JavaScript, HTML, CSS

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Revision as of 14:42, 16 December 2013 by Ghenne (talk | contribs) (→‎Translator)
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What's behind the scenes?

  • In this section, we will learn more about the internals of AppStudio.
  • AppStudio is built on top of HTML5, css3 and JavaScript.
  • We deliberately left those parts accessible.
  • Makes it easy to learn more about HTML5, css3 and JavaScript.
  • Advanced users can build almost anything.

Translator


  • When an AppStudio program is run, all BASIC code is converted to JavaScript.
  • JavaScript is fast!
  • JavaScript on a iPhone 5S is almost twice as fast as VB.Net on a desktop!
  • Latest iPhones are 100x faster than the original.
  • Translation happens only to code modules which have changed.
  • You can see your BASIC translated to JavaScript by right clicking in the Code Window.

Controls

  • The forms and controls in your project generate css and HTML
  • The css defines the controls.
  • Controls are identified by their ids.
  • The ids are declared in the DOM window object.
  • While is why we can do TextBox1.value.
  • For each control, a string of HTML is also created.
  • These strings are put into an array.
  • The array is joined together and put into the form's innerHTML.
  • Just like what we were doing the HTMLview!
  • Let's look at the css for a button:
#Button1 {position:absolute; left:43px; right:auto; top:96px; 
bottom:auto; height:29px; width:100px}
  • Here is the generated HTML and JavaScript for that same button:
Form1.innerHTML=[  "<div id='Button1' data-role='button' data-inline=true 
data-theme=c data-icon=false data-iconpos=none data-mini=true 
data-corners='true' class=' ' style='margin:0px; overflow:visible; 
font-size:12px; font-family:helvetica; font-style:normal; font-weight:bold; 
color:; background-color:; '>Button</div>",
  ].join('');

Generated Index.html

  • The translated code for the app and the css, HTML and Javascript for the controls are all written to a file called Index.html.
  • Let's have a look at the file.
  • First, there is the manifest.
  • This file contains the list of files to be saved locally on the device.
  • An app cannot run offline unless all files are listed here.
<!DOCTYPE HTML>
<html manifest="OfflineApp.appcache">
  • The <head> section sets up general information about the app.
  • Much of it comes from the information in Project Properties.
<head>
<meta charset="utf-8">
<title>Project2</title>
<meta name="generator" content="NSB/AppStudio 3.3.0.0$mgvb" />
<meta name="date" content="2013-12-12 13:44:58.613000" />
<meta name="version" content="1.0.0" />
<meta name="viewport" content="width=device-width minimum-scale=1.0, maximum-scale=0.6667, user-scalable=no" />
<meta name="apple-mobile-web-app-capable" content="YES" />
<meta name="mobile-web-app-capable" content="yes" />
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
<meta name="apple-mobile-web-app-title" content="">
<meta name="copyright" content="Copyright 2013 ABC Company" />
<link rel="apple-touch-icon" href="nsb/images/LauncherIcon57.png" />
<link rel="apple-touch-startup-image" href="nsb/images/SplashScreen.png" />
<link rel="shortcut icon" sizes="196x196" href="nsb/images/196.png"/>
  • This is where the files the app uses get loaded.
  • JavaScript files use a script tag.
  • css files use a link tag.
  • The list of files depends on the controls which are used.
<script src="nsb/hfunc.js"></script>
<script src="nsb/messages.js"></script>
<link href="nsb/nsbstyle.css" rel="stylesheet">
<script src="nsb/fastclick.js"></script>
<script src="nsb/jquery.js"></script>
<script src="nsb/jquery.mobile.js"></script>
<link href="nsb/jquery.mobile.css" rel="stylesheet">
  • Next comes the css for the controls
  • and we define the default font for the form, also a Project Property.
<style type="text/css">
#Button1 {position:absolute; left:43px; right:auto; top:96px; bottom:auto; height:29px; width:100px}
body * {font-family:helvetica}
</style>
</head>
  • Now it's time the body of our app.
  • FastClick is a library which makes touch events as fast as clicks.
<body style="margin:0px;">
<script>window.addEventListener('load', function() {new FastClick(document.body)}, false)</script>
  • Now it's time to define our forms.
  • This project only has one: Form1
<div data-role="page" id="Page_Project2" data-theme="c" style="">
<form id="Form1" action="" method="GET" onsubmit="return false;" style="display:none; height:100%; position:absolute; top:0px; left:0px; width:100%; ">
<script>
Form1.innerHTML=[  "<div id='Button1' data-role='button' data-inline=true data-theme=c data-icon=false data-iconpos=none data-mini=true data-corners='true' class=' ' style='margin:0px; overflow:visible; font-size:12px; font-family:helvetica; font-style:normal; font-weight:bold; color:; background-color:; '>Button</div>",
  ].join('');
</script>
</form>
</div>
  • With all that set up, we can start on the code.
  • General housekeeping comes first.
  • Put all the ids into the DOM window:
<script>
(function(){var all=document.getElementsByTagName('*');for(var i=0;i<all.length;i++)if(typeof all[i].id!='undefined'&&typeof window[all[i].id]=='undefined')window[all[i].id]=all[i];})()
  • Put up a message if the browser does not support AppStudio
browserWarningMessage('Please use Google Chrome, Apple Safari or another supported browser.');
  • Use a different splashscreen if running on an iPad
if (navigator.userAgent.indexOf('iPad') !== -1) {
  var splashscreen = document.createElement('link');
  splashscreen.rel = 'apple-touch-startup-image';
  splashscreen.href = '';
  document.getElementsByTagName('head')[0].appendChild(splashscreen);
}
  • Add some properties to the controls and form so they act more like VB
window.addEventListener('load', function() {
  Form1.style.display = 'block';
  NSB.addDisableProperty(Button1);
  NSB.addProperties(Button1);

