Johann Philipp Strathausen

maker of dracula.js co-founder of FitAnalytics

March 2nd, 2010

Dracula Graph Library

I was searching for an easy way to display graphs in the browser without having to rely on plug-ins like Flash or Java and I found a piece of code named "Graph JavaScript framework, version 0.0.1". You could simply add some nodes to a graph model, and then layout and having it displayed.

Unfortunately, it was soo three years ago and had a PrototypeJS dependency that I didn't really need. Besides that, nothing happened to the code since then. So I took the RaphaelJS example to connect some shapes and plugged it together with that code I found. The algorithm used by the Graph Frameork 0.0.1 is quite solid and mostly produces pleasant results. You can now even have fun dragging around the nodes.

Example

Here's an example on how easy it is to use (it doesn't differ much from the original code, but includes some customizations):

var redraw;
      var height = 300;
      var width = 400;
      
      var g = new Graph();
      
      /* add simple nodes */
      g.addNode("strawberry");
      g.addNode("cherry");
      
      /* add a node with a customized label */
      g.addNode("id34", { label : "Tomato" });
      
      /* add a node with a customized shape
         (the Raphael graph drawing implementation can draw
         this shape, please consult the RaphaelJS reference
         for details raphaeljs.com) */
      g.addNode("id35", {
        label : "Meat" ,
        /* filling the shape with a color
           makes it easier to be dragged */
        getShape : function(r,x,y) {
          return r.rect(x-30, y-13, 62, 33)
            .attr({"fill": "#f00", "stroke-width": 2});
        }
      });
      
      /* connect nodes with edges */
      g.addEdge("strawberry", "cherry");
      g.addEdge("cherry", "apple");
      g.addEdge("id34", "cherry");
      
      /* customize the colors of that edge */
      g.addEdge("id35", "apple",
        { color : "#38a" , colorbg : "#bdf" });
      
      /* add an unknown node implicitly by adding an edge */
      g.addEdge("strawberry", "apple");
      
      /* layout the graph using the Spring layout implementation */
      var layouter = new Graph.Layout.Spring(g);
      layouter.layout();
      
      /* draw the graph using the RaphaelJS draw implementation */
      var renderer =
        new Graph.Renderer.Raphael('canvas', g, width, height);
      renderer.draw();
      
      redraw = function() {
        layouter.layout();
        renderer.draw();
      };
      

The result will look like this:

You can try it at dracula.ameisenbar.de, get the code via launchpad at GitHub or get the zip archive. There are still some optimizations necessary for the layout algorithm as well as the code structure. I already commented most of the code and there's also an example HTML page demonstrating all possible options. Enjoy!

Thanks for any comments! (Comment section will be back at some point)

Update: There's a new version to try!