SVG Essentials

Chapter 11. Animating and Scripting SVG

Up to this point we have produced static images; once constructed, they never change. In this chapter, we will examine two methods of making graphic images move. The first method, animation, is movement that is controlled by you, the author. The second method, scripting, lets the person viewing the graphic interact with and modify the image.

In Chapter 10 we suggested that filters should be used as a means to enhance a graphic’s message, not as an end in themselves. This suggestion is even more crucial with animation. Drunk with the power of animation, you will be tempted to turn your every graphic into an all-dancing, all-singing, Broadway spectacular. As long as your goal is experimentation, this is fine. If your goal is to convey a message, however, nothing is worse than gratuitous use or overuse of animation. Let me state this clearly: nobody except the company CEO is interested in repeated viewing of a spinning, flashing, color-changing, strobe-lit version of the company logo.

In this chapter, our message is the animation, so most of our examples will be remarkably free of any content. We will, of course, avoid gratuitous and overwrought animation as much as possible.

Animation Basics

The animation features of SVG are based on the World Wide Web Consortium’s Synchronized Multimedia Integration Language Level 2 (SMIL2) specification http://www.w3.org/TR/smil20/. In this system, you specify the starting and ending values of the attribute, ...