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pegs.c
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pegs.c
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/*
* pegs.c: the classic Peg Solitaire game.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#ifdef NO_TGMATH_H
# include <math.h>
#else
# include <tgmath.h>
#endif
#include "puzzles.h"
#include "tree234.h"
#define GRID_HOLE 0
#define GRID_PEG 1
#define GRID_OBST 2
#define GRID_CURSOR 10
#define GRID_JUMPING 20
enum {
COL_BACKGROUND,
COL_HIGHLIGHT,
COL_LOWLIGHT,
COL_PEG,
COL_CURSOR,
NCOLOURS
};
/*
* Grid shapes. I do some macro ickery here to ensure that my enum
* and the various forms of my name list always match up.
*/
#define TYPELIST(A) \
A(CROSS,Cross,cross) \
A(OCTAGON,Octagon,octagon) \
A(RANDOM,Random,random)
#define ENUM(upper,title,lower) TYPE_ ## upper,
#define TITLE(upper,title,lower) #title,
#define LOWER(upper,title,lower) #lower,
#define CONFIG(upper,title,lower) ":" #title
enum { TYPELIST(ENUM) TYPECOUNT };
static char const *const pegs_titletypes[] = { TYPELIST(TITLE) };
static char const *const pegs_lowertypes[] = { TYPELIST(LOWER) };
#define TYPECONFIG TYPELIST(CONFIG)
#define FLASH_FRAME 0.13F
struct game_params {
int w, h;
int type;
};
struct game_state {
int w, h;
bool completed;
unsigned char *grid;
};
static game_params *default_params(void)
{
game_params *ret = snew(game_params);
ret->w = ret->h = 7;
ret->type = TYPE_CROSS;
return ret;
}
static const struct game_params pegs_presets[] = {
{5, 7, TYPE_CROSS},
{7, 7, TYPE_CROSS},
{5, 9, TYPE_CROSS},
{7, 9, TYPE_CROSS},
{9, 9, TYPE_CROSS},
{7, 7, TYPE_OCTAGON},
{5, 5, TYPE_RANDOM},
{7, 7, TYPE_RANDOM},
{9, 9, TYPE_RANDOM},
};
static bool game_fetch_preset(int i, char **name, game_params **params)
{
game_params *ret;
char str[80];
if (i < 0 || i >= lenof(pegs_presets))
return false;
ret = snew(game_params);
*ret = pegs_presets[i];
strcpy(str, pegs_titletypes[ret->type]);
if (ret->type == TYPE_CROSS || ret->type == TYPE_RANDOM)
sprintf(str + strlen(str), " %dx%d", ret->w, ret->h);
*name = dupstr(str);
*params = ret;
return true;
}
static void free_params(game_params *params)
{
sfree(params);
}
static game_params *dup_params(const game_params *params)
{
game_params *ret = snew(game_params);
*ret = *params; /* structure copy */
return ret;
}
static void decode_params(game_params *params, char const *string)
{
char const *p = string;
int i;
params->w = atoi(p);
while (*p && isdigit((unsigned char)*p)) p++;
if (*p == 'x') {
p++;
params->h = atoi(p);
while (*p && isdigit((unsigned char)*p)) p++;
} else {
params->h = params->w;
}
for (i = 0; i < lenof(pegs_lowertypes); i++)
if (!strcmp(p, pegs_lowertypes[i]))
params->type = i;
}
static char *encode_params(const game_params *params, bool full)
{
char str[80];
sprintf(str, "%dx%d", params->w, params->h);
if (full) {
assert(params->type >= 0 && params->type < lenof(pegs_lowertypes));
strcat(str, pegs_lowertypes[params->type]);
}
return dupstr(str);
}
static config_item *game_configure(const game_params *params)
{
config_item *ret = snewn(4, config_item);
char buf[80];
ret[0].name = "Width";
ret[0].type = C_STRING;
sprintf(buf, "%d", params->w);
ret[0].u.string.sval = dupstr(buf);
ret[1].name = "Height";
ret[1].type = C_STRING;
sprintf(buf, "%d", params->h);
ret[1].u.string.sval = dupstr(buf);
ret[2].name = "Board type";
ret[2].type = C_CHOICES;
ret[2].u.choices.choicenames = TYPECONFIG;
ret[2].u.choices.selected = params->type;
ret[3].name = NULL;
ret[3].type = C_END;
return ret;
}
static game_params *custom_params(const config_item *cfg)
{
game_params *ret = snew(game_params);
ret->w = atoi(cfg[0].u.string.sval);
ret->h = atoi(cfg[1].u.string.sval);
ret->type = cfg[2].u.choices.selected;
return ret;
}
static const char *validate_params(const game_params *params, bool full)
{
if (full && (params->w <= 3 || params->h <= 3))
return "Width and height must both be greater than three";
if (params->w < 1 || params->h < 1)
return "Width and height must both be at least one";
if (params->w > INT_MAX / params->h)
return "Width times height must not be unreasonably large";
/*
* At http://www.gibell.net/pegsolitaire/GenCross/GenCrossBoards0.html
* George I. Bell asserts that various generalised cross-shaped
* boards are soluble starting (and finishing) with the centre
* hole. We permit the symmetric ones. Bell's notation for each
* soluble board is listed.
