frm_driver.c

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/****************************************************************************
 * Copyright (c) 1998-2004,2005 Free Software Foundation, Inc.              *
 *                                                                          *
 * Permission is hereby granted, free of charge, to any person obtaining a  *
 * copy of this software and associated documentation files (the            *
 * "Software"), to deal in the Software without restriction, including      *
 * without limitation the rights to use, copy, modify, merge, publish,      *
 * distribute, distribute with modifications, sublicense, and/or sell       *
 * copies of the Software, and to permit persons to whom the Software is    *
 * furnished to do so, subject to the following conditions:                 *
 *                                                                          *
 * The above copyright notice and this permission notice shall be included  *
 * in all copies or substantial portions of the Software.                   *
 *                                                                          *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
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 * Except as contained in this notice, the name(s) of the above copyright   *
 * holders shall not be used in advertising or otherwise to promote the     *
 * sale, use or other dealings in this Software without prior written       *
 * authorization.                                                           *
 ****************************************************************************/

/****************************************************************************
 *   Author:  Juergen Pfeifer, 1995,1997                                    *
 ****************************************************************************/

#include "form.priv.h"

MODULE_ID("$Id: frm_driver.c,v 1.71 2005/10/01 19:42:40 tom Exp $")

/*----------------------------------------------------------------------------
  This is the core module of the form library. It contains the majority
  of the driver routines as well as the form_driver function.

  Essentially this module is nearly the whole library. This is because
  all the functions in this module depends on some others in the module,
  so it makes no sense to split them into separate files because they
  will always be linked together. The only acceptable concern is turnaround
  time for this module, but now we have all Pentiums or RISCs, so what!

  The driver routines are grouped into nine generic categories:

   a)   Page Navigation            ( all functions prefixed by PN_ )
        The current page of the form is left and some new page is
        entered.
   b)   Inter-Field Navigation     ( all functions prefixed by FN_ )
        The current field of the form is left and some new field is
        entered.
   c)   Intra-Field Navigation     ( all functions prefixed by IFN_ )
        The current position in the current field is changed.
   d)   Vertical Scrolling         ( all functions prefixed by VSC_ )
        Essentially this is a specialization of Intra-Field navigation.
        It has to check for a multi-line field.
   e)   Horizontal Scrolling       ( all functions prefixed by HSC_ )
        Essentially this is a specialization of Intra-Field navigation.
        It has to check for a single-line field.
   f)   Field Editing              ( all functions prefixed by FE_ )
        The content of the current field is changed
   g)   Edit Mode requests         ( all functions prefixed by EM_ )
        Switching between insert and overlay mode
   h)   Field-Validation requests  ( all functions prefixed by FV_ )
        Perform verifications of the field.
   i)   Choice requests            ( all functions prefixed by CR_ )
        Requests to enumerate possible field values
  --------------------------------------------------------------------------*/

/*----------------------------------------------------------------------------
  Some remarks on the placements of assert() macros :
  I use them only on "strategic" places, i.e. top level entries where
  I want to make sure that things are set correctly. Throughout subordinate
  routines I omit them mostly.
  --------------------------------------------------------------------------*/

/*
Some options that may effect compatibility in behavior to SVr4 forms,
but they are here to allow a more intuitive and user friendly behavior of
our form implementation. This doesn't affect the API, so we feel it is
uncritical.

The initial implementation tries to stay very close with the behavior
of the original SVr4 implementation, although in some areas it is quite
clear that this isn't the most appropriate way. As far as possible this
sources will allow you to build a forms lib that behaves quite similar
to SVr4, but now and in the future we will give you better options.
Perhaps at some time we will make this configurable at runtime.
*/

/* Implement a more user-friendly previous/next word behavior */
#define FRIENDLY_PREV_NEXT_WORD (1)
/* Fix the wrong behavior for forms with all fields inactive */
#define FIX_FORM_INACTIVE_BUG (1)
/* Allow dynamic field growth also when navigating past the end */
#define GROW_IF_NAVIGATE (1)

#if USE_WIDEC_SUPPORT
#define myADDNSTR(w, s, n) wadd_wchnstr(w, s, n)
#define myINSNSTR(w, s, n) wins_wchnstr(w, s, n)
#define myINNSTR(w, s, n)  fix_wchnstr(w, s, n)
#define myWCWIDTH(w, y, x) cell_width(w, y, x)
#else
#define myADDNSTR(w, s, n) waddnstr(w, s, n)
#define myINSNSTR(w, s, n) winsnstr(w, s, n)
#define myINNSTR(w, s, n)  winnstr(w, s, n)
#define myWCWIDTH(w, y, x) 1
#endif

/*----------------------------------------------------------------------------
  Forward references to some internally used static functions
  --------------------------------------------------------------------------*/
static int Inter_Field_Navigation(int (*const fct) (FORM *), FORM *form);
static int FN_Next_Field(FORM *form);
static int FN_Previous_Field(FORM *form);
static int FE_New_Line(FORM *);
static int FE_Delete_Previous(FORM *);

/*----------------------------------------------------------------------------
  Macro Definitions.

