/*
 * File: ui-term.c
 * Purpose: A generic, efficient, terminal window package
 *
 * Copyright (c) 1997 Ben Harrison
 * Copyright (c) 2019 MAngband and PWMAngband Developers
 *
 * This work is free software; you can redistribute it and/or modify it
 * under the terms of either:
 *
 * a) the GNU General Public License as published by the Free Software
 *    Foundation, version 2, or
 *
 * b) the "Angband licence":
 *    This software may be copied and distributed for educational, research,
 *    and not for profit purposes provided that this copyright and statement
 *    are included in all such copies.  Other copyrights may also apply.
 */


#include "c-angband.h"


/*
 * This file provides a generic, efficient, terminal window package,
 * which can be used not only on standard terminal environments such
 * as dumb terminals connected to a Unix box, but also in more modern
 * "graphic" environments, such as the Macintosh or Unix/X11.
 *
 * Each "window" works like a standard "dumb terminal", that is, it
 * can display a two dimensional array of grids containing colored
 * textual symbols, plus an optional cursor, and it can be used to
 * get keypress events from the user.
 *
 * In fact, this package can simply be used, if desired, to support
 * programs which will look the same on a dumb terminal as they do
 * on a graphic platform such as the Macintosh.
 *
 * This package was designed to help port the game "Angband" to a wide
 * variety of different platforms.  Angband, like many other games in
 * the "rogue-like" heirarchy, requires, at the minimum, the ability
 * to display "colored textual symbols" in a standard 80x24 "window",
 * such as that provided by most dumb terminals, and many old personal
 * computers, and to check for "keypresses" from the user.  The major
 * concerns were thus portability and efficiency, so Angband could be
 * easily ported to many different systems, with minimal effort, and
 * yet would run quickly on each of these systems, no matter what kind
 * of underlying hardware/software support was being used.
 *
 * It is important to understand the differences between the older
 * "dumb terminals" and the newer "graphic interface" machines, since
 * this package was designed to work with both types of systems.
 *
 * New machines:
 *   waiting for a keypress is complex
 *   checking for a keypress is often cheap
 *   changing "colors" may be expensive
 *   the "color" of a "blank" is rarely important
 *   moving the "cursor" is relatively cheap
 *   use a "software" cursor (only moves when requested)
 *   drawing characters normally will not erase old ones
 *   drawing a character on the cursor often erases it
 *   may have fast routines for "clear a region"
 *   the bottom right corner is usually not special
 *
 * Old machines:
 *   waiting for a keypress is simple
 *   checking for a keypress is often expensive
 *   changing "colors" is usually cheap
 *   the "color" of a "blank" may be important
 *   moving the "cursor" may be expensive
 *   use a "hardware" cursor (moves during screen updates)
 *   drawing new symbols automatically erases old ones
 *   characters may only be drawn at the cursor location
 *   drawing a character on the cursor will move the cursor
 *   may have fast routines for "clear entire window"
 *   may have fast routines for "clear to end of line"
 *   the bottom right corner is often dangerous
 *
 *
 * This package provides support for multiple windows, each of an
 * arbitrary size (up to 255x255), each with its own set of flags,
 * and its own hooks to handle several low-level procedures which
 * differ from platform to platform.  Then the main program simply
 * creates one or more "term" structures, setting the various flags
 * and hooks in a manner appropriate for the current platform, and
 * then it can use the various "term" structures without worrying
 * about the underlying platform.
 *
 *
 * This package allows each "grid" in each window to hold an attr/char
 * pair, with each ranging from 0 to 255, and makes very few assumptions
 * about the meaning of any attr/char values.  Normally, we assume that
 * "attr 0" is "black", with the semantics that "black" text should be
 * sent to "Term_wipe()" instead of "Term_text()", but this sematics is
 * modified if either the "always_pict" or the "always_text" flags are
 * set.  We assume that "char 0" is "dangerous", since placing such a
 * "char" in the middle of a string "terminates" the string, and usually
 * we prevent its use.
 *
 * Finally, we use a special attr/char pair, defaulting to "attr 0" and
 * "char 32", also known as "black space", when we "erase" or "clear"
 * any window, but this pair can be redefined to any pair, including
 * the standard "white space", or the bizarre "emptiness" ("attr 0"
 * and "char 0"), as long as various obscure restrictions are met.
 *
 *
 * This package provides several functions which allow a program to
 * interact with the "term" structures.  Most of the functions allow
 * the program to "request" certain changes to the current "term",
 * such as moving the cursor, drawing an attr/char pair, erasing a
 * region of grids, hiding the cursor, etc.  Then there is a special
 * function which causes all of the "pending" requests to be performed
 * in an efficient manner.  There is another set of functions which
 * allow the program to query the "requested state" of the current
 * "term", such as asking for the cursor location, or what attr/char
 * is at a given location, etc.  There is another set of functions
 * dealing with "keypress" events, which allows the program to ask if
 * the user has pressed any keys, or to forget any keys the user pressed.
 * There is a pair of functions to allow this package to memorize the
 * contents of the current "term", and to restore these contents at
 * a later time.  There is a special function which allows the program
 * to specify which "term" structure should be the "current" one.  At
 * the lowest level, there is a set of functions which allow a new
 * "term" to be initialized or destroyed, and which allow this package,
 * or a program, to access the special "hooks" defined for the current
 * "term", and a set of functions which those "hooks" can use to inform
 * this package of the results of certain occurances, for example, one
 * such function allows this package to learn about user keypresses,
 * detected by one of the special "hooks".
 *
 * We provide, among other things, the functions "Term_keypress()"
 * to "react" to keypress events, and "Term_redraw()" to redraw the
 * entire window, plus "Term_resize()" to note a new size.
 *
 *
 * Note that the current "term" contains two "window images".  One of
 * these images represents the "requested" contents of the "term", and
 * the other represents the "actual" contents of the "term", at the time
 * of the last performance of pending requests.  This package uses these
 * two images to determine the "minimal" amount of work needed to make
 * the "actual" contents of the "term" match the "requested" contents of
 * the "term".  This method is not perfect, but it often reduces the
 * amount of work needed to perform the pending requests, which thus
 * increases the speed of the program itself.  This package promises
 * that the requested changes will appear to occur either "all at once"
 * or in a "top to bottom" order.  In addition, a "cursor" is maintained,
 * and this cursor is updated along with the actual window contents.
 *
 * Currently, the "Term_fresh()" routine attempts to perform the "minimum"
 * number of physical updates, in terms of total "work" done by the hooks
 * Term_wipe(), Term_text(), and Term_pict(), making use of the fact that
 * adjacent characters of the same color can both be drawn together using
 * the "Term_text()" hook, and that "black" text can often be sent to the
 * "Term_wipe()" hook instead of the "Term_text()" hook, and if something
 * is already displayed in a window, then it is not necessary to display
 * it again.  Unfortunately, this may induce slightly non-optimal results
 * in some cases, in particular, those in which, say, a string of ten
 * characters needs to be written, but the fifth character has already
 * been displayed.  Currently, this will cause the "Term_text()" routine
 * to be called once for each half of the string, instead of once for the
 * whole string, which, on some machines, may be non-optimal behavior.
 *
 * The new formalism includes a "displayed" screen image (old) which
 * is actually seen by the user, a "requested" screen image (scr)
 * which is being prepared for display, a "memorized" screen image
 * (mem) which is used to save and restore screen images, and a
 * "temporary" screen image (tmp) which is currently unused.
 *
 *
 * Several "flags" are available in each "term" to allow the underlying
 * visual system (which initializes the "term" structure) to "optimize"
 * the performance of this package for the given system, or to request
 * certain behavior which is helpful/required for the given system.
 *
 * The "soft_cursor" flag indicates the use of a "soft" cursor, which
 * only moves when explicitly requested,and which is "erased" when
 * any characters are drawn on top of it.  This flag is used for all
 * "graphic" systems which handle the cursor by "drawing" it.
 *
 * The "icky_corner" flag indicates that the bottom right "corner"
 * of the windows are "icky", and "printing" anything there may
 * induce "messy" behavior, such as "scrolling".  This flag is used
 * for most old "dumb terminal" systems.
 *
 *
 * The "term" structure contains the following function "hooks":
 *
 *   Term->init_hook = Init the term
 *   Term->nuke_hook = Nuke the term
 *   Term->xtra_hook = Perform extra actions
 *   Term->curs_hook = Draw (or Move) the cursor
 *   Term->bigcurs_hook = Draw (or Move) the big cursor (bigtile mode)
 *   Term->wipe_hook = Draw some blank spaces
 *   Term->text_hook = Draw some text in the window
 *   Term->pict_hook = Draw some attr/chars in the window
 *
 * The "Term->xtra_hook" hook provides a variety of different functions,
 * based on the first parameter (which should be taken from the various
 * TERM_XTRA_* defines) and the second parameter (which may make sense
 * only for some first parameters).  It is available to the program via
 * the "Term_xtra()" function, though some first parameters are only
 * "legal" when called from inside this package.
 *
 * The "Term->curs_hook" hook provides this package with a simple way
 * to "move" or "draw" the cursor to the grid "x,y", depending on the
 * setting of the "soft_cursor" flag.  Note that the cursor is never
 * redrawn if "nothing" has happened to the screen (even temporarily).
 * This hook is required.
 *
 * The "Term->wipe_hook" hook provides this package with a simple way
 * to "erase", starting at "x,y", the next "n" grids.  This hook assumes
 * that the input is valid.  This hook is required, unless the setting
 * of the "always_pict" or "always_text" flags makes it optional.
 *
 * The "Term->text_hook" hook provides this package with a simple way
 * to "draw", starting at "x,y", the "n" chars contained in "cp", using
 * the attr "a".  This hook assumes that the input is valid, and that
 * "n" is between 1 and 256 inclusive, but it should NOT assume that
 * the contents of "cp" are null-terminated.  This hook is required,
 * unless the setting of the "always_pict" flag makes it optional.
 *
 * The "Term->pict_hook" hook provides this package with a simple way
 * to "draw", starting at "x,y", the "n" attr/char pairs contained in
 * the arrays "ap" and "cp".  This hook assumes that the input is valid,
 * and that "n" is between 1 and 256 inclusive, but it should NOT assume
 * that the contents of "cp" are null-terminated.  This hook is optional,
 * unless the setting of the "always_pict" or "higher_pict" flags make
 * it required.  Note that recently, this hook was changed from taking
 * a byte "a" and a char "c" to taking a length "n", an array of bytes
 * "ap" and an array of chars "cp".  Old implementations of this hook
 * should now iterate over all "n" attr/char pairs.
 * The two new arrays "tap" and "tcp" can contain the attr/char pairs
 * of the terrain below the values in "ap" and "cp".  These values can
 * be used to implement transparency when using graphics by drawing
 * the terrain values as a background and the "ap", "cp" values in
 * the foreground.
 *
 * The game "Angband" uses a set of files called "main-xxx.c", for
 * various "xxx" suffixes.  Most of these contain a function called
 * "init_xxx()", that will prepare the underlying visual system for
 * use with Angband, and then create one or more "term" structures,
 * using flags and hooks appropriate to the given platform, so that
 * the "main()" function can call one (or more) of the "init_xxx()"
 * functions, as appropriate, to prepare the required "term" structs
 * (one for each desired sub-window), and these "init_xxx()" functions
 * are called from a centralized "main()" function in "main.c".  Other
 * "main-xxx.c" systems contain their own "main()" function which, in
 * addition to doing everything needed to initialize the actual program,
 * also does everything that the normal "init_xxx()" functions would do.
 *
 * The game "Angband" defines, in addition to "attr 0", all of the
 * attr codes from 1 to 15, using definitions in "z-color.h", and
 * thus the "main-xxx.c" files used by Angband must handle these
 * attr values correctly.  Also, they must handle all other attr
 * values, though they may do so in any way they wish, for example,
 * by always taking every attr code mod 16.  Many of the "main-xxx.c"
 * files use "white space" ("attr 1" / "char 32") to "erase" or "clear"
 * any window, for efficiency.
 *
 * See "main-xxx.c" for a simple skeleton file which can be used to
 * create a "visual system" for a new platform when porting Angband.
 */


