What is the GD library in PHP and how to enable it

1.What is GD library?

##​

GD library is an extension library for PHP to process graphics. The GD library provides a series of API# for processing images. ##, use GD library to process images or generate images. On websites, GD library is usually used to generate thumbnails or to add watermarks to images or to generate reports on website data. Cloud virtual host (Linux operating system) currently supports the GD library and supports JPG, GIF, PNG, WBMP format files. Specific supported GD version Since the selected PHP version is different, the supported GD version is also different.

2. What is the purpose of GD library?

Using the

GD

library in PHP can draw various graphic images and statistical charts on the page, if used with Ajax The combination of technologies can also produce a variety of powerful dynamic charts. There is also the verification code used in the website login page, which can also be implemented using the GD library. It should be noted that the GD library initially supported the GIF format, but because GIF used the copyright-controversial LZW algorithm, it would cause legal issues, so starting from GD library version 1.6, all GIF support Removed, but added back in GD library version 2.0.28. If a version of the GD library between the two is used, the GIF related functions are not available.

3. How to open the GD library?

GD library

is installed by default in PHP5 and above versions. If you are using a lower version, you can click Download address. If you cannot confirm whether you have activated the GD library, you can search for extension = php_gd2.dll in php.in and delete the previous ";".

## Verify whether GD library

is open

<?php
header("Content-Type:text/html; charset=utf-8");
phpinfo();
?>

As shown above, GD library

Opened successfully.

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