X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=midend.c;h=190840af62531cdc08de4f8c642c474327aff7c6;hb=3234912f921916a1b8da164fd61dc75579358577;hp=833cbeff6a116912284ba151ac8e58093d039c3c;hpb=f07576f49e9b08c9a9b2482b07e14a3e846224eb;p=sgt-puzzles.git

diff --git a/midend.c b/midend.c
index 833cbef..190840a 100644
--- a/midend.c
+++ b/midend.c
@@ -31,7 +31,7 @@ struct midend {
     const game *ourgame;
 
     game_params **presets;
-    char **preset_names;
+    char **preset_names, **preset_encodings;
     int npresets, presetsize;
 
     /*
@@ -81,6 +81,9 @@ struct midend {
     int pressed_mouse_button;
 
     int preferred_tilesize, tilesize, winwidth, winheight;
+
+    void (*game_id_change_notify_function)(void *);
+    void *game_id_change_notify_ctx;
 };
 
 #define ensure(me) do { \
@@ -91,6 +94,29 @@ struct midend {
     } \
 } while (0)
 
+void midend_reset_tilesize(midend *me)
+{
+    me->preferred_tilesize = me->ourgame->preferred_tilesize;
+    {
+        /*
+         * Allow an environment-based override for the default tile
+         * size by defining a variable along the lines of
+         * `NET_TILESIZE=15'.
+         */
+
+	char buf[80], *e;
+	int j, k, ts;
+
+	sprintf(buf, "%s_TILESIZE", me->ourgame->name);
+	for (j = k = 0; buf[j]; j++)
+	    if (!isspace((unsigned char)buf[j]))
+		buf[k++] = toupper((unsigned char)buf[j]);
+	buf[k] = '\0';
+	if ((e = getenv(buf)) != NULL && sscanf(e, "%d", &ts) == 1 && ts > 0)
+	    me->preferred_tilesize = ts;
+    }
+}
+
 midend *midend_new(frontend *fe, const game *ourgame,
 		   const drawing_api *drapi, void *drhandle)
 {
@@ -102,10 +128,29 @@ midend *midend_new(frontend *fe, const game *ourgame,
 
     me->frontend = fe;
     me->ourgame = ourgame;
-    me->random = random_init(randseed, randseedsize);
+    me->random = random_new(randseed, randseedsize);
     me->nstates = me->statesize = me->statepos = 0;
     me->states = NULL;
     me->params = ourgame->default_params();
+    me->game_id_change_notify_function = NULL;
+    me->game_id_change_notify_ctx = NULL;
+
+    /*
+     * Allow environment-based changing of the default settings by
+     * defining a variable along the lines of `NET_DEFAULT=25x25w'
+     * in which the value is an encoded parameter string.
+     */
+    {
+        char buf[80], *e;
+        int j, k;
+        sprintf(buf, "%s_DEFAULT", me->ourgame->name);
+	for (j = k = 0; buf[j]; j++)
+	    if (!isspace((unsigned char)buf[j]))
+		buf[k++] = toupper((unsigned char)buf[j]);
+	buf[k] = '\0';
+        if ((e = getenv(buf)) != NULL)
+            me->ourgame->decode_params(me->params, e);
+    }
     me->curparams = NULL;
     me->desc = me->privdesc = NULL;
     me->seedstr = NULL;
@@ -115,6 +160,7 @@ midend *midend_new(frontend *fe, const game *ourgame,
     me->oldstate = NULL;
     me->presets = NULL;
     me->preset_names = NULL;
+    me->preset_encodings = NULL;
     me->npresets = me->presetsize = 0;
     me->anim_time = me->anim_pos = 0.0F;
     me->flash_time = me->flash_pos = 0.0F;
@@ -126,35 +172,31 @@ midend *midend_new(frontend *fe, const game *ourgame,
     me->elapsed = 0.0F;
     me->tilesize = me->winwidth = me->winheight = 0;
     if (drapi)
-	me->drawing = drawing_init(drapi, drhandle);
+	me->drawing = drawing_new(drapi, me, drhandle);
     else
 	me->drawing = NULL;
 
