[javascript] Blocking device rotation on mobile web pages

Is it possible to detect on my page, for example using Javascript, when user visit it using mobile device in portrait mode, and stop orientation changing when user rotate its phone to landscape? There is game on my page, optimized for portrait display only and I don't want it in landscape.

You can detect the orientation change, but I don't think you can prevent it.

• https://developer.apple.com/library/content/documentation/AppleApplications/Reference/SafariWebContent/HandlingEvents/HandlingEvents.html
• http://articles.sitepoint.com/article/iphone-development-12-tips/2

With the new CSS3 features, you could rotate the page the opposite orientation that they rotated. Sorry, no IE7- support. :(.

var rotate = 0 - window.orientation;
setAttribute("transform:rotate("+rotate+"deg);-ms-transform:rotate("+rotate+"deg);-webkit-transform:rotate("+rotate+"deg)", "style");

New API's are developing (and are currently available)!

screen.orientation.lock();   // webkit only

and

screen.lockOrientation("orientation");

Where "orientation" can be any of the following:

portrait-primary - It represents the orientation of the screen when it is in its primary portrait mode. A screen is considered in its primary portrait mode if the device is held in its normal position and that position is in portrait, or if the normal position of the device is in landscape and the device held turned by 90° clockwise. The normal position is device dependant.

portrait-secondary - It represents the orientation of the screen when it is in its secondary portrait mode. A screen is considered in its secondary portrait mode if the device is held 180° from its normal position and that position is in portrait, or if the normal position of the device is in landscape and the device held is turned by 90° anticlockwise. The normal position is device dependant.

landscape-primary - It represents the orientation of the screen when it is in its primary landscape mode. A screen is considered in its primary landscape mode if the device is held in its normal position and that position is in landscape, or if the normal position of the device is in portrait and the device held is turned by 90° clockwise. The normal position is device dependant.

landscape-secondary - It represents the orientation of the screen when it is in its secondary landscape mode. A screen is considered in its secondary landscape mode if the device held is 180° from its normal position and that position is in landscape, or if the normal position of the device is in portrait and the device held is turned by 90° anticlockwise. The normal position is device dependant.

portrait - It represents both portrait-primary and portrait-secondary.

landscape - It represents both landscape-primary and landscape-secondary.

default - It represents either portrait-primary and landscape-primary depends on natural orientation of devices. For example, if the panel resolution is 1280*800, default will make it landscape, if the resolution is 800*1280, default will make it to portrait.

Mozilla recommends adding a lockOrientationUniversal to screen to make it more cross-browser compatible.

screen.lockOrientationUniversal = screen.lockOrientation || screen.mozLockOrientation || screen.msLockOrientation;

Go here for more info: https://developer.mozilla.org/en-US/docs/Web/API/Screen/lockOrientation

In JavaScript-enabled browsers it should be easy to determine if the screen is in landscape or portrait mode and compensate using CSS. It may be helpful to give users the option to disable this or at least warn them that device rotation will not work properly.

Edit

The easiest way to detect the orientation of the browser is to check the width of the browser versus the height of the browser. This also has the advantage that you'll know if the game is being played on a device that is naturally oriented in landscape mode (as some mobile devices like the PSP are). This makes more sense than trying to disable device rotation.

Edit 2

Daz has shown how you can detect device orientation, but detecting orientation is only half of the solution. If want to reverse the automatic orientation change, you'll need to rotate everything either 90° or 270°/-90°, e.g.

$(window).bind('orientationchange resize', function(event){
  if (event.orientation) {
    if (event.orientation == 'landscape') {
      if (window.rotation == 90) {
        rotate(this, -90);
      } else {
        rotate(this, 90);
      }
    }
  }
});

function rotate(el, degs) {
  iedegs = degs/90;
  if (iedegs < 0) iedegs += 4;
  transform = 'rotate('+degs+'deg)';
  iefilter = 'progid:DXImageTransform.Microsoft.BasicImage(rotation='+iedegs+')';
  styles = {
    transform: transform,
    '-webkit-transform': transform,
    '-moz-transform': transform,
    '-o-transform': transform,
    filter: iefilter,
    '-ms-filter': iefilter
  };
  $(el).css(styles);
}

Note: if you want to rotate in IE by an arbitrary angle (for other purposes), you'll need to use matrix transform, e.g.

rads = degs * Math.PI / 180;
m11 = m22 = Math.cos(rads);
m21 = Math.sin(rads);
m12 = -m21;
iefilter = "progid:DXImageTransform.Microsoft.Matrix("
  + "M11 = " + m11 + ", "
  + "M12 = " + m12 + ", "
  + "M21 = " + m21 + ", "
  + "M22 = " + m22 + ", sizingMethod = 'auto expand')";
styles['filter'] = styles['-ms-filter'] = iefilter;

—or use CSS Sandpaper. Also, this applies the rotation style to the window object, which I've never actually tested and don't know if works or not. You may need to apply the style to a document element instead.

Anyway, I would still recommend simply displaying a message that asks the user to play the game in portrait mode.

Simple Javascript code to make mobile browser display either in portrait or landscape..

(Even though you have to enter html code twice in the two DIVs (one for each mode), arguably this will load faster than using javascript to change the stylesheet...

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Mobile Device</title>
<script type="text/javascript">
// Detect whether device supports orientationchange event, otherwise fall back to
// the resize event.
var supportsOrientationChange = "onorientationchange" in window,
    orientationEvent = supportsOrientationChange ? "orientationchange" : "resize";

window.addEventListener(orientationEvent, function() {
    if(window.orientation==0)
    {
      document.getElementById('portrait').style.display = '';
      document.getElementById('landscape').style.display = 'none';
    }
    else if(window.orientation==90)
    {
      document.getElementById('portrait').style.display = 'none';
      document.getElementById('landscape').style.display = '';
    }
}, false);
</script>
<meta name="HandheldFriendly" content="true" />
<meta name="viewport" content="width=device-width, height=device-height, user-scalable=no" />
</head>
<body>
<div id="portrait" style="width:100%;height:100%;font-size:20px;">Portrait</div>
<div id="landscape" style="width:100%;height:100%;font-size:20px;">Landscape</div>

<script type="text/javascript">
if(window.orientation==0)
{
  document.getElementById('portrait').style.display = '';
  document.getElementById('landscape').style.display = 'none';
}
else if(window.orientation==90)
{
  document.getElementById('portrait').style.display = 'none';
  document.getElementById('landscape').style.display = '';
}
</script>
</body>
</html>

Tested and works on Android HTC Sense and Apple iPad.

You could use the screenSize.width and screenSize.height properties and detect when the width > height and then handle that situation, either by letting the user know or by adjusting your screen accordingly.

But the best solution is what @Doozer1979 says... Why would you override what the user prefers?

seems weird that no one proposed the CSS media query solution:

@media screen and (orientation: portrait) {
  ...
}

and the option to use a specific style sheet:

<link rel="stylesheet" type="text/css" href="css/style_p.css" media="screen and (orientation: portrait)">

MDN: https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Media_queries#orientation