360 degree car rotation – common code for mobiles and computer browsers

I had been updating my examples and tutorials off  lately and trying to create a more general approach to application development – Write a single app that runs in mobile browsers as well as computer browsers. Following the same approach, this time I am updating one of my previous tutorials – 360 Degree Car/Product rotation for iPhones. So, I worked on a 36o degree car rotation code that runs in both mobile and desktop browsers.

This tutorial is an update to my previous one, I also present a new demo. I will not go into the details, which I have talked about in my previous tutorial. Have a look at the demo, open it in either an iOS browser or a computer web-kit browser.

Link: http://jbk404.site50.net/360DegreeView/mobile/common.html

360 degree car rotation in mobile safari

What are the changes?

All the changes are in the javascript code. I have introduced a device detection mechanism and then automatically assign either touch events (for mobiles) or mouse events (for computer browsers). These are the same changes that I have recently talked of in my last post – Replicating the iPhone Swipe Gesture — common code for mobiles and computer browsers. That should help you out.

Other than that just try the example link in a computer web-kit browser – Chrome/Safari or an iOS device browser which is also a web-kit browser. Android devices need some changes and the same code might not work. I have talked on this in my previous post.

For the code, right click to view the source.

JavaScript Touch event or Mouse event – detect and handle according to device

You might have faced this issue before or even might have wondered – How to write a single piece of code that establishes correct event in the device i.e touch events for mobile web browsers and mouse events for desktop browsers. You need not hard code the events for your app code. Once you detect and handle those events, you can run your app everywhere – mobiles and computer browsers. Normally when we develop an app for mobile browsers we test it in a desktop browser, so if you have touch events hard-coded into your script then it is a pain to change the script and make it work for computer browsers(replacing touch events with mouse events) and then change it back again to touch for mobiles. So, here is a small script/trick to universally handle the event and need not worry about devices,

var isTouchSupported = 'ontouchstart' in window;
var startEvent = isTouchSupported ? 'touchstart' : 'mousedown';
var moveEvent = isTouchSupported ? 'touchmove' : 'mousemove';
var endEvent = isTouchSupported ? 'touchend' : 'mouseup';

If you see the first line of the script, it detects if ontouchstart property is available in the global window object. It it is available or it is a part of the window object, then it returns true else it returns false. Note that ontouchstart is a standard javascript touch event attribute. Now, if you are making this check in a computer browser (for e.g FF, Chrome or IE) then ontouchstart is not a property of the window object. So isTouchSupported will be set to false. Had it been a mobile browser (e.g iOS, Android) then ontouchstart would have been automatically a part of the window object and correspondingly isTouchSupported variable will set to true. This is all we need to detect. The next three lines establish a common platform for the touch vs mouse events i.e I am mapping the touch events to its corresponding mouse events.

Now, all you need is to register the event listener to your element so that some action is performed when the event is triggered on the element. Here is an example, (where myButton is the ID of my imaginary button)

document.getElementById("myButton").addEventListener(startEvent,function(){},false);

The startEvent variable acts as a placeholder. It will be replaced by mousedown for computer browsers and touchstart for mobile browsers. Similarly the other two events can be used. This way a single app can run everywhere.

Here is a good example with the usage (make sure you look at the javascript script code) - http://jbkflex.wordpress.com/2012/07/21/replicating-the-iphone-swipe-gesture-common-code-for-mobiles-and-desktop-browsers/

Here is another one - http://jbkflex.wordpress.com/2012/07/25/360-degree-car-rotation-common-code-for-mobiles-and-computer-browsers/

Please do suggest me if there are any better methods of mapping touch v/s mouse events.