-    me->preferred_tilesize = ourgame->preferred_tilesize;
-    {
-        /*
-         * Allow an environment-based override for the default tile
-         * size by defining a variable along the lines of
-         * `NET_TILESIZE=15'.
-         */
-
-	char buf[80], *e;
-	int j, k, ts;
-
-	sprintf(buf, "%s_TILESIZE", me->ourgame->name);
-	for (j = k = 0; buf[j]; j++)
-	    if (!isspace((unsigned char)buf[j]))
-		buf[k++] = toupper((unsigned char)buf[j]);
-	buf[k] = '\0';
-	if ((e = getenv(buf)) != NULL && sscanf(e, "%d", &ts) == 1 && ts > 0)
-	    me->preferred_tilesize = ts;
-    }
+    midend_reset_tilesize(me);
 
     sfree(randseed);
 
     return me;
 }
 
+const game *midend_which_game(midend *me)
+{
+    return me->ourgame;
+}
+
+static void midend_purge_states(midend *me)
+{
+    while (me->nstates > me->statepos) {
+        me->ourgame->free_game(me->states[--me->nstates].state);
+        if (me->states[me->nstates].movestr)
+            sfree(me->states[me->nstates].movestr);
+    }
+}
+
 static void midend_free_game(midend *me)
 {
     while (me->nstates > 0) {
@@ -186,9 +228,11 @@ void midend_free(midend *me)
 	for (i = 0; i < me->npresets; i++) {
 	    sfree(me->presets[i]);
 	    sfree(me->preset_names[i]);
+	    sfree(me->preset_encodings[i]);
 	}
 	sfree(me->presets);
 	sfree(me->preset_names);
+	sfree(me->preset_encodings);
     }
     if (me->ui)
         me->ourgame->free_ui(me->ui);
@@ -212,7 +256,7 @@ static void midend_size_new_drawstate(midend *me)
     }
 }
 
-void midend_size(midend *me, int *x, int *y, int expand)
+void midend_size(midend *me, int *x, int *y, int user_size)
 {
     int min, max;
     int rx, ry;
@@ -230,11 +274,14 @@ void midend_size(midend *me, int *x, int *y, int expand)
 
     /*
      * Find the tile size that best fits within the given space. If
-     * `expand' is TRUE, we must actually find the _largest_ such
-     * tile size; otherwise, we bound above at the game's preferred
-     * tile size.
+     * `user_size' is TRUE, we must actually find the _largest_ such
+     * tile size, in order to get as close to the user's explicit
+     * request as possible; otherwise, we bound above at the game's
+     * preferred tile size, so that the game gets what it wants
+     * provided that this doesn't break the constraint from the
+     * front-end (which is likely to be a screen size or similar).
      */
-    if (expand) {
+    if (user_size) {
 	max = 1;
 	do {
 	    max *= 2;
@@ -264,11 +311,16 @@ void midend_size(midend *me, int *x, int *y, int expand)
      */
 
     me->tilesize = min;
+    if (user_size)
+        /* If the user requested a change in size, make it permanent. */
+        me->preferred_tilesize = me->tilesize;
     midend_size_new_drawstate(me);
     *x = me->winwidth;
     *y = me->winheight;
 }
 
+int midend_tilesize(midend *me) { return me->tilesize; }
+
 void midend_set_params(midend *me, game_params *params)
 {
     me->ourgame->free_params(me->params);
@@ -303,6 +355,7 @@ void midend_force_redraw(midend *me)
 
 void midend_new_game(midend *me)
 {
+    midend_stop_anim(me);
     midend_free_game(me);
 
     assert(me->nstates == 0);
@@ -326,9 +379,9 @@ void midend_new_game(midend *me)
             char newseed[16];
             int i;
             newseed[15] = '\0';
-            newseed[0] = '1' + random_upto(me->random, 9);
+            newseed[0] = '1' + (char)random_upto(me->random, 9);
             for (i = 1; i < 15; i++)
-                newseed[i] = '0' + random_upto(me->random, 10);
+                newseed[i] = '0' + (char)random_upto(me->random, 10);
             sfree(me->seedstr);
             me->seedstr = dupstr(newseed);
 
