + Math.max(doc.documentElement.scrollTop, doc.body.scrollTop));
// IE adds the HTML element's border, by default it is medium which is 2px
// IE 6 and 7 quirks mode the border width is overwritable by the following css html { border: 0; }
// IE 7 standards mode, the border is always 2px
// This border/offset is typically represented by the clientLeft and clientTop properties
// However, in IE6 and 7 quirks mode the clientLeft and clientTop properties are not updated when overwriting it via CSS
// Therefore this method will be off by 2px in IE while in quirksmode
add( -doc.documentElement.clientLeft, -doc.documentElement.clientTop );
// Otherwise loop through the offsetParents and parentNodes
} else {
// Initial element offsets
add( elem.offsetLeft, elem.offsetTop );
// Get parent offsets
while ( offsetParent ) {
// Add offsetParent offsets
add( offsetParent.offsetLeft, offsetParent.offsetTop );
// Mozilla and Safari > 2 does not include the border on offset parents
// However Mozilla adds the border for table or table cells
if ( mozilla && !/^t(able|d|h)$/i.test(offsetParent.tagName) || safari && !safari2 )
border( offsetParent );
// Add the document scroll offsets if position is fixed on any offsetParent
if ( !fixed && css(offsetParent, "position") == "fixed" )
fixed = true;
// Set offsetChild to previous offsetParent unless it is the body element
offsetChild = /^body$/i.test(offsetParent.tagName) ? offsetChild : offsetParent;
// Get next offsetParent
offsetParent = offsetParent.offsetParent;
}
// Get parent scroll offsets
while ( parent && parent.tagName && !/^body|html$/i.test(parent.tagName) ) {
// Remove parent scroll UNLESS that parent is inline or a table to work around Opera inline/table scrollLeft/Top bug
if ( !/^inline|table.*$/i.test(css(parent, "display")) )
// Subtract parent scroll offsets
add( -parent.scrollLeft, -parent.scrollTop );
// Mozilla does not add the border for a parent that has overflow != visible
if ( mozilla && css(parent, "overflow") != "visible" )
border( parent );
// Get next parent
parent = parent.parentNode;
}
// Safari <= 2 doubles body offsets with a fixed position element/offsetParent or absolutely positioned offsetChild
// Mozilla doubles body offsets with a non-absolutely positioned offsetChild
if ( (safari2 && (fixed || css(offsetChild, "position") == "absolute")) ||
(mozilla && css(offsetChild, "position") != "absolute") )
add( -doc.body.offsetLeft, -doc.body.offsetTop );
// Add the document scroll offsets if position is fixed
if ( fixed )
add(Math.max(doc.documentElement.scrollLeft, doc.body.scrollLeft),
Math.max(doc.documentElement.scrollTop, doc.body.scrollTop));
}
// Return an object with top and left properties
results = { top: top, left: left };
}
function border(elem) {
add( jQuery.curCSS(elem, "borderLeftWidth", true), jQuery.curCSS(elem, "borderTopWidth", true) );
}
function add(l, t) {
left += parseInt(l, 10) || 0;
top += parseInt(t, 10) || 0;
}
return results;
};
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jQuery.fn.extend({
position: function() {
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var left = 0, top = 0, results;
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if ( this[0] ) {
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// Get *real* offsetParent
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var offsetParent = this.offsetParent(),
// Get correct offsets
offset = this.offset(),
parentOffset = /^body|html$/i.test(offsetParent[0].tagName) ? { top: 0, left: 0 } : offsetParent.offset();
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// Subtract element margins
// note: when an element has margin: auto the offsetLeft and marginLeft
// are the same in Safari causing offset.left to incorrectly be 0
offset.top -= num( this, 'marginTop' );
offset.left -= num( this, 'marginLeft' );
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// Add offsetParent borders
parentOffset.top += num( offsetParent, 'borderTopWidth' );
parentOffset.left += num( offsetParent, 'borderLeftWidth' );
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// Subtract the two offsets
results = {
top: offset.top - parentOffset.top,
left: offset.left - parentOffset.left
};
}
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return results;
},
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offsetParent: function() {
var offsetParent = this[0].offsetParent || document.body;
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while ( offsetParent && (!/^body|html$/i.test(offsetParent.tagName) && jQuery.css(offsetParent, 'position') == 'static') )
offsetParent = offsetParent.offsetParent;
return jQuery(offsetParent);
}
});
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// Create scrollLeft and scrollTop methods
jQuery.each( ['Left', 'Top'], function(i, name) {
var method = 'scroll' + name;
jQuery.fn[ method ] = function(val) {
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if (!this[0]) return;
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return val != undefined ?
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// Set the scroll offset
this.each(function() {
this == window || this == document ?
window.scrollTo(
!i ? val : jQuery(window).scrollLeft(),
i ? val : jQuery(window).scrollTop()
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) :
this[ method ] = val;
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}) :
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// Return the scroll offset
this[0] == window || this[0] == document ?
self[ i ? 'pageYOffset' : 'pageXOffset' ] ||
jQuery.boxModel && document.documentElement[ method ] ||
document.body[ method ] :
this[0][ method ];
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};
});