  Some Remarks on that: I use the convention to use UPPERCASE for constants
  defined by Macros. If I provide a macro as a kind of inline routine to
  provide some logic, I use my Upper_Lower case style.
  --------------------------------------------------------------------------*/

/* Calculate the position of a single row in a field buffer */
#define Position_Of_Row_In_Buffer(field,row) ((row)*(field)->dcols)

/* Calculate start address for the fields buffer# N */
#define Address_Of_Nth_Buffer(field,N) \
  ((field)->buf + (N)*(1+Buffer_Length(field)))

/* Calculate the start address of the row in the fields specified buffer# N */
#define Address_Of_Row_In_Nth_Buffer(field,N,row) \
  (Address_Of_Nth_Buffer(field,N) + Position_Of_Row_In_Buffer(field,row))

/* Calculate the start address of the row in the fields primary buffer */
#define Address_Of_Row_In_Buffer(field,row) \
  Address_Of_Row_In_Nth_Buffer(field,0,row)

/* Calculate the start address of the row in the forms current field
   buffer# N */
#define Address_Of_Current_Row_In_Nth_Buffer(form,N) \
   Address_Of_Row_In_Nth_Buffer((form)->current,N,(form)->currow)

/* Calculate the start address of the row in the forms current field
   primary buffer */
#define Address_Of_Current_Row_In_Buffer(form) \
   Address_Of_Current_Row_In_Nth_Buffer(form,0)

/* Calculate the address of the cursor in the forms current field
   primary buffer */
#define Address_Of_Current_Position_In_Nth_Buffer(form,N) \
   (Address_Of_Current_Row_In_Nth_Buffer(form,N) + (form)->curcol)

/* Calculate the address of the cursor in the forms current field
   buffer# N */
#define Address_Of_Current_Position_In_Buffer(form) \
  Address_Of_Current_Position_In_Nth_Buffer(form,0)

/* Logic to decide whether or not a field is actually a field with
   vertical or horizontal scrolling */
#define Is_Scroll_Field(field)          \
   (((field)->drows > (field)->rows) || \
    ((field)->dcols > (field)->cols))

/* Logic to decide whether or not a field needs to have an individual window
   instead of a derived window because it contains invisible parts.
   This is true for non-public fields and for scrollable fields. */
#define Has_Invisible_Parts(field)     \
  (!((field)->opts & O_PUBLIC)      || \
   Is_Scroll_Field(field))

/* Logic to decide whether or not a field needs justification */
#define Justification_Allowed(field)        \
   (((field)->just != NO_JUSTIFICATION)  && \
    (Single_Line_Field(field))           && \
    (((field)->dcols == (field)->cols)   && \
    ((field)->opts & O_STATIC))             )

/* Logic to determine whether or not a dynamic field may still grow */
#define Growable(field) ((field)->status & _MAY_GROW)

/* Macro to set the attributes for a fields window */
#define Set_Field_Window_Attributes(field,win) \
(  wbkgdset((win),(chtype)((field)->pad | (field)->back)), \
   wattrset((win),(field)->fore) )

/* Logic to decide whether or not a field really appears on the form */
#define Field_Really_Appears(field)         \
  ((field->form)                          &&\
   (field->form->status & _POSTED)        &&\
   (field->opts & O_VISIBLE)              &&\
   (field->page == field->form->curpage))

/* Logic to determine whether or not we are on the first position in the
   current field */
#define First_Position_In_Current_Field(form) \
  (((form)->currow==0) && ((form)->curcol==0))

#define Minimum(a,b) (((a)<=(b)) ? (a) : (b))
#define Maximum(a,b) (((a)>=(b)) ? (a) : (b))

/*----------------------------------------------------------------------------
  Useful constants
  --------------------------------------------------------------------------*/
static FIELD_CELL myBLANK = BLANK;
static FIELD_CELL myZEROS;

#ifdef TRACE
static void
check_pos(FORM *form, int lineno)
{
  int y, x;

  if (form && form->w)
    {
      getyx(form->w, y, x);
      if (y != form->currow || x != form->curcol)
        {
          T(("CHECKPOS %s@%d have position %d,%d vs want %d,%d",
             __FILE__, lineno,
             y, x,
             form->currow, form->curcol));
        }
    }
}
#define CHECKPOS(form) check_pos(form, __LINE__)
#else
#define CHECKPOS(form)          /* nothing */
#endif

