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.