GD Graphics Library
File:Gdlogo small.png | |
Developer(s) | Thomas Boutell |
---|---|
Initial release | 1994 |
Repository | https://github.com/libgd/libgd |
Written in | C |
Operating system | Cross-platform |
Type | Graphics 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
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
- GDAL - for geospatial images
- GraphicsMagick
- ImageMagick
- Netpbm
- Python Imaging Library
References
- ^ "LibGD releases".
- ^ Gleeson, Martin. "fly: create images on the fly".
External links
- GD Graphics Library
- PHP GD Bar Chart archived
- Image Functions (PHP), support in PHP