Hi Paulo,
Indeed you can develop your own chart types in sonar plugins. The extension point is
org.sonar.plugins.api.charts.Chart in sonar-plugin-api module. It's recommended to extend AbstractChart and to use JFreechart. For the moment all needed data have to be passed in http parameters. The chart can not directly load measures from database.
Unfortunatly the
helloworld project still does not contain chart samples. We'll fix it as soon as possible.
Regards,
Simon