  Form1.style.display = 'none';
}, false);
Form1.onsubmit=function(event){window.event.stopPropagation();window.event.preventDefault()};
NSB.addProperties(Form1);
  • Here is our actual code, converted to JavaScript
Button1.onclick = function() { savethefunction_rvar="";
  _msgbox_confirm("Hello World!");
return savethefunction_rvar; }
  • When loading is done, show the first form and call Sub Main()
window.addEventListener('load', function() {
  Form1.style.display = 'block';
  Main();
  if (typeof(Form1.onshow)=='function') Form1.onshow();
}, false);

var NSBCurrentForm = Form1;
  • and the rest is HTML formatting.
</script>
</body>
</html>
  • Note that the details of the above may change in future releases.

JavaScript Libraries

  • AppStudio makes it easy to include JavaScript libraries.
  • These are equally easy to use from BASIC or JavaScript.
  • If something can be done in JavaScript, there probably is a library for it already.

Ways to include

  1. Drag it into the Project Window. It will get loaded into your Index.html when your app is generated.
  2. Create a new Code Module. Set its language to JavaScript. Paste the code in.
  3. Create a <script> line in the extraheaders Project Property.
  4. Put it in the middle of your BASIC code. Using the JavaScript statement, you can mix JavaScript and BASIC in the same module.
x = x + 1                    'BASIC
JavaScript
  if(x==3){alert('x=3!');    //JavaScript
End JavaScript
x = x + 1                    'BASIC

Included Libraries

  • A number of libraries are installed with AppStudio
  • To use them, select Project Properties and Global code in the Project Explorer
  • The ToolBox will then show the list of libraries.
  • Include one by clicking on its checkbox.
  • Sample for these are in the folder 8 of the Samples directory.

Add to Home Screen

  • This library is iOS only. When your app is run in the browser, it prompts you to save to the Home Screen.

jQuery

  • This library is the most widely used JavaScript library on the net.
  • jQuery Mobile and jqWidgets both use it.
  • Usually no need to select it, since it will already be included.

Retina Display Support

  • Displays Hi Res versions of images where supported.
  • Requires two sets of all images in your project.
  • Hi Res set is named filename@2x.jpg.

Sencha Touch

  • This is large, fairly well known framework.
  • Not so much used with AppStudio any more.

Spinning Wheel

  • Nice spin control for selecting dates, etc.

Stanford Crypto Library

  • Allow strings to be strongly encrypted for transmission over the net.
  • Here's how to use it:
Function btnEncrypt_onclick()
  txtEncrypted.value=sjcl.encrypt(txtPassword.value, txtPlain.value)
End Function

Function btnDecrypt_onclick()
  txtPlain.value=sjcl.decrypt(txtPassword.value, txtEncrypted.value)
End Function

xml2json

  • Convert XML formatted data to a JSON structure.

Other Libraries

  • There are several repositories which list hundred or even thousands of JavaScript libraries
  • Lots more!
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