@@ -342,7 +395,7 @@ void midend_new_game(midend *me)
         sfree(me->aux_info);
 	me->aux_info = NULL;
 
-        rs = random_init(me->seedstr, strlen(me->seedstr));
+        rs = random_new(me->seedstr, strlen(me->seedstr));
 	/*
 	 * If this midend has been instantiated without providing a
 	 * drawing API, it is non-interactive. This means that it's
@@ -374,6 +427,25 @@ void midend_new_game(midend *me)
     me->states[me->nstates].state =
 	me->ourgame->new_game(me, me->params, me->desc);
 
+    /*
+     * As part of our commitment to self-testing, test the aux
+     * string to make sure nothing ghastly went wrong.
+     */
+    if (me->ourgame->can_solve && me->aux_info) {
+	game_state *s;
+	char *msg, *movestr;
+
+	msg = NULL;
+	movestr = me->ourgame->solve(me->states[0].state,
+				     me->states[0].state,
+				     me->aux_info, &msg);
+	assert(movestr && !msg);
+	s = me->ourgame->execute_move(me->states[0].state, movestr);
+	assert(s);
+	me->ourgame->free_game(s);
+	sfree(movestr);
+    }
+
     me->states[me->nstates].movestr = NULL;
     me->states[me->nstates].movetype = NEWGAME;
     me->nstates++;
@@ -382,11 +454,26 @@ void midend_new_game(midend *me)
 					       me->states[0].state);
     midend_size_new_drawstate(me);
     me->elapsed = 0.0F;
+    me->flash_pos = me->flash_time = 0.0F;
+    me->anim_pos = me->anim_time = 0.0F;
     if (me->ui)
         me->ourgame->free_ui(me->ui);
     me->ui = me->ourgame->new_ui(me->states[0].state);
     midend_set_timer(me);
     me->pressed_mouse_button = 0;
+
+    if (me->game_id_change_notify_function)
+        me->game_id_change_notify_function(me->game_id_change_notify_ctx);
+}
+
+int midend_can_undo(midend *me)
+{
+    return (me->statepos > 1);
+}
+
+int midend_can_redo(midend *me)
+{
+    return (me->statepos < me->nstates);
 }
 
 static int midend_undo(midend *me)
@@ -462,8 +549,6 @@ void midend_restart_game(midend *me)
 {
     game_state *s;
 
-    midend_stop_anim(me);
-
     assert(me->statepos >= 1);
     if (me->statepos == 1)
         return;                        /* no point doing anything at all! */
@@ -481,8 +566,7 @@ void midend_restart_game(midend *me)
      * Now enter the restarted state as the next move.
      */
     midend_stop_anim(me);
-    while (me->nstates > me->statepos)
-	me->ourgame->free_game(me->states[--me->nstates].state);
+    midend_purge_states(me);
     ensure(me);
     me->states[me->nstates].state = s;
     me->states[me->nstates].movestr = dupstr(me->desc);
@@ -492,7 +576,7 @@ void midend_restart_game(midend *me)
         me->ourgame->changed_state(me->ui,
                                    me->states[me->statepos-2].state,
                                    me->states[me->statepos-1].state);
-    me->anim_time = 0.0;
+    me->flash_pos = me->flash_time = 0.0F;
     midend_finish_move(me);
     midend_redraw(me);
     midend_set_timer(me);
@@ -513,11 +597,10 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
 
