James Padolsey» PHP category – James Padolsey

“wordwrap” for JavaScript

James — Fri, 26 Jun 2009 08:17:01 +0000

This function emulates PHP’s wordwrap. It takes four arguments:

The string to be wrapped.
The column width (a number, default: 75)
The character(s) to be inserted at every break. (default: ‘\n’)
The cut: a Boolean value (false by default). See PHP docs for more info.

The code

function wordwrap( str, width, brk, cut ) {
 
    brk = brk || '\n';
    width = width || 75;
    cut = cut || false;
 
    if (!str) { return str; }
 
    var regex = '.{1,' +width+ '}(\\s|$)' + (cut ? '|.{' +width+ '}|.+$' : '|\\S+?(\\s|$)');
 
    return str.match( RegExp(regex, 'g') ).join( brk );
 
}

Usage

wordwrap('The quick brown fox jumped over the lazy dog.', 20, '
\n');

The quick brown fox 

jumped over the lazy 

dog.

I know there are other solutions out there; the ones I saw seemed a bit slow though, not to mention unnecessarily complicated/bloated…

‘tweetFromFile’ PHP Class

James — Mon, 02 Mar 2009 21:45:04 +0000

This recently created PHP class is part of today’s ongoing struggle of trying to create a Twitter ‘drip’ that will automatically update Twitter at pre-defined intervals with status updates specified in a text file.

// (C) Copyright JAMES PADOLSEY
class tweetFromFile {
 
    private $curlHandle;
    private $updateFile;
    private $archiveFile;
 
    private function getNewStatus() {
 
        $upcomingTweetsFile = $this->files['upcoming'];
        $archivedTweetsFile = $this->files['archive'];
 
        $upcomingTweets_R = fopen($upcomingTweetsFile, "r");
 
        // Get upcoming Tweets:
        $contents = fread($upcomingTweets_R, filesize($upcomingTweetsFile));
        $splitContents = preg_split('/\n/', $contents, 2);
 
        // ARCHIVE OLD POSTS:
        $archive = fopen($archivedTweetsFile, "a");
        fwrite($archive, $splitContents[0]."\n");
 
        // Remove top line from upcoming:
        $upcomingTweets_W = fopen($upcomingTweetsFile, "w");
        fwrite($upcomingTweets_W, $splitContents[1]);
 
        // Clean up
        fclose($upcomingTweets_W);
        fclose($upcomingTweets_R);
        fclose($archive);
 
        return $splitContents[0];
    }
 
    public $files = array('upcoming' => '', 'archive' => '');
 
    public function __construct($username, $password, $filename) {
 
        $this->curlHandle = curl_init();
        $this->files['upcoming'] = $filename;
        $this->files['archive'] = 'ARCHIVE_' . $filename;
 
        // Shortcut:
        $ch = $this->curlHandle;
 
        curl_setopt($ch, CURLOPT_URL, "http://twitter.com/statuses/update.xml");
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 2);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_USERPWD, "$username:$password");
 
    }
 
    public function __destruct() {
        curl_close($this->curlHandle);
    }
 
    public function updateStatus() {
 
        $status = $this->getNewStatus();
 
        curl_setopt($this->curlHandle, CURLOPT_POSTFIELDS, "status=$status");
 
        $result = curl_exec($this->curlHandle);	
	$resultArray = curl_getinfo($this->curlHandle);
 
        if ($resultArray['http_code'] == 200) return true;
 
        return false;
 
    }
 
}
 
// ==================
// ===== USAGE ======
// ==================
 
$tweet = new tweetFromFile('twitterUsername', 'password', 'textfile.txt');
$success = $tweet->updateStatus();
if ($success) {
    echo 'Twitter updated!';
} else {
    echo 'Hmm, an error...';
}

The class will retrieve each new update from the specified text file. Each update needs to be on a new line; an example text file:

Blah blah blah, this is the first update...
And another update!
Third and last update!!! ARGH!

The PHP class will remove each update from this file when it’s added to Twitter so all you need to do is keep adding to the bottom of the file…

This won’t do the dripping automatically. You’ll need to setup a ‘cron job’ to request the script at selected intervals (e.g. every two hours). I’m rubbish at Apache and anything to do with the command line so I haven’t quite accomplished this part yet… maybe someone else wants to give it a go?

Getting the real time in JavaScript

James — Thu, 29 Jan 2009 00:03:51 +0000

Getting the time in JavaScript is pretty simple. Using the Date constructor will give us the time as set on the user’s computer, but what if we want the accurate time, or the time in a different timezone?

Even with getTimezoneOffset() you’re still relying on the client!

It turns out that the only way of getting a complete and accurate time from any timezone requires a little bit of server interaction. Luckily there are a few APIs out there that offer this service (actually, there’s only one; well I couldn’t find any others)!

