Các hàm hữu dụng PHP phần 2

How to Resize Image Dynamically in PHP

Today almost every website you visit show content in form of thumbnails. Thumbnails are nothing but images displayed next to the content. Be it News website or a blog, displaying images next to content is key to appeal user. Even our blog shows images as thumbnails on home page.

A prerequisites to show Thumbnail in a webpage is that thumbnail must be small enough. So that many thumbnails can be loaded as fast as possible. Hence almost every website resize the image to create small thumbnails.

So how to do this on the fly? How to resize an Image dynamically in PHP?

There is an extremely useful PHP library called timthumb which comes very handy. It’s just a simple PHP script that you need to download and put in some folder under your website. And then simply call it with appropriate arguments.

1. Download timthumb.php and put under any folder.
2. Upload this script timthumb.php though FTP to your web hosting. Put it under a directory /script.
3. Just call timthumb.php with appropriate arguments, For example:

   <img src="/script/timthumb.php?src=/some/path/myimage.png&w=100&h=80"     alt="resized image" />

And that’s all!!

One thing worth noting here is that this library will create a folder cache in the directory where timthumb.php script resides. This folder will cache the resized image for better performance.

You can refer following table for different parameters and its meaning.

	Parameter	Values	Meaning
src	source	url to image	Tells TimThumb which image to resize
w	width	the width to resize to	Remove the width to scale proportionally (will then need the height)
h	height	the height to resize to	Remove the height to scale proportionally (will then need the width)
q	quality	0 – 100	Compression quality. The higher the number the nicer the image will look. I wouldn’t recommend going any higher than about 95 else the image will get too large
a	alignment	c, t, l, r, b, tl, tr, bl, br	Crop alignment. c = center, t = top, b = bottom, r = right, l = left. The positions can be joined to create diagonal positions
zc	zoom / crop	0, 1, 2, 3	Change the cropping and scaling settings
f	filters	too many to mention	Let’s you apply image filters to change the resized picture. For instance you can change brightness/ contrast or even blur the image
s	sharpen		Apply a sharpen filter to the image, makes scaled down images look a little crisper
cc	canvas colour	hexadecimal colour value (#ffffff)	Change background colour. Most used when changing the zoom and crop settings, which in turn can add borders to the image.
ct	canvas transparency	true (1)	Use transparency and ignore background colour

Hope this is useful for you 

Caching Dynamic PHP pages easily

Things to think about

It’s not a good idea to go away and cache your entire site, you need to think about which pages receive high traffic, and which pages make a number of database requests. Static HTML pages aren’t going to see a benefit from caching and may in fact be served slower due to PHP invoking the request to the cached version. as an example I’m using caching on dotdashcreate.com homepage as there are a number of database requests that could easily be cached, the cached version of the page is stored here.

If you run a big site or blog I would certainly recommend caching your homepage as this will usually be your visitors first point of contact thus generating more traffic. Its probably not a good idea to cache individual posts that allow comments etc, unless you are willing to write a script to re-cache the page.

You need to allow write access to the cache directory, in the code example this is /cache/. There’s quite a bit going on in the script, the first two lines set the path to the cached directory and the time frame to refresh the cache, we then do a check to see if the cached file is older than the cache time, if it is then it refreshes the cached version (which is the block of code at the bottom), if not it just serves the cached version.

The Code:

$cachefile = 'cache.html';




$cachetime = 4 * 60;




// Serve from the cache if it is younger than $cachetime




if (file_exists($cachefile) && time() - $cachetime < filemtime($cachefile)) {




    include($cachefile);




    echo "<!-- Cached copy, generated ".date('H:i', filemtime($cachefile))." -->\n";




    exit;




}




ob_start(); // Start the output buffer







/* Heres where you put your page content */







// Cache the contents to a file




$cached = fopen($cacheFile, 'w');




fwrite($cached, ob_get_contents());




fclose($cached);




ob_end_flush(); // Send the output to the browser





Super simple page caching

When your project isn’t based on a CMS or framework, it can be a good idea to implement a simple caching system on your pages. The following code snippet is very simple, but works well for small websites.
<?php
    // define the path and name of cached file
    $cachefile = 'cached-files/'.date('M-d-Y').'.php';
    // define how long we want to keep the file in seconds. I set mine to 5 hours.
    $cachetime = 18000;
    // Check if the cached file is still fresh. If it is, serve it up and exit.
    if (file_exists($cachefile) && time() - $cachetime < filemtime($cachefile)) {
    include($cachefile);
        exit;
    }
    // if there is either no file OR the file to too old, render the page and capture the HTML.
    ob_start();
?>
    <html>
        output all your html here.
    </html>
<?php
    // We're done! Save the cached content to a file
    $fp = fopen($cachefile, 'w');
    fwrite($fp, ob_get_contents());
    fclose($fp);
    // finally send browser output
    ob_end_flush();
?>


Using Glob() to Find Files


Many PHP functions have long and descriptive names. However it may be hard to tell what a function namedglob() does unless you are already familiar with that term from elsewhere.


Think of it like a more capable version of the scandir() function. It can let you search for files by using patterns.




