NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | NOTES | PORTABILITY | AUTHORS | COLOPHON

form_driver(3X)                                              form_driver(3X)

NAME         top

       form_driver, form_driver_w - command-processing loop of the form sys‐
       tem

SYNOPSIS         top

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

DESCRIPTION         top

   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         top

       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         top

       curses(3X), form(3X), form_field_buffer(3X),
       form_field_validation(3X), form_fieldtype(3X), form_variables(3X),
       getch(3X).

NOTES         top

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

PORTABILITY         top

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

AUTHORS         top

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

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
       about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository 
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2017-03-13.  If you
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       you believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a mail
       to man-pages@man7.org

                                                             form_driver(3X)