     if (!movestr) {
 	if (button == 'n' || button == 'N' || button == '\x0E') {
-	    midend_stop_anim(me);
 	    midend_new_game(me);
 	    midend_redraw(me);
 	    goto done;		       /* never animate */
-	} else if (button == 'u' || button == 'u' ||
+	} else if (button == 'u' || button == 'U' ||
 		   button == '\x1A' || button == '\x1F') {
 	    midend_stop_anim(me);
 	    type = me->states[me->statepos-1].movetype;
@@ -529,6 +612,9 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
 	    midend_stop_anim(me);
 	    if (!midend_redo(me))
 		goto done;
+	} else if (button == '\x13' && me->ourgame->can_solve) {
+	    if (midend_solve(me))
+		goto done;
 	} else if (button == 'q' || button == 'Q' || button == '\x11') {
 	    ret = 0;
 	    goto done;
@@ -550,11 +636,11 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
              * state has been updated and a redraw is called for.
              */
             midend_redraw(me);
+            midend_set_timer(me);
             goto done;
         } else if (s) {
 	    midend_stop_anim(me);
-            while (me->nstates > me->statepos)
-                me->ourgame->free_game(me->states[--me->nstates].state);
+            midend_purge_states(me);
             ensure(me);
             assert(movestr != NULL);
             me->states[me->nstates].state = s;
@@ -578,7 +664,7 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
      * See if this move requires an animation.
      */
     if (special(type) && !(type == SOLVE &&
-			   (me->ourgame->mouse_priorities & SOLVE_ANIMATES))) {
+			   (me->ourgame->flags & SOLVE_ANIMATES))) {
         anim_time = 0;
     } else {
         anim_time = me->ourgame->anim_length(oldstate,
@@ -673,6 +759,14 @@ int midend_process_key(midend *me, int x, int y, int button)
      * like a left click for the benefit of users of other
      * implementations. So the last of the above points is modified
      * in the presence of an (optional) button priority order.
+     *
+     * A further addition: we translate certain keyboard presses to
+     * cursor key 'select' buttons, so that a) frontends don't have
+     * to translate these themselves (like they do for CURSOR_UP etc),
+     * and b) individual games don't have to hard-code button presses
+     * of '\n' etc for keyboard-based cursors. The choice of buttons
+     * here could eventually be controlled by a runtime configuration
+     * option.
      */
     if (IS_MOUSE_DRAG(button) || IS_MOUSE_RELEASE(button)) {
         if (me->pressed_mouse_button) {
@@ -690,7 +784,7 @@ int midend_process_key(midend *me, int x, int y, int button)
 	 * If the new button has lower priority than the old one,
 	 * don't bother doing this.
 	 */
-	if (me->ourgame->mouse_priorities &
+	if (me->ourgame->flags &
 	    BUTTON_BEATS(me->pressed_mouse_button, button))
 	    return ret;		       /* just ignore it */
 
@@ -702,6 +796,23 @@ int midend_process_key(midend *me, int x, int y, int button)
                         (LEFT_RELEASE - LEFT_BUTTON)));
     }
 
+    /*
+     * Translate keyboard presses to cursor selection.
+     */
+    if (button == '\n' || button == '\r')
+      button = CURSOR_SELECT;
+    if (button == ' ')
+      button = CURSOR_SELECT2;
+
+    /*
+     * Normalise both backspace characters (8 and 127) to \b. Easier
+     * to do this once, here, than to require all front ends to
+     * carefully generate the same one - now each front end can
+     * generate whichever is easiest.
+     */
+    if (button == '\177')
+	button = '\b';
+
     /*
      * Now send on the event we originally received.
      */
@@ -739,8 +850,21 @@ void midend_redraw(midend *me)
     }
 }
 
+/*
+ * Nasty hacky function used to implement the --redo option in
+ * gtk.c. Only used for generating the puzzles' icons.
+ */
+void midend_freeze_timer(midend *me, float tprop)
+{
+    me->anim_pos = me->anim_time * tprop;
+    midend_redraw(me);
+    deactivate_timer(me->frontend);
+}
+
 void midend_timer(midend *me, float tplus)
 {
+    int need_redraw = (me->anim_time > 0 || me->flash_time > 0);
+
     me->anim_pos += tplus;
     if (me->anim_pos >= me->anim_time ||
         me->anim_time == 0 || !me->oldstate) {
@@ -753,7 +877,8 @@ void midend_timer(midend *me, float tplus)
 	me->flash_pos = me->flash_time = 0;
     }
 
-    midend_redraw(me);
+    if (need_redraw)
+        midend_redraw(me);
 
     if (me->timing) {
 	float oldelapsed = me->elapsed;
@@ -767,20 +892,9 @@ void midend_timer(midend *me, float tplus)
 
 float *midend_colours(midend *me, int *ncolours)
 {
-    game_state *state = NULL;
     float *ret;
 
