Showing posts with label tutorial. Show all posts
Showing posts with label tutorial. Show all posts

Wednesday, 17 July 2013

HTML5 Data methods

Here are various ways you can use data through HTML5. The code is larger than usual, that's because I've provided code for 8 different methods of storing and using data. I have tried to highlight the related code and method using colours. To run this, you'll need 3 files:

  • index.php
  • twittieserver.php
  • webworker.plugin.js

The code for all of these files is below. So, let's start with index.php
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>HTML5 Localstorage</title>
<!--[if IE]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<link rel="stylesheet" href="http://meyerweb.com/eric/tools/css/reset/reset.css" />
<style>
body
{
font:0.9em/1.1em Sans-serif;
color:#808080;
}
.column
{
float:left;
width:440px;
}
form, section
{
margin:10px;
padding:10px;
width:400px;
border:2px solid #808080;
}
p.description, section article ul
{
margin:4px 4px 8px 0px;
padding:4px;
}
section article ul
{
background:#F5DA55;
}
p.description
{
background:#F5F555;
}
h1, h2
{
font:1.4em/1.5em Georgia, Serif;
}
h1
{
margin:14px 0 10px 10px;
}
strong
{
font-weight:bold;
}
</style>
<script src="http://www.google.com/jsapi"></script>
<script>
google.load("jquery", "1");
</script>
</head>
<body>
<h1>HTML5 Data Options</h1>
<div class="column">
<form>
<h2>Input</h2>
<p class="description">This form will be used to add content to the sessionStorage, localStorage and Web SQL Objects.</p>
<input type="text" id="one" /><br />
<button>Save</button>
</form>
<section id="customdataattribute">
<h2>Custom Data attributes</h2>
<p class="description">Allows you to hold data values within a selector.<p>
<p class="description">E.g &lt;li data-no="20"&gt;<br />Can therefore be called through jQuery as $('li').data('no');<p>
<article>
<ul>
<li data-no="22">This value is 22<li>
<li data-no="33">This value is 33<li>
</ul>
</article>
</section>
<section id="sessionstorage">
<h2>sessionStorage</h2>
<p class="description">This data will be lost when the browser is closed.<p>
<article></article>
</section>
<section id="localstorage">
<h2>localStorage</h2>
<p class="description">This data will be retained after the browser is closed. It persists until deleted by user through browser settings or by this application.<p>
<article></article>
</section>
</div>
<div class="column">
<section id="cachemanifest">
<h2>cache-manifest</h2>
<p class="description">A file which tells the browser what to cache, and not cache. <br /><strong>CACHE MANIFEST</strong> entries will be cached after they are downloaded for the first time.
<br /><strong>NETWORK</strong> entries require a connection to the server, and will not be cached.
<br /><strong>FALLBACK</strong> are fallback pages, if a page is unavailable.
<br />Instructions below:</p>
<article>
<p>First create a .htaccess file for your site (if you are using a proper web server) and add to it the following line:</p>
<p>AddType text/cache-manifest    .manifest</p>
<p>Next, create a file called cache.manifest. In this file, add the lines:</p>
<p><strong>CACHE MANIFEST</strong></p>
<p>index.html</p>
<p><strong>NETWORK</strong>:</p>
<p>login.html</p>
<p><strong>FALLBACK</strong>:</p>
<p>/html/ /offline.html</p>
</article>
</section>
<section id="sse">
<h2>Server-Sent Events</h2>
<p class="description">Allows this application to get data updates from a server. In this example I've simulated a twittie server using a PHP script called twittieserver.php. This data will be lost when the browser is closed.</p>
<article>
<ul>
</ul>
</article>
</section>
<section id="webworker">
<h2>Web Worker</h2>
<p class="description">A piece of JavaScript or jQuery running in the background, without affecting the performance of this application.</p>
<article></article>
</section>
<section id="websql">
<h2>Web SQL</h2>
<p class="description">Allows an application such as this to build a SQL database at the client end. It is also possible to synchronise this data at the server end. This supports applications which ahve both and online and offline state. It persists until deleted by user through browser settings or by this application.</p>
<article>
<ul>
</ul>
</article>
</section>
</div>
<script>
/* Calculates the custom data attributes and appends them to the result of a selector */
$.fn.calculatecustomattributes = function()
{
lis = $(this).children('li');
res = 0;
ve = 0;
$(lis).each(function()
{
ve = parseInt($(this).data('no'));
if(!isNaN(ve))
{
res += ve;
}
});
$(this).append('<li>Result is '+res+'</li>');
};

