Think Blue - blogs@bluerhinos.co.uk

My First GitHub Project: phpMQTT

andrew@bluerhinos.co.uk (Andrew Milsted) — Thu, 09 Sep 2010 22:33:10 +0100

So I may be a bit late to the party, but I have now created by first GitHub project. For my project I decided to actually finish my MQTT class.

I have posted it at http://github.com/bluerhinos/phpMQTT

At the moment the publishing part works a treat, but there currently a problem with the subscribe part (hangs after about 3 hours) I am trying to trace the fault. Also at the moment it will only support quality of service (qos) of 0.

Example Publishing:

php code:
require("../phpMQTT.php");
$mqtt = new phpMQTT();
/* broker(broker address, broker port, client id); */
$mqtt->broker("example.com", 1883, "PHP MQTT Client");
$mqtt->connect();
/* publish( topic, message, qos); */
$mqtt->publish("bluerhinos/phpMQTT/examples/publishtest","Hello World!",0);
$mqtt->close();

Keeping the GeoIP databases up to date

andrew@bluerhinos.co.uk (Andrew Milsted) — Fri, 26 Mar 2010 21:47:26 +0000

I needed to keep my GeoIP db up to date for my stats package so I decided to write a cron script that would do it for me.

bash code:
#!/bin/bash
 
#############################################################
# ./geoipupdate = Auto updates the free GeoIP databases
# (c) andrew[at]bluerhinos.co.uk 2010 : Creative Commons
#############################################################
 
#list of urls
URLS=" http://geolite.maxmind.com/download/geoip/database/GeoLiteCountry/GeoIP.dat.gz"
URLS="$URLS http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz"
 
#target directory
TARGETDIR="/var/lib/GeoIP"
 
for URL in $URLS
do
        wget -q -N -P "$TARGETDIR" "$URL"
        BASENAME=`basename "$URL"`
        gunzip -f  "$TARGETDIR/$BASENAME";
done

Place the above code (or download here http://blogs.bluerhinos.co.uk/data/files/9/geoipupdate ) into /etc/cron.monthly/geoipupdate

Note: they update their db on the 1st or 2nd so I changed my /etc/crontab so that the monthly scrips run on the 3rd

A simple way to make pretty urls

andrew@bluerhinos.co.uk (Andrew Milsted) — Mon, 25 Jan 2010 23:06:46 +0000

If you are like me, you dislike the .php extension for web pages that display content, eg /contactus.php . To me this is a web page that is displaying HTML, so lets give it an .html suffix. but the easist way to implements templates is to use html.

To achieve this easily just create a .htaccess file to redirect .html's to .php.

.htaccess code:
 
RewriteEngine On
RewriteRule (.*).html $1.php [QSA]

(The QSA just forwards all variables to the .php script)
Requirements: are apache and mod_rewrite
More Info: http://www.kuro5hin.org/story/2003/7/31/2335/08552

PHP Function to return Beaufort Scale

andrew@bluerhinos.co.uk (Andrew Milsted) — Sat, 28 Nov 2009 23:23:08 +0000

I was working on a project that needed to list the Beaufort wind force. The first attempt was to do a lookup based function using the data here: http://en.wikipedia.org/wiki/Beaufort_scale

Attempt 1

php code:
function beaufort_scale($speed, $unit="m/s"){
 
    $units['m/s'] = 1;
    $units['kph'] = 1/3.6;
    $units['mph'] = 0.44704;
    $units['kts'] = 0.514444444;
 
    if(!in_array($unit,array_keys($units))){
        return "Error: couldn't recognise unit";
    }
 
    $speed *= $units[$unit];
 
    $scale = array(0.3,1.5,3.4,5.4,7.9,10.7,13.8,17.1,20.7,24.4,28.4,32.6,1000);
 
    foreach($scale as $key=>$val){
        if($speed <= $val) return $key;
    }
    return 'Error';
}

I then noticed on the wikipedia page the scale's empirical formula
so i thought i could improve the function ;)

v = 0.866 * B^3/2 (units m/s)

