I am working on a page that needs to display a number of graphs and when an individual bar is clicked a popup needs to be displayed to display a pie chart that is relevant to that bar.

At the moment I am using Flotr to produce the graphs and to handle the events, which is working very well, but flotr does not handle pie charts. I have included the plotr javascript in an attempt to draw pie charts but it seems to be causing errors with canvasNodes.

Does anyone know any graphing libraries in javascript that can be used to draw graphs and pie charts and handle events or a suitable replacement?