-    if (me->nstates == 0) {
-	char *aux = NULL;
-        char *desc = me->ourgame->new_desc(me->params, me->random,
-					   &aux, TRUE);
-        state = me->ourgame->new_game(me, me->params, desc);
-        sfree(desc);
-        sfree(aux);
-    } else
-        state = me->states[0].state;
-
-    ret = me->ourgame->colours(me->frontend, state, ncolours);
+    ret = me->ourgame->colours(me->frontend, ncolours);
 
     {
         int i;
@@ -803,16 +917,13 @@ float *midend_colours(midend *me, int *ncolours)
 	    buf[k] = '\0';
             if ((e = getenv(buf)) != NULL &&
                 sscanf(e, "%2x%2x%2x", &r, &g, &b) == 3) {
-                ret[i*3 + 0] = r / 255.0;
-                ret[i*3 + 1] = g / 255.0;
-                ret[i*3 + 2] = b / 255.0;
+                ret[i*3 + 0] = r / 255.0F;
+                ret[i*3 + 1] = g / 255.0F;
+                ret[i*3 + 2] = b / 255.0F;
             }
         }
     }
 
-    if (me->nstates == 0)
-        me->ourgame->free_game(state);
-
     return ret;
 }
 
@@ -829,10 +940,14 @@ int midend_num_presets(midend *me)
                                       game_params *);
                 me->preset_names = sresize(me->preset_names, me->presetsize,
                                            char *);
+                me->preset_encodings = sresize(me->preset_encodings,
+					       me->presetsize, char *);
             }
 
             me->presets[me->npresets] = preset;
             me->preset_names[me->npresets] = name;
+            me->preset_encodings[me->npresets] =
+		me->ourgame->encode_params(preset, TRUE);;
             me->npresets++;
         }
     }
@@ -883,12 +998,17 @@ int midend_num_presets(midend *me)
                                           game_params *);
                     me->preset_names = sresize(me->preset_names,
                                                me->presetsize, char *);
+                    me->preset_encodings = sresize(me->preset_encodings,
+						   me->presetsize, char *);
                 }
 
                 me->presets[me->npresets] = preset;
                 me->preset_names[me->npresets] = dupstr(name);
+                me->preset_encodings[me->npresets] =
+		    me->ourgame->encode_params(preset, TRUE);
                 me->npresets++;
             }
+            sfree(e);
         }
     }
 
@@ -903,9 +1023,31 @@ void midend_fetch_preset(midend *me, int n,
     *params = me->presets[n];
 }
 
+int midend_which_preset(midend *me)
+{
+    char *encoding = me->ourgame->encode_params(me->params, TRUE);
+    int i, ret;
+
+    ret = -1;
+    for (i = 0; i < me->npresets; i++)
+	if (!strcmp(encoding, me->preset_encodings[i])) {
+	    ret = i;
+	    break;
+	}
+
+    sfree(encoding);
+    return ret;
+}
+
 int midend_wants_statusbar(midend *me)
 {
-    return me->ourgame->wants_statusbar();
+    return me->ourgame->wants_statusbar;
+}
+
+void midend_request_id_changes(midend *me, void (*notify)(void *), void *ctx)
+{
+    me->game_id_change_notify_function = notify;
+    me->game_id_change_notify_ctx = ctx;
 }
 
 void midend_supersede_game_desc(midend *me, char *desc, char *privdesc)
@@ -914,6 +1056,8 @@ void midend_supersede_game_desc(midend *me, char *desc, char *privdesc)
     sfree(me->privdesc);
     me->desc = dupstr(desc);
     me->privdesc = privdesc ? dupstr(privdesc) : NULL;
+    if (me->game_id_change_notify_function)
+        me->game_id_change_notify_function(me->game_id_change_notify_ctx);
 }
 
 config_item *midend_get_config(midend *me, int which, char **wintitle)
@@ -1035,7 +1179,45 @@ static char *midend_game_id_int(midend *me, char *id, int defmode)
     newcurparams = newparams = oldparams1 = oldparams2 = NULL;
 
