# form_driver 3x

    form_driver(3x)                                         form_driver(3x)

## 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:

           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)