Attempt 2

php code:
function beaufort_scale($speed, $unit="m/s", $rnd=0){
 
   $units['m/s'] = 1;
   $units['kph'] = 1/3.6;
   $units['mph'] = 0.44704;
   $units['kts'] = 0.514444444;
 
   if(!in_array($unit,array_keys($units))){
      return "Error: couldn't recognise unit";
   }
 
   $speed *= $units[$unit];
 
   $scale = pow(($speed/0.836),(2/3));
 
   return round($scale,$rnd);
}

This one has the added ability of returning a decimal answer

Getting php-ffmpeg and an x264 enabled ffmpeg of the same machine (debian)

andrew@bluerhinos.co.uk (Andrew Milsted) — Wed, 29 Jul 2009 08:44:54 +0100

Oh and it has to be stable ish.

Yesterday I had to try and get php-ffmpeg and x264 enabled ffmpeg to sit side by side each other on a Debian Lenny install. The problem is that debian's ffmpeg that ships in the lenny package tree is not 264 enabled. But when you use the ffmpeg from debian-multimedia it breaks the installed php-ffmpeg.

So I suggest you do this:

Start With vanilla debian install

Install your php, apache, php-ffmpeg etc

Then add your debian-multimedia.org as a apt source.

Then follow these instructions
http://tovid.wikia.com/wiki/Installing_svn_ffmpeg_on_a_Debian_based_distro
(I have attahed a pdf of the page incase its not there when you read this, Data: Instruction for compiling ffmpeg

Happy Hunting

Large Webpage Screen Shots

andrew@bluerhinos.co.uk (Andrew Milsted) — Tue, 27 Jan 2009 22:53:11 +0000

Example Screen Shot from the BBC

Ever needed to create screen shots of websites like this one, but the site is longer that your screen resolution. Well I have found a simple tool that makes it easy in firefox. WebShots, a Firefox Addon, that allows you to save a screen shot at a click of a button,

Installation:
Go to https://addons.mozilla.org/en-US/firefox/addon/6168 and click the "Add to Firefox" link.
Works on Windows, OS X and Linux

Plotting on a World Map

andrew@bluerhinos.co.uk (Andrew Milsted) — Wed, 07 Jan 2009 17:34:45 +0000

I needed to plot visitors to a web site onto a world map to demonstrate world wide coverage. I had an initial google around and couldn't really find anything. It didn't take too long to realise what i needed to make this work with my own script. I also chose to make it pretty so have gone for a lights at night look.

Plotting on a World Map (Website Visitors)

Problem
* Put locations of visitors (for which i already had in a mysql database) on to a world map.

Pre-Requisites
* The data (this example will assume from mysql)
* A World Map (I have gone for "AVHRR Pathfinder" shot from here) the bigger the better)
* PHP with gd2 (I run this from the command line as it might take a while to render)

Understanding the Maths
Firstly to make this work you need a linear cylindrical (latitude/longitude) projection world map, the ones from the source outlined above are. This means that the latitude/longitude are directly proportional to the x/y of the image. So if you have the dimensions the image as $img_x, $img_y you can then plot a long/lat with this:

php code:
$pos_x = (int)(($img_x/2) + (($row['long']/180)*($img_x/2)));
$pos_y = (int)(($img_y/2) - (($row['lat']/90)*($img_y/2)));

For Longitude ($row['long']): the range is from -180°:180° so the above code work out the equivalent x position on the image. The same applies for Latitude($row['long']) with the range -90°:90°

With this sorted the rest of the code is simple.

