If you have the GD library (available at » http://www.libgd.org/) you will also be able to create and manipulate images.
The format of images you are able to manipulate depend on the version of GD you install, and any other libraries GD might need to access those image formats. Versions of GD older than gd-1.6 support GIF format images, and do not support PNG, where versions greater than gd-1.6 and less than gd-2.0.28 support PNG, not GIF. GIF support was re-enabled in gd-2.0.28.
Note: Since PHP 4.3 there is a bundled version of the GD lib. This bundled version has some additional features like alpha blending, and should be used in preference to the external library since its codebase is better maintained and more stable.
You may wish to enhance GD to handle more image formats.
| Image format | Library to download | Notes |
|---|---|---|
| gif | Only supported in GD versions older than gd-1.6 and newer than gd-2.0.28. Read-only GIF support is available with PHP 4.3.0 and the bundled GD-library. Write support is available since PHP 4.3.9 and PHP 5.0.1. | |
| jpeg | » http://www.ijg.org/ | When building the jpeg library (prior to building PHP) you must use the --enable-shared option in the configure step. If you do not, you will receive an error saying libjpeg.(a|so) not found when you get to the configure step of building PHP. |
| png | » http://www.libpng.org/pub/png/libpng.html | Only supported in GD versions greater than gd-1.6. |
| xpm | » ftp://metalab.unc.edu/pub/Linux/libs/X/!INDEX.html | It's likely you have this library already available, if your system has an installed X-Environment. |
You may wish to enhance GD to deal with different fonts. The following font libraries are supported:
| Font library | Download | Notes |
|---|---|---|
| FreeType 1.x | » http://www.freetype.org/ | 本过时特性将肯定会在未来被移除。 |
| FreeType 2 | » http://www.freetype.org/ | |
| T1lib | » ftp://sunsite.unc.edu/pub/Linux/libs/graphics/) | Support for Postscript Type 1 fonts. |