What is the GD library? Detailed introduction to loading GD library in PHP

What is the GD library? A detailed introduction to loading the GD library in PHP

What is the GD library?

First of all, we need to introduce what the GD library is: GD library is an extension library for PHP to process graphics. The GD library provides a series of APIs for processing images, which can be processed using the GD library. Picture, or generate picture, GD library is an open, dynamically created image, source code public function library, which can be downloaded from the official website. Currently, the GD library supports GIF, PNG, JPEG, WBMP and XBM and other image formats for image processing!

The GD library is installed by default in PHP5, but the GD library must be activated. The php.ini file must be set up by removing the semicolon ";" before the ";extension = php_gd2.dll" option in the file. Then save the modified file and restart the Apache server to take effect!

After successfully loading the GD2 function library, you can obtain the installation information of the GD2 function library through the phpinfo() function, verify whether the GD library is installed successfully, and check whether there is GD support on the page. If not, you need Install additional extensions.

There are two ways to verify the GD library. The first is to create a php file and then directly output phpinfo(). The code is as follows:

The second method is to enter the browser address Enter "127.0.0.1/phpinfo.php" in the column and press Enter. The results obtained by the first and second methods are the same. If the installation information of the GD library is retrieved in the page, it means that the GD library The installation was successful! As shown below:

Instructions:

1. If you use the integrated installation package Don't worry about this problem when configuring the PHP development environment, because in the integrated installation package, the default GD2 function library has been loaded.

2. The GD library can be used under both Linux and Windows systems, and the functions are exactly the same, but the coordinates of the graphics will be offset. If the two systems are ported to each other, the interface must be revisited.

We will introduce loading the GD library in PHP here. In the next article, we will introduce the application of graphics and images. For details, please read "Detailed explanation of creating images and colors and filling background colors (PHP Typical application tutorials for graphics and images 1)》!

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