NAME

       form_driver - command-processing loop of the form system

SYNOPSIS

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

DESCRIPTION

       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.

       •   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.

       The form driver requests are as follows:

       REQ_NEXT_PAGE
            Move to the next page.

       REQ_PREV_PAGE
            Move to the previous page.

       REQ_FIRST_PAGE
            Move to the first page.

       REQ_LAST_PAGE
            Move to the last field.

       REQ_NEXT_FIELD
            Move to the next field.

       REQ_PREV_FIELD
            Move to the previous field.

       REQ_FIRST_FIELD
            Move to the first field.

       REQ_LAST_FIELD
            Move to the last field.

       REQ_SNEXT_FIELD
            Move to the sorted next field.

       REQ_SPREV_FIELD
            Move to the sorted previous field.

       REQ_SFIRST_FIELD
            Move to the sorted first field.

       REQ_SLAST_FIELD
            Move to the sorted last field.

       REQ_LEFT_FIELD
            Move left to a field.

       REQ_RIGHT_FIELD
            Move right to a field.

       REQ_UP_FIELD
            Move up to a field.

       REQ_DOWN_FIELD
            Move down to a field.

       REQ_NEXT_CHAR
            Move to the next char.

       REQ_PREV_CHAR
            Move to the previous char.

       REQ_NEXT_LINE
            Move to the next line.

       REQ_PREV_LINE
            Move to the previous line.

       REQ_NEXT_WORD
            Move to the next word.

       REQ_PREV_WORD
            Move to the previous word.

       REQ_BEG_FIELD
            Move to the beginning of the field.

       REQ_END_FIELD
            Move to the end of the field.

       REQ_BEG_LINE
            Move to the beginning of the line.

       REQ_END_LINE
            Move to the end of the line.

       REQ_LEFT_CHAR
            Move left in the field.

       REQ_RIGHT_CHAR
            Move right in the field.

       REQ_UP_CHAR
            Move up in the field.

       REQ_DOWN_CHAR
            Move down in the field.

       REQ_NEW_LINE
            Insert or overlay a new line.

       REQ_INS_CHAR
            Insert a blank at the cursor.

       REQ_INS_LINE
            Insert a blank line at the cursor.

       REQ_DEL_CHAR
            Delete character at the cursor.

       REQ_DEL_PREV
            Delete character before the cursor.

       REQ_DEL_LINE
            Delete line at the cursor.

       REQ_DEL_WORD
            Delete blank-delimited word at the cursor.

       REQ_CLR_EOL
            Clear to end of line from cursor.

       REQ_CLR_EOF
            Clear to end of field from cursor.

       REQ_CLR_FIELD
            Clear the entire field.

       REQ_OVL_MODE
            Enter overlay mode.

       REQ_INS_MODE
            Enter insert mode.

       REQ_SCR_FLINE
            Scroll the field forward a line.

       REQ_SCR_BLINE
            Scroll the field backward a line.

       REQ_SCR_FPAGE
            Scroll the field forward a page.

       REQ_SCR_BPAGE
            Scroll the field backward a page.

       REQ_SCR_FHPAGE
            Scroll the field forward half a page.

       REQ_SCR_BHPAGE
            Scroll the field backward half a page.

       REQ_SCR_FCHAR
            Scroll the field forward a character.

       REQ_SCR_BCHAR
            Scroll the field backward a character.

       REQ_SCR_HFLINE
            Horizontal scroll the field forward 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_HBHALF
            Horizontal scroll the field backward half a line.

       REQ_VALIDATION
            Validate field.

       REQ_NEXT_CHOICE
            Display next field choice.

       REQ_PREV_CHOICE
            Display previous field choice.

       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)