Presentation Space Models

The HACL presentation space model is easier to use than that of EHLLAPI. The HACL presentation space consists of a number of planes, each of which contains one type of data. The planes are:
  • Text
  • Field attributes
  • Color
  • Extended attributes

The planes are all the same size and contain one byte for each character position in the host presentation space. An application can obtain any plane of interest using the ECLPS::GetScreen method.

This model is different from the EHLLAPI, in which text and non-text presentation space data is often interleaved in a buffer. An application must set the EHLLAPI session parameter to specify what type of data to retrieve, then make another call to copy the data to a buffer. The HACL model allows the application to get the data of interest in a single call and different data types are never mixed in a single buffer.