/* Sets the form contents which were stored in the sessionStorage object to the calling selector */
$.fn.displaysessionstorage = function()
{
$(this).html('<p>Content is '+sessionStorage.getItem('one')+'</p>');
};

/* Sets the form contents which were stored in the localStorage object to the calling selector */
$.fn.displaylocalstorage = function()
{
$(this).html('<p>Content is '+localStorage.one+'</p>');
};

/* Lists contents of the Web SQL object in the calling selector */
$.fn.displaywebsql = function(db)
{
container = $(this);
db.transaction(function(tx)
{
tx.executeSql('SELECT * FROM jimmy', [], function(tx, results)
{
  var len = results.rows.length, i;
for (i = 0; i < len; i++)
{
$(container).append('<li>'+results.rows.item(i).text+'</li>');
}
});
});
};

/* This function is called when the 'Save' button is clicked */
$.fn.saveit = function(db)
{
/* Put the value of the form input in a variable */
one = $('form #one').val();

/* Create an item in the sessionStorage object and apply the value of our variable */
sessionStorage.setItem('one', one);

/* Create an item in the localStorage object and apply the value of our variable */
localStorage.one = one;

/* Insert the value of our variable into the Web SQL object */
db.transaction(function(tx)
{
tx.executeSql('INSERT INTO jimmy (text) VALUES (?)',[one]);
});

/* Refresh the contents of our containers */
$('#sessionstorage article').displaysessionstorage();
$('#localstorage article').displaylocalstorage();
$('#websql article ul').displaywebsql(db);
};

(function()
{
/* Check to see if web storage is supported */
if(typeof(Storage) == 'undefined')
        {
            alert('Sorry! No web storage support..');
        };

        /* Check to see if web workers are supported */
        if(typeof(Worker) == 'undefined')
{
    alert('Sorry! No web worker support..');
}

/* Check to see if Server-Sent Events are supported */
if(typeof(EventSource) =='undefined')
{
alert('Sorry! No server-sent events support..');
}

/* Calculate custom attibutes */
$('#customdataattribute article ul').calculatecustomattributes();

/* Create a Web SQL object */
var db = openDatabase('mydb', '1.0', 'jimmy database', 2 * 1024 * 1024);
db.transaction(function(tx)
{
tx.executeSql('CREATE TABLE jimmy (id unique, text)');
});

/* Refresh the contents of our containers */
$('#sessionstorage article').displaysessionstorage();
$('#localstorage article').displaylocalstorage();
$('#websql article ul').displaywebsql(db);

/* Call the saveit function when the button is clicked */
$('button').click(function()
{
$(document).saveit(db);
});

/* Get updates for a server, here I've simulated the server with a PHP script */
var feed = new EventSource('twittieserver.php');
feed.onmessage = function(event)
{
/* Add new articles to the top of the list and limit the list to 4, thus removing the fourth item from the list */
$('#sse article ul').prepend(event.data);
if($('#sse article ul > li').size() == 4)
{
$('#sse article ul li:last-child').remove();
}
};

/* Get updates from a JavaScript, simply replacing the contents of the container with each new value returned */
w = new Worker("webworker.plugin.js");
w.onmessage = function(event)
{
$('#webworker article').html(event.data);
};
})();
</script>
</body>
</html>

Now twittieserve.php
<?php
header('Content-Type:text/event-stream');
header('Cache-Control:no-cache');
$seconds = date('s');
echo 'data:<li>Item '.$seconds.'</li>'.PHP_EOL.PHP_EOL;
flush();
?>

And finally, webworker.plugin.js
var i=0;
function timedCount()
{
i=i+1;
postMessage(i);
setTimeout("timedCount()",500);
}
timedCount();

Enjoy!

Monday, 17 June 2013

Your first jQuery plugin

Here is a quick tutorial in how to create a jQuery plugin. Below is my basic page with a call to:
A file called 'first.plugin.js' containing the plugin (in red).
A call to a method called 'changetored' within that plugin (in blue).

