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resizeterm.c

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/****************************************************************************
 *  Author: Thomas E. Dickey                                                *
 ****************************************************************************/

/*
 * This is an extension to the curses library.  It provides callers with a hook
 * into the NCURSES data to resize windows, primarily for use by programs
 * running in an X Window terminal (e.g., xterm).  I abstracted this module
 * from my application library for NCURSES because it must be compiled with
 * the private data structures -- T.Dickey 1995/7/4.
 */

#include <curses.priv.h>
#include <term.h>

MODULE_ID("$Id: resizeterm.c,v 1.15 2002/12/28 01:21:34 tom Exp $")

#define stolen_lines (screen_lines - SP->_lines_avail)

static int current_lines;
static int current_cols;

NCURSES_EXPORT(bool)
is_term_resized(int ToLines, int ToCols)
{
    return (ToLines != screen_lines
          || ToCols != screen_columns);
}

/*
 * Return the number of levels of child-windows under the current window.
 */
static int
child_depth(WINDOW *cmp)
{
    int depth = 0;

    if (cmp != 0) {
      WINDOWLIST *wp;

      for (wp = _nc_windows; wp != 0; wp = wp->next) {
          WINDOW *tst = &(wp->win);
          if (tst->_parent == cmp) {
            depth = 1 + child_depth(tst);
            break;
          }
      }
    }
    return depth;
}

/*
 * Return the number of levels of parent-windows above the current window.
 */
static int
parent_depth(WINDOW *cmp)
{
    int depth = 0;

    if (cmp != 0) {
      WINDOW *tst;
      while ((tst = cmp->_parent) != 0) {
          ++depth;
          cmp = tst;
      }
    }
    return depth;
}

/*
 * FIXME: must adjust position so it's within the parent!
 */
static int
adjust_window(WINDOW *win, int ToLines, int ToCols, int stolen)
{
    int result;
    int bottom = current_lines + SP->_topstolen - stolen;
    int myLines = win->_maxy + 1;
    int myCols = win->_maxx + 1;

    T((T_CALLED("adjust_window(%p,%d,%d) currently %dx%d at %d,%d"),
       win, ToLines, ToCols,
       getmaxy(win), getmaxx(win),
       getbegy(win), getbegx(win)));

    if (win->_begy >= bottom) {
      win->_begy += (ToLines - current_lines);
    } else {
      if (myLines == current_lines - stolen
          && ToLines != current_lines)
          myLines = ToLines - stolen;
      else if (myLines == current_lines
             && ToLines != current_lines)
          myLines = ToLines;
    }

    if (myLines > ToLines)
      myLines = ToLines;

    if (myCols > ToCols)
      myCols = ToCols;

    if (myLines == current_lines
      && ToLines != current_lines)
      myLines = ToLines;

    if (myCols == current_cols
      && ToCols != current_cols)
      myCols = ToCols;

    result = wresize(win, myLines, myCols);
    returnCode(result);
}

/*
 * If we're decreasing size, recursively search for windows that have no
 * children, decrease those to fit, then decrease the containing window, etc.
 */
static int
decrease_size(int ToLines, int ToCols, int stolen)
{
    bool found;
    int depth = 0;
    WINDOWLIST *wp;

    T((T_CALLED("decrease_size(%d, %d)"), ToLines, ToCols));

    do {
      found = FALSE;
      TR(TRACE_UPDATE, ("decreasing size of windows to %dx%d, depth=%d",
                    ToLines, ToCols, depth));
      for (wp = _nc_windows; wp != 0; wp = wp->next) {
          WINDOW *win = &(wp->win);

          if (!(win->_flags & _ISPAD)) {
            if (child_depth(win) == depth) {
                if (adjust_window(win, ToLines, ToCols, stolen) != OK)
                  returnCode(ERR);
            }
          }
      }
      ++depth;
    } while (found);
    returnCode(OK);
}

/*
 * If we're increasing size, recursively search for windows that have no
 * parent, increase those to fit, then increase the contained window, etc.
 */
static int
increase_size(int ToLines, int ToCols, int stolen)
{
    bool found;
    int depth = 0;
    WINDOWLIST *wp;

    T((T_CALLED("increase_size(%d, %d)"), ToLines, ToCols));

    do {
      found = FALSE;
      TR(TRACE_UPDATE, ("increasing size of windows to %dx%d, depth=%d",
                    ToLines, ToCols, depth));
      for (wp = _nc_windows; wp != 0; wp = wp->next) {
          WINDOW *win = &(wp->win);

          if (!(win->_flags & _ISPAD)) {
            if (parent_depth(win) == depth) {
                if (adjust_window(win, ToLines, ToCols, stolen) != OK)
                  returnCode(ERR);
            }
          }
      }
      ++depth;
    } while (found);
    returnCode(OK);
}

/*
 * This function reallocates NCURSES window structures, with no side-effects
 * such as ungetch().
 */
NCURSES_EXPORT(int)
resize_term(int ToLines, int ToCols)
{
    int result = OK;
    int was_stolen = (screen_lines - SP->_lines_avail);

    T((T_CALLED("resize_term(%d,%d) old(%d,%d)"),
       ToLines, ToCols,
       screen_lines, screen_columns));

    if (is_term_resized(ToLines, ToCols)) {
      int myLines = current_lines = screen_lines;
      int myCols = current_cols = screen_columns;

      if (ToLines > screen_lines) {
          increase_size(myLines = ToLines, myCols, was_stolen);
          current_lines = myLines;
          current_cols = myCols;
      }

      if (ToCols > screen_columns) {
          increase_size(myLines, myCols = ToCols, was_stolen);
          current_lines = myLines;
          current_cols = myCols;
      }

      if (ToLines < myLines ||
          ToCols < myCols) {
          decrease_size(ToLines, ToCols, was_stolen);
      }

      screen_lines = lines = ToLines;
      screen_columns = columns = ToCols;

      SP->_lines_avail = lines - was_stolen;

      if (SP->oldhash) {
          FreeAndNull(SP->oldhash);
      }
      if (SP->newhash) {
          FreeAndNull(SP->newhash);
      }
    }

    /*
     * Always update LINES, to allow for call from lib_doupdate.c which
     * needs to have the count adjusted by the stolen (ripped off) lines.
     */
    LINES = ToLines - was_stolen;
    COLS = ToCols;

    returnCode(result);
}

/*
 * This function reallocates NCURSES window structures.  It is invoked in
 * response to a SIGWINCH interrupt.  Other user-defined windows may also need
 * to be reallocated.
 *
 * Because this performs memory allocation, it should not (in general) be
 * invoked directly from the signal handler.
 */
NCURSES_EXPORT(int)
resizeterm(int ToLines, int ToCols)
{
    int result = OK;

    SP->_sig_winch = FALSE;

    T((T_CALLED("resizeterm(%d,%d) old(%d,%d)"),
       ToLines, ToCols,
       screen_lines, screen_columns));

    if (is_term_resized(ToLines, ToCols)) {

#if USE_SIGWINCH
      ungetch(KEY_RESIZE);    /* so application can know this */
      clearok(curscr, TRUE);  /* screen contents are unknown */
#endif

      result = resize_term(ToLines, ToCols);
    }

    returnCode(result);
}

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