NAME

       form_driver, form_driver_w - command-processing loop of the form system

SYNOPSIS

       #include <form.h>
       int form_driver(FORM *form, int c);
       int form_driver_w(FORM *form, int c, wchar_t wch);

DESCRIPTION

   form_driver
       Once  a  form  has  been  posted (displayed), you should funnel input events to it through
       form_driver.  This routine has three major input cases:

       •   The input is a form  navigation  request.   Navigation  request  codes  are  constants
           defined  in <form.h>, which are distinct from the key- and character codes returned by
           wgetch(3X).

       •   The input is a printable character.  Printable characters  (which  must  be  positive,
           less than 256) are checked according to the program's locale settings.

       •   The input is the KEY_MOUSE special key associated with an mouse event.

   form_driver_w
       This  extension  simplifies the use of the forms library using wide characters.  The input
       is either a key code (a request) or a wide character returned by  get_wch(3X).   The  type
       must be passed as well, to enable the library to determine whether the parameter is a wide
       character or a request.

   Form-driver requests
       The form driver requests are as follows:

       Name               Description
       ─────────────────────────────────────────────────────────────────────────
       REQ_BEG_FIELD      Move to the beginning of the field.
       REQ_BEG_LINE       Move to the beginning of the line.
       REQ_CLR_EOF        Clear to end of field from cursor.
       REQ_CLR_EOL        Clear to end of line from cursor.
       REQ_CLR_FIELD      Clear the entire field.
       REQ_DEL_CHAR       Delete character at the cursor.
       REQ_DEL_LINE       Delete line at the cursor.
       REQ_DEL_PREV       Delete character before the cursor.
       REQ_DEL_WORD       Delete blank-delimited word at the cursor.
       REQ_DOWN_CHAR      Move down in the field.
       REQ_DOWN_FIELD     Move down to a field.
       REQ_END_FIELD      Move to the end of the field.
       REQ_END_LINE       Move to the end of the line.
       REQ_FIRST_FIELD    Move to the first field.
       REQ_FIRST_PAGE     Move to the first page.
       REQ_INS_CHAR       Insert a blank at the cursor.
       REQ_INS_LINE       Insert a blank line at the cursor.
       REQ_INS_MODE       Enter insert mode.
       REQ_LAST_FIELD     Move to the last field.
       REQ_LAST_PAGE      Move to the last field.
       REQ_LEFT_CHAR      Move left in the field.
       REQ_LEFT_FIELD     Move left to a field.
       REQ_NEW_LINE       Insert or overlay a new line.
       REQ_NEXT_CHAR      Move to the next char.
       REQ_NEXT_CHOICE    Display next field choice.
       REQ_NEXT_FIELD     Move to the next field.
       REQ_NEXT_LINE      Move to the next line.
       REQ_NEXT_PAGE      Move to the next page.

       REQ_NEXT_PAGE      Move to the next page.
       REQ_NEXT_WORD      Move to the next word.
       REQ_OVL_MODE       Enter overlay mode.
       REQ_PREV_CHAR      Move to the previous char.
       REQ_PREV_CHOICE    Display previous field choice.
       REQ_PREV_FIELD     Move to the previous field.
       REQ_PREV_LINE      Move to the previous line.
       REQ_PREV_PAGE      Move to the previous page.
       REQ_PREV_WORD      Move to the previous word.
       REQ_RIGHT_CHAR     Move right in the field.
       REQ_RIGHT_FIELD    Move right to a field.
       REQ_SCR_BCHAR      Scroll the field backward a character.
       REQ_SCR_BHPAGE     Scroll the field backward half a page.
       REQ_SCR_BLINE      Scroll the field backward a line.
       REQ_SCR_BPAGE      Scroll the field backward a page.
       REQ_SCR_FCHAR      Scroll the field forward a character.
       REQ_SCR_FHPAGE     Scroll the field forward half a page.
       REQ_SCR_FLINE      Scroll the field forward a line.
       REQ_SCR_FPAGE      Scroll the field forward a page.
       REQ_SCR_HBHALF     Horizontal scroll the field backward half a line.
       REQ_SCR_HBLINE     Horizontal scroll the field backward a line.
       REQ_SCR_HFHALF     Horizontal scroll the field forward half a line.
       REQ_SCR_HFLINE     Horizontal scroll the field forward a line.
       REQ_SFIRST_FIELD   Move to the sorted first field.
       REQ_SLAST_FIELD    Move to the sorted last field.
       REQ_SNEXT_FIELD    Move to the sorted next field.
       REQ_SPREV_FIELD    Move to the sorted previous field.
       REQ_UP_CHAR        Move up in the field.
       REQ_UP_FIELD       Move up to a field.
       REQ_VALIDATION     Validate field.

       If the second argument is a printable character, the  driver  places  it  in  the  current
       position  in  the  current  field.   If it is one of the forms requests listed above, that
       request is executed.

   Mouse handling
       If the second argument is the  KEY_MOUSE  special  key,  the  associated  mouse  event  is
       translated  into one of the above pre-defined requests.  Currently only clicks in the user
       window (e.g., inside the form display area or the decoration window) are handled.

       If you click above the display region of the form:

          a REQ_PREV_FIELD is generated for a single click,

          a REQ_PREV_PAGE is generated for a double-click and

          a REQ_FIRST_FIELD is generated for a triple-click.

       If you click below the display region of the form:

          a REQ_NEXT_FIELD is generated for a single click,

          a REQ_NEXT_PAGE is generated for a double-click and

          a REQ_LAST_FIELD is generated for a triple-click.

       If you click at an field inside the display area of the form:

          •   the form cursor is positioned to that field.

          •   If you double-click a field, the form  cursor  is  positioned  to  that  field  and
              E_UNKNOWN_COMMAND  is  returned.   This  return value makes sense, because a double
              click usually means that an  field-specific  action  should  be  returned.   It  is
              exactly  the  purpose  of  this return value to signal that an application specific
              command should be executed.

          •   If a translation into a request was done, form_driver returns the  result  of  this
              request.

       If  you  clicked outside the user window or the mouse event could not be translated into a
       form request an E_REQUEST_DENIED is returned.

   Application-defined commands
       If the second argument is  neither  printable  nor  one  of  the  above  pre-defined  form
       requests,   the   driver  assumes  it  is  an  application-specific  command  and  returns
       E_UNKNOWN_COMMAND.   Application-defined  commands   should   be   defined   relative   to
       MAX_COMMAND, the maximum value of these pre-defined requests.

RETURN VALUE

       form_driver returns one of the following error codes:

       E_OK The routine succeeded.

       E_BAD_ARGUMENT
            Routine detected an incorrect or out-of-range argument.

       E_BAD_STATE
            Routine was called from an initialization or termination function.

       E_NOT_POSTED
            The form has not been posted.

       E_INVALID_FIELD
            Contents of field is invalid.

       E_REQUEST_DENIED
            The form driver could not process the request.

       E_SYSTEM_ERROR
            System error occurred (see errno).

       E_UNKNOWN_COMMAND
            The form driver code saw an unknown request code.

SEE ALSO

       ncurses(3NCURSES), form(3FORM), form_variables(3FORM), getch(3X).

NOTES

       The header file <form.h> automatically includes the header files <curses.h>.

PORTABILITY

       These  routines  emulate the System V forms library.  They were not supported on Version 7
       or BSD versions.

AUTHORS

       Juergen Pfeifer.  Manual pages and adaptation for new curses by Eric S. Raymond.

                                                                                    driver(3FORM)