Fix iOS Orientation Change Zoom Bug

fixorientationzoom.js

/*




NOTE!!!!

The most updated version of this code is here:

https://github.com/scottjehl/iOS-Orientationchange-Fix











 A fix for the dreaded iOS orientationchange zoom bug http://adactio.com/journal/5088/. Seems to work!
 Authored by @scottjehl. Props to @wilto for addressing a tilt caveat.
 MIT License.

FOR LATEST, SEE https://github.com/scottjehl/iOS-Orientationchange-Fix
*/

(function(w){
    var doc = w.document;

    if( !doc.querySelectorAll ){ return; }

    var meta = doc.querySelectorAll( "meta[name=viewport]" )[ 0 ],
        initialContent = meta && meta.getAttribute( "content" ),
        disabledZoom = initialContent + ", maximum-scale=1.0",
        enabledZoom = initialContent + ", maximum-scale=10.0",
        enabled = true,
        orientation = w.orientation,
        rotation = 0;

    if( !meta ){ return; }

    function restoreZoom(){
        meta.setAttribute( "content", enabledZoom );
        document.body.innerHTML = document.body.innerHTML;
        enabled = true;
    }

    function disableZoom(){
        meta.setAttribute( "content", disabledZoom );
        enabled = false;
    }

    function checkTilt( e ){
        orientation = Math.abs( w.orientation );
        rotation = Math.abs( e.gamma );

        if( rotation > 8 && orientation === 0 ){
            if( enabled ){
                disableZoom();
            }   
        }
        else {
            if( !enabled ){
                restoreZoom();
            }
        }

    }

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

})( this );

interesting. I'm not sure about setting width to device height… that doesn't seem quite what we'd usually want or expect, and introducing a css3 transform may bring undesirable results to the layout. Hmm. Not sure. Cool idea. I guess I'll need to think about it more. FWIW, the approach above has been improved since this gist and is now using devicemotion instead of orientation (which brings wider iOS support). It's close to "bulletproof" with fast flips and different tilts too. We included the latest (modified a bit) in jQuery Mobile. https://github.com/scottjehl/iOS-Orientationchange-Fix

…

On Feb 28, 2012, at 4:27 PM, Sérgio Lopes wrote: I'm proposing another solution that aims to fix the issues people found in this one. It's a highly different approach (no gesture/accelerometer hacking). https://github.com/sergiolopes/ios-zoom-bug-fix --- Reply to this email directly or view it on GitHub: https://gist.github.com/1568180

@scottjehl Hi Scott! Thanks for your feedback on my approach!

The CSS3 transform doesn't impact the layout, it just scales the entire page with the original layout unchanged. And setting width to device-height mean we have to scale up content when in portrait mode. I have an alternate version of the script that works with device-width and in this case we have to scale down in landscape mode. Working with scale up is a lot easier than with scale down, but maybe I could publish the other version too and let people choose.

And I knew about your new project and its evolutions. Using devicemotion seems much better than deviceorientation! I still have some issues with it, specially when quickly rotating my iPad (couldn't reproduce on my old iPod Touch 2nd gen; its hardware is so slow that a fast rotation doesn't affect the script :)