/*
 * The array[ANGBAND_TERM_MAX] of window pointers
 */
term *angband_term[ANGBAND_TERM_MAX];


/*
 * The array[ANGBAND_TERM_MAX] of window names
 */
const char *angband_term_name[ANGBAND_TERM_MAX] =
{
    "Main window",
    "Term-1",
    "Term-2",
    "Term-3",
    "Chat window",
    "Term-5",
    "Term-6",
    "Term-7"
};


/* Window flags */
u32b window_flag[ANGBAND_TERM_MAX];


/*
 * The current "term"
 */
term *Term = NULL;


byte tile_width = 1;
byte tile_height = 1;
bool tile_distorted = false;


/*
 * Local routines
 */


/*
 * Nuke a term_win (see below)
 */
static errr term_win_nuke(term_win *s)
{
    /* Free the window access arrays */
    mem_free(s->a);
    mem_free(s->c);

    /* Free the window content arrays */
    mem_free(s->va);
    mem_free(s->vc);

    /* Free the terrain access arrays */
    mem_free(s->ta);
    mem_free(s->tc);

    /* Free the terrain content arrays */
    mem_free(s->vta);
    mem_free(s->vtc);

    /* Success */
    return (0);
}


/*
 * Initialize a "term_win" (using the given window size)
 */
static errr term_win_init(term_win *s, int w, int h)
{
    int y;

    /* Make the window access arrays */
    s->a = mem_zalloc(h * sizeof(u16b*));
    s->c = mem_zalloc(h * sizeof(char*));

    /* Make the window content arrays */
    s->va = mem_zalloc(h * w * sizeof(u16b));
    s->vc = mem_zalloc(h * w * sizeof(char));

    /* Make the terrain access arrays */
    s->ta = mem_zalloc(h * sizeof(u16b*));
    s->tc = mem_zalloc(h * sizeof(char*));

    /* Make the terrain content arrays */
    s->vta = mem_zalloc(h * w * sizeof(u16b));
    s->vtc = mem_zalloc(h * w * sizeof(char));

    /* Prepare the window access arrays */
    for (y = 0; y < h; y++)
    {
        s->a[y] = s->va + w * y;
        s->c[y] = s->vc + w * y;

        s->ta[y] = s->vta + w * y;
        s->tc[y] = s->vtc + w * y;
    }

    /* Success */
    return (0);
}


/*
 * Copy a "term_win" from another
 */
static errr term_win_copy(term_win *s, term_win *f, int w, int h)
{
    int x, y;

    /* Copy contents */
    for (y = 0; y < h; y++)
    {
        u16b *f_aa = f->a[y];
        char *f_cc = f->c[y];

        u16b *s_aa = s->a[y];
        char *s_cc = s->c[y];

        u16b *f_taa = f->ta[y];
        char *f_tcc = f->tc[y];

        u16b *s_taa = s->ta[y];
        char *s_tcc = s->tc[y];

        for (x = 0; x < w; x++)
        {
            memcpy(s_aa, f_aa, w * sizeof(u16b));
            memcpy(s_cc, f_cc, w);

            memcpy(s_taa, f_taa, w * sizeof(u16b));
            memcpy(s_tcc, f_tcc, w);
        }
    }

    /* Copy cursor */
    s->cx = f->cx;
    s->cy = f->cy;
    s->cu = f->cu;
    s->cv = f->cv;

    /* Success */
    return (0);
}


/*
 * External hooks
 */


/*
 * Execute the "Term->xtra_hook" hook, if available (see above).
 */
errr Term_xtra(int n, int v)
{
    /* Verify the hook */
    if (!Term->xtra_hook) return (-1);

    /* Call the hook */
    return ((*Term->xtra_hook)(n, v));
}


/*
 * Fake hooks
 */


/*
 * Hack -- fake hook for "Term_curs()" (see above)
 */
static errr Term_curs_hack(int x, int y)
{
    /* Compiler silliness */
    if (x || y) return (-2);

    /* Oops */
    return (-1);
}


/*
 * Hack -- fake hook for "Term_wipe()" (see above)
 */
static errr Term_wipe_hack(int x, int y, int n)
{
    /* Compiler silliness */
    if (x || y || n) return (-2);

    /* Oops */
    return (-1);
}


/*
 * Hack -- fake hook for "Term_text()" (see above)
 */
static errr Term_text_hack(int x, int y, int n, u16b a, const char *cp)
{
    /* Compiler silliness */
    if (x || y || n || a || cp) return (-2);

    /* Oops */
    return (-1);
}


/*
 * Hack -- fake hook for "Term_pict()" (see above)
 */
static errr Term_pict_hack(int x, int y, int n, const u16b *ap, const char *cp,
    const u16b *tap, const char *tcp)
{
    /* Compiler silliness */
    if (x || y || n || ap || cp || tap || tcp) return (-2);

    /* Oops */
    return (-1);
}


/*
 * Efficient routines
 */


/*
 * Mentally draw an attr/char at a given location
 *
 * Assumes given location and values are valid.
 */
void Term_queue_char(term *t, int x, int y, u16b a, char c, u16b ta, char tc)
{
    u16b *scr_aa = t->scr->a[y];
    char *scr_cc = t->scr->c[y];

    u16b oa = scr_aa[x];
    char oc = scr_cc[x];

    u16b *scr_taa = t->scr->ta[y];
    char *scr_tcc = t->scr->tc[y];

    u16b ota = scr_taa[x];
    char otc = scr_tcc[x];

    /* Don't change is the terrain value is 0 */
    if (!ta) ta = ota;
    if (!tc) tc = otc;

    /* Hack -- ignore non-changes */
    if ((oa == a) && (oc == c) && (ota == ta) && (otc == tc)) return;

    /* Save the "literal" information */
    scr_aa[x] = a;
    scr_cc[x] = c;

    scr_taa[x] = ta;
    scr_tcc[x] = tc;

    /* Check for new min/max row info */
    if (y < t->y1) t->y1 = y;
    if (y > t->y2) t->y2 = y;

