79 lines
3.5 KiB
JavaScript
79 lines
3.5 KiB
JavaScript
(function($){
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/**
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* Copyright 2012, Digital Fusion
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* Licensed under the MIT license.
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* http://teamdf.com/jquery-plugins/license/
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*
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* @author Sam Sehnert
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* @desc A small plugin that checks whether elements are within
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* the user visible viewport of a web browser.
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* only accounts for vertical position, not horizontal.
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*/
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$.fn.visible = function(partial,hidden,direction,container){
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if (this.length < 1)
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return;
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var $t = this.length > 1 ? this.eq(0) : this,
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isContained = typeof container !== 'undefined' && container !== null,
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$w = isContained ? $(container) : $(window),
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wPosition = isContained ? $w.position() : 0,
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t = $t.get(0),
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vpWidth = $w.outerWidth(),
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vpHeight = $w.outerHeight(),
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direction = (direction) ? direction : 'both',
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clientSize = hidden === true ? t.offsetWidth * t.offsetHeight : true;
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if (typeof t.getBoundingClientRect === 'function'){
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// Use this native browser method, if available.
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var rec = t.getBoundingClientRect(),
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tViz = isContained ?
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rec.top - wPosition.top >= 0 && rec.top < vpHeight + wPosition.top :
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rec.top >= 0 && rec.top < vpHeight,
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bViz = isContained ?
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rec.bottom - wPosition.top > 0 && rec.bottom <= vpHeight + wPosition.top :
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rec.bottom > 0 && rec.bottom <= vpHeight,
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lViz = isContained ?
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rec.left - wPosition.left >= 0 && rec.left < vpWidth + wPosition.left :
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rec.left >= 0 && rec.left < vpWidth,
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rViz = isContained ?
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rec.right - wPosition.left > 0 && rec.right < vpWidth + wPosition.left :
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rec.right > 0 && rec.right <= vpWidth,
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vVisible = partial ? tViz || bViz : tViz && bViz,
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hVisible = partial ? lViz || rViz : lViz && rViz;
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if(direction === 'both')
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return clientSize && vVisible && hVisible;
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else if(direction === 'vertical')
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return clientSize && vVisible;
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else if(direction === 'horizontal')
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return clientSize && hVisible;
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} else {
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var viewTop = isContained ? 0 : wPosition,
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viewBottom = viewTop + vpHeight,
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viewLeft = $w.scrollLeft(),
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viewRight = viewLeft + vpWidth,
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position = $t.position(),
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_top = position.top,
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_bottom = _top + $t.height(),
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_left = position.left,
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_right = _left + $t.width(),
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compareTop = partial === true ? _bottom : _top,
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compareBottom = partial === true ? _top : _bottom,
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compareLeft = partial === true ? _right : _left,
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compareRight = partial === true ? _left : _right;
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if(direction === 'both')
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return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop)) && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
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else if(direction === 'vertical')
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return !!clientSize && ((compareBottom <= viewBottom) && (compareTop >= viewTop));
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else if(direction === 'horizontal')
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return !!clientSize && ((compareRight <= viewRight) && (compareLeft >= viewLeft));
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}
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};
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})(jQuery);
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