*/
if (full && params->type == TYPE_CROSS) {
if (!((params->w == 9 && params->h == 5) || /* (3,1,3,1) */
(params->w == 5 && params->h == 9) || /* (1,3,1,3) */
(params->w == 9 && params->h == 9) || /* (3,3,3,3) */
(params->w == 7 && params->h == 5) || /* (2,1,2,1) */
(params->w == 5 && params->h == 7) || /* (1,2,1,2) */
(params->w == 9 && params->h == 7) || /* (3,2,3,2) */
(params->w == 7 && params->h == 9) || /* (2,3,2,3) */
(params->w == 7 && params->h == 7))) /* (2,2,2,2) */
return "This board type is only supported at "
"5x7, 5x9, 7x7, 7x9, and 9x9";
}
/*
* It might be possible to implement generalisations of
* Octagon, but only if I can find a proof that they're all
* soluble. For the moment, therefore, I'm going to disallow
* it at any size other than the standard one.
*/
if (full && params->type == TYPE_OCTAGON) {
if (params->w != 7 || params->h != 7)
return "This board type is only supported at 7x7";
}
return NULL;
}
/* ----------------------------------------------------------------------
* Beginning of code to generate random Peg Solitaire boards.
*
* This procedure is done with no aesthetic judgment, no effort at
* symmetry, no difficulty grading and generally no finesse
* whatsoever. We simply begin with an empty board containing a
* single peg, and repeatedly make random reverse moves until it's
* plausibly full. This typically yields a scrappy haphazard mess
* with several holes, an uneven shape, and no redeeming features
* except guaranteed solubility.
*
* My only concessions to sophistication are (a) to repeat the
* generation process until I at least get a grid that touches
* every edge of the specified board size, and (b) to try when
* selecting moves to reuse existing space rather than expanding
* into new space (so that non-rectangular board shape becomes a
* factor during play).
*/
struct move {
/*
* x,y are the start point of the move during generation (hence
* its endpoint during normal play).
*
* dx,dy are the direction of the move during generation.
* Absolute value 1. Hence, for example, x=3,y=5,dx=1,dy=0
* means that the move during generation starts at (3,5) and
* ends at (5,5), and vice versa during normal play.
*/
int x, y, dx, dy;
/*
* cost is 0, 1 or 2, depending on how many GRID_OBSTs we must
* turn into GRID_HOLEs to play this move.
*/
int cost;
};
static int movecmp(void *av, void *bv)
{
struct move *a = (struct move *)av;
struct move *b = (struct move *)bv;
if (a->y < b->y)
return -1;
else if (a->y > b->y)
return +1;
if (a->x < b->x)
return -1;
else if (a->x > b->x)
return +1;
if (a->dy < b->dy)
return -1;
else if (a->dy > b->dy)
return +1;
if (a->dx < b->dx)
return -1;
else if (a->dx > b->dx)
return +1;
return 0;
}
static int movecmpcost(void *av, void *bv)
{
struct move *a = (struct move *)av;
struct move *b = (struct move *)bv;
if (a->cost < b->cost)
return -1;
else if (a->cost > b->cost)
return +1;
return movecmp(av, bv);
}
struct movetrees {
tree234 *bymove, *bycost;
};
static void update_moves(unsigned char *grid, int w, int h, int x, int y,
struct movetrees *trees)
{
struct move move;
int dir, pos;
/*
* There are twelve moves that can include (x,y): three in each
* of four directions. Check each one to see if it's possible.