    /* Check for new min/max col info for this row */
    if (x < t->x1[y]) t->x1[y] = x;
    if (x > t->x2[y]) t->x2[y] = x;
}


/*
 * Queue a large-sized tile
 */
void Term_big_queue_char(term *t, int x, int y, u16b a, char c, u16b a1, char c1)
{
    int hor, vert;

    /* No tall skinny tiles */
    if (tile_width > 1)
    {
        /* Horizontal first */
        for (hor = 0; hor <= tile_width; hor++)
        {
            /* Queue dummy character */
            if (hor != 0)
            {
                if (a & 0x80)
                    Term_queue_char(t, x + hor, y, 255, -1, 0, 0);
                else
                    Term_queue_char(t, x + hor, y, COLOUR_WHITE, ' ', a1, c1);
            }

            /* Now vertical */
            for (vert = 1; vert <= tile_height; vert++)
            {
                /* Leave space on bottom for status */
                if (y + vert + 1 < t->hgt)
                {
                    /* Queue dummy character */
                    if (a & 0x80)
                        Term_queue_char(t, x + hor, y + vert, 255, -1, 0, 0);
                    else
                        Term_queue_char(t, x + hor, y + vert, COLOUR_WHITE, ' ', a1, c1);
                }
            }
        }
    }
    else
    {
        /* Only vertical */
        for (vert = 1; vert <= tile_height; vert++)
        {
            /* Leave space on bottom for status */
            if (y + vert + 1 < t->hgt)
            {
                /* Queue dummy character */
                if (a & 0x80)
                    Term_queue_char(t, x, y + vert, 255, -1, 0, 0);
                else
                    Term_queue_char(t, x, y + vert, COLOUR_WHITE, ' ', a1, c1);
            }
        }
    }
}


/*
 * Mentally draw some attr/chars at a given location
 *
 * Assumes that (x,y) is a valid location, that the first "n" characters
 * of the string "s" are all valid (non-zero), and that (x+n-1,y) is also
 * a valid location, so the first "n" characters of "s" can all be added
 * starting at (x,y) without causing any illegal operations.
 */
void Term_queue_chars(int x, int y, int n, u16b a, const char *s)
{
    int x1 = -1, x2 = -1;

    u16b *scr_aa = Term->scr->a[y];
    char *scr_cc = Term->scr->c[y];

    u16b *scr_taa = Term->scr->ta[y];
    char *scr_tcc = Term->scr->tc[y];

    /* Queue the attr/chars */
    for ( ; n; x++, s++, n--)
    {
        u16b oa = scr_aa[x];
        char oc = scr_cc[x];

        u16b ota = scr_taa[x];
        char otc = scr_tcc[x];

        /* Hack -- ignore non-changes */
        if ((oa == a) && (oc == *s) && (ota == 0) && (otc == 0)) continue;

        /* Save the "literal" information */
        scr_aa[x] = a;
        scr_cc[x] = *s;

        scr_taa[x] = 0;
        scr_tcc[x] = 0;

        /* Note the "range" of window updates */
        if (x1 < 0) x1 = x;
        x2 = x;
    }

    /* Expand the "change area" as needed */
    if (x1 >= 0)
    {
        /* Check for new min/max row info */
        if (y < Term->y1) Term->y1 = y;
        if (y > Term->y2) Term->y2 = y;

        /* Check for new min/max col info in this row */
        if (x1 < Term->x1[y]) Term->x1[y] = x1;
        if (x2 > Term->x2[y]) Term->x2[y] = x2;
    }
}


/*
 * Refresh routines
 */


/*
 * Flush a row of the current window (see "Term_fresh")
 *
 * Display text using "Term_pict()"
 */
static void Term_fresh_row_pict(int y, int x1, int x2)
{
    int x;

    u16b *old_aa = Term->old->a[y];
    char *old_cc = Term->old->c[y];

    u16b *scr_aa = Term->scr->a[y];
    char *scr_cc = Term->scr->c[y];

    u16b *old_taa = Term->old->ta[y];
    char *old_tcc = Term->old->tc[y];

    u16b *scr_taa = Term->scr->ta[y];
    char *scr_tcc = Term->scr->tc[y];

    u16b ota;
    char otc;

    u16b nta;
    char ntc;

    /* Pending length */
    int fn = 0;

    /* Pending start */
    int fx = 0;

    u16b oa;
    char oc;

    u16b na;
    char nc;

    /* Scan "modified" columns */
    for (x = x1; x <= x2; x++)
    {
        /* See what is currently here */
        oa = old_aa[x];
        oc = old_cc[x];

        /* See what is desired there */
        na = scr_aa[x];
        nc = scr_cc[x];

        ota = old_taa[x];
        otc = old_tcc[x];

        nta = scr_taa[x];
        ntc = scr_tcc[x];

        /* Handle unchanged grids */
        if ((na == oa) && (nc == oc) && (nta == ota) && (ntc == otc))
        {
            /* Flush */
            if (fn)
            {
                /* Draw pending attr/char pairs */
                (*Term->pict_hook)(fx, y, fn, &scr_aa[fx], &scr_cc[fx], &scr_taa[fx], &scr_tcc[fx]);

                /* Forget */
                fn = 0;
            }

            /* Skip */
            continue;
        }
        
        /* Save new contents */
        old_aa[x] = na;
        old_cc[x] = nc;

        old_taa[x] = nta;
        old_tcc[x] = ntc;

        /* Restart and Advance */
        if (fn++ == 0) fx = x;
    }

    /* Flush */
    if (fn)
    {
        /* Draw pending attr/char pairs */
        (*Term->pict_hook)(fx, y, fn, &scr_aa[fx], &scr_cc[fx], &scr_taa[fx], &scr_tcc[fx]);
    }
}



/*
 * Flush a row of the current window (see "Term_fresh")
 *
 * Display text using "Term_text()" and "Term_wipe()",
 * but use "Term_pict()" for high-bit attr/char pairs
 */
static void Term_fresh_row_both(int y, int x1, int x2)
{
    int x;

    u16b *old_aa = Term->old->a[y];
    char *old_cc = Term->old->c[y];

    u16b *scr_aa = Term->scr->a[y];
    char *scr_cc = Term->scr->c[y];

    u16b *old_taa = Term->old->ta[y];
    char *old_tcc = Term->old->tc[y];

    u16b *scr_taa = Term->scr->ta[y];
    char *scr_tcc = Term->scr->tc[y];

    u16b ota;
    char otc;

    u16b nta;
    char ntc;

    /* The "always_text" flag */
    int always_text = Term->always_text;

    /* Pending length */
    int fn = 0;

    /* Pending start */
    int fx = 0;

    /* Pending attr */
    u16b fa = Term->attr_blank;

    u16b oa;
    char oc;

    u16b na;
    char nc;

    /* Scan "modified" columns */
    for (x = x1; x <= x2; x++)
    {
        /* See what is currently here */
        oa = old_aa[x];
        oc = old_cc[x];

        /* See what is desired there */
        na = scr_aa[x];
        nc = scr_cc[x];

        ota = old_taa[x];
        otc = old_tcc[x];

        nta = scr_taa[x];
        ntc = scr_tcc[x];

        /* Handle unchanged grids */
        if ((na == oa) && (nc == oc) && (nta == ota) && (ntc == otc))
        {
            /* Flush */
            if (fn)
            {
                /* Draw pending chars (normal or black) */
                if (fa || always_text)
                    (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
                else
                    (*Term->wipe_hook)(fx, y, fn);

                /* Forget */
                fn = 0;
            }

            /* Skip */
            continue;
        }

        /* Save new contents */
        old_aa[x] = na;
        old_cc[x] = nc;
        old_taa[x] = nta;
        old_tcc[x] = ntc;

        /* Handle high-bit attr/chars */
        if (na & 0x80)
        {
            /* Flush */
            if (fn)
            {
                /* Draw pending chars (normal or black) */
                if (fa || always_text)
                    (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
                else
                    (*Term->wipe_hook)(fx, y, fn);

                /* Forget */
                fn = 0;
            }

            /* Bigtile mode */
            if (na % MAX_COLORS == 255) continue;

            /* Hack -- draw the special attr/char pair */
            (*Term->pict_hook)(x, y, 1, &na, &nc, &nta, &ntc);

            /* Skip */
            continue;
        }

        /* Notice new color */
        if (fa != na)
        {
            /* Flush */
            if (fn)
            {
                /* Draw the pending chars, erase leading spaces */
                if (fa || always_text)
                    (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
                else
                    (*Term->wipe_hook)(fx, y, fn);

                /* Forget */
                fn = 0;
            }

            /* Save the new color */
            fa = na;
        }

        /* Restart and Advance */
        if (fn++ == 0) fx = x;
    }

    /* Flush */
    if (fn)
    {
        /* Draw pending chars (normal or black) */
        if (fa || always_text)
            (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
        else
            (*Term->wipe_hook)(fx, y, fn);
    }
}


/*
 * Flush a row of the current window (see "Term_fresh")
 *
 * Display text using "Term_text()" and "Term_wipe()"
 */
static void Term_fresh_row_text(int y, int x1, int x2)
{
    int x;

    u16b *old_aa = Term->old->a[y];
    char *old_cc = Term->old->c[y];

    u16b *scr_aa = Term->scr->a[y];
    char *scr_cc = Term->scr->c[y];