     if (par) {
-        newcurparams = me->ourgame->dup_params(me->params);
+        /*
+         * The params string may underspecify the game parameters, so
+         * we must first initialise newcurparams with a full set of
+         * params from somewhere else before we decode_params the
+         * input string over the top.
+         *
+         * But which set? It depends on what other data we have.
+         *
+         * If we've been given a _descriptive_ game id, then that may
+         * well underspecify by design, e.g. Solo game descriptions
+         * often start just '3x3:' without specifying one of Solo's
+         * difficulty settings, because it isn't necessary once a game
+         * has been generated (and you might not even know it, if
+         * you're manually transcribing a game description). In that
+         * situation, I've always felt that the best thing to set the
+         * difficulty to (for use if the user hits 'New Game' after
+         * pasting in that game id) is whatever it was previously set
+         * to. That is, we use whatever is already in me->params as
+         * the basis for our decoding of this input string.
+         *
+         * A random-seed based game id, however, should use the real,
+         * built-in default params, and not even check the
+         * <game>_DEFAULT environment setting, because when people
+         * paste each other random seeds - whether it's two users
+         * arranging to generate the same game at the same time to
+         * race solving them, or a user sending a bug report upstream
+         * - the whole point is for the random game id to always be
+         * interpreted the same way, even if it does underspecify.
+         *
+         * A parameter string typed in on its own, with no seed _or_
+         * description, gets treated the same way as a random seed,
+         * because again I think the most likely reason for doing that
+         * is to have a portable representation of a set of params.
+         */
+        if (desc) {
+            newcurparams = me->ourgame->dup_params(me->params);
+        } else {
+            newcurparams = me->ourgame->default_params();
+        }
         me->ourgame->decode_params(newcurparams, par);
         error = me->ourgame->validate_params(newcurparams, desc == NULL);
         if (error) {
@@ -1133,6 +1315,21 @@ char *midend_get_game_id(midend *me)
     return ret;
 }
 
+char *midend_get_random_seed(midend *me)
+{
+    char *parstr, *ret;
+
+    if (!me->seedstr)
+        return NULL;
+
+    parstr = me->ourgame->encode_params(me->curparams, TRUE);
+    assert(parstr);
+    ret = snewn(strlen(parstr) + strlen(me->seedstr) + 2, char);
+    sprintf(ret, "%s#%s", parstr, me->seedstr);
+    sfree(parstr);
+    return ret;
+}
+
 char *midend_set_config(midend *me, int which, config_item *cfg)
 {
     char *error;
@@ -1164,9 +1361,18 @@ char *midend_set_config(midend *me, int which, config_item *cfg)
     return NULL;
 }
 
+int midend_can_format_as_text_now(midend *me)
+{
+    if (me->ourgame->can_format_as_text_ever)
+	return me->ourgame->can_format_as_text_now(me->params);
+    else
+	return FALSE;
+}
+
 char *midend_text_format(midend *me)
 {
-    if (me->ourgame->can_format_as_text && me->statepos > 0)
+    if (me->ourgame->can_format_as_text_ever && me->statepos > 0 &&
+	me->ourgame->can_format_as_text_now(me->params))
 	return me->ourgame->text_format(me->states[me->statepos-1].state);
     else
 	return NULL;
@@ -1199,11 +1405,7 @@ char *midend_solve(midend *me)
      * Now enter the solved state as the next move.
      */
     midend_stop_anim(me);
-    while (me->nstates > me->statepos) {
-	me->ourgame->free_game(me->states[--me->nstates].state);
-        if (me->states[me->nstates].movestr)
-            sfree(me->states[me->nstates].movestr);
-    }
+    midend_purge_states(me);
     ensure(me);
     me->states[me->nstates].state = s;
     me->states[me->nstates].movestr = movestr;
@@ -1214,7 +1416,7 @@ char *midend_solve(midend *me)
                                    me->states[me->statepos-2].state,
                                    me->states[me->statepos-1].state);
     me->dir = +1;
-    if (me->ourgame->mouse_priorities & SOLVE_ANIMATES) {
+    if (me->ourgame->flags & SOLVE_ANIMATES) {
 	me->oldstate = me->ourgame->dup_game(me->states[me->statepos-2].state);
         me->anim_time =
 	    me->ourgame->anim_length(me->states[me->statepos-2].state,
@@ -1225,11 +1427,29 @@ char *midend_solve(midend *me)
 	me->anim_time = 0.0;
 	midend_finish_move(me);
     }
-    midend_redraw(me);
+    if (me->drawing)
+        midend_redraw(me);
     midend_set_timer(me);
     return NULL;
 }
 
