GD Graphics Library

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GD Graphics Library
Gdlogo small.png
Developer(s) Thomas Boutell
Initial release 1994 (1994)[1]
Stable release 2.1.0 / May 24, 2013
Written in C
Operating system Cross-platform
Type Graphical Library
License BSD-like license
Website LibGD

The GD Graphics Library is a graphics software library by Thomas Boutell and others for dynamically manipulating images. Its native programming language is ANSI C, but it has interfaces for many other programming languages. It can create GIFs, JPEGs, PNGs, and WBMPs. 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.

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

GD can create images composed of lines, arcs, text (using program-selected fonts), other images, and multiple colors. Version 2.0 adds support for truecolor images, alpha channels, resampling (for smooth resizing of truecolor images), and many other features.

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.

Example[edit]

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);
?>

See also[edit]

References[edit]

  1. ^ http://www.boutell.com/gd/faq.html
  2. ^ http://martin.gleeson.com/fly/ "fly" site by Martin Gleeson

External links[edit]