    /* The "always_text" flag */
    int always_text = Term->always_text;

    /* Pending length */
    int fn = 0;

    /* Pending start */
    int fx = 0;

    /* Pending attr */
    u16b fa = Term->attr_blank;

    u16b oa;
    char oc;

    u16b na;
    char nc;

    /* Scan "modified" columns */
    for (x = x1; x <= x2; x++)
    {
        /* See what is currently here */
        oa = old_aa[x];
        oc = old_cc[x];

        /* See what is desired there */
        na = scr_aa[x];
        nc = scr_cc[x];

        /* Handle unchanged grids */
        if ((na == oa) && (nc == oc))
        {
            /* Flush */
            if (fn)
            {
                /* Draw pending chars (normal or black) */
                if (fa || always_text)
                    (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
                else
                    (*Term->wipe_hook)(fx, y, fn);

                /* Forget */
                fn = 0;
            }

            /* Skip */
            continue;
        }

        /* Save new contents */
        old_aa[x] = na;
        old_cc[x] = nc;

        /* Notice new color */
        if (fa != na)
        {
            /* Flush */
            if (fn)
            {
                /* Draw the pending chars, erase leading spaces */
                if (fa || always_text)
                    (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
                else
                    (*Term->wipe_hook)(fx, y, fn);

                /* Forget */
                fn = 0;
            }

            /* Save the new color */
            fa = na;
        }

        /* Restart and Advance */
        if (fn++ == 0) fx = x;
    }

    /* Flush */
    if (fn)
    {
        /* Draw pending chars (normal or black) */
        if (fa || always_text)
            (*Term->text_hook)(fx, y, fn, fa, &scr_cc[fx]);
        else
            (*Term->wipe_hook)(fx, y, fn);
    }
}


/*
 * Actually perform all requested changes to the window
 *
 * If absolutely nothing has changed, not even temporarily, or if the
 * current "Term" is not mapped, then this function will return 1 and
 * do absolutely nothing.
 *
 * Note that when "soft_cursor" is true, we erase the cursor (if needed)
 * whenever anything has changed, and redraw it (if needed) after all of
 * the screen updates are complete.  This will induce a small amount of
 * "cursor flicker" but only when the screen has been updated.  If the
 * screen is updated and then restored, you may still get this flicker.
 *
 * When "soft_cursor" is not true, we make the cursor invisible before
 * doing anything else if it is supposed to be invisible by the time we
 * are done, and we make it visible after moving it to its final location
 * after all of the screen updates are complete.
 *
 * Note that "Term_xtra(TERM_XTRA_CLEAR,0)" must erase the entire screen,
 * including the cursor, if needed, and may place the cursor anywhere.
 *
 * Note that "Term_xtra(TERM_XTRA_FROSH,y)" will be always be called
 * after any row "y" has been "flushed", unless the "Term->never_frosh"
 * flag is set, and "Term_xtra(TERM_XTRA_FRESH,0)" will be called after
 * all of the rows have been "flushed".
 *
 * Note the use of three different functions to handle the actual flush,
 * based on the settings of the "Term->always_pict" and "Term->higher_pict"
 * flags (see below).
 *
 * The three helper functions (above) work by collecting similar adjacent
 * grids into stripes, and then sending each stripe to "Term->pict_hook",
 * "Term->text_hook", or "Term->wipe_hook", based on the settings of the
 * "Term->always_pict" and "Term->higher_pict" flags, which select which
 * of the helper functions to call to flush each row.
 *
 * The helper functions currently "skip" any grids which already contain
 * the desired contents.  This may or may not be the best method, especially
 * when the desired content fits nicely into the current stripe.  For example,
 * it might be better to go ahead and queue them while allowed, but keep a
 * count of the "trailing skipables", then, when time to flush, or when a
 * "non skippable" is found, force a flush if there are too many skippables.
 *
 * Perhaps an "initialization" stage, where the "text" (and "attr")
 * buffers are "filled" with information, converting "blanks" into
 * a convenient representation, and marking "skips" with "zero chars",
 * and then some "processing" is done to determine which chars to skip.
 *
 * Currently, the helper functions are optimal for systems which prefer
 * to "print a char + move a char + print a char" to "print three chars",
 * and for applications that do a lot of "detailed" color printing.
 *
 * In the two "queue" functions, total "non-changes" are "pre-skipped".
 * The helper functions must also handle situations in which the contents
 * of a grid are changed, but then changed back to the original value,
 * and situations in which two grids in the same row are changed, but
 * the grids between them are unchanged.
 *
 * If the "Term->always_pict" flag is set, then "Term_fresh_row_pict()"
 * will be used instead of "Term_fresh_row_text()".  This allows all the
 * modified grids to be collected into stripes of attr/char pairs, which
 * are then sent to the "Term->pict_hook" hook, which can draw these pairs
 * in whatever way it would like.
 *
 * If the "Term->higher_pict" flag is set, then "Term_fresh_row_both()"
 * will be used instead of "Term_fresh_row_text()".  This allows all the
 * "special" attr/char pairs (in which both the attr and char have the
 * high-bit set) to be sent (one pair at a time) to the "Term->pict_hook"
 * hook, which can draw these pairs in whatever way it would like.
 *
 * Normally, the "Term_wipe()" function is used only to display "blanks"
 * that were induced by "Term_clear()" or "Term_erase()", and then only
 * if the "attr_blank" and "char_blank" fields have not been redefined
 * to use "white space" instead of the default "black space".  Actually,
 * the "Term_wipe()" function is used to display all "black" text, such
 * as the default "spaces" created by "Term_clear()" and "Term_erase()".
 *
 * Note that the "Term->always_text" flag will disable the use of the
 * "Term_wipe()" function hook entirely, and force all text, even text
 * drawn in the color "black", to be explicitly drawn.  This is useful
 * for machines which implement "Term_wipe()" by just drawing spaces.
 *
 * Note that the "Term->always_pict" flag will disable the use of the
 * "Term_wipe()" function entirely, and force everything, even text
 * drawn in the attr "black", to be explicitly drawn.
 *
 * Note that if no "black" text is ever drawn, and if "attr_blank" is
 * not "zero", then the "Term_wipe" hook will never be used, even if
 * the "Term->always_text" flag is not set.
 *
 * This function does nothing unless the "Term" is "mapped", which allows
 * certain systems to optimize the handling of "closed" windows.
 *
 * On systems with a "soft" cursor, we must explicitly erase the cursor
 * before flushing the output, if needed, to prevent a "jumpy" refresh.
 * The actual method for this is horrible, but there is very little that
 * we can do to simplify it efficiently.  XXX XXX XXX
 *
 * On systems with a "hard" cursor, we will "hide" the cursor before
 * flushing the output, if needed, to avoid a "flickery" refresh.  It
 * would be nice to *always* hide the cursor during the refresh, but
 * this might be expensive (and/or ugly) on some machines.
 *
 * The "Term->icky_corner" flag is used to avoid calling "Term_wipe()"
 * or "Term_pict()" or "Term_text()" on the bottom right corner of the
 * window, which might induce "scrolling" or other nasty stuff on old
 * dumb terminals.  This flag is handled very efficiently.  We assume
 * that the "Term_curs()" call will prevent placing the cursor in the
 * corner, if needed, though I doubt such placement is ever a problem.
 * Currently, the use of "Term->icky_corner" and "Term->soft_cursor"
 * together may result in undefined behavior.
 */
errr Term_fresh(void)
{
    int x, y;

    int w = Term->wid;
    int h = Term->hgt;

    int y1 = Term->y1;
    int y2 = Term->y2;

    term_win *old = Term->old;
    term_win *scr = Term->scr;

    /* Do nothing unless "mapped" */
    if (!Term->mapped_flag) return (1);

    /* Trivial Refresh */
    if ((y1 > y2) && (scr->cu == old->cu) && (scr->cv == old->cv) &&
        (scr->cx == old->cx) && (scr->cy == old->cy) && !(Term->total_erase))
    {
        /* Nothing */
        if (Term == term_screen) Term->minimap_active = false;
        return (1);
    }

    /* Paranoia -- use "fake" hooks to prevent core dumps */
    if (!Term->curs_hook) Term->curs_hook = Term_curs_hack;
    if (!Term->bigcurs_hook) Term->bigcurs_hook = Term->curs_hook;
    if (!Term->wipe_hook) Term->wipe_hook = Term_wipe_hack;
    if (!Term->text_hook) Term->text_hook = Term_text_hack;
    if (!Term->pict_hook) Term->pict_hook = Term_pict_hack;

    /* Handle "total erase" */
    if (Term->total_erase)
    {
        u16b na = Term->attr_blank;
        char nc = Term->char_blank;

        /* Physically erase the entire window */
        Term_xtra(TERM_XTRA_CLEAR, 0);

        /* Hack -- clear all "cursor" data */
        old->cv = old->cu = false;
        old->cx = old->cy = 0;

