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

Chapter 6 251
USING VPLUS INTRINSICS
USING TERMINAL FEATURES
terminal memory into from one to four workspaces to store forms. Total available space is
equal to 119 lines of forms, with the minimum size of a workspace being 26 lines. One
full-screen window is used to display a form.
A form is displayed by attaching a workspace to the window. Any enhancements and data
entered onto the form are part of the form as long as it is in the terminal — a "fresh" form
is not available in local storage. If a fresh copy of the form is to be displayed, it must be
written from the form definition area of system memory.
One workspace is always attached to the window and displayed, even if there are no forms
loaded. The workspace being displayed is frozen — no form can be loaded into this frozen
workspace. Therefore, only three forms can actually be loaded in a single call to
VLOADFORMS. To get a fourth form into the terminal, display it in the window with
VSHOWFORM.
Forms can be purged from the terminal if there is not room for the form you are trying to
load. Forms are purged on a "least recently used" basis. During a load operation, each form
is frozen until all forms have been loaded, thus preventing loading and purging in a single
operation.
If you want to purge the currently displayed form from the terminal, it is not erased from
the screen, but the form storage directory entry for this workspace is marked available.
(The form storage directory is discussed later in this section.)
On the HP 2624B/HP 2394A terminals, forms stored locally are copied from terminal
memory to the screen. A fresh copy of the form remains available in local storage. When
the terminal is opened, enough memory is reserved to display the largest form in the forms
file and this affects how many forms can actually be loaded.
Form Storage Directory
The
comarea variable formstoresize , which must be set before opening the terminal and
the forms file, indicates the maximum number of forms you are going to store locally. A
form storage directory with an entry for each form is created on the user stack. This
directory is used to keep track of loaded forms and of how much terminal memory each
form is using. Note that setting this variable does not load any forms — it just reserves
space for them. VSHOWFORM searches the directory to determine if a form to be displayed is
in local storage.
When a form is purged from local storage, the corresponding directory entry is marked
available to indicate that the form is no longer in the terminal and is not taking up any
terminal memory space.
NOTE VCLOSETERM deallocates local form storage space — both VOPENTERM and
VOPENFORMF must be called if local form storage space is to be reallocated.
Loading Forms
Forms can be loaded into local form storage in the following ways:
• Preload the current form when VSHOWFORM is called by setting
showcontrol bit 9 to one.
• Load the next form when VREADFIELDS is called by setting
lookahead to zero.