/*----------------------------------------------------------------------------
  Wide-character special functions
  --------------------------------------------------------------------------*/
#if USE_WIDEC_SUPPORT
/* like winsnstr */
static int
wins_wchnstr(WINDOW *w, cchar_t *s, int n)
{
  int code = ERR;
  int y, x;

  while (n-- > 0)
    {
      getyx(w, y, x);
      if ((code = wins_wch(w, s++)) != OK)
        break;
      if ((code = wmove(w, y, x + 1)) != OK)
        break;
    }
  return code;
}

/* win_wchnstr is inconsistent with winnstr, since it returns OK rather than
 * the number of items transferred.
 */
static int
fix_wchnstr(WINDOW *w, cchar_t *s, int n)
{
  win_wchnstr(w, s, n);
  return n;
}

/*
 * Returns the column of the base of the given cell.
 */
static int
cell_base(WINDOW *win, int y, int x)
{
  int result = x;

  while (LEGALYX(win, y, x))
    {
      cchar_t *data = &(win->_line[y].text[x]);

      if (isWidecBase(CHDEREF(data)) || !isWidecExt(CHDEREF(data)))
        {
          result = x;
          break;
        }
      --x;
    }
  return result;
}

/*
 * Returns the number of columns needed for the given cell in a window.
 */
static int
cell_width(WINDOW *win, int y, int x)
{
  int result = 1;

  if (LEGALYX(win, y, x))
    {
      cchar_t *data = &(win->_line[y].text[x]);

      if (isWidecExt(CHDEREF(data)))
        {
          /* recur, providing the number of columns to the next character */
          result = cell_width(win, y, x - 1);
        }
      else
        {
          result = wcwidth(CharOf(CHDEREF(data)));
        }
    }
  return result;
}

/*
 * There is no wide-character function such as wdel_wch(), so we must find
 * all of the cells that comprise a multi-column character and delete them
 * one-by-one.
 */
static void
delete_char(FORM *form)
{
  int cells = cell_width(form->w, form->currow, form->curcol);

  form->curcol = cell_base(form->w, form->currow, form->curcol);
  wmove(form->w, form->currow, form->curcol);
  while (cells-- > 0)
    {
      wdelch(form->w);
    }
}
#define DeleteChar(form) delete_char(form)
#else
#define DeleteChar(form) \
          wmove((form)->w, (form)->currow, (form)->curcol), \
          wdelch((form)->w)
#endif

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static char *Get_Start_Of_Data(char * buf, int blen)
|
|   Description   :  Return pointer to first non-blank position in buffer.
|                    If buffer is empty return pointer to buffer itself.
|
|   Return Values :  Pointer to first non-blank position in buffer
+--------------------------------------------------------------------------*/
INLINE static FIELD_CELL *
Get_Start_Of_Data(FIELD_CELL *buf, int blen)
{
  FIELD_CELL *p = buf;
  FIELD_CELL *end = &buf[blen];

  assert(buf && blen >= 0);
  while ((p < end) && ISBLANK(*p))
    p++;
  return ((p == end) ? buf : p);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static char *After_End_Of_Data(char * buf, int blen)
|
|   Description   :  Return pointer after last non-blank position in buffer.
|                    If buffer is empty, return pointer to buffer itself.
|
|   Return Values :  Pointer to position after last non-blank position in
|                    buffer.
+--------------------------------------------------------------------------*/
INLINE static FIELD_CELL *
After_End_Of_Data(FIELD_CELL *buf, int blen)
{
  FIELD_CELL *p = &buf[blen];

  assert(buf && blen >= 0);
  while ((p > buf) && ISBLANK(p[-1]))
    p--;
  return (p);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static char *Get_First_Whitespace_Character(
|                                     char * buf, int   blen)
|
|   Description   :  Position to the first whitespace character.
|
|   Return Values :  Pointer to first whitespace character in buffer.
+--------------------------------------------------------------------------*/
INLINE static FIELD_CELL *
Get_First_Whitespace_Character(FIELD_CELL *buf, int blen)
{
  FIELD_CELL *p = buf;
  FIELD_CELL *end = &p[blen];

  assert(buf && blen >= 0);
  while ((p < end) && !ISBLANK(*p))
    p++;
  return ((p == end) ? buf : p);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static char *After_Last_Whitespace_Character(
|                                     char * buf, int blen)
|
|   Description   :  Get the position after the last whitespace character.
|
|   Return Values :  Pointer to position after last whitespace character in
|                    buffer.
+--------------------------------------------------------------------------*/
INLINE static FIELD_CELL *
After_Last_Whitespace_Character(FIELD_CELL *buf, int blen)
{
  FIELD_CELL *p = &buf[blen];

  assert(buf && blen >= 0);
  while ((p > buf) && !ISBLANK(p[-1]))
    p--;
  return (p);
}