        /* Wipe each row */
        for (y = 0; y < h; y++)
        {
            u16b *aa = old->a[y];
            char *cc = old->c[y];
            u16b *taa = old->ta[y];
            char *tcc = old->tc[y];

            /* Wipe each column */
            for (x = 0; x < w; x++)
            {
                /* Wipe each grid */
                *aa++ = na;
                *cc++ = nc;

                *taa++ = na;
                *tcc++ = nc;
            }
        }

        /* Redraw every row */
        Term->y1 = y1 = 0;
        Term->y2 = y2 = h - 1;

        /* Redraw every column */
        memset(Term->x1, 0, h);
        memset(Term->x2, w - 1, h);

        /* Forget "total erase" */
        Term->total_erase = false;
    }

    /* Cursor update -- erase old cursor */
    if (Term->soft_cursor)
    {
        /* Cursor was visible */
        if (!old->cu && old->cv)
        {
            int tx = old->cx;
            int ty = old->cy;

            /*u16b *old_aa = old->a[ty];
            char *old_cc = old->c[ty];*/
            u16b *scr_aa = scr->a[ty];
            char *scr_cc = scr->c[ty];

            u16b sa = scr_aa[tx];
            char sc = scr_cc[tx];

            /*u16b *old_taa = old->ta[ty];
            char *old_tcc = old->tc[ty];*/
            u16b *scr_taa = scr->ta[ty];
            char *scr_tcc = scr->tc[ty];

            u16b sta = scr_taa[tx];
            char stc = scr_tcc[tx];

            /* Graphics, character (fallback or intended), or erase */
            if (Term->always_pict)
                (*Term->pict_hook)(tx, ty, 1, &sa, &sc, &sta, &stc);
            else if (Term->higher_pict && (sa & 0x80))
                (*Term->pict_hook)(tx, ty, 1, &sa, &sc, &sta, &stc);
            else if (sa || Term->always_text)
            {
                if (Setup.initialized && !Term->saved && (ty > 0) &&
                    !((tx == scr->cx) && (ty == scr->cy)))
                {
                    int i, j;

                    /* Hack -- erase a big cursor */
                    for (i = tx; ((i < tx + tile_width) && (i < w)); i++)
                    {
                        for (j = ty; ((j < ty + tile_height) && (j < h)); j++)
                        {
                            sa = scr->a[j][i];
                            sc = scr->c[j][i];
                            (*Term->text_hook)(i, j, 1, sa, &sc);
                        }
                    }
                }
                else
                    (*Term->text_hook)(tx, ty, 1, sa, &sc);
            }
            else
                (*Term->wipe_hook)(tx, ty, 1);
        }
    }
    else
    {
        /* Cursor will be invisible */
        if (scr->cu || !scr->cv)
            Term_xtra(TERM_XTRA_SHAPE, 0);
    }

    /* Something to update */
    if (y1 <= y2)
    {
        /* Handle "icky corner" */
        if (Term->icky_corner && (y2 >= h - 1) && (Term->x2[h - 1] > w - 2))
            Term->x2[h - 1] = w - 2;

        /* Scan the "modified" rows */
        for (y = y1; y <= y2; ++y)
        {
            int x1 = Term->x1[y];
            int x2 = Term->x2[y];

            /* Flush each "modified" row */
            if (x1 <= x2)
            {
                /* Use "Term_pict()" - always, sometimes or never */
                if (Term->always_pict)
                {
                    /* Flush the row */
                    Term_fresh_row_pict(y, x1, x2);
                }
                else if (Term->higher_pict)
                {
                    /* Flush the row */
                    Term_fresh_row_both(y, x1, x2);
                }
                else
                {
                    /* Flush the row */
                    Term_fresh_row_text(y, x1, x2);
                }

                /* This row is all done */
                Term->x1[y] = w;
                Term->x2[y] = 0;

                /* Hack -- flush that row (if allowed) */
                if (!Term->never_frosh) Term_xtra(TERM_XTRA_FROSH, y);
            }
        }

        /* No rows are invalid */
        Term->y1 = h;
        Term->y2 = 0;
    }

    /* Cursor update -- show new cursor */
    if (Term->soft_cursor)
    {
        /* Draw the (large or small) cursor */
        if (!scr->cu && scr->cv && !Term->no_cursor)
        {
            if (Setup.initialized && !Term->saved && (scr->cy > 0))
                (*Term->bigcurs_hook)(scr->cx, scr->cy);
            else
                (*Term->curs_hook)(scr->cx, scr->cy);
        }
    }
    else
    {
        /* The cursor is useless or invisible ignore it, otherwise display */
        if (scr->cu)
        {
            /* Paranoia -- put the cursor NEAR where it belongs */
            (*Term->curs_hook)(w - 1, scr->cy);
        }
        else if (!scr->cv)
        {
            /* Paranoia -- put the cursor where it belongs */
            (*Term->curs_hook)(scr->cx, scr->cy);
        }
        else
        {
            /* Put the cursor where it belongs */
            (*Term->curs_hook)(scr->cx, scr->cy);

            /* Make the cursor visible */
            Term_xtra(TERM_XTRA_SHAPE, 1);
        }
    }

    /* Save the "cursor state" */
    old->cu = scr->cu;
    old->cv = scr->cv;
    old->cx = scr->cx;
    old->cy = scr->cy;

    /* Actually flush the output */
    Term_xtra(TERM_XTRA_FRESH, 0);

    /* Success */
    if (Term == term_screen) Term->minimap_active = false;
    return (0);
}


/*
 * Output routines
 */


/*
 * Set the cursor visibility
 */
errr Term_set_cursor(bool v)
{
    /* Already done */
    if (Term->scr->cv == v) return (1);

    /* Change */
    Term->scr->cv = v;

    /* Success */
    return (0);
}


/*
 * Place the cursor at a given location
 *
 * Note -- "illegal" requests do not move the cursor.
 */
errr Term_gotoxy(int x, int y)
{
    int w = Term->wid;
    int h = Term->hgt;

    /* Verify */
    if ((x < 0) || (x >= w)) return (-1);
    if ((y < 0) || (y >= h)) return (-1);

    /* Remember the cursor */
    Term->scr->cx = x;
    Term->scr->cy = y;

    /* The cursor is not useless */
    Term->scr->cu = 0;

    /* Success */
    return (0);
}


/*
 * At a given location, place an attr/char
 * Do not change the cursor position
 * No visual changes until "Term_fresh()".
 */
errr Term_draw(int x, int y, u16b a, char c)
{
    int w = Term->wid;
    int h = Term->hgt;

    /* Verify location */
    if ((x < 0) || (x >= w)) return (-1);
    if ((y < 0) || (y >= h)) return (-1);

    /* Paranoia -- illegal char */
    if (!c) return (-2);

    /* Queue it for later */
    Term_queue_char(Term, x, y, a, c, 0, 0);

    /* Success */
    return (0);
}


/*
 * Using the given attr, add the given char at the cursor.
 *
 * We return "-2" if the character is "illegal". XXX XXX
 *
 * We return "-1" if the cursor is currently unusable.
 *
 * We queue the given attr/char for display at the current
 * cursor location, and advance the cursor to the right,
 * marking it as unuable and returning "1" if it leaves
 * the screen, and otherwise returning "0".
 *
 * So when this function, or the following one, return a
 * positive value, future calls to either function will
 * return negative ones.
 */
errr Term_addch(u16b a, char c)
{
    int w = Term->wid;

    /* Handle "unusable" cursor */
    if (Term->scr->cu) return (-1);

    /* Paranoia -- no illegal chars */
    if (!c) return (-2);

    /* Queue the given character for display */
    Term_queue_char(Term, Term->scr->cx, Term->scr->cy, a, c, 0, 0);

    /* Advance the cursor */
    Term->scr->cx++;

    /* Success */
    if (Term->scr->cx < w) return (0);

    /* Note "Useless" cursor */
    Term->scr->cu = 1;

    /* Note "Useless" cursor */
    return (1);
}


/*
 * At the current location, using an attr, add a string
 *
 * We also take a length "n", using negative values to imply
 * the largest possible value, and then we use the minimum of
 * this length and the "actual" length of the string as the
 * actual number of characters to attempt to display, never
 * displaying more characters than will actually fit, since
 * we do NOT attempt to "wrap" the cursor at the screen edge.
 *
 * We return "-1" if the cursor is currently unusable.
 * We return "N" if we were "only" able to write "N" chars,
 * even if all of the given characters fit on the screen,
 * and mark the cursor as unusable for future attempts.
 *
 * So when this function, or the preceding one, return a
 * positive value, future calls to either function will
 * return negative ones.
 */
errr Term_addstr(int n, u16b a, const char *buf)
{
    int k;
    int w = Term->wid;
    errr res = 0;
    char s[MSG_LEN];

    /* Copy to a rewriteable string */
    my_strcpy(s, buf, MSG_LEN);

    /* Handle "unusable" cursor */
    if (Term->scr->cu) return (-1);

    /* Obtain maximal length */
    k = (n < 0) ? (w + 1) : n;

    /* Obtain the usable string length */
    for (n = 0; (n < k) && s[n]; n++) /* loop */;