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// get all php files  
$files = glob('*.php');  
  
print_r($files);  
/* output looks like: 
Array 
( 
    [0] => phptest.php 
    [1] => pi.php 
    [2] => post_output.php 
    [3] => test.php 
) 
*/  




You can fetch multiple file types like this:




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// get all php files AND txt files  
$files = glob('*.{php,txt}', GLOB_BRACE);  
  
print_r($files);  
/* output looks like: 
Array 
( 
    [0] => phptest.php 
    [1] => pi.php 
    [2] => post_output.php 
    [3] => test.php 
    [4] => log.txt 
    [5] => test.txt 
) 
*/  




Note that the files can actually be returned with a path, depending on your query:




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$files = glob('../images/a*.jpg');  
  
print_r($files);  
/* output looks like: 
Array 
( 
    [0] => ../images/apple.jpg 
    [1] => ../images/art.jpg 
) 
*/  




If you want to get the full path to each file, you can just call the realpath() function on the returned values:




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$files = glob('../images/a*.jpg');  
  
// applies the function to each array element  
$files = array_map('realpath',$files);  
  
print_r($files);  
/* output looks like: 
Array 
( 
    [0] => C:\wamp\www\images\apple.jpg 
    [1] => C:\wamp\www\images\art.jpg 
) 
*/  






Whois query using PHP

If you need to get the whois information for a specific domain, why not using PHP to do it? The following function take a domain name as a parameter, and then display the whois info related to the domain.
function whois_query($domain) {
 
    // fix the domain name:
    $domain = strtolower(trim($domain));
    $domain = preg_replace('/^http:\/\//i', '', $domain);
    $domain = preg_replace('/^www\./i', '', $domain);
    $domain = explode('/', $domain);
    $domain = trim($domain[0]);
 
    // split the TLD from domain name
    $_domain = explode('.', $domain);
    $lst = count($_domain)-1;
    $ext = $_domain[$lst];
 
    // You find resources and lists 
    // like these on wikipedia: 
    //
    // http://de.wikipedia.org/wiki/Whois
    //
    $servers = array(
        "biz" => "whois.neulevel.biz",
        "com" => "whois.internic.net",
        "us" => "whois.nic.us",
        "coop" => "whois.nic.coop",
        "info" => "whois.nic.info",
        "name" => "whois.nic.name",
        "net" => "whois.internic.net",
        "gov" => "whois.nic.gov",
        "edu" => "whois.internic.net",
        "mil" => "rs.internic.net",
        "int" => "whois.iana.org",
        "ac" => "whois.nic.ac",
        "ae" => "whois.uaenic.ae",
        "at" => "whois.ripe.net",
        "au" => "whois.aunic.net",
        "be" => "whois.dns.be",
        "bg" => "whois.ripe.net",
        "br" => "whois.registro.br",
        "bz" => "whois.belizenic.bz",
        "ca" => "whois.cira.ca",
        "cc" => "whois.nic.cc",
        "ch" => "whois.nic.ch",
        "cl" => "whois.nic.cl",
        "cn" => "whois.cnnic.net.cn",
        "cz" => "whois.nic.cz",
        "de" => "whois.nic.de",
        "fr" => "whois.nic.fr",
        "hu" => "whois.nic.hu",
        "ie" => "whois.domainregistry.ie",
        "il" => "whois.isoc.org.il",
        "in" => "whois.ncst.ernet.in",
        "ir" => "whois.nic.ir",
        "mc" => "whois.ripe.net",
        "to" => "whois.tonic.to",
        "tv" => "whois.tv",
        "ru" => "whois.ripn.net",
        "org" => "whois.pir.org",
        "aero" => "whois.information.aero",
        "nl" => "whois.domain-registry.nl"
    );
 
    if (!isset($servers[$ext])){
        die('Error: No matching nic server found!');
    }
 
    $nic_server = $servers[$ext];
 
    $output = '';
 
    // connect to whois server:
    if ($conn = fsockopen ($nic_server, 43)) {
        fputs($conn, $domain."\r\n");
        while(!feof($conn)) {
            $output .= fgets($conn,128);
        }
        fclose($conn);
    }
    else { die('Error: Could not connect to ' . $nic_server . '!'); }
 
    return $output;
}


Source: http://www.jonasjohn.de/snippets/php/whois-query.htm


Detect location by IP

Here is an useful code snippet to detect the location of a specific IP. The function below takes one IP as a parameter, and returns the location of the IP. If no location is found, UNKNOWN is returned.
function detect_city($ip) {
        
        $default = 'UNKNOWN';

        if (!is_string($ip) || strlen($ip) < 1 || $ip == '127.0.0.1' || $ip == 'localhost')
            $ip = '8.8.8.8';

        $curlopt_useragent = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)';
        
        $url = 'http://ipinfodb.com/ip_locator.php?ip=' . urlencode($ip);
        $ch = curl_init();
        
        $curl_opt = array(
            CURLOPT_FOLLOWLOCATION  => 1,
            CURLOPT_HEADER      => 0,
            CURLOPT_RETURNTRANSFER  => 1,
            CURLOPT_USERAGENT   => $curlopt_useragent,
            CURLOPT_URL       => $url,
            CURLOPT_TIMEOUT         => 1,
            CURLOPT_REFERER         => 'http://' . $_SERVER['HTTP_HOST'],
        );
        
        curl_setopt_array($ch, $curl_opt);
        
        $content = curl_exec($ch);
        
        if (!is_null($curl_info)) {
            $curl_info = curl_getinfo($ch);
        }
        
        curl_close($ch);
        
        if ( preg_match('{<li>City : ([^<]*)</li>}i', $content, $regs) )  {
            $city = $regs[1];
        }
        if ( preg_match('{<li>State/Province : ([^<]*)</li>}i', $content, $regs) )  {
            $state = $regs[1];
        }

        if( $city!='' && $state!='' ){
          $location = $city . ', ' . $state;
          return $location;
        }else{
          return $default; 
        }
        
    }


Source: http://snipplr.com/view/48386/detect-location-by-ip-city-state/