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Unit 12: Images

If you cannot install PHP, “Installing and Configuring PHP,” and are stuck with a version of Notes
PHP earlier than 4.3.0, you will have to go to http://www.boutell.com/gd/ and download the
source of the GD library. Follow the instructions included with that software, and consult its
manual for difficulties with installation.

To enable the use of the GD library at installation time, Linux/Unix users must add the following
to the configure parameters when preparing to build PHP:
—with-gd

If you download your own version of GD, you must specify the path, as in
—with-gd=/path/to/gd.

After running the PHP configure program again, you must go through the make and make
install process. Windows users who want to enable GD simply have to activate php_gd2.dll as
an extension in the php.ini file.
When using the GD library, you are limited to working with files in GIF format. However, by
installing additional libraries, you can work with JPEG and PNG files as well.
12.2.1 Obtaining Additional Libraries

Working with GIF files might suit your needs perfectly, but if you want to create JPEG or PNG
files, you will need to download and install a few libraries, and make some modifications to
your PHP installation.
JPEG libraries and information can be found at ftp://ftp.uu.net/graphics/jpeg/.

PNG libraries and information can be found at http://www.libpng.org/pub/png/libpng.html.

If you are working with PNG files, you should also install the zlib library, found at
http://www.gzip.org/zlib/.

Follow the instructions at these sites to install the libraries. After installation, Linux/Unix users
must again reconfigure and rebuild PHP by first adding the following to the PHP configures
parameters (assuming that you want to use all three, if not, just add the applicable ones):

—with-jpeg-dir=[path to jpeg directory]

—with-png-dir=[path to PNG directory]
—with-zlib=[path to zlib directory]

After running the PHP configure program again, you need to go through the make and make
install process. Your libraries should then be activated and ready for use.

12.3 Drawing a New Image

Drawing shapes and lines with PHP is nothing like drawing with image editing program.
Actually, when drawing with PHP you become the editing program. You use individual PHP
functions to define colours, draw and fill shapes, re-size and save the image. These functions
are part of the GD graphics library that was bundled beginning with PHP version 4.3.0.

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