Developing Portable Mobile Web Applications

What if you could write iPhone and iPad applications on Linux? And, what if those applications also ran on Android phones? Well, you can, by writing your application as a portable mobile Web application. Take advantage of HTML5 and JavaScript libraries to write rich Web applications that users can't tell from native applications. You even can have them install from iTunes and Android Market. Plus,

After the HTML declaration, there is the <head> section of the document. The <title> element is the HTML title for the page. The iPhone and Android browsers display it as the window title until we make the application full screen. The next two <link> elements tell the browser where to find CSS files referenced in the application. Two styles come with jQTouch: “/themes/apple” and “themes/jqt”. We've chosen the latter here, to be a little more device-independent. The next three elements are <script> references—the first two for jQuery and jQTouch, and the next for webnotes.js. The order is important—the <script> element for jQuery must precede the one for jQTouch, and they must both precede any scripts that use them.

After the header, the <body> element of Listing 1 contains three first-level <div> elements, one for each screen. The top levels of the three screens are very similar. Each has a unique id attribute that we use to refer to the screen from JavaScript. Each also includes an inner <div> with class="toolbar" that defines the bar at the top of the screen. The <h1> element in these <div>s is the screen title. The toolbars also each have an anchor element of class="button cancel". This jQTouch class defines the arrow-shaped cancel button, and the href says clicking on it takes us to the “home” screen. The anchor also defines text (“Cancel”) that appears in the button. On the “home” screen, we've included a + button to add a note. We've specified the “slideup” animation for that button's action, so the “addNote” screen will slide into view from the bottom of the screen.

The “home” screen also contains an inner <div> with a list containing one list item. That item is a template that defines the display of note titles. You'll see how we use it below.

In the “addNote” screen, after the “toolbar” <div> there is another <div> that contains a <form>. This <form> contains a list that has three list items:

  • Text input for the title of the note.

  • Text area for the contents of the note.

  • Button to submit the <form>.

We've given the list items class names to make them easy to find with jQTouch.

The “editNote” screen looks like “addNote”, with one addition. There's an <input> of class="button" in the toolbar to give the user a way to delete a note. The onclick attribute for this button tells the browser to call a JavaScript routine deleteNoteById(), which we define in webnotes.js.

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Rick Rogers has been a professional embedded developer for more than 30 years. Now specializing in mobile application software, when Rick isn't writing software for a living, he's writing books and magazine articles like this one.

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Android compatibility.

tuna's picture

I'm getting my feet wet with mobile development and am trying to get this working. I'm developing on an HTC Droid Eris with Android 2.1. All I'm getting is a black screen. Any one have any ideas if it should work? Or where I should be looking?

"well documented elsewhere"

Anonymous's picture

"Installation of the tools is well documented elsewhere. The Resources section for this article gives pointers to the download URLs."

The resources indeed gives the pointers to the download URLs.
Is there also a link available for "well documented elsewhere"?
Is there also a pointer to the installation of the tools?

Regards,
M. Moon

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