<!DOCTYPE html>
<html lang="en">
<head>
<title>First jquery plugin test page</title>
<script src="http://www.google.com/jsapi"></script>
<script>
google.load("jquery", "1");
</script>
<style>
.red
{
color:red;
}
</style>
</head>
<body>
<p>First paragraph</p>
<p>Second paragraph</p>
<p>Third paragraph</p>
</body>
<!-- Call the plugin -->
<script src="first.plugin.js"></script>
<script>
(function()
{
/*
* changetored is a method declared in first.plugin.js
*/
$('p').changetored();
})();
</script>
</html>
Now for the plugin. Here is the file 'first.plugin.js'.

(function($)
{
$.fn.changetored = function()
{
/*
* In the context of a call like $('p').changetored();
* $(this) would become all paragraphs
*/
$(this).addClass('red');
};
})(jQuery);

Thursday, 9 August 2012

Lessons learned from the coal face of git repositories


I've just been going through a bit of pain, setting up a git repo.

A git repo is a place to put your open source project. It allows users to get hold of your project, contribute to it and create their own version from it. A git repo also gives you useful things like change control for your project.

GitHub have tried to make the process simple with good help, but there are a few do's and don'ts which I discovered along the way so here, I compose my learning as a reminder to myself. Hopefully we'll all feel the benefit.

I'm going to assume that you have already gone through all the pain of creating a GitHub account. There are many places on the web you can learn how to do this. I'm also assuming that you have logged in to GitHub and that you have reached the homepage of your account. Finally, I'll have to assume you've set git up on your server so that all the local software is in place.

1. It's best to create a new repository from GitHub. Not, as they recommend from your server. Start by clicking the 'New repository' buutton.
2. I recommend you name the repository as the directory on your server. Do not take the option to create the README file. By avoiding it, you will be provided with some starting commands, which I recommend you save to a text file. They'll look something like this:
Create a new repository on the command line
touch README.md
git init
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/yourusername/yourdirectory.git
git push -u origin master

Push an existing repository from the command line
git remote add origin https://github.com/yourusername/yourdirectory.git
git push -u origin master

3. Follow the instructions provided by GitHub within the directory on your server.
4. You may already have a project ready to go up. Then you'll need to do:
git add *.*
git commit -m "your comments"
git push origin master
Followed by:
git add .
git commit -m "your comments"
git push origin master
5. Now you're ready to start pushing your updates. Make some changes. Test that you're happy with them on your server. Now commit using:
git add *.*
git commit -m "your comments"
git push origin master
6. Let's say you messed up (each and every minute of every day in my case (yes, even when I'm sleeping)) and you want to remove a file you've committed. First delete it from your server then:
git add . -A
git commit -m "removed some files"
git push origin master

Have fun with GitHub!

Monday, 16 May 2011

Letterpress

I use GIMP a lot. It's an excellent program. A lot of people, used to using Photoshop have difficulty getting used to the GUI. I'd never used Photoshop, so I didn't have anything to get used to. I compared the feature list of the 2 programs and GIMP came out very well, so that's the one I used.

This page is a tutorial on how to create a letterpress effect in GIMP.

See demo.


<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Font effects</title>
<style type="text/css">
body
{
font-family:Sans-serif;
background:#737373 url(images/darkcoursepaper.jpg);
color:#FFFFFF;
}
</style>
</head>
<body>
<img src="images/letterpress.png" alt="letterpress" />
<h1>Letterpress example using GIMP</h1>
<h2>Prepare your gimp canvas</h2>
<p>Start with a new clean canvas lets say 640px width and 480px height.</p>
<h2>Add some text</h2>
<p>Choose a font you like but I recommend to use a bold text.</p>
<h2>Inner gradient</h2>
<p>Right click on the layer with the text and choose Text to selection.</p>
<p>Choose Edit->Clear</p>
<p>Select a gradient tool and use a colour which is darker than the background. Use gradient FG to Transparent and make the gradient from bottom of the text somewhere to the middle.</p>
<h2>White Drop Shadow</h2>
<p>Select Filters > Light and Shadow > Drop Shadow.</p>
<p>Set Offset X, Offset Y and Blur radius to 1. Colour white. Opacity 20.0.</p>
<h2>Inner Shadow</h2>
<p>Select from top navigation Select > Invert</p>
<p>Then Filters > Light and Shadow > Drop Shadow</p>
<p>Set Offset X and Offset Y to 1. Blur radius to 6. Colour black. Opacity 100.0.</p>
<h2>Done!</h2>

</body>
</html>