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    Length: 5416 (0x1528)
    Types: TextFile
    Names: »screen.c«

└─⟦2d1937cfd⟧ Bits:30007241 EUUGD22: P.P 5.0
    └─⟦e83f91978⟧ »EurOpenD22/isode/osimis-2.0.tar.Z« 
        └─⟦d846658bd⟧ 
            └─⟦this⟧ »osimis/smap/screen.c« 

TextFile

/*
 * Copyright (c) 1988 University College London
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the Department of Computer Science, University College London.
 * The name of the University may not be used to
 * endorse or promote products derived from this software without
 * specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/*
 * Keeps track of which records are currently displayed in osimon display
 * and allows that set to be manipulated
 */

/*
 * Initially by Graham Knight, modified by George Pavlou
 * October 1988
 */

#include <stdio.h>
#include "disp.h"
#include "recs.h"


/* routines to change the current screen delimiters */

static RECID fid;               /* pointer to first record on screen */
static RECID lid;               /* pointer to next record off screen */
				/* both supposed to reflect reality */

RECID   settop ();
RECID   setbottom ();
RECID   setmiddle ();

extern RECID validrec ();       /* force a record id to be valid */
extern int LINES;               /* max. number of lines on screen */

extern REC  recs[];
extern RECID  endrec;

static int gap;


/* initialise things */

screeninit (g)
int     g;
{
    gap = g;
}


/*
 * return screen delimiters (ids of top and bottom recs on screen)
 */

delim (fp, lp)
RECID  *fp, *lp;
{
    *fp = fid;
    *lp = lid;
}


/*
 * arrange to point at a screen which includes rid. If rid is already
 * on the screen then don't move and return 0
 */

lookat (rid)
RECID   rid;
{
    register RECID id;

    id = fid;                   /* start of page */

    settop (fid);               /* in case a record has been removed (?) */

    while (id != lid) {
	if (id == rid)
	    return (0);         /* already on display */
	incr (id);
    }

    setmiddle (rid);
    return (1);
}


/*
 * get rid as near to the top of the screen as possible if recs is
 * non-empty rid must identify a real record
 */

RECID  settop (rid)
RECID  rid;
{
    register int nl = 0;

    if (empty ()) {
	fid = lid = first ();
	return (fid);
    }
    nl = linecnt (rid);
    fid = rid;                  /* sets top record pointer */

    while (!pastend (incr (rid))) {
	/*
	 * count how many recs will fit -
	 * there may be different lenghts
	 */
	if ((nl += (linecnt (rid) + gap)) > LINES - TTLNS) {
	    lid = rid;
	    decr (rid);
	    return (fid);
	}
    }

    /* at end of records, try to add more to front */

    lid = rid;
    if (!atstart (fid))
	setbottom (prev (rid));

    return (fid);
}


/*
 * get rid as near to the bottom of the screen as possible if recs is
 * non-empty rid must identify a real record
 */

static  RECID  setbottom (rid)
RECID  rid;
{
    register int nl = 0;

    if (empty ()) {
	fid = lid = first ();
	return (fid);
    }
    nl = linecnt (rid);
    lid = next (rid);           /* sets bottom record pointer */

    while (!atstart (rid)) {
	decr (rid);
	if ((nl += (linecnt (rid) + gap)) > LINES - TTLNS) {
	    /*
	     * counts how many records will fit: might be able to fit
	     * further records at the bottom (it is rather used to
	     * avoid having a gap at the top)
	     */
	    fid = next (rid);
	    return ((pastend (lid)) ? fid : settop (fid));
	}
    }

    /* at start of records, try to add more to end */

    fid = rid;
    if (!pastend (lid))
	settop (rid);

    return (fid);
}


/* get rid as near to the middle of the screen as possible */

static  RECID  setmiddle (rid)
RECID  rid;
{
    register RECID mid, id;

    rid = validrec (rid);       /* get rid in range */

    settop (rid);

    mid = middle (fid, lid);
    id = fid;

    while (before (id, rid) && before (mid, lid)) {
	incr (id);
	incr (mid);
    }

    setbottom (mid);

    return (fid);
}


/* move up/down one record if possible */

upone ()
{
    if (atstart (fid))
	return (0);
    settop (prev (fid));
    return (1);
}


downone ()
{
    if (pastend (lid))
	return (0);
    setbottom (lid);
    return (1);
}


/* move up/down one page if possible */

uppage ()
{
    if (atstart (fid))
	return (0);
    setbottom (prev (fid));
    return (1);
}


downpage ()
{
    if (pastend (lid))
	return (0);
    settop (lid);
    return (1);
}


/* go to extremes */

home ()
{
    if (atstart (fid))
	return (0);
    settop (first ());
    return (1);
}


fin ()
{
    if (pastend (lid))
	return (0);
    setbottom (last ());
    return (1);
}


pagelen ()
{
    register int ln = 0;
    register RECID id;

    id = fid;
    while (before (id, lid)) {
	ln += (linecnt (id) + gap);
	incr (id);
    }
    return ((ln < gap) ? 0 : ln - gap);
}


/* say whether rid is on page commencing with sid */

onpage (sid, rid)
RECID   sid, rid;
{
    register RECID id;
    int     nl = 0;

    sid = validrec (sid);
    rid = validrec (rid);

    id = sid;

    while ((!pastend (id)) &&
	    ((nl += linecnt (rid)) <= LINES - TTLNS)) {
	if (equal (id, rid))
	    return (1);
	nl += gap;
	incr (id);
    }
    return (0);
}