The Code

php code:
//Setup Image
$imagein = "PathfinderMap.jpg";
$imageout = "output.jpg";
 
//Get Image Dimentions
list($img_x,$img_y) = getimagesize($imagein);
 
//Load in image
$im = imagecreatefromjpeg($imagein);
 
//Make Image "Night time"
$darkblue = imagecolorallocatealpha($im, 0x00, 0x00, 0x00, 25);
imagefilledrectangle($im, 0, 0, $img_x,$img_y, $darkblue);
 
//Mysql Bit
$mysqli = new mysqli("**","**","**","**");
if ($mysqli->connect_error) {
    printf("Connect failed: %sn", mysqli_connect_error());
    exit();
}
 
	$sql = "** Protected for Security **";
 
 
if ($result = $mysqli->query($sql)) {
 
    while ($row = $result->fetch_array(MYSQLI_ASSOC)) {	
 
	// work out long/lat on image
	$pos_x = (int)(($img_x/2) + (($row['long']/180)*($img_x/2)));
	$pos_y = (int)(($img_y/2) - (($row['lat']/90)*($img_y/2)));
 
	//if two positions share the same pixel then combine the result 
	if(!isset($data["{$pos_x}_{$pos_y}"])){
		$data["{$pos_x}_{$pos_y}"] = $row['Rows'];
	}else{
		$data["{$pos_x}_{$pos_y}"] += $row['Rows'];
	}
 
    }
    //free result set 
    $result->close();
 
}
 
// close connection 
$mysqli->close();
 
//Size of data array
$count = count($data);
 
echo "\n"; //debug
 
foreach($data as $key=>$value){
	//Decides for each value
	//	$yellow is the light color
	//	$size is the diameter of the light
	if($value>10000){
		$yellow = imagecolorallocatealpha($im, 0xFF, 0xFF, 0x00,0);
		$size = 15;
	}elseif($value>1000){
		$yellow = imagecolorallocatealpha($im, 0xFF, 0xFF, 0x00,0);
		$size = 10;
	}elseif($value>100){
		$yellow = imagecolorallocatealpha($im, 0xFF, 0xFF, 0x00,0);
		$size = 7;
	}else{
		$yellow = imagecolorallocatealpha($im, 0xFF, 0xFF, 0x00,0);
		$size = 5;
	}
 
	// Draw light
	list($pos_x,$pos_y) = split("_",$key);
	imagefilledellipse($im, $pos_x, $pos_y, $size,$size, $yellow);
 
	$i++; //Debug
	echo "\r$i/$count (".number_format(($i/$count)*100,1)."%)";
}
 
echo "\rSaving Image this could take a bit\n";
//save Image 
imagejpeg($im,$imageout);

So there we go, I welcome any comments.

QRCode Button V1.0 Released

andrew@bluerhinos.co.uk (Andrew Milsted) — Thu, 01 Jan 2009 19:30:57 +0000

What is the QRCode Button?
The QR Code Button is a simple tool, that easily allows you to add a qr code to your website/blog.
A QR Code is a matrix code (or two-dimensional bar code) created by Japanese corporation Denso-Wave in 1994. The "QR" is derived from "Quick Response", as the creator intended the code to allow its contents to be decoded at high speed. QR Codes are common in Japan where they are currently the most popular type of two dimensional codes. The can be read by webcams and mobile phones, and can be used to store urls to websites and special offers.

How to use the QRCode Button?
To use the QR Code Button all you need to use a small amount of HTML.

HTML code:
<!-- qrcode Button BEGIN -->
<script type="text/javascript">
// Please put your url in here (can be left blank 
// if you want hide your id)
  qrcode_user = 'http://example.com'  
</script> 
<a href="http://www.bluerhinos.co.uk/qrcode/njs.php"  onclick="return false"
  onmouseover="return qrcode_open(this, 'http://example.com/')" >
    <img src="http://www.bluerhinos.co.uk/qrcode/qr_img.png"  width="16" height="16"
         border="0" alt="QR Button From bluerhinos.co.uk" />
</a> 
<script type="text/javascript" src="http://www.bluerhinos.co.uk/qrcode/qrcode_box.js"></script>
<!-- Qrcode Button END -->

Just change the "example.com" to the uri you want to encode.
And you are Done, easy.

Find out more from here: http://bluerhinos.co.uk/qrcode/

First Post

andrew@bluerhinos.co.uk (Andrew Milsted) — Thu, 18 Dec 2008 19:57:41 +0000

This is my first post, as you can proberbly see.

This is going to be the place where I put my thoughts on things and some useful tips on my quest of scripting bits and bobs.