More FlexCharts Goodness

Another batch of changes to FlexChart.

First is grouped series, which is hard to explain, but easy to understand.  Go hit the demo and select "Grouped Series" from the dropdown.  The chart layout has always been possible, but the legend just displayed a flat series list with no awareness of the groupings.  To see the old behaviour, change the 'legendStyle' attribute of the chart tag to "simple", and hit "Update Chart".

Second is direct support for PNG exports of the chart.  A Base64-encoded PNG can be requested via an ExternalInterface callback which you can then do whatever you want with.  The demo app just sends it server side (in a new window) for deserialization with CFIMAGE and immediately sends it back to the client.  Hardly interesting, but definitely illustrative.

Finally, I've abandoned the compile-in-page model, Flex SDK 2.0.1, and a single file architecture completely.  You can drop the binary anywhere you want without any dependency on FlexBuilder, a Flex SDK, or any server component, which is nice.  Of course, if you want to customize, it required FlexBuilder 3.  I think that's the right tradeoff.  I've also started splitting up the engine for easier maintenance, now that there's no need to keep it single file (which there was when it was server-compiled).  I haven't done much, but that'll come.  Definitely make it easier to work with.

Soon to come down the pipe are custom colors for series and sets, support for multiple y-axes, and a grid legend style which is basically a headerless datagrid under the chart with a row per series and a column per x-axis item, all lined up evenly.