HP Data Entry and Forms Management System (VPLUS) Reference Manual (32209-90024)

250 Chapter6
USING VPLUS INTRINSICS
USING TERMINAL FEATURES
USING TERMINAL FEATURES
VPLUS provides a way to take advantage of special terminal features, using processing
specifications (refer to Section 4), VPLUS intrinsics, and selections on the FORMSPEC
menus (refer to Section 3). Two of the special terminal features that can be controlled with
VPLUS intrinsics are touch and local form storage, as described below. Refer to Appendix
G for a list of terminals that support these features.
The Touch Feature
VPLUS supports the touch feature available with specified terminals, as listed in
Appendix G. The touch feature is aimed to improve programmer productivity for the
design of intuitive, friendly user interfaces.
To activate the touch feature, an application must set bit 0 of the
showcontrol word in the
comarea to 1 before calling VSHOWFORM. This feature will remain activated until the
showcontrol bit 0 is set to 0, or until VCLOSETERM is called.
With the touch enhancement enabled, VREADFIELDS returns a number when a field on the
form is touched. This number is the negative of the field number that was assigned by
FORMSPEC at form design time. All fields as currently defined on a form return a
negative of their assigned field number when touched. No additional definition of touch
fields is necessary. The number returned is negative in order to distinguish it from the
positive numbers returned for function keys. In this manner, fields on the form can be
treated just like function keys.
Thus, touch applications can be designed using the same VPLUS intrinsics and the same
forms file. The negative field number returned to the
lastkey field in the comarea can
then be interpreted for further processing.
Local Form Storage
Certain terminals allow forms to be stored locally in terminal memory, which can reduce
the overhead of writing a form image from the form definition area of memory. Frequently
displayed forms can be loaded into the terminal to be written directly to the screen. Only
form images are loaded — not the associated data. The HP 2626A terminal can store as
many as four forms locally. The HP 2624B and HP 2394A terminal can store a maximum of
255 forms locally depending on the size of the forms and the size of terminal memory
available.
The VPLUS intrinsics and communication area items activate and control local form
storage. The same intrinsics and variables are used with local form storage terminals, but
there are some differences as to how the form storage is handled. These differences, along
with general information about using form storage, are described here. The specifics of the
intrinsics involved are contained in the individual intrinsic descriptions later in this
section.
The HP 2626A vs. the HP 2624B/HP 2394A
VPLUS utilizes the workspace/window feature of the HP 2626A terminal, configuring