The High Level Utilities (HLUs) are a library of tools that provide a consistent programming interface to NCAR Graphics functionality. Some HLUs are independent of the traditional NCAR Graphics libraries of C and Fortran subroutines, while others make calls into the low level libraries. A goal of the HLUs is to free the user from having to understand the implementation details of the low level libraries. Thus, when the low level libraries are invoked by the HLU, the HLU manages the graphics state, properly initializes and orders the calls to the low level routines, and manages all internal work arrays.
The HLU interface is distinctly different from the LLU interface. The LLU model is the classic programming paradigm. Subroutine calls with selected arguments are stacked in an order that acheives the desired result. The HLU model is object oriented. Objects are created that have a range of action which is determined by the values assigned to a set of object resources. Thus, the functionality of the HLU program depends both on the set of objects created and the set of values assigned to the object resources.
From this module, you can access the following subjects and information about HLUs.
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