*/
for (dir = 0; dir < 4; dir++) {
int dx, dy;
if (dir & 1)
dx = 0, dy = dir - 2;
else
dy = 0, dx = dir - 1;
assert(abs(dx) + abs(dy) == 1);
for (pos = 0; pos < 3; pos++) {
int v1, v2, v3;
move.dx = dx;
move.dy = dy;
move.x = x - pos*dx;
move.y = y - pos*dy;
if (move.x < 0 || move.x >= w || move.y < 0 || move.y >= h)
continue; /* completely invalid move */
if (move.x+2*move.dx < 0 || move.x+2*move.dx >= w ||
move.y+2*move.dy < 0 || move.y+2*move.dy >= h)
continue; /* completely invalid move */
v1 = grid[move.y * w + move.x];
v2 = grid[(move.y+move.dy) * w + (move.x+move.dx)];
v3 = grid[(move.y+2*move.dy)*w + (move.x+2*move.dx)];
if (v1 == GRID_PEG && v2 != GRID_PEG && v3 != GRID_PEG) {
struct move *m;
move.cost = (v2 == GRID_OBST) + (v3 == GRID_OBST);
/*
* This move is possible. See if it's already in
* the tree.
*/
m = find234(trees->bymove, &move, NULL);
if (m && m->cost != move.cost) {
/*
* It's in the tree but listed with the wrong
* cost. Remove the old version.
*/
#ifdef GENERATION_DIAGNOSTICS
printf("correcting %d%+d,%d%+d at cost %d\n",
m->x, m->dx, m->y, m->dy, m->cost);
#endif
del234(trees->bymove, m);
del234(trees->bycost, m);
sfree(m);
m = NULL;
}
if (!m) {
struct move *m, *m2;
m = snew(struct move);
*m = move;
m2 = add234(trees->bymove, m);
m2 = add234(trees->bycost, m);
assert(m2 == m);
#ifdef GENERATION_DIAGNOSTICS
printf("adding %d%+d,%d%+d at cost %d\n",
move.x, move.dx, move.y, move.dy, move.cost);
#endif
} else {
#ifdef GENERATION_DIAGNOSTICS
printf("not adding %d%+d,%d%+d at cost %d\n",
move.x, move.dx, move.y, move.dy, move.cost);
#endif
}
} else {
/*
* This move is impossible. If it is already in the
* tree, delete it.
*
* (We make use here of the fact that del234
* doesn't have to be passed a pointer to the
* _actual_ element it's deleting: it merely needs
* one that compares equal to it, and it will
* return the one it deletes.)
*/
struct move *m = del234(trees->bymove, &move);
#ifdef GENERATION_DIAGNOSTICS
printf("%sdeleting %d%+d,%d%+d\n", m ? "" : "not ",
move.x, move.dx, move.y, move.dy);
#endif
if (m) {
del234(trees->bycost, m);
sfree(m);
}
}
}
}
}
static void pegs_genmoves(unsigned char *grid, int w, int h, random_state *rs)
{
struct movetrees atrees, *trees = &atrees;
struct move *m;
int x, y, i, nmoves;
trees->bymove = newtree234(movecmp);
trees->bycost = newtree234(movecmpcost);
for (y = 0; y < h; y++)
for (x = 0; x < w; x++)
if (grid[y*w+x] == GRID_PEG)
update_moves(grid, w, h, x, y, trees);
nmoves = 0;
while (1) {
int limit, maxcost, index;
struct move mtmp, move, *m;
/*
* See how many moves we can make at zero cost. Make one,
* if possible. Failing that, make a one-cost move, and
* then a two-cost one.
