PHP6 and MySQL® 6 Bible

Chapter 42. Creating Graphics with PHP

IN THIS CHAPTER

Overview of images in web scripting

Creating graphics in HTML

Introduction to the gd image manipulation library

Troubleshooting image creation code

In this chapter, we delve into how to use PHP to create graphics of your own and display them to the user. Although we spend a little bit of time on pure HTML "graphics," our primary focus is on creating images on the fly by using the gd library. This library helps you create images such as PNGs and JPEGs, which you can then link to from dynamically generated HTML pages or send to the user as standalone web pages.

Your Options

Just to see where image creation fits into the web-scripting world, look at the following spectrum of choices, in order of increasing dynamics:

• You can have no graphics at all and display purely textual information.

• You can embed static images in your HTML, whether created by yourself or by other people.

• You can write programmatically generated HTML pseudographics.

• You can embed static image graphics (or even image animations, if you insist) in your HTML pages, but display different ones conditionally.

• You can use gd to pre-generate static graphics for all the cases that may possibly arise from your code, store them in files, and display them conditionally.

• You can create graphic images on demand in response to user input.

We start off with the third option (HTML graphics) and then devote most of the rest of the chapter to the last one, which is the most interesting case. ...