What is the best approach to producing graphical charts in a browser?

I've started a new open source project aimed at providing a quality project management experience. To do this, I need access to a set of chart tools (Flash is off the table), and very specifically one that includes a Gantt chart. I've done my homework and shopped around the web and I've more or less come to the conclusion that what I want doesn't exist, at least not for free. So chances are I'm going to have to write this from scratch.

If I was going to create a Gantt chart with which people could interact with (which I'm assuming means having excellent DOM support), then what technology would I use? Should I go with SVG? Or HTML5 Canvas? Something else? Your suggestions are much appreciated.

Also, a requirement would be that whatever library I use needs开发者_Go百科 to be actively supported in the community (i.e. no dead projects).

I would not think there would be many free options as this is a niche-need.

JS Option:

• http://www.jsgantt.com/
• http://code.google.com/p/flot/

Promising Perl modules:

• http://cpansearch.perl.org/src/DARNOLD/DBD-Chart-0.82/dbdchart.html
• http://search.cpan.org/~awestholm/Project-Gantt-1.03/Gantt.pm

Update:

There's been amazing advancements in terms of interactive/web charts in the past few years. Shortly before your question was asked, D3.js was created, which has become a generally accepted library, which uses SVG to implement visualizations. Here's a basic example and a more advanced implementation using D3. Note; Gantt charting is still in its infancy; D3 will most likely revisit it in the future.

The argument of Canvas vs SVG is one that has been considered many times. You should read this article by Microsoft; How to Choose Between Canvas and SVG for your Site. Basically, if you have many elements you have to display, Canvas will perform much better. If accessibility is a priority, SVG is better.

In terms of working with Canvas vs SVG, canvas feels more fluid and it is certainly more capable with WebGL, but SVG is more transportable. They both have their merits.

If you're going to make your own, I'd recommend the SVG library Raphaël, which allows you to draw things using SVG fairly easily. It's also simple to make mouse event handlers and other things, which you could use to make it interactive.

I haven't had much experience creating interactive graphics with canvas, but my instinct is that it would be hard to handle mouse events since you don't have "elements" to add event listeners to.