Here we’re using the ‘json-time’ API developed by Simon Willson:

JSON-time

function getTime(zone, success) {
    var url = 'http://json-time.appspot.com/time.json?tz=' + zone,
        ud = 'json' + (+new Date());
    window[ud]= function(o){
        success && success(new Date(o.datetime), o);
    };
    document.getElementsByTagName('head')[0].appendChild((function(){
        var s = document.createElement('script');
        s.type = 'text/javascript';
        s.src = url + '&callback=' + ud;
        return s;
    })());
}

Usage

The first parameter of the callback function is the time (having been passed through the Date constructor), so you can use Date methods such as getSeconds() etc. The second parameter is the entire object returned from the JSON request.

// Alert GMT:
getTime('GMT', function(time){
    alert(time);
});
 
// Get London time, and format it:
getTime('Europe/London', function(time){
    var formatted = time.getHours() + ':' 
                  + time.getMinutes() + ':'
                  + time.getSeconds();
    alert( 'The time in London is ' + formatted );
});

For reference, here’s a list of all the available timezones (to use one, remove the backslash).

jQuery version

$.getTime = function(zone, success) {
    var url = 'http://json-time.appspot.com/time.json?tz='
            + zone + '&callback=?';
    $.getJSON(url, function(o){
        success && success(new Date(o.datetime), o);
    });
};
 
// Usage:
$.getTime('GMT', function(time){
    alert(time);
});

MooTools version

You’ll need to download the JsonP class.

function getTime(zone, success) {
    var url = 'http://json-time.appspot.com/time.json';
    new JsonP(url, {
        data: { tz: zone },
        onComplete: function(o){
            success && success(new Date(o.datetime), o);
        }
    }).request();
}
 
// Usage:
getTime('GMT', function(time){
    alert(time);
});

Thank you Simon Willison for making this API; seriously, I searched around the entire internets just for one damn API and I almost lost hope!

Preloading images from a directory

James — Wed, 07 Jan 2009 00:23:42 +0000

Here’s a very handy script which will scan through a directory of images, form an array of the contents of that directory and then return the array in JSON format to the client-side where the images will be preloaded into the user’s cache.

There are two components to this: the PHP script and some simple JavaScript:

The Code (PHP):

/* PHP file, e.g. scanImageDirectory.json.php */
 
// Check that a callback function has been specified:
if (!isset($_GET['callback']) || !isset($_GET['directory'])) exit;
 
// Use PHP5's scandir function to scan all
// of images directory:
$dirContents = scandir($_GET['directory']);
 
// Define function to confirm each
// filename is a valid image name/extension:
function isImageFile($src) {
    return preg_match('/^.+\.(gif|png|jpe?g|bmp|tif)$/i', $src);
}
 
// Loop through directory files and add to
// $arrayContents on each iteration:
$arrayContents = '';
foreach($dirContents as $image) {
    if (isImageFile($image)) {
        $arrayContents .= !empty($arrayContents) ? ',' : '';
        $arrayContents .= '"' . 'images/' . $image . '"';
    }
}
 
// Prepate JSON(P) output
$output = $_GET['callback'] . '({\'images\':[' . $arrayContents . ']});';
 
// Output the output:
echo $output;

The above PHP script will use PHP5’s scandir to scan the ‘images’ directory and it outputs a list of all images in JSON format. (so it can be used by our JavaScript). The JavaScript is below:

The Code (JavaScript):

/* JavaScript Component */
 
function preloadImagesFromDirectory(dir) {
 
    if(!dir) return;
 
    function getJSON(URL,success){
 
        // Create new function (within global namespace)
        // (With unique name):
        var uniqueID = 'json'+(+(new Date()));
            window[uniqueID] = function(data){
                success && success(data);
            };
 
        // Append new SCRIPT element to DOM:
        document.getElementsByTagName('body')[0].appendChild((function(){
            var script = document.createElement('script');
            script.type = 'text/javascript';
            script.src = URL.replace('callback=?','callback=' + uniqueID);
            return script;
        })());
 
    }
 
    function preload(srcArray) {
        for(var i = 0; i < srcArray.length; i++) {
            (new Image()).src = srcArray[i];
        }
    }
 
    // Get that JSON data:
    getJSON('scanImageDirectory.php?directory=' + encodeURIComponent(dir) + '&callback=?', function(data){
        return data.images ? preload( data.images ) : false;
    });
 
}

The above JavaScript uses JSONP to load the PHP file into a SCRIPT element as if it were a JavaScript file itself, then the automatically generated function is fired which then executes the specified callback (’success’) function which is specified when calling getJSON. The callback then preloads the passed data (i.e. the array of images).

Usage:

// We don't want to disturb anything so we'll wait
// until everything's done loading before preloading:
window.onload = function(){
    preloadImagesFromDirectory('images/');
}

Security concerns:

Since the directory to be scanned is specified in a query string it would be VERY easy for ANYONE to gain information on your file structure/nomenclature. The regular expression used to validate the image names on the server-side (the PHP script) will stop any files from being listed that do not end in gif, png, jpg, jpeg, bmp or tif. If you’re still concerned then simply specify the directory to be scanned from within the PHP script instead of having it passed through the query string.