    /* React to reaching the edge of the screen */
    if (Term->scr->cx + n >= w) res = n = w - Term->scr->cx;

    /* Queue the first "n" characters for display */
    Term_queue_chars(Term->scr->cx, Term->scr->cy, n, a, s);

    /* Advance the cursor */
    Term->scr->cx += n;

    /* Hack -- notice "useless" cursor */
    if (res) Term->scr->cu = 1;

    /* Success (usually) */
    return (res);
}


/*
 * Move to a location and, using an attr, add a char
 */
errr Term_putch(int x, int y, u16b a, char c)
{
    errr res;
    bool cv;
    int cx, cy;

    /* Save old cursor */
    if (Term->cursor_icky)
    {
        Term_locate(&cx, &cy);
        Term_get_cursor(&cv);
        Term_set_cursor(false);
    }

    /* Move first */
    res = Term_gotoxy(x, y);

    /* Then add the char */
    if (!res) res = Term_addch(a, c);

    /* Restore old cursor */
    if (Term->cursor_icky)
    {
        Term_gotoxy(cx, cy);
        Term_set_cursor(cv);
    }

    return (res);
}


/*
 * Move to a location and, using an attr, add a big tile
 */
void Term_big_putch(int x, int y, u16b a, char c)
{
    int hor, vert;

    /* No tall skinny tiles */
    if (tile_width > 1)
    {
        /* Horizontal first */
        for (hor = 0; hor <= tile_width; hor++)
        {
            /* Queue dummy character */
            if (hor != 0)
            {
                if (a & 0x80)
                    Term_putch(x + hor, y, 255, -1);
                else
                    Term_putch(x + hor, y, COLOUR_WHITE, ' ');
            }

            /* Now vertical */
            for (vert = 1; vert <= tile_height; vert++)
            {
                /* Queue dummy character */
                if (a & 0x80)
                    Term_putch(x + hor, y + vert, 255, -1);
                else
                    Term_putch(x + hor, y + vert, COLOUR_WHITE, ' ');
            }
        }
    }
    else
    {
        /* Only vertical */
        for (vert = 1; vert <= tile_height; vert++)
        {
            /* Queue dummy character */
            if (a & 0x80)
                Term_putch(x, y + vert, 255, -1);
            else
                Term_putch(x, y + vert, COLOUR_WHITE, ' ');
        }
    }
}


/*
 * Move to a location and, using an attr, add a string
 */
errr Term_putstr(int x, int y, int n, u16b a, const char *s)
{
    errr res;
    bool cv;
    int cx, cy;

    if (!Term) return 0;

    /* Save old cursor */
    if (Term->cursor_icky)
    {
        Term_locate(&cx, &cy);
        Term_get_cursor(&cv);
        Term_set_cursor(false);
    }

    /* Move first */
    res = Term_gotoxy(x, y);

    /* Then add the string */
    if (!res) res = Term_addstr(n, a, s);

    /* Restore old cursor */
    if (Term->cursor_icky)
    {
        Term_gotoxy(cx, cy);
        Term_set_cursor(cv);
    }

    return (res);
}


/*
 * Place cursor at (x,y), and clear the next "n" chars
 */
static errr Term_erase_aux(int x, int y, int n, bool check_icky)
{
    int i;
    int w = Term->wid;
    int x1 = -1;
    int x2 = -1;

    u16b na = Term->attr_blank;
    char nc = Term->char_blank;

    u16b *scr_aa;
    char *scr_cc;

    u16b *scr_taa;
    char *scr_tcc;

    errr res;
    bool cv;
    int cx, cy;

    /* Save old cursor */
    if (Term->cursor_icky && check_icky)
    {
        Term_locate(&cx, &cy);
        Term_get_cursor(&cv);
        Term_set_cursor(false);
    }

    /* Place cursor */
    res = Term_gotoxy(x, y);
    if (!res)
    {
        /* Force legal size */
        if (x + n > w) n = w - x;

        /* Fast access */
        scr_aa = Term->scr->a[y];
        scr_cc = Term->scr->c[y];

        scr_taa = Term->scr->ta[y];
        scr_tcc = Term->scr->tc[y];

        /* Hack -- always start at the beginning of a tile in bigtile mode */
        if ((n > 0) && (scr_aa[x] % MAX_COLORS == 255))
        {
            int x0 = ((x - COL_MAP) / tile_width) * tile_width + COL_MAP;

            x = x0;
            n = n + x - x0;
        }

        /* Scan every column */
        for (i = 0; i < n; i++, x++)
        {
            u16b oa = scr_aa[x];
            char oc = scr_cc[x];

            /* Hack -- ignore "non-changes" */
            if ((oa == na) && (oc == nc)) continue;

            /* Save the "literal" information */
            scr_aa[x] = na;
            scr_cc[x] = nc;

            scr_taa[x] = 0;
            scr_tcc[x] = 0;

            /* Track minimum changed column */
            if (x1 < 0) x1 = x;

            /* Track maximum changed column */
            x2 = x;
        }

        /* Expand the "change area" as needed */
        if (x1 >= 0)
        {
            /* Check for new min/max row info */
            if (y < Term->y1) Term->y1 = y;
            if (y > Term->y2) Term->y2 = y;

            /* Check for new min/max col info in this row */
            if (x1 < Term->x1[y]) Term->x1[y] = x1;
            if (x2 > Term->x2[y]) Term->x2[y] = x2;
        }
    }

    /* Restore old cursor */
    if (Term->cursor_icky && check_icky)
    {
        Term_gotoxy(cx, cy);
        Term_set_cursor(cv);
    }

    return (res);
}


errr Term_erase(int x, int y, int n)
{
    return Term_erase_aux(x, y, n, true);
}


errr Term_erase_icky(int x, int y, int n)
{
    return Term_erase_aux(x, y, n, false);
}


/*
 * Clear the entire window, and move to the top left corner
 *
 * Note the use of the special "total_erase" code
 */
errr Term_clear(void)
{
    int x, y;

    int w = Term->wid;
    int h = Term->hgt;

    u16b na = Term->attr_blank;
    char nc = Term->char_blank;

    /* Cursor usable */
    Term->scr->cu = 0;

    /* Cursor to the top left */
    Term->scr->cx = Term->scr->cy = 0;

    /* Wipe each row */
    for (y = 0; y < h; y++)
    {
        u16b *scr_aa = Term->scr->a[y];
        char *scr_cc = Term->scr->c[y];
        u16b *scr_taa = Term->scr->ta[y];
        char *scr_tcc = Term->scr->tc[y];

        /* Wipe each column */
        for (x = 0; x < w; x++)
        {
            /* Wipe each grid */
            *scr_aa++ = na;
            *scr_cc++ = nc;

            *scr_taa++ = na;
            *scr_tcc++ = nc;
        }
    }

    /* Every column has changed */
    memset(Term->x1, 0, h);
    memset(Term->x2, w - 1, h);

    /* Every row has changed */
    Term->y1 = 0;
    Term->y2 = h - 1;

    /* Force "total erase" */
    Term->total_erase = true;

    /* Success */
    return (0);
}


/*
 * Redraw (and refresh) the whole window.
 */
errr Term_redraw(void)
{
    /* Force "total erase" */
    Term->total_erase = true;

    /* Hack -- refresh */
    Term_fresh();

    /* Success */
    return (0);
} 


/*
 * Redraw part of a window.
 */
errr Term_redraw_section(int x1, int y1, int x2, int y2)
{
    int i, j;
    char *c_ptr;

    /* Bounds checking */
    if (y2 >= Term->hgt) y2 = Term->hgt - 1;
    if (x2 >= Term->wid) x2 = Term->wid - 1;
    if (y1 < 0) y1 = 0;
    if (x1 < 0) x1 = 0;

    /* Sanity checks */
    if ((y2 < y1) || (x2 < x1)) return 1;

    /* Set y limits */
    Term->y1 = y1;
    Term->y2 = y2;

    /* Set the x limits */
    for (i = Term->y1; i <= Term->y2; i++)
    {
        /* Hack -- always start at the beginning of a tile in bigtile mode */
        if ((x1 > 0) && (Term->old->a[i][x1] % MAX_COLORS == 255))
            x1 = ((x1 - COL_MAP) / tile_width) * tile_width + COL_MAP;

        Term->x1[i] = x1;
        Term->x2[i] = x2;

        c_ptr = Term->old->c[i];

        /* Clear the section so it is redrawn */
        for (j = x1; j <= x2; j++)
        {
            /* Hack -- set the old character to "none" */
            c_ptr[j] = 0;
        }
    }

    /* Hack -- refresh */
    Term_fresh();

    /* Success */
    return (0);
}


/*
 * Mark a spot as needing refresh (see "Term_fresh")
 */
errr Term_mark(int x, int y)
{
    u16b *old_aa;
    char *old_cc;
    u16b *old_taa;
    char *old_tcc;

    int w = Term->wid;
    int h = Term->hgt;

    /* Verify */
    if ((x < 0) || (x >= w)) return (-1);
    if ((y < 0) || (y >= h)) return (-1);

    old_aa = Term->old->a[y];
    old_cc = Term->old->c[y];
    old_taa = Term->old->ta[y];
    old_tcc = Term->old->tc[y];

