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js-mindmap

Kenneth Kufluk 2008/09/10/11

This code is provided at:
https://github.com/kennethkufluk/js-mindmap

A demo is provided at:
http://kenneth.kufluk.com/google/js-mindmap/

Requires jQuery for basic shortcuts ($) and stuff.
Requires Raphael for drawing.
jQuery UI may be used to allow draggable nodes.

This code is released under license.  Please leave acknowledgements and copyright messages in the code.


WHAT IS THIS?
-------------

This is a small demo script, intended for fun applications.
My favourite is this:
http://www.pcworld.com/misc/edit/195163/index.htm

If you feel like building it out into a massively overfeatured application, please go ahead.  While I've stuck some liberal licensing on it, the basic principles of a force directed layout controlling nodes are as free as the birds in the trees.
My favourite massively overfeatured application is this:
http://www.mindjet.com/ (great for meeting notes)


HOW THIS WORKS
--------------

It's relatively easy to build a mindmap.  Take a collection of HTML nodes, and position them absolutely.  Use a Force Directed Layout to link them together and yet keep them apart.

http://en.wikipedia.org/wiki/Force-based_algorithms_(graph_drawing)

Once you've got that, you need to add some filters, to define which nodes are properly connected. All nodes should repel, to prevent overlap, but connected nodes should have a string between them.  This is where you use a springy force (hooke's law) to pull them together.

Drawing lines in HTML is not an easy feat.  IE has/had VML, all browsers (except Android) support SVG (albeit slowly), and all except IE support Canvas.  I tried using a diagonal line in a JPG, stretching it to fit.  It looks daft.  I then switched to Canvas, and now I'm on SVG (using Raphael to support IE VML too).  So it works everywhere except Android.


ALTERNATIVES
------------

Before I wrote this, I used an open-source mindmap written in Flex.  It was beautiful.
It's here:
http://www.rubenswieringa.com/blog/interactive-mindmap
It uses Mark Shepard's SpringGraph component, which has lots of interesting demos:
http://mark-shepherd.com/blog/springgraph-flex-component/

I considered migrating this component to JS, but found it massively over-complicated for the simple uses I had in mind.


APPLICATIONS IN THE WILD
------------------------

I use this code for my own mindmap website here:
http://sunshinemisiu.com/

Also, there's a PCWorld page about Google here:
http://www.pcworld.com/misc/edit/195163/index.htm

Let me know of any others to add here.