Chapter 10. Graphics
The web is much more visual than textual; that is obvious. Images appear in the form of logos, buttons, photographs, charts, advertisements, and icons. Many of these images are static and never change, built with tools such as Photoshop. But many are dynamically created—from advertisements for Amazon’s referral program that include your name to graphs of stock performance.
PHP supports graphics creation with the built-in GD extension library. In this chapter, we’ll show you how to generate images dynamically within PHP.
Embedding an Image in a Page
A common misconception is that there is a mixture of text and graphics flowing across a single HTTP request. After all, when you view a page, you see a single page containing such a mixture. It is important to understand that a standard web page containing text and graphics is created through a series of HTTP requests from the web browser; each request is answered by a response from the web server. Each response can contain one and only one type of data, and each image requires a separate HTTP request and web server response. Thus, if you see a page that contains some text and two images, you know that it has taken three HTTP requests and corresponding responses to construct this page.
Take this HTML page, for example:
<html><head><title>Example Page</title></head><body>This page contains two images.<imgsrc="image1.png"alt="Image 1"/><imgsrc="image2.png"alt="Image 2"/></body></html>
The series of ...
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