/* Set this to 1 to use the div_t version. This is a good idea if your
   compiler has an intrinsic div() support. Unfortunately GNU-C has it
   not yet.
   N.B.: This only works if form->curcol follows immediately form->currow
         and both are of type int.
*/
#define USE_DIV_T (0)

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Adjust_Cursor_Position(
|                                       FORM * form, const char * pos)
|
|   Description   :  Set current row and column of the form to values
|                    corresponding to the buffer position.
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
INLINE static void
Adjust_Cursor_Position(FORM *form, const FIELD_CELL *pos)
{
  FIELD *field;
  int idx;

  field = form->current;
  assert(pos >= field->buf && field->dcols > 0);
  idx = (int)(pos - field->buf);
#if USE_DIV_T
  *((div_t *) & (form->currow)) = div(idx, field->dcols);
#else
  form->currow = idx / field->dcols;
  form->curcol = idx - field->cols * form->currow;
#endif
  if (field->drows < form->currow)
    form->currow = 0;
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Buffer_To_Window(
|                                      const FIELD  * field,
|                                      WINDOW * win)
|
|   Description   :  Copy the buffer to the window. If it is a multi-line
|                    field, the buffer is split to the lines of the
|                    window without any editing.
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
static void
Buffer_To_Window(const FIELD *field, WINDOW *win)
{
  int width, height;
  int y, x;
  int len;
  int row;
  FIELD_CELL *pBuffer;

  assert(win && field);

  getyx(win, y, x);
  width = getmaxx(win);
  height = getmaxy(win);

  for (row = 0, pBuffer = field->buf;
       row < height;
       row++, pBuffer += width)
    {
      if ((len = (int)(After_End_Of_Data(pBuffer, width) - pBuffer)) > 0)
        {
          wmove(win, row, 0);
          myADDNSTR(win, pBuffer, len);
        }
    }
  wmove(win, y, x);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Window_To_Buffer(
|                                          WINDOW * win,
|                                          FIELD  * field)
|
|   Description   :  Copy the content of the window into the buffer.
|                    The multiple lines of a window are simply
|                    concatenated into the buffer. Pad characters in
|                    the window will be replaced by blanks in the buffer.
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
static void
Window_To_Buffer(WINDOW *win, FIELD *field)
{
  int pad;
  int len = 0;
  FIELD_CELL *p;
  int row, height;

  assert(win && field && field->buf);

  pad = field->pad;
  p = field->buf;
  height = getmaxy(win);

  for (row = 0; (row < height) && (row < field->drows); row++)
    {
      wmove(win, row, 0);
      len += myINNSTR(win, p + len, field->dcols);
    }
  p[len] = myZEROS;

  /* replace visual padding character by blanks in buffer */
  if (pad != C_BLANK)
    {
      int i;

      for (i = 0; i < len; i++, p++)
        {
          if ((unsigned long)CharOf(*p) == ChCharOf(pad)
#if USE_WIDEC_SUPPORT
              && p->chars[1] == 0
#endif
              && AttrOf(*p) == ChAttrOf(pad))
            *p = myBLANK;
        }
    }
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Synchronize_Buffer(FORM * form)
|
|   Description   :  If there was a change, copy the content of the
|                    window into the buffer, so the buffer is synchronized
|                    with the windows content. We have to indicate that the
|                    buffer needs validation due to the change.
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
INLINE static void
Synchronize_Buffer(FORM *form)
{
  if (form->status & _WINDOW_MODIFIED)
    {
      form->status &= ~_WINDOW_MODIFIED;
      form->status |= _FCHECK_REQUIRED;
      Window_To_Buffer(form->w, form->current);
      wmove(form->w, form->currow, form->curcol);
    }
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static bool Field_Grown( FIELD *field, int amount)
|
|   Description   :  This function is called for growable dynamic fields
|                    only. It has to increase the buffers and to allocate
|                    a new window for this field.
|                    This function has the side effect to set a new
|                    field-buffer pointer, the dcols and drows values
|                    as well as a new current Window for the field.
|
|   Return Values :  TRUE     - field successfully increased
|                    FALSE    - there was some error
+--------------------------------------------------------------------------*/
static bool
Field_Grown(FIELD *field, int amount)
{
  bool result = FALSE;