*
* After filling at least half the input grid, we no longer
* accept cost-2 moves: if that's our only option, we give
* up and finish.
*/
mtmp.y = h+1;
maxcost = (nmoves < w*h/2 ? 2 : 1);
m = NULL; /* placate optimiser */
for (mtmp.cost = 0; mtmp.cost <= maxcost; mtmp.cost++) {
limit = -1;
m = findrelpos234(trees->bycost, &mtmp, NULL, REL234_LT, &limit);
#ifdef GENERATION_DIAGNOSTICS
printf("%d moves available with cost %d\n", limit+1, mtmp.cost);
#endif
if (m)
break;
}
if (!m)
break;
index = random_upto(rs, limit+1);
move = *(struct move *)index234(trees->bycost, index);
#ifdef GENERATION_DIAGNOSTICS
printf("selecting move %d%+d,%d%+d at cost %d\n",
move.x, move.dx, move.y, move.dy, move.cost);
#endif
grid[move.y * w + move.x] = GRID_HOLE;
grid[(move.y+move.dy) * w + (move.x+move.dx)] = GRID_PEG;
grid[(move.y+2*move.dy)*w + (move.x+2*move.dx)] = GRID_PEG;
for (i = 0; i <= 2; i++) {
int tx = move.x + i*move.dx;
int ty = move.y + i*move.dy;
update_moves(grid, w, h, tx, ty, trees);
}
nmoves++;
}
while ((m = delpos234(trees->bymove, 0)) != NULL) {
del234(trees->bycost, m);
sfree(m);
}
freetree234(trees->bymove);
freetree234(trees->bycost);
}
static void pegs_generate(unsigned char *grid, int w, int h, random_state *rs)
{
while (1) {
int x, y, extremes;
memset(grid, GRID_OBST, w*h);
grid[(h/2) * w + (w/2)] = GRID_PEG;
#ifdef GENERATION_DIAGNOSTICS
printf("beginning move selection\n");
#endif
pegs_genmoves(grid, w, h, rs);
#ifdef GENERATION_DIAGNOSTICS
printf("finished move selection\n");
#endif
extremes = 0;
for (y = 0; y < h; y++) {
if (grid[y*w+0] != GRID_OBST)
extremes |= 1;
if (grid[y*w+w-1] != GRID_OBST)
extremes |= 2;
}
for (x = 0; x < w; x++) {
if (grid[0*w+x] != GRID_OBST)
extremes |= 4;
if (grid[(h-1)*w+x] != GRID_OBST)
extremes |= 8;
}
if (extremes == 15)
break;
#ifdef GENERATION_DIAGNOSTICS
printf("insufficient extent; trying again\n");
#endif
}
#ifdef GENERATION_DIAGNOSTICS
fflush(stdout);
#endif
}
/* ----------------------------------------------------------------------
* End of board generation code. Now for the client code which uses
* it as part of the puzzle.
*/
static char *new_game_desc(const game_params *params, random_state *rs,
char **aux, bool interactive)
{
int w = params->w, h = params->h;
unsigned char *grid;
char *ret;
int i;
grid = snewn(w*h, unsigned char);
if (params->type == TYPE_RANDOM) {
pegs_generate(grid, w, h, rs);
} else {
int x, y, cx, cy, v;
for (y = 0; y < h; y++)
for (x = 0; x < w; x++) {
v = GRID_OBST; /* placate optimiser */
switch (params->type) {
case TYPE_CROSS:
cx = abs(x - w/2);
cy = abs(y - h/2);
if (cx == 0 && cy == 0)
v = GRID_HOLE;
else if (cx > 1 && cy > 1)
v = GRID_OBST;
else
v = GRID_PEG;
break;
case TYPE_OCTAGON:
cx = abs(x - w/2);
cy = abs(y - h/2);
if (cx + cy > 1 + max(w,h)/2)
v = GRID_OBST;
else
v = GRID_PEG;
break;
}
grid[y*w+x] = v;
}
if (params->type == TYPE_OCTAGON) {
/*
* The octagonal (European) solitaire layout is
* actually _insoluble_ with the starting hole at the
* centre. Here's a proof:
*
* Colour the squares of the board diagonally in
* stripes of three different colours, which I'll call
* A, B and C. So the board looks like this:
*
* A B C
* A B C A B
* A B C A B C A
* B C A B C A B
* C A B C A B C
* B C A B C
* A B C
*
* Suppose we keep running track of the number of pegs
* occuping each colour of square. This colouring has
* the property that any valid move whatsoever changes
* all three of those counts by one (two of them go
* down and one goes up), which means that the _parity_
* of every count flips on every move.
