The example Stardraw HAL driver serves as the bridge between the Stardraw application and the Halogen/HAL Control Server. Its purpose is to provide suitable properties and events for the Stardraw application and to handle Halogen/HAL Control System messages – both sending them to the Halogen/HAL Control Server when the Stardraw application changes a control and receiving messages from Halogen/HAL and making sure the Stardraw application knows about them.
This section describes the example Stardraw HAL driver in two parts. The more generic part is first, and discusses how the driver communicates with the Halogen/HAL Control Server. This part is suitable for use as the basis of any HAL driver. The second part describes methods, properties and events that the driver provides for the Stardraw application and how these are hooked to the HAL communications driver portions. These methods, properties and events are specific to the external controls configured in the HAL1x example configuration file and allow the Stardraw application to use them.