  if (field && Growable(field))
    {
      bool single_line_field = Single_Line_Field(field);
      int old_buflen = Buffer_Length(field);
      int new_buflen;
      int old_dcols = field->dcols;
      int old_drows = field->drows;
      FIELD_CELL *oldbuf = field->buf;
      FIELD_CELL *newbuf;

      int growth;
      FORM *form = field->form;
      bool need_visual_update = ((form != (FORM *)0) &&
                                 (form->status & _POSTED) &&
                                 (form->current == field));

      if (need_visual_update)
        Synchronize_Buffer(form);

      if (single_line_field)
        {
          growth = field->cols * amount;
          if (field->maxgrow)
            growth = Minimum(field->maxgrow - field->dcols, growth);
          field->dcols += growth;
          if (field->dcols == field->maxgrow)
            field->status &= ~_MAY_GROW;
        }
      else
        {
          growth = (field->rows + field->nrow) * amount;
          if (field->maxgrow)
            growth = Minimum(field->maxgrow - field->drows, growth);
          field->drows += growth;
          if (field->drows == field->maxgrow)
            field->status &= ~_MAY_GROW;
        }
      /* drows, dcols changed, so we get really the new buffer length */
      new_buflen = Buffer_Length(field);
      newbuf = (FIELD_CELL *)malloc(Total_Buffer_Size(field));
      if (!newbuf)
        {
          /* restore to previous state */
          field->dcols = old_dcols;
          field->drows = old_drows;
          if ((single_line_field && (field->dcols != field->maxgrow)) ||
              (!single_line_field && (field->drows != field->maxgrow)))
            field->status |= _MAY_GROW;
        }
      else
        {
          /* Copy all the buffers.  This is the reason why we can't just use
           * realloc().
           */
          int i, j;
          FIELD_CELL *old_bp;
          FIELD_CELL *new_bp;

          result = TRUE;        /* allow sharing of recovery on failure */

          field->buf = newbuf;
          for (i = 0; i <= field->nbuf; i++)
            {
              new_bp = Address_Of_Nth_Buffer(field, i);
              old_bp = oldbuf + i * (1 + old_buflen);
              for (j = 0; j < old_buflen; ++j)
                new_bp[j] = old_bp[j];
              while (j < new_buflen)
                new_bp[j++] = myBLANK;
              new_bp[new_buflen] = myZEROS;
            }

#if USE_WIDEC_SUPPORT
          if (wresize(field->working, 1, Buffer_Length(field) + 1) == ERR)
            result = FALSE;
#endif

          if (need_visual_update && result)
            {
              WINDOW *new_window = newpad(field->drows, field->dcols);

              if (new_window != 0)
                {
                  assert(form != (FORM *)0);
                  if (form->w)
                    delwin(form->w);
                  form->w = new_window;
                  Set_Field_Window_Attributes(field, form->w);
                  werase(form->w);
                  Buffer_To_Window(field, form->w);
                  untouchwin(form->w);
                  wmove(form->w, form->currow, form->curcol);
                }
              else
                result = FALSE;
            }

          if (result)
            {
              free(oldbuf);
              /* reflect changes in linked fields */
              if (field != field->link)
                {
                  FIELD *linked_field;

                  for (linked_field = field->link;
                       linked_field != field;
                       linked_field = linked_field->link)
                    {
                      linked_field->buf = field->buf;
                      linked_field->drows = field->drows;
                      linked_field->dcols = field->dcols;
                    }
                }
            }
          else
            {
              /* restore old state */
              field->dcols = old_dcols;
              field->drows = old_drows;
              field->buf = oldbuf;
              if ((single_line_field &&
                   (field->dcols != field->maxgrow)) ||
                  (!single_line_field &&
                   (field->drows != field->maxgrow)))
                field->status |= _MAY_GROW;
              free(newbuf);
            }
        }
    }
  return (result);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  int _nc_Position_Form_Cursor(FORM * form)
|
|   Description   :  Position the cursor in the window for the current
|                    field to be in sync. with the currow and curcol
|                    values.
|
|   Return Values :  E_OK              - success
|                    E_BAD_ARGUMENT    - invalid form pointer
|                    E_SYSTEM_ERROR    - form has no current field or
|                                        field-window
+--------------------------------------------------------------------------*/
NCURSES_EXPORT(int)
_nc_Position_Form_Cursor(FORM *form)
{
  FIELD *field;
  WINDOW *formwin;

  if (!form)
    return (E_BAD_ARGUMENT);