*
* If the centre square starts off unoccupied, then
* there are twelve pegs on each colour and all three
* counts start off even; therefore, after 35 moves all
* three counts would have to be odd, which isn't
* possible if there's only one peg left. []
*
* This proof works just as well if the starting hole
* is _any_ of the thirteen positions labelled B. Also,
* we can stripe the board in the opposite direction
* and rule out any square labelled B in that colouring
* as well. This leaves:
*
* Y n Y
* n n Y n n
* Y n n Y n n Y
* n Y Y n Y Y n
* Y n n Y n n Y
* n n Y n n
* Y n Y
*
* where the ns are squares we've proved insoluble, and
* the Ys are the ones remaining.
*
* That doesn't prove all those starting positions to
* be soluble, of course; they're merely the ones we
* _haven't_ proved to be impossible. Nevertheless, it
* turns out that they are all soluble, so when the
* user requests an Octagon board the simplest thing is
* to pick one of these at random.
*
* Rather than picking equiprobably from those twelve
* positions, we'll pick equiprobably from the three
* equivalence classes
*/
switch (random_upto(rs, 3)) {
case 0:
/* Remove a random corner piece. */
{
int dx, dy;
dx = random_upto(rs, 2) * 2 - 1; /* +1 or -1 */
dy = random_upto(rs, 2) * 2 - 1; /* +1 or -1 */
if (random_upto(rs, 2))
dy *= 3;
else
dx *= 3;
grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
}
break;
case 1:
/* Remove a random piece two from the centre. */
{
int dx, dy;
dx = 2 * (random_upto(rs, 2) * 2 - 1);
if (random_upto(rs, 2))
dy = 0;
else
dy = dx, dx = 0;
grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
}
break;
default /* case 2 */:
/* Remove a random piece one from the centre. */
{
int dx, dy;
dx = random_upto(rs, 2) * 2 - 1;
if (random_upto(rs, 2))
dy = 0;
else
dy = dx, dx = 0;
grid[(3+dy)*w+(3+dx)] = GRID_HOLE;
}
break;
}
}
}
/*
* Encode a game description which is simply a long list of P
* for peg, H for hole or O for obstacle.
*/
ret = snewn(w*h+1, char);
for (i = 0; i < w*h; i++)
ret[i] = (grid[i] == GRID_PEG ? 'P' :
grid[i] == GRID_HOLE ? 'H' : 'O');
ret[w*h] = '\0';
sfree(grid);
return ret;
}
static const char *validate_desc(const game_params *params, const char *desc)
{
int len, i, npeg = 0, nhole = 0;
len = params->w * params->h;
if (len != strlen(desc))
return "Game description is wrong length";
if (len != strspn(desc, "PHO"))
return "Invalid character in game description";
for (i = 0; i < len; i++) {
npeg += desc[i] == 'P';
nhole += desc[i] == 'H';
}
/* The minimal soluble game has two pegs and a hole: "3x1:PPH". */
if (npeg < 2)
return "Too few pegs in game description";
if (nhole < 1)
return "Too few holes in game description";
return NULL;
}
static game_state *new_game(midend *me, const game_params *params,
const char *desc)
{
int w = params->w, h = params->h;
game_state *state = snew(game_state);
int i;
state->w = w;
state->h = h;
state->completed = false;
state->grid = snewn(w*h, unsigned char);
for (i = 0; i < w*h; i++)
state->grid[i] = (desc[i] == 'P' ? GRID_PEG :
desc[i] == 'H' ? GRID_HOLE : GRID_OBST);
return state;
}
