Canvas set to boost AJAX

Canvas, a planned HTML standard for arbitrary graphical rendering in browsers, presents a game-changing technology for high-quality graphics in AJAX applications, an advocate said at the ZendCon 2008 conference in Santa Clara, Calif. this week.

With Canvas, developers can paint anything they like and are no longer wedded to merely a paradigm of boxes and images, according to Ben Galbraith, co-founder of the Ajaxian.com Web site and a speaker at ZendCon.

"This is sort of a radical departure," he said.

Canvas is a retained image drawing API in which the JavaScript environment sends instructions to the Canvas implementation. Canvas then retains all these instructions and is responsible for doing repainting to the screen, Galbraith said.

"The result is you can actually create some really, really responsive user interfaces," he said.

"Canvas is really, really exciting," Galbraith stressed. The technology is going to change the game for Web application development, he said.

Canvas is part of the proposed HTML 5 standard, which is under jurisdiction of the World Wide Web Consortium and the WHATWG community. There already are multiple implementations of Canvas.

Galbraith touted a responsive text editor he co-developed that was implemented in JavaScript entirely in Canvas and features syntax highlighting. Canvas has functioned in browsers including Google Chrome, Firefox, Opera and Safari, said Galbraith. It also can work in Internet Explorer through a Google-built experimental bridge or an ActiveX plugin created by Mozilla, he said.

With the Google bridge, Canvas can be mapped to Microsoft's Silverlight technology, said Galbraith. There also is a Canvas API port to Flash as well as a Canvas implementation for Apple iPhone, even though the iPhone itself is not used for writing code, said Galbraith.

Also set to boost JavaScript application performance is the appearance of high-performing JavaScript interpreters, such as Mozilla TraceMonkey and the Chrome interpreter, Galbraith said.

"Today, desktop applications can wallop AJAX applications in terms of performance," Galbraith said. Desktop runtimes are much faster, he said. But TraceMonkey, planned for the Firefox 3.1 browser, is "dramatically faster than the current interpreter," Galbraith said.