  if (!form->w || !form->current)
    return (E_SYSTEM_ERROR);

  field = form->current;
  formwin = Get_Form_Window(form);

  wmove(form->w, form->currow, form->curcol);
  if (Has_Invisible_Parts(field))
    {
      /* in this case fieldwin isn't derived from formwin, so we have
         to move the cursor in formwin by hand... */
      wmove(formwin,
            field->frow + form->currow - form->toprow,
            field->fcol + form->curcol - form->begincol);
      wcursyncup(formwin);
    }
  else
    wcursyncup(form->w);
  return (E_OK);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  int _nc_Refresh_Current_Field(FORM * form)
|
|   Description   :  Propagate the changes in the fields window to the
|                    window of the form.
|
|   Return Values :  E_OK              - on success
|                    E_BAD_ARGUMENT    - invalid form pointer
|                    E_SYSTEM_ERROR    - general error
+--------------------------------------------------------------------------*/
NCURSES_EXPORT(int)
_nc_Refresh_Current_Field(FORM *form)
{
  WINDOW *formwin;
  FIELD *field;

  T((T_CALLED("_nc_Refresh_Current_Field(%p)"), form));

  if (!form)
    RETURN(E_BAD_ARGUMENT);

  if (!form->w || !form->current)
    RETURN(E_SYSTEM_ERROR);

  field = form->current;
  formwin = Get_Form_Window(form);

  if (field->opts & O_PUBLIC)
    {
      if (Is_Scroll_Field(field))
        {
          /* Again, in this case the fieldwin isn't derived from formwin,
             so we have to perform a copy operation. */
          if (Single_Line_Field(field))
            {
              /* horizontal scrolling */
              if (form->curcol < form->begincol)
                form->begincol = form->curcol;
              else
                {
                  if (form->curcol >= (form->begincol + field->cols))
                    form->begincol = form->curcol - field->cols + 1;
                }
              copywin(form->w,
                      formwin,
                      0,
                      form->begincol,
                      field->frow,
                      field->fcol,
                      field->frow,
                      field->cols + field->fcol - 1,
                      0);
            }
          else
            {
              /* A multi-line, i.e. vertical scrolling field */
              int row_after_bottom, first_modified_row, first_unmodified_row;

              if (field->drows > field->rows)
                {
                  row_after_bottom = form->toprow + field->rows;
                  if (form->currow < form->toprow)
                    {
                      form->toprow = form->currow;
                      field->status |= _NEWTOP;
                    }
                  if (form->currow >= row_after_bottom)
                    {
                      form->toprow = form->currow - field->rows + 1;
                      field->status |= _NEWTOP;
                    }
                  if (field->status & _NEWTOP)
                    {
                      /* means we have to copy whole range */
                      first_modified_row = form->toprow;
                      first_unmodified_row = first_modified_row + field->rows;
                      field->status &= ~_NEWTOP;
                    }
                  else
                    {
                      /* we try to optimize : finding the range of touched
                         lines */
                      first_modified_row = form->toprow;
                      while (first_modified_row < row_after_bottom)
                        {
                          if (is_linetouched(form->w, first_modified_row))
                            break;
                          first_modified_row++;
                        }
                      first_unmodified_row = first_modified_row;
                      while (first_unmodified_row < row_after_bottom)
                        {
                          if (!is_linetouched(form->w, first_unmodified_row))
                            break;
                          first_unmodified_row++;
                        }
                    }
                }
              else
                {
                  first_modified_row = form->toprow;
                  first_unmodified_row = first_modified_row + field->rows;
                }
              if (first_unmodified_row != first_modified_row)
                copywin(form->w,
                        formwin,
                        first_modified_row,
                        0,
                        field->frow + first_modified_row - form->toprow,
                        field->fcol,
                        field->frow + first_unmodified_row - form->toprow - 1,
                        field->cols + field->fcol - 1,
                        0);
            }
          wsyncup(formwin);
        }
      else
        {
          /* if the field-window is simply a derived window, i.e. contains no
           * invisible parts, the whole thing is trivial
           */
          wsyncup(form->w);
        }
    }
  untouchwin(form->w);
  returnCode(_nc_Position_Form_Cursor(form));
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Perform_Justification(
|                                        FIELD  * field,
|                                        WINDOW * win)
|
|   Description   :  Output field with requested justification
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
static void
Perform_Justification(FIELD *field, WINDOW *win)
{
  FIELD_CELL *bp;
  int len;
  int col = 0;

  bp = Get_Start_Of_Data(field->buf, Buffer_Length(field));
  len = (int)(After_End_Of_Data(field->buf, Buffer_Length(field)) - bp);

