Learning To SMILe - Anatomy 101 (
Page 3 of 8 )
SMIL files are based on XML, and therefore
inherit all the attributes (and constraints) of that toolkit. An SMIL document
consists of a series of nested elements, or tags, each one controlling some
aspect of the final result. As with any XML document, element names are
case-sensitive, and must be correctly nested in order for the document to be
well-formed.
Here's a simple SMIL document:
<smil xmlns="http://www.w3.org/2001/SMIL20/Language">
<head>
<layout>
<root-layout width="500" height="400" backgroundColor="white" />
<region id="alpha" left="120" top="150" width="250" height="200" />
</layout>
</head>
<body>
<img src="logo.jpg" alt="First image" region="alpha" />
</body>
</smil>
In order to see how this works, save this document with a
".smil" file extension - for example, "simple.smil" - and then pop open your
copy of the RealOne player and load this file into it. Once the player parses
the file, you should see something like this:
Not very exciting, huh? Don't worry - we'll jazz it up
a little further down. For the moment, let's just dissect the code above and see
what each of those elements actually does.
Every SMIL document must begin
and end with a pair of <smil>...</smil> elements; everything
contained within these elements forms part of the SMIL presentation. The XML
namespace for SMIL should be included in these elements via the "xmlns"
attribute.
<smil xmlns="http://www.w3.org/2001/SMIL20/Language">
...
</smil>
The remainder of the document can broadly be divided into the
<head> and the <body>, in much the same way as a regular HTML
document. The <head> contains metadata (a description of the media
presentation or a copyright notice) and layout information, while the
<body> contains the elements that reference the actual media content or
set up timers.
<smil xmlns="http://www.w3.org/2001/SMIL20/Language">
<head>
...
</head>
<body>
...
</body>
</smil>
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