    /*
     * Using 0x80 as the blank attribute and an impossible value for
     * the blank char is ok since this function is only called by tile
     * functions, but ideally there should be a test to use the blank text
     * attr/char pair
     */
    old_aa[x] = 0x80;
    old_cc[x] = 0;
    old_taa[x] = 0x80;
    old_tcc[x] = 0;

    return (0);
}


/*
 * Access routines
 */


/*
 * Extract the cursor visibility
 */
errr Term_get_cursor(bool *v)
{
    /* Extract visibility */
    (*v) = Term->scr->cv;

    /* Success */
    return (0);
}


/*
 * Extract the current window size
 */
errr Term_get_size(int *w, int *h)
{
    *w = Term->wid;
    *h = Term->max_hgt;
    return 0;
}


/*
 * Extract the current cursor location
 */
errr Term_locate(int *x, int *y)
{
    /* Access the cursor */
    (*x) = Term->scr->cx;
    (*y) = Term->scr->cy;

    /* Warn about "useless" cursor */
    if (Term->scr->cu) return (1);

    /* Success */
    return (0);
}


/*
 * At a given location, determine the "current" attr and char
 * Note that this refers to what will be on the window after the
 * next call to "Term_fresh()".  It may or may not already be there.
 */
errr Term_what(int x, int y, u16b *a, char *c)
{
    int w = Term->wid;
    int h = Term->hgt;

    /* Verify location */
    if ((x < 0) || (x >= w)) return (-1);
    if ((y < 0) || (y >= h)) return (-1);

    /* Direct access */
    (*a) = Term->scr->a[y][x];
    (*c) = Term->scr->c[y][x];

    /* Success */
    return (0);
}


errr Term_info(int x, int y, u16b *a, char *c, u16b *ta, char *tc)
{
    int w = Term->wid;
    int h = Term->hgt;

    /* Verify location */
    if ((x < 0) || (x >= w)) return (-1);
    if ((y < 0) || (y >= h)) return (-1);

    /* Get background tile info */
    *ta = Term->scr->ta[y][x];
    *tc = Term->scr->tc[y][x];
    if ((*ta == Term->attr_blank) && (*tc == Term->char_blank))
    {
        *ta = Term->old->ta[y][x];
        *tc = Term->old->tc[y][x];
    }
    if (!*tc) return (-1);

    /* Get foreground tile info */
    *a = Term->scr->a[y][x];
    *c = Term->scr->c[y][x];
    if ((*a == Term->attr_blank) && (*c == Term->char_blank))
    {
        *a = Term->old->a[y][x];
        *c = Term->old->c[y][x];
    }
    if (!*c)
    {
        *a = *ta;
        *c = *tc;
    }

    /* Success */
    return (0);
}


/*
 * Input routines
 */


/*
 * Flush and forget the input
 */
errr Term_flush(void)
{
    if (!Term) return 0;

    /* Hack -- flush all events */
    Term_xtra(TERM_XTRA_FLUSH, 0);

    /* Forget all keypresses */
    Term->key_head = Term->key_tail = 0;

    /* Success */
    return (0);
}


/*
 * Copy keys from key queue to buffer dest
 */
static void Term_copy_queue(ui_event *dest)
{
    /* Check if the queue has wrapped */
    if (Term->key_head > Term->key_tail)
    {
        /* Copy the queue */
        memcpy(dest, &Term->key_queue[Term->key_tail], Term->key_head - Term->key_tail);
    }
    else
    {
        /* Copy the buffer in two parts */
        int end = Term->key_size - Term->key_tail;

        memcpy(dest, &Term->key_queue[Term->key_tail], end);
        memcpy(&dest[end], Term->key_queue, Term->key_head);
    }
}


/*
 * Double the key queue size.
 */
static void Term_increase_queue(void)
{
    ui_event *new_queue;

    /* Allocate a new queue */
    new_queue = mem_zalloc(Term->key_size * 2 * sizeof(ui_event));

    /* Copy the queue */
    Term_copy_queue(new_queue);

    /* Free the old queue */
	mem_free(Term->key_queue);

    /* Put the new queue in place */
    Term->key_queue = new_queue;
    Term->key_tail = 0;
    Term->key_head = Term->key_length;
    Term->key_size *= 2;
}


/*
 * Cut the key queue size in half.
 */
static void Term_decrease_queue(void)
{
    ui_event *new_queue;

    /* Allocate a new queue */
    new_queue = mem_zalloc((Term->key_size / 2) * sizeof(ui_event));

    /* Copy the queue */
    Term_copy_queue(new_queue);

    /* Free the old queue */
    mem_free(Term->key_queue);

    /* Put the new queue in place */
    Term->key_queue = new_queue;
    Term->key_tail = 0;
    Term->key_head = Term->key_length;
    Term->key_size /= 2;
}


/*
 * Add a keypress to the "queue"
 */
errr Term_keypress(keycode_t k, byte mods)
{
    /* Hack -- refuse to enqueue non-keys */
    if (!k) return (-1);

    if (!Term->complex_input)
    {
        switch (k)
        {
            case '\r':
            case '\n':
                k = KC_ENTER;
                break;
            case 8:
                k = KC_BACKSPACE;
                break;
            case 9:
                k = KC_TAB;
                break;
            case 27:
                k = ESCAPE;
                break;
        }
    }

    /* Store the char, advance the queue */
    Term->key_queue[Term->key_head].type = EVT_KBRD;
    Term->key_queue[Term->key_head].key.code = k;
    Term->key_queue[Term->key_head].key.mods = mods;
    Term->key_head++;

    /* Increase queue length */
    Term->key_length++;

    /* Check if we need more space */
    if (Term->key_length >= Term->key_size) Term_increase_queue();

    /* Circular queue, handle wrap */
    if (Term->key_head == Term->key_size) Term->key_head = 0;

    /* Success */
    return (0);
}


/*
 * Add a keypress to the FRONT of the "queue"
 */
errr Term_key_push(int k)
{
    ui_event ke;

    if (!k) return (-1);

    ke.type = EVT_KBRD;
    ke.key.code = k;
    ke.key.mods = 0;

    return Term_event_push(&ke);
}


errr Term_event_push(const ui_event *ke)
{
    /* Hack -- refuse to enqueue non-keys */
    if (!ke) return (-1);

    /* Hack -- overflow may induce circular queue */
    if (Term->key_tail == 0) Term->key_tail = Term->key_size;

    /* Back up, Store the char */
    Term->key_queue[--Term->key_tail] = *ke;

    /* Increase queue length */
    Term->key_length++;

    /* Check if we need more space */
    if (Term->key_length >= Term->key_size) Term_increase_queue();

    /* Success */
    return (0);
}


/*
 * Check for a pending keypress on the key queue.
 *
 * Store the keypress, if any, in "ch", and return "0".
 * Otherwise store "zero" in "ch", and return "1".
 *
 * Wait for a keypress if "wait" is true.
 *
 * Remove the keypress if "take" is true.
 */
errr Term_inkey(ui_event *ch, bool wait, bool take)
{
    /* Assume no key */
    memset(ch, 0, sizeof(*ch));

    /* Hack -- get bored */
    if (!Term->never_bored)
    {
        /* Process random events */
        Term_xtra(TERM_XTRA_BORED, 0);
    }

    /* Wait or not */
    if (wait)
    {
        /* Process pending events while necessary */
        while (Term->key_head == Term->key_tail)
        {
            /* Process events (wait for one) */
            Term_xtra(TERM_XTRA_EVENT, true);
        }
    }
    else
    {
        /* Process pending events if necessary */
        if (Term->key_head == Term->key_tail)
        {
            /* Process events (do not wait) */
            Term_xtra(TERM_XTRA_EVENT, false);
        }
    }

    /* No keys are ready */
    if (Term->key_head == Term->key_tail) return (1);

    /* Extract the next keypress */
    (*ch) = Term->key_queue[Term->key_tail];

    /* If requested, advance the queue */
    if (take)
    {
        Term->key_tail++;

        /* Decrease queue length */
        Term->key_length--;

        /* Check if we could decrease the queue size */
        if (Term->key_length < Term->key_size / 4 && Term->key_size > Term->key_size_orig)
            Term_decrease_queue();

        /* Wrap around if necessary */
        if (Term->key_tail == Term->key_size) Term->key_tail = 0;
    }

    /* Success */
    return (0);
}


/*
 * Extra routines
 */


/*
 * Save the "requested" screen into the "memorized" screen
 *
 * Every "Term_save()" should match exactly one "Term_load()"
 */
errr Term_save(void)
{
    int w = Term->wid;
    int h = Term->hgt;
    term_win *mem;

    /* Allocate window */
    mem = mem_zalloc(sizeof(term_win));

    /* Initialize window */
    term_win_init(mem, w, h);

    /* Grab */
    term_win_copy(mem, Term->scr, w, h);

    /* Front of the queue */
    mem->next = Term->mem;
    Term->mem = mem;

    /* One more saved */
    Term->saved++;

