# form_driver

## 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.
    
       **Field validation**
           The form library makes updates to the window associated with form
           fields rather than directly to the field buffers.
    
           The form driver provides low-level control over updates to the
           form fields.  The form driver also provides for validating
           modified fields to ensure that the contents meet whatever
           constraints an application may attach using **set_field_type**.
    
           You can validate a field without making any changes to it using
           **REQ_VALIDATION**.  The form driver also validates a field in these
           cases:
    
           •   a call to **set_current_field** attempts to move to a different
               field.
    
           •   a call to **set_current_page** attempts to move to a different
               page of the form.
    
           •   a request attempts to move to a different field.
    
           •   a request attempts to move to a different page of the form.
    
           In each case, the move fails if the field is invalid.
    
           If the modified field is valid, the form driver copies the
           modified data from the window associated with the field to the
           field buffer.
    
       **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_NOT_CONNECTED**
                No fields are connected to the form.
    
           **E_REQUEST_DENIED**
                The form driver could not process the request.
    
           **E_SYSTEM_ERROR**
                System error occurred (see errno(3)).
    
           **E_UNKNOWN_COMMAND**
                The form driver code saw an unknown request code.
    


## 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.
    


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