static game_state *dup_game(const game_state *state)
{
int w = state->w, h = state->h;
game_state *ret = snew(game_state);
ret->w = state->w;
ret->h = state->h;
ret->completed = state->completed;
ret->grid = snewn(w*h, unsigned char);
memcpy(ret->grid, state->grid, w*h);
return ret;
}
static void free_game(game_state *state)
{
sfree(state->grid);
sfree(state);
}
static bool game_can_format_as_text_now(const game_params *params)
{
return true;
}
static char *game_text_format(const game_state *state)
{
int w = state->w, h = state->h;
int x, y;
char *ret;
ret = snewn((w+1)*h + 1, char);
for (y = 0; y < h; y++) {
for (x = 0; x < w; x++)
ret[y*(w+1)+x] = (state->grid[y*w+x] == GRID_HOLE ? '-' :
state->grid[y*w+x] == GRID_PEG ? '*' : ' ');
ret[y*(w+1)+w] = '\n';
}
ret[h*(w+1)] = '\0';
return ret;
}
struct game_ui {
bool dragging; /* is a drag in progress? */
int sx, sy; /* grid coords of drag start cell */
int dx, dy; /* pixel coords of current drag posn */
int cur_x, cur_y;
bool cur_visible, cur_jumping;
};
static game_ui *new_ui(const game_state *state)
{
game_ui *ui = snew(game_ui);
int x, y, v;
ui->sx = ui->sy = ui->dx = ui->dy = 0;
ui->dragging = false;
ui->cur_visible = getenv_bool("PUZZLES_SHOW_CURSOR", false);
ui->cur_jumping = false;
/* make sure we start the cursor somewhere on the grid. */
for (x = 0; x < state->w; x++) {
for (y = 0; y < state->h; y++) {
v = state->grid[y*state->w+x];
if (v == GRID_PEG || v == GRID_HOLE) {
ui->cur_x = x; ui->cur_y = y;
goto found;
}
}
}
assert(!"new_ui found nowhere for cursor");
found:
return ui;
}
static void free_ui(game_ui *ui)
{
sfree(ui);
}
static void game_changed_state(game_ui *ui, const game_state *oldstate,
const game_state *newstate)
{
/*
* Cancel a drag, in case the source square has become
* unoccupied.
*/
ui->dragging = false;
/*
* Also, cancel a keyboard-driven jump if one is half way to being
* input.
*/
ui->cur_jumping = false;
}
static const char *current_key_label(const game_ui *ui,
const game_state *state, int button)
{
int w = state->w;
if (IS_CURSOR_SELECT(button)) {
if (!ui->cur_visible) return "";
if (ui->cur_jumping) return "Cancel";
if (state->grid[ui->cur_y*w+ui->cur_x] == GRID_PEG) return "Select";
}
return "";
}
#define PREFERRED_TILE_SIZE 33
#define TILESIZE (ds->tilesize)
#define BORDER (TILESIZE / 2)
#define HIGHLIGHT_WIDTH (TILESIZE / 16)
#define COORD(x) ( BORDER + (x) * TILESIZE )
#define FROMCOORD(x) ( ((x) + TILESIZE - BORDER) / TILESIZE - 1 )
struct game_drawstate {
int tilesize;
blitter *drag_background;
bool dragging;
int dragx, dragy;
int w, h;
unsigned char *grid;
bool started;
int bgcolour;
};
static char *interpret_move(const game_state *state, game_ui *ui,
const game_drawstate *ds,
int x, int y, int button)
{
int w = state->w, h = state->h;
char buf[80];
if (button == LEFT_BUTTON) {
int tx, ty;
/*
* Left button down: we attempt to start a drag.
*/
/*
* There certainly shouldn't be a current drag in progress,
* unless the midend failed to send us button events in
* order; it has a responsibility to always get that right,
* so we can legitimately punish it by failing an
* assertion.