    /* Success */
    return (0);
}


/*
 * Restore the "requested" contents (see above).
 *
 * Every "Term_save()" should match exactly one "Term_load()"
 */
errr Term_load(void)
{
    int w = Term->wid;
    int h = Term->hgt;
    term_win *tmp;

    /* Pop off window from the list */
    if (Term->mem)
    {
        /* Save pointer to old mem */
        tmp = Term->mem;

        /* Forget it */
        Term->mem = Term->mem->next;

        /* Load */
        term_win_copy(Term->scr, tmp, w, h);

        /* Free the old window */
        term_win_nuke(tmp);

        /* Kill it */
        mem_free(tmp);
    }

    /* Assume change */
    memset(Term->x1, 0, h);
    memset(Term->x2, w - 1, h);

    /* Assume change */
    Term->y1 = 0;
    Term->y2 = h - 1;

    /* One less saved */
    Term->saved--;

    /* Success */
    return (0);
}


/*
 * React to a new physical window size.
 */
errr Term_resize(int w, int h, int hmax)
{
    int i;
    int wid, hgt;
    byte *hold_x1;
    byte *hold_x2;
    term_win *hold_old;
    term_win *hold_scr;
    term_win *hold_mem;
    term_win *hold_tmp;
    ui_event evt = {EVT_RESIZE};

    /* Resizing is forbidden */
    if (Term->fixed_shape) return (-1);

    /* Ignore illegal changes */
    if ((w < 1) || (h < 1)) return (-1);

    /* Ignore non-changes */
    if ((Term->wid == w) && (Term->hgt == h)) return (1);

    /* Minimum dimensions */
    wid = MIN(Term->wid, w);
    hgt = MIN(Term->hgt, h);

    /* Save scanners */
    hold_x1 = Term->x1;
    hold_x2 = Term->x2;

    /* Save old window */
    hold_old = Term->old;

    /* Save old window */
    hold_scr = Term->scr;

    /* Save old window */
    hold_mem = Term->mem;

    /* Save old window */
    hold_tmp = Term->tmp;

    /* Create new scanners */
    Term->x1 = mem_zalloc(h * sizeof(byte));
    Term->x2 = mem_zalloc(h * sizeof(byte));

    /* Create new window */
    Term->old = mem_zalloc(sizeof(term_win));

    /* Initialize new window */
    term_win_init(Term->old, w, h);

    /* Save the contents */
    term_win_copy(Term->old, hold_old, wid, hgt);

    /* Create new window */
    Term->scr = mem_zalloc(sizeof(term_win));

    /* Initialize new window */
    term_win_init(Term->scr, w, h);

    /* Save the contents */
    term_win_copy(Term->scr, hold_scr, wid, hgt);

    /* If needed */
    if (hold_mem)
    {
        /* Create new window */
        Term->mem = mem_zalloc(sizeof(term_win));

        /* Initialize new window */
        term_win_init(Term->mem, w, h);

        /* Save the contents */
        term_win_copy(Term->mem, hold_mem, wid, hgt);
    }

    /* If needed */
    if (hold_tmp)
    {
        /* Create new window */
        Term->tmp = mem_zalloc(sizeof(term_win));

        /* Initialize new window */
        term_win_init(Term->tmp, w, h);

        /* Save the contents */
        term_win_copy(Term->tmp, hold_tmp, wid, hgt);
    }

    /* Free some arrays */
    mem_free(hold_x1);
    mem_free(hold_x2);

    /* Nuke */
    term_win_nuke(hold_old);

    /* Kill */
    mem_free(hold_old);

    /* Illegal cursor */
    if (Term->old->cx >= w) Term->old->cu = 1;
    if (Term->old->cy >= h) Term->old->cu = 1;

    /* Nuke */
    term_win_nuke(hold_scr);

    /* Kill */
    mem_free(hold_scr);

    /* Illegal cursor */
    if (Term->scr->cx >= w) Term->scr->cu = 1;
    if (Term->scr->cy >= h) Term->scr->cu = 1;

    /* If needed */
    if (hold_mem)
    {
        /* Nuke */
        term_win_nuke(hold_mem);

        /* Kill */
        mem_free(hold_mem);

        /* Illegal cursor */
        if (Term->mem->cx >= w) Term->mem->cu = 1;
        if (Term->mem->cy >= h) Term->mem->cu = 1;
    }

    /* If needed */
    if (hold_tmp)
    {
        /* Nuke */
        term_win_nuke(hold_tmp);

        /* Kill */
        mem_free(hold_tmp);

        /* Illegal cursor */
        if (Term->tmp->cx >= w) Term->tmp->cu = 1;
        if (Term->tmp->cy >= h) Term->tmp->cu = 1;
    }

    /* Save new size */
    Term->wid = w;
    Term->hgt = h;
    Term->max_hgt = hmax;

    /* Force "total erase" */
    Term->total_erase = true;

    /* Assume change */
    for (i = 0; i < h; i++)
    {
        /* Assume change */
        Term->x1[i] = 0;
        Term->x2[i] = w - 1;
    }

    /* Assume change */
    Term->y1 = 0;
    Term->y2 = h - 1;

    /* Push a resize event onto the stack */
    Term_event_push(&evt);

    /* Success */
    return (0);
}


/*
 * Activate a new Term (and deactivate the current Term)
 *
 * This function is extremely important, and also somewhat bizarre.
 * It is the only function that should "modify" the value of "Term".
 *
 * To "create" a valid "term", one should do "term_init(t)", then
 * set the various flags and hooks, and then do "Term_activate(t)".
 */
errr Term_activate(term *t)
{
    /* Hack -- already done */
    if (Term == t) return (1);

    /* Deactivate the old Term */
    if (Term) Term_xtra(TERM_XTRA_LEVEL, 0);

    /* Hack -- call the special "init" hook */
    if (t && !t->active_flag)
    {
        /* Call the "init" hook */
        if (t->init_hook) (*t->init_hook)(t);

        /* Remember */
        t->active_flag = true;

        /* Assume mapped */
        t->mapped_flag = true;
    }

    /* Remember the Term */
    Term = t;

    /* Activate the new Term */
    if (Term) Term_xtra(TERM_XTRA_LEVEL, 1);

    /* Success */
    return (0);
}


/*
 * Nuke a term
 */
errr term_nuke(term *t)
{
    /* Hack -- call the special "nuke" hook */
    if (t->active_flag)
    {
        /* Call the "nuke" hook */
        if (t->nuke_hook) (*t->nuke_hook)(t);

        /* Remember */
        t->active_flag = false;

        /* Assume not mapped */
        t->mapped_flag = false;
    }

    /* Nuke "displayed" */
    term_win_nuke(t->old);

    /* Kill "displayed" */
    mem_free(t->old);

    /* Nuke "requested" */
    term_win_nuke(t->scr);

    /* Kill "requested" */
    mem_free(t->scr);

    /* If needed */
    if (t->mem)
    {
        /* Nuke "memorized" */
        term_win_nuke(t->mem);

        /* Kill "memorized" */
        mem_free(t->mem);
    }

    /* If needed */
    if (t->tmp)
    {
        /* Nuke "temporary" */
        term_win_nuke(t->tmp);

        /* Kill "temporary" */
        mem_free(t->tmp);
    }

    /* Free some arrays */
    mem_free(t->x1);
    mem_free(t->x2);

    /* Free the input queue */
    mem_free(t->key_queue);

    /* Success */
    return (0);
}


/*
 * Initialize a term, using a window of the given size.
 * Also prepare the "input queue" for "k" keypresses
 * By default, the cursor starts out "invisible"
 * By default, we "erase" using "black spaces"
 */
errr term_init(term *t, int w, int h, int hmax, int k)
{
    int y;

    /* Wipe it */
    memset(t, 0, sizeof(term));

    /* Prepare the input queue */
    t->key_head = t->key_tail = t->key_length = 0;

    /* Determine the input queue size */
    t->key_size_orig = t->key_size = k;

    /* Allocate the input queue */
    t->key_queue = mem_zalloc(t->key_size * sizeof(ui_event));

    /* Save the size */
    t->wid = w;
    t->hgt = h;
    t->max_hgt = hmax;

    /* Allocate change arrays */
    t->x1 = mem_zalloc(h * sizeof(byte));
    t->x2 = mem_zalloc(h * sizeof(byte));

    /* Allocate "displayed" */
    t->old = mem_zalloc(sizeof(term_win));

    /* Initialize "displayed" */
    term_win_init(t->old, w, h);

    /* Allocate "requested" */
    t->scr = mem_zalloc(sizeof(term_win));

    /* Initialize "requested" */
    term_win_init(t->scr, w, h);

    /* Assume change */
    for (y = 0; y < h; y++)
    {
        /* Assume change */
        t->x1[y] = 0;
        t->x2[y] = w - 1;
    }

    /* Assume change */
    t->y1 = 0;
    t->y2 = h - 1;

    /* Force "total erase" */
    t->total_erase = true;

    /* Default "blank" */
    t->attr_blank = 0;
    t->char_blank = ' ';

    /* No saves yet */
    t->saved = 0;

    /* Success */
    return (0);
}


void reset_tile_params(void)
{
    tile_width = 1;
    tile_height = 1;
    tile_distorted = false;
}
