GD Graphics Library

Developer(s)	Thomas Boutell
Initial release	1994; 30 years ago (1994)
Stable release	2.3.1  / 30 January 2021; 12 September 2021; Error: first parameter cannot be parsed as a date or time. (30 January 2021; 12 September 2021)[1]
Repository	https://github.com/libgd/libgd
Written in	C
Operating system	Cross-platform
Type	Graphics library
License	BSD-like license
Website	libgd.github.io

The GD Graphics Library is a graphics software library for dynamically manipulating images. It can create GIFs, JPEGs, PNGs, and WBMPs. The images can be composed of lines, arcs, text (using program-selected fonts), other images, and multiple colors, supporting truecolor images, alpha channels, resampling, and many other features.

Its native programming language is ANSI C, but it has interfaces for many other programming languages. GD supports numerous programming languages including C, PHP, Perl, Python, OCaml, Tcl, Lua, Pascal, GNU Octave, Rexx, Ruby and Go. In addition, the "Fly" command line interpreter allows for image creation ("on the fly") using GD. GD scripts can thus be written in potentially any language and run using this tool.^[2]

GD is extensively used with PHP, where a modified version supporting additional features is included by default as of PHP 4.3 and was an option before that. As of PHP 5.3, a system version of GD may be used as well, to get the additional features that were previously available only to the bundled version of GD.

History

The software was developed in 1994 by Thomas Boutell and others.

GD originally stood for "GIF Draw". However, since the revoking of the Unisys license, it has informally stood for "Graphics Draw".

Support for drawing GIFs was dropped in 1999 when Unisys revoked the royalty-free license granted to non-commercial software projects for the LZW compression method used by GIFs. When the Unisys patent expired worldwide on July 7, 2004, GIF support was subsequently re-enabled.

Version 2.0 added support for truecolor images, alpha channels, resampling (for smooth resizing of truecolor images), and many other features.

Example

The following is an example which outputs a 3D looking pie chart (from the PHP GD documentation on the imagefilledarc() function).

<?php
    // Create an image
    $image = imagecreatetruecolor(100, 100);

    // Allocate some colors
    $white    = imagecolorallocate($image, 0xFF, 0xFF, 0xFF);
    $gray     = imagecolorallocate($image, 0xC0, 0xC0, 0xC0);
    $darkgray = imagecolorallocate($image, 0x90, 0x90, 0x90);
    $navy     = imagecolorallocate($image, 0x00, 0x00, 0x80);
    $darknavy = imagecolorallocate($image, 0x00, 0x00, 0x50);
    $red      = imagecolorallocate($image, 0xFF, 0x00, 0x00);
    $darkred  = imagecolorallocate($image, 0x90, 0x00, 0x00);

    // Make the 3D effect
    for ($i = 60; $i > 50; $i--) {
        imagefilledarc($image, 50, $i, 100, 50, 0,   45, $darknavy, IMG_ARC_PIE);
        imagefilledarc($image, 50, $i, 100, 50, 45,  75, $darkgray, IMG_ARC_PIE);
        imagefilledarc($image, 50, $i, 100, 50, 75, 360, $darkred,  IMG_ARC_PIE);
    }

    imagefilledarc($image, 50, 50, 100, 50,  0,  45, $navy, IMG_ARC_PIE);
    imagefilledarc($image, 50, 50, 100, 50, 45,  75, $gray, IMG_ARC_PIE);
    imagefilledarc($image, 50, 50, 100, 50, 75, 360, $red,  IMG_ARC_PIE);

    // Flush the image
    header('Content-type: image/png');
    imagepng($image);
    imagedestroy($image);
?>