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GChart 2.3 Release Notes

  1. Order of magnitude faster line charts via canvas**
    **Canvas implementation not included. A canvas graphics library must be downloaded and interfaced separately.

    2. This release adds a special symbol type that draws solidly connected line charts using a vector graphics (aka canvas) drawing library:

    Lines are typically drawn an order of magnitude faster (and also look a lot crisper) than with the original, HTML-element-based, LINE symbol type.

    The catch is that, to assure that GChart can deliver on its promise of requiring only its ~2K lines of pure GWT-Java and the standard GWT libraries, GChart doesn't include an appropriate canvas facility for you. Instead, you have to "bring your own canvas" by implementing GChart's GChartCanvasLite and GChartCanvasFactory interfaces.

    For example code that illustrates how easy it is to do this, check out the source code of the updated live demo's sine/cosine curve. This example shows how, with just a few lines of code, you can use the GWT incubator's GWTCanvas widget to give GChart the vector graphics capabilities it needs. Similar code should also work with other GWT vector graphics libraries, should you prefer one of them.

    Note that if you never use any of GChart's canvas-powered symbol types (right now there's only LINE_CANVAS, but others are planned) you don't have to bother implementing these GChartCanvasLite and GChartCanvasFactory interfaces.

    Once GWT's standard libraries include a vector graphics capability, GChart will simply use that. So this interface approach is a stopgap until a standard GWT canvas library is added. There's an issue on the GWT issue tracker for such a standard graphics library. If you think this interface-only approach is a big hassle, please vote for ("star") this issue to help raise the priority of getting vector graphics into the standard GWT distribution.

    Until then, you can get the canvas implementation I used in my demo and test chart by visiting the GWT incubator project and using the GWTCanvas widget its gwt-incubator.jar contains. I used the most recent, GWT 1.5-required, incubator release.

  2. GWT 1.5.2 tested (but not 1.4.62 tested, any more)

    3. The results of this informal poll on the GWT Forum revealed there was almost no value in a least common denominator approach of sticking with a GWT 1.4.62 compatible code base until all the 1.4.62 users died out because...they had almost all died out already.

    Client-side GChart users who are still using 1.4.62 are strongly urged to upgrade to 1.5.2 to assure they are working with the same version that we use for testing. Of course you can always just keep using the last 1.4.62 tested GChart (v2.2) but then you miss out on the latest features/upgrades/bugfixes. Plus, your charts will draw faster (rougly 10% speedups were observed in informal testing) if compiled with 1.5.2.

    Sorry if you still need 1.4.62 compatibility. My original inclination was to maintain backward compatibility with 1.4.62, but given the very rapid migration to 1.5.2 among GWT developers, it just didn't seem like it was worth the effort.