*/
assert(!ui->dragging);
tx = FROMCOORD(x);
ty = FROMCOORD(y);
if (tx >= 0 && tx < w && ty >= 0 && ty < h) {
switch (state->grid[ty*w+tx]) {
case GRID_PEG:
ui->dragging = true;
ui->sx = tx;
ui->sy = ty;
ui->dx = x;
ui->dy = y;
ui->cur_visible = false;
ui->cur_jumping = false;
return MOVE_UI_UPDATE;
case GRID_HOLE:
return MOVE_NO_EFFECT;
case GRID_OBST:
default:
return MOVE_UNUSED;
}
}
} else if (button == LEFT_DRAG && ui->dragging) {
/*
* Mouse moved; just move the peg being dragged.
*/
ui->dx = x;
ui->dy = y;
return MOVE_UI_UPDATE;
} else if (button == LEFT_RELEASE && ui->dragging) {
int tx, ty, dx, dy;
/*
* Button released. Identify the target square of the drag,
* see if it represents a valid move, and if so make it.
*/
ui->dragging = false; /* cancel the drag no matter what */
tx = FROMCOORD(x);
ty = FROMCOORD(y);
if (tx < 0 || tx >= w || ty < 0 || ty >= h)
return MOVE_UI_UPDATE; /* target out of range */
dx = tx - ui->sx;
dy = ty - ui->sy;
if (max(abs(dx),abs(dy)) != 2 || min(abs(dx),abs(dy)) != 0)
return MOVE_UI_UPDATE; /* move length was wrong */
dx /= 2;
dy /= 2;
if (state->grid[ty*w+tx] != GRID_HOLE ||
state->grid[(ty-dy)*w+(tx-dx)] != GRID_PEG ||
state->grid[ui->sy*w+ui->sx] != GRID_PEG)
return MOVE_UI_UPDATE; /* grid contents were invalid */
/*
* We have a valid move. Encode it simply as source and
* destination coordinate pairs.
*/
sprintf(buf, "%d,%d-%d,%d", ui->sx, ui->sy, tx, ty);
return dupstr(buf);
} else if (IS_CURSOR_MOVE(button)) {
if (!ui->cur_jumping) {
/* Not jumping; move cursor as usual, making sure we don't
* leave the gameboard (which may be an irregular shape) */
int cx = ui->cur_x, cy = ui->cur_y;
move_cursor(button, &cx, &cy, w, h, false, NULL);
ui->cur_visible = true;
if (state->grid[cy*w+cx] == GRID_HOLE ||
state->grid[cy*w+cx] == GRID_PEG) {
ui->cur_x = cx;
ui->cur_y = cy;
}
return MOVE_UI_UPDATE;
} else {
int dx, dy, mx, my, jx, jy;
/* We're jumping; if the requested direction has a hole, and
* there's a peg in the way, */
assert(state->grid[ui->cur_y*w+ui->cur_x] == GRID_PEG);
dx = (button == CURSOR_RIGHT) ? 1 : (button == CURSOR_LEFT) ? -1 : 0;
dy = (button == CURSOR_DOWN) ? 1 : (button == CURSOR_UP) ? -1 : 0;
mx = ui->cur_x+dx; my = ui->cur_y+dy;
jx = mx+dx; jy = my+dy;
ui->cur_jumping = false; /* reset, whatever. */
if (jx >= 0 && jy >= 0 && jx < w && jy < h &&
state->grid[my*w+mx] == GRID_PEG &&
state->grid[jy*w+jx] == GRID_HOLE) {
/* Move cursor to the jumped-to location (this felt more
* natural while playtesting) */
sprintf(buf, "%d,%d-%d,%d", ui->cur_x, ui->cur_y, jx, jy);
ui->cur_x = jx; ui->cur_y = jy;
return dupstr(buf);
}
return MOVE_UI_UPDATE;
}
} else if (IS_CURSOR_SELECT(button)) {
if (!ui->cur_visible) {
ui->cur_visible = true;
return MOVE_UI_UPDATE;
}
if (ui->cur_jumping) {
ui->cur_jumping = false;
return MOVE_UI_UPDATE;
}
if (state->grid[ui->cur_y*w+ui->cur_x] == GRID_PEG) {
/* cursor is on peg: next arrow-move will jump. */
ui->cur_jumping = true;
return MOVE_UI_UPDATE;
}
return MOVE_NO_EFFECT;
}
return MOVE_UNUSED;
}