  if (len > 0)
    {
      assert(win && (field->drows == 1) && (field->dcols == field->cols));

      switch (field->just)
        {
        case JUSTIFY_LEFT:
          break;
        case JUSTIFY_CENTER:
          col = (field->cols - len) / 2;
          break;
        case JUSTIFY_RIGHT:
          col = field->cols - len;
          break;
        default:
          break;
        }

      wmove(win, 0, col);
      myADDNSTR(win, bp, len);
    }
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static void Undo_Justification(
|                                     FIELD  * field,
|                                     WINDOW * win)
|
|   Description   :  Display field without any justification, i.e.
|                    left justified
|
|   Return Values :  -
+--------------------------------------------------------------------------*/
static void
Undo_Justification(FIELD *field, WINDOW *win)
{
  FIELD_CELL *bp;
  int len;

  bp = Get_Start_Of_Data(field->buf, Buffer_Length(field));
  len = (int)(After_End_Of_Data(field->buf, Buffer_Length(field)) - bp);

  if (len > 0)
    {
      assert(win);
      wmove(win, 0, 0);
      myADDNSTR(win, bp, len);
    }
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static bool Check_Char(
|                                           FIELDTYPE * typ,
|                                           int ch,
|                                           TypeArgument *argp)
|
|   Description   :  Perform a single character check for character ch
|                    according to the fieldtype instance.
|
|   Return Values :  TRUE             - Character is valid
|                    FALSE            - Character is invalid
+--------------------------------------------------------------------------*/
static bool
Check_Char(FIELDTYPE *typ, int ch, TypeArgument *argp)
{
  if (typ)
    {
      if (typ->status & _LINKED_TYPE)
        {
          assert(argp);
          return (
                   Check_Char(typ->left, ch, argp->left) ||
                   Check_Char(typ->right, ch, argp->right));
        }
      else
        {
          if (typ->ccheck)
            return typ->ccheck(ch, (void *)argp);
        }
    }
  return (!iscntrl(UChar(ch)) ? TRUE : FALSE);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static int Display_Or_Erase_Field(
|                                           FIELD * field,
|                                           bool bEraseFlag)
|
|   Description   :  Create a subwindow for the field and display the
|                    buffer contents (apply justification if required)
|                    or simply erase the field.
|
|   Return Values :  E_OK           - on success
|                    E_SYSTEM_ERROR - some error (typical no memory)
+--------------------------------------------------------------------------*/
static int
Display_Or_Erase_Field(FIELD *field, bool bEraseFlag)
{
  WINDOW *win;
  WINDOW *fwin;

  if (!field)
    return E_SYSTEM_ERROR;

  fwin = Get_Form_Window(field->form);
  win = derwin(fwin,
               field->rows, field->cols, field->frow, field->fcol);

  if (!win)
    return E_SYSTEM_ERROR;
  else
    {
      if (field->opts & O_VISIBLE)
        Set_Field_Window_Attributes(field, win);
      else
        wattrset(win, getattrs(fwin));
      werase(win);
    }

  if (!bEraseFlag)
    {
      if (field->opts & O_PUBLIC)
        {
          if (Justification_Allowed(field))
            Perform_Justification(field, win);
          else
            Buffer_To_Window(field, win);
        }
      field->status &= ~_NEWTOP;
    }
  wsyncup(win);
  delwin(win);
  return E_OK;
}

/* Macros to preset the bEraseFlag */
#define Display_Field(field) Display_Or_Erase_Field(field,FALSE)
#define Erase_Field(field)   Display_Or_Erase_Field(field,TRUE)

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static int Synchronize_Field(FIELD * field)
|
|   Description   :  Synchronize the windows content with the value in
|                    the buffer.
|
|   Return Values :  E_OK                - success
|                    E_BAD_ARGUMENT      - invalid field pointer
|                    E_SYSTEM_ERROR      - some severe basic error
+--------------------------------------------------------------------------*/
static int
Synchronize_Field(FIELD *field)
{
  FORM *form;
  int res = E_OK;

  if (!field)
    return (E_BAD_ARGUMENT);

  if (((form = field->form) != (FORM *)0)
      && Field_Really_Appears(field))
    {
      if (field == form->current)
        {
          form->currow = form->curcol = form->toprow = form->begincol = 0;
          werase(form->w);

          if ((field->opts & O_PUBLIC) && Justification_Allowed(field))
            Undo_Justification(field, form->w);
          else
            Buffer_To_Window(field, form->w);

