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/*! A fix for the iOS orientationchange zoom bug.

 Script by @scottjehl, rebound by @wilto.

 MIT / GPLv2 License.

*/

(function(w){

        // This fix addresses an iOS bug, so return early if the UA claims it's something else.

        var ua = navigator.userAgent;

        if( !( /iPhone|iPad|iPod/.test( navigator.platform ) && /OS [1-5]_[0-9_]* like Mac OS X/i.test(ua) && ua.indexOf( "AppleWebKit" ) > -1 ) ){

                return;

        }

    var doc = w.document;

    if( !doc.querySelector ){ return; }

    var meta = doc.querySelector( "meta[name=viewport]" ),

        initialContent = meta && meta.getAttribute( "content" ),

        disabledZoom = initialContent + ",maximum-scale=1",

        enabledZoom = initialContent + ",maximum-scale=10",

        enabled = true,

                x, y, z, aig;

    if( !meta ){ return; }

    function restoreZoom(){

        meta.setAttribute( "content", enabledZoom );

        enabled = true;

    }

    function disableZoom(){

        meta.setAttribute( "content", disabledZoom );

        enabled = false;

    }

    function checkTilt( e ){

                aig = e.accelerationIncludingGravity;

                x = Math.abs( aig.x );

                y = Math.abs( aig.y );

                z = Math.abs( aig.z );

                // If portrait orientation and in one of the danger zones

        if( (!w.orientation || w.orientation === 180) && ( x > 7 || ( ( z > 6 && y < 8 || z < 8 && y > 6 ) && x > 5 ) ) ){

                        if( enabled ){

                                disableZoom();

                        }

        }

                else if( !enabled ){

                        restoreZoom();

        }

    }

        w.addEventListener( "orientationchange", restoreZoom, false );

        w.addEventListener( "devicemotion", checkTilt, false );

})( this );