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Articles Thoughts

In defense of reinventing wheels

One of the first things a software engineer learns is “don’t reinvent the wheel”. If something is already made, use that instead of writing your own. “Stand on the shoulders of giants, they know what they’re doing better than you”. Writing your own tools and libraries, even when one already exists, is labelled “NIH syndrome”  and is considered quite bad.

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Original Tips

Convert PHP serialized data to Unicode

I recently had to convert a database of a large greek website from single-byte greek to Unicode (UTF-8). One of the problems I faced was the stored PHP serialized data: As PHP stores the length of the data (in bytes) inside the serialized string, the stored serialized strings could not be unserialized after the conversion.

I didn’t want anyone to go through the frustration I went through while searching for a solution, so here is a little function I wrote to recount the string lengths, since I couldn’t find anything on this:

function recount_serialized_bytes($text) {
	mb_internal_encoding("UTF-8");
	mb_regex_encoding("UTF-8");

	mb_ereg_search_init($text, 's:[0-9]+:"');

	$offset = 0;

	while(preg_match('/s:([0-9]+):"/u', $text, $matches, PREG_OFFSET_CAPTURE, $offset) ||
		  preg_match('/s:([0-9]+):"/u', $text, $matches, PREG_OFFSET_CAPTURE, ++$offset)) {
		$number = $matches[1][0];
		$pos = $matches[1][1];

		$digits = strlen("$number");
		$pos_chars = mb_strlen(substr($text, 0, $pos)) + 2 + $digits;

		$str = mb_substr($text, $pos_chars, $number);

		$new_number = strlen($str);
		$new_digits = strlen($new_number);

		if($number != $new_number) {
			// Change stored number
			$text = substr_replace($text, $new_number, $pos, $digits);
			$pos += $new_digits - $digits;
		}

		$offset = $pos + 2 + $new_number;
	}

	return $text;
}

My initial approach was to do it with regular expressions, but the PHP serialized data format is not a regular language and cannot be properly parsed with regular expressions. All approaches fail on edge cases, and I had lots of edge cases in my data (I even had nested serialized strings!).

Note that this will only work when converting from single-byte encoded data, since it assumes the stored lengths are the string lengths in characters. Admittedly, it’s not my best code, it could be optimized in many ways. It was something I had to write quickly and was only going to be used by me in a one-time conversion process. However, it works smoothly and has been tested with lots of different serialized data. I know that not many people will find it useful, but it’s going to be a lifesaver for the few ones that need it.

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News Original

rgba.php v1.2: Improved URL syntax, now at Github

I wrote the first version of rgba.php as a complement to an article on RGBA that I posted on Februrary 2009.
Many people seemed to like the idea and started using it. With their valuable input, I made many changes and released v.1.1 (1.1.1 shortly after I posted the article due to another little fix) on October 2009.
More than a year after, quite a lot of people still ask me about it and use it, so I decided to make a github repo for it and release a new version, with a much easier to use syntax for the URL, which lets you just copy and paste the color instead of rewriting it:

background: url('rgba.php/rgba(255, 255, 255, 0.3)');
background: rgba(255, 255, 255, 0.3);

instead of:

background: url('rgba.php?r=255&g=255&b=255&a=30');
background: rgba(255, 255, 255, 0.3);

I also made a quick about/demo page for it.
Enjoy 🙂

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Original

Quickly find the Gravatar that cor­res­ponds to a given email

Today I needed to quickly find the Gravatars that corresponded to a bunch of email addresses for some reason (don’t ask). After a bit of googling and wandering around in Gravatar’s official site and others, I firgured out it’s probably much quicker to write a short PHP script for that myself, than keep looking.

Here it is, in case someone ever needs to do something similar: (click on the screenshot)

Quickly find the Gravatar that cor­res­ponds to a given email

(has anyone noticed my latest love affair with Helvetica/Arial? 😛 )

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Original

New version of rgba.php is out!

It’s been a while since I posted my little server-side solution for cross-browser RGBA colors (in a nutshell: native rgba for the cool browsers that support it, a PHP-generated image for those that don’t). For features, advantages, disadvantages etc, go see the original post. In this one I’ll only discuss the new version.

So, since it’s release I’ve received suggestions from many people regarding this script. Some other ideas were gathered during troubleshooting issues that some others faced while trying to use it. I hope I didn’t forget anything/anyone 🙂

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News Personal

CSS3 colors, today (MediaCampAthens session)

Yesterday, I had a session at MediaCampAthens (a BarCamp-style event), regarding CSS3 colors. If you’ve followed my earlier posts tagged with “colors”, my presentation was mostly a sum-up of these.

It was my first presentation ever, actually, the first time I talked to an audience for more than 1 minute 😛 . This caused some goofs:

  • When introducing myself, I said completely different things than I intended to and ended up sounding like an arrogant moron 😛
  • I tried not to look at the audience too much, in order to avoid sounding nervous, and this caused me to completely ignore 2 questions (as I found out afterwards)! How embarrasing!
  • At a certain point, I said “URL” instead of “domain” 😛

Also, I had prepared some screenshots (you’ll see them in the ppt) and the projector completely screwed them up, as it showed any dark color as black.

Apart from those, I think it went very well, I received lots of positive feedback about it and the audience was paying attention, so I guess they found it interesting (something that I didn’t expect 😛 ).

Here is the presentation:

Please note that Slideshare messed up slide #8 and the background seems semi-transparent grey instead of semi-transparent white.

By the way, I also thought afterwards that I had made a mistake: -ms-filter is not required if we combine the gradient filter with Data URIs, since IE8 supports Data URIs (for images at least). Oops, I hate making mistakes that I can’t correct.

Here are some photos from my session. If I did it correctly, every facebook user can see them. If I messed things up, tell me 😛

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Apps & scripts Articles Original

Bulletproof, cross-browser RGBA backgrounds, today

UPDATE: New version

First of all, happy Valentine’s day for yersterday. 🙂 This is the second part of my “Using CSS3 today” series. This article discusses current RGBA browser support and ways to use RGBA backgrounds in non-supporting browsers. Bonus gift: A PHP script of mine that creates fallback 1-pixel images on the fly that allow you to easily utilize RGBA backgrounds in any browser that can support png transparency. In addition, the images created are forced to be cached by the client and they are saved on the server’s hard drive for higher performance.