PHP qrencode extension, binding to libqrencode.

This PHP extension is essentially the work found at http://hirokawa.netflowers.jp/entry/4900/ (I can not find the author's name).

That site doesn't seem to exist anymore, so I am putting the code here for the benefit of everyone. I've also made some improvements (see CHANGELOG.md for details).

C programming is not my forté, so if you have any suggested improvements, please fork and send a pull request.

First, you need to compile and install libqrencode. Please see that package's README for instructions.

Then, compile php-qrencode:

	cd ../php-qrencode
	phpize
	./configure
	make
	sudo make install

Finally, add the following to the end of your php.ini file:

	extension=qrencode.so

	array qrencode( string $data, int $ecc, int $version, int $mode );

$data is the information to encode in the QR Code (e.g. URL, vCard, phone number, etc.).

$ecc is one of the error correction level constants defined below.

$version (integer in the range 1-40) defines the overall block size of the generated image (block size = (version * 4) + 17). If you pass in more data than can fit in the requested size, the function will increase the size as required so this, in effect, defines the minimum size of the resulting QR Code.

$mode is one of the storage modes defined below.

The returned two-dimensional array defines the on/off state for each pixel "block" in the resulting QR code.

To turn this data into an image, you will need to use GD functions, and loop through the array, building the image as you go. e.g.:

	<?php

	$data = qrencode( 'Hello world!', QR_ECLEVEL_L, 1, QR_MODE_8 );

	$size = count( $data );
	$im = imagecreate( $size, $size );

	$color_bg = imagecolorallocate( $im, 255, 255, 255 );
	$color_fg = imagecolorallocate( $im, 0, 0, 0 );

	imagefill( $im, 0, 0, $color_bg );

	for( $y = 0; $y < $size; $y++ ) {
		for( $x = 0; $x < $size; $x++ ) {
			if ( $data[$y][$x] ) {
				imagesetpixel( $im, $x, $y, $color_fg );
			}
		}
	}

	imagepng( $im );

QR_MODE_NUM - numeric only, max. 7,089 characters, 0-9 QR_MODE_AN - alphanumeric, max. 4,296 characters, 0-9, A-Z (uppercase only), space, $, %, *, +, -, ., /, : QR_MODE_8 - binary/byte, max. 2,953 characters (8-bit bytes) or 23624 bits QR_MODE_KANJI - Kanji/Kana, max. 1,817 characters

QR_ECLEVEL_L - Low (approximately 7% of codewords can be restored) QR_ECLEVEL_M - Medium (15%) QR_ECLEVEL_Q - Quartile (25%) QR_ECLEVEL_H - High (30%)

"QR Code" is a registered trademark of Denso Wave Incorporated.