form - form library
The form library provides a terminal independent form system using the
curses(3) library. Before using the form functions the terminal must be
set up by curses(3) using the initscr() function or similar. Programs
using form functions must be linked with the curses(3) library -lcurses.
The form library provides facilities for defining form fields, placing a
form on the terminal screen, assign pre and post change operations and
setting the attributes of both the form and its fields.
Defining default attributes for forms and fields [Toc] [Back]
The form library allows any settable attribute or option of both the form
and field objects to be defined such that any new form or field automatically
inherits the value as default. Setting the default value will not
affect any field or form that has already been created but will be
applied to subsequent objects. To set the default attribute or option
the set routine is passed a NULL pointer in the field or form parameter
when calling the set routine. The current default value can be retrieved
by calling the get routine with a NULL pointer for the field or form
Form Routine Name Manual Page Name
Any function returning a string pointer will return NULL if an error
occurs. Functions returning an integer will return one of the following:
E_OK The function was successful
E_SYSTEM_ERROR There was a system error during the call.
E_BAD_ARGUMENT One or more of the arguments passed to the function
E_POSTED The form is already posted.
E_CONNECTED An field was already connected to a form.
E_BAD_STATE The function was called from within an initialisation
or termination routine.
E_NO_ROOM The form does not fit within the subwindow.
E_NOT_POSTED The form is not posted
E_UNKNOWN_COMMAND The form driver does not recognise the request
passed to it.
E_NOT_SELECTABLE The field could not be selected.
E_NOT_CONNECTED The field is not connected to a form.
E_REQUEST_DENIED The form driver could not process the request.
E_INVALID_FIELD The field is invalid.
E_CURRENT The field is the active one on the form.
This implementation of the forms library does depart in behaviour subtly
from the original AT T implementation. Some of the more notable departures
field wrapping For multiline fields the data will be wrapped as it is
entered, this does not happen in the ATT implementation.
buffer 0 In this implementation, the contents of buffer 0 are
always current regardless of whether the field has been
validated or not.
circular fields In the ATT implementation fields are circular on a page,
that is, a next field from the last field will go to the
first field on the curent page. In this implementation
a next field request on the last field of a page will
result in the forms library positioning the cursor on
the first field of the next page. If the field is the
last field in the form then going to the next field will
be denied, in the ATT it would result in the cursor
being placed on the first field of the first page.
buffer returns In this implementation only the data entered by the user
in the form field will be returned, unlike the ATT
library which would return the contents of the field
padded to the size of the field with the pad character.
The TAB character
The handling of the TAB character in fields varies
between implementations. In ncurses attempting to set a
field contents with a string containing a TAB will
result in an error and will not allow a TAB to be
entered into a field. The ATT library statically converts
tabs to the equivalent number of spaces when the
field buffer is set but the form driver will not allow a
TAB to be inserted into the field buffer. This implementation
allows TAB when setting the field buffer and
also will allow TAB to be inserted into a field buffer
via the form driver and correctly calculates the cursor
position allowing for expansion of the TAB character.
BSD January 1, 2001 BSD
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