# form_driver 3x

    form_driver(3x)                                         form_driver(3x)

## NAME

           form_driver - 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:

           o   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).

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

           o   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  decora-
           tion 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:

              o   the form cursor is positioned to that field.

              o   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  pur-
                  pose  of this return value to signal that an appli-
                  cation specific command should be executed.

              o   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_COM-
           MAND.  Application-defined commands should be defined rel-
           ative  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  argu-
                ment.

           E_BAD_STATE
                Routine was called from an initialization or termina-
                tion 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

           curses(3x), form(3x), form_variables(3x), curs_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.

                                                            form_driver(3x)