          field->status |= _NEWTOP;
          res = _nc_Refresh_Current_Field(form);
        }
      else
        res = Display_Field(field);
    }
  field->status |= _CHANGED;
  return (res);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  static int Synchronize_Linked_Fields(FIELD * field)
|
|   Description   :  Propagate the Synchronize_Field function to all linked
|                    fields. The first error that occurs in the sequence
|                    of updates is the return value.
|
|   Return Values :  E_OK                - success
|                    E_BAD_ARGUMENT      - invalid field pointer
|                    E_SYSTEM_ERROR      - some severe basic error
+--------------------------------------------------------------------------*/
static int
Synchronize_Linked_Fields(FIELD *field)
{
  FIELD *linked_field;
  int res = E_OK;
  int syncres;

  if (!field)
    return (E_BAD_ARGUMENT);

  if (!field->link)
    return (E_SYSTEM_ERROR);

  for (linked_field = field->link;
       linked_field != field;
       linked_field = linked_field->link)
    {
      if (((syncres = Synchronize_Field(linked_field)) != E_OK) &&
          (res == E_OK))
        res = syncres;
    }
  return (res);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  int _nc_Synchronize_Attributes(FIELD * field)
|
|   Description   :  If a fields visual attributes have changed, this
|                    routine is called to propagate those changes to the
|                    screen.
|
|   Return Values :  E_OK             - success
|                    E_BAD_ARGUMENT   - invalid field pointer
|                    E_SYSTEM_ERROR   - some severe basic error
+--------------------------------------------------------------------------*/
NCURSES_EXPORT(int)
_nc_Synchronize_Attributes(FIELD *field)
{
  FORM *form;
  int res = E_OK;
  WINDOW *formwin;

  T((T_CALLED("_nc_Synchronize_Attributes(%p)"), field));

  if (!field)
    returnCode(E_BAD_ARGUMENT);

  CHECKPOS(field->form);
  if (((form = field->form) != (FORM *)0)
      && Field_Really_Appears(field))
    {
      if (form->current == field)
        {
          Synchronize_Buffer(form);
          Set_Field_Window_Attributes(field, form->w);
          werase(form->w);
          wmove(form->w, form->currow, form->curcol);

          if (field->opts & O_PUBLIC)
            {
              if (Justification_Allowed(field))
                Undo_Justification(field, form->w);
              else
                Buffer_To_Window(field, form->w);
            }
          else
            {
              formwin = Get_Form_Window(form);
              copywin(form->w, formwin,
                      0, 0,
                      field->frow, field->fcol,
                      field->rows - 1, field->cols - 1, 0);
              wsyncup(formwin);
              Buffer_To_Window(field, form->w);
              field->status |= _NEWTOP;         /* fake refresh to paint all */
              _nc_Refresh_Current_Field(form);
            }
        }
      else
        {
          res = Display_Field(field);
        }
    }
  CHECKPOS(form);
  returnCode(res);
}

/*---------------------------------------------------------------------------
|   Facility      :  libnform
|   Function      :  int _nc_Synchronize_Options(FIELD * field,
|                                                Field_Options newopts)
|
|   Description   :  If a fields options have changed, this routine is
|                    called to propagate these changes to the screen and
|                    to really change the behavior of the field.
|
|   Return Values :  E_OK                - success
|                    E_BAD_ARGUMENT      - invalid field pointer
|                    E_SYSTEM_ERROR      - some severe basic error
+--------------------------------------------------------------------------*/
NCURSES_EXPORT(int)
_nc_Synchronize_Options(FIELD *field, Field_Options newopts)
{
  Field_Options oldopts;
  Field_Options changed_opts;
  FORM *form;
  int res = E_OK;

  T((T_CALLED("_nc_Synchronize_Options(%p,%#x)"), field, newopts));

  if (!field)
    returnCode(E_BAD_ARGUMENT);

  oldopts = field->opts;
  changed_opts = oldopts ^ newopts;
  field->opts = newopts;
  form = field->form;

  if (form)
    {
      if (form->current == field)
        {
          field->opts = oldopts;
          returnCode(E_CURRENT);
        }

      if (form->status & _POSTED)
        {
          if ((form->curpage == field->page))
            {
              if (changed_opts & O_VISIBLE)
                {
                  if (newopts & O_VISIBLE)
                    res = Display_Field(field);
                  else
                    res = Erase_Field(field);
                }
              else
                {
                  if ((changed_opts & O_PUBLIC) &&
                      (newopts & O_VISIBLE))
                    res = Display_Field(field);
                }
            }
        }
    }

  if (changed_opts & O_STATIC)
    {
      bool single_line_field = Single_Line_Field(field);
      int res2 = E_OK;

      if (newopts & O_STATIC)
        {
          /* the field becomes now static */
          fie