NAME
form —
form library
LIBRARY
Curses Form Library (libform, -lform)
SYNOPSIS
#include <form.h>
DESCRIPTION
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.
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 parameter.
RETURN VALUES
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 was incorrect. |
E_POSTED |
The form is already
posted. |
E_CONNECTED |
A field was already connected to a
form. |
E_BAD_STATE |
The function was called from within
an initialization 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 recognize
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. |
SEE ALSO
curses(3),
menus(3)
NOTES
This implementation of the forms library does depart in behavior subtly from the
original AT&T implementation. Some of the more notable departures are:
- field wrapping
- For multi-line fields the data will be wrapped as it is
entered, this does not happen in the AT&T 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 AT&T implementation fields are circular on a
page, that is, a next field from the last field will go to the first field
on the current 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 AT&T
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 AT&T 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 AT&T 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.
- set_field_printf
- This function is a NetBSD extension
and must not be used in portable code.
O_REFORMAT
- This field option is a NetBSD
extension and must not be used in portable code.