+int midend_status(midend *me)
+{
+    /*
+     * We should probably never be called when the state stack has no
+     * states on it at all - ideally, midends should never be left in
+     * that state for long enough to get put down and forgotten about.
+     * But if we are, I think we return _true_ - pedantically speaking
+     * a midend in that state is 'vacuously solved', and more
+     * practically, a user whose midend has been left in that state
+     * probably _does_ want the 'new game' option to be prominent.
+     */
+    if (me->statepos == 0)
+        return +1;
+
+    return me->ourgame->status(me->states[me->statepos-1].state);
+}
+
 char *midend_rewrite_statusbar(midend *me, char *text)
 {
     /*
@@ -1245,7 +1465,7 @@ char *midend_rewrite_statusbar(midend *me, char *text)
 	char timebuf[100], *ret;
 	int min, sec;
 
-	sec = me->elapsed;
+	sec = (int)me->elapsed;
 	min = sec / 60;
 	sec %= 60;
 	sprintf(timebuf, "[%d:%02d] ", min, sec);
@@ -1549,7 +1769,7 @@ char *midend_deserialise(midend *me,
                 uistr = val;
                 val = NULL;
             } else if (!strcmp(key, "TIME")) {
-                elapsed = atof(val);
+                elapsed = (float)atof(val);
             } else if (!strcmp(key, "NSTATES")) {
                 nstates = atoi(val);
                 if (nstates <= 0) {
@@ -1760,6 +1980,111 @@ char *midend_deserialise(midend *me,
     return ret;
 }
 
+/*
+ * This function examines a saved game file just far enough to
+ * determine which game type it contains. It returns NULL on success
+ * and the game name string in 'name' (which will be dynamically
+ * allocated and should be caller-freed), or an error message on
+ * failure.
+ */
+char *identify_game(char **name, int (*read)(void *ctx, void *buf, int len),
+                    void *rctx)
+{
+    int nstates = 0, statepos = -1, gotstates = 0;
+    int started = FALSE;
+
+    char *val = NULL;
+    /* Initially all errors give the same report */
+    char *ret = "Data does not appear to be a saved game file";
+
+    *name = NULL;
+
+    /*
+     * Loop round and round reading one key/value pair at a time from
+     * the serialised stream, until we've found the game name.
+     */
+    while (nstates <= 0 || statepos < 0 || gotstates < nstates-1) {
+        char key[9], c;
+        int len;
+
+        do {
+            if (!read(rctx, key, 1)) {
+                /* unexpected EOF */
+                goto cleanup;
+            }
+        } while (key[0] == '\r' || key[0] == '\n');
+
+        if (!read(rctx, key+1, 8)) {
+            /* unexpected EOF */
+            goto cleanup;
+        }
+
+        if (key[8] != ':') {
+            if (started)
+                ret = "Data was incorrectly formatted for a saved game file";
+	    goto cleanup;
+        }
+        len = strcspn(key, ": ");
+        assert(len <= 8);
+        key[len] = '\0';
+
+        len = 0;
+        while (1) {
+            if (!read(rctx, &c, 1)) {
+                /* unexpected EOF */
+                goto cleanup;
+            }
+
+            if (c == ':') {
+                break;
+            } else if (c >= '0' && c <= '9') {
+                len = (len * 10) + (c - '0');
+            } else {
+                if (started)
+                    ret = "Data was incorrectly formatted for a"
+                    " saved game file";
+                goto cleanup;
+            }
+        }
+
+        val = snewn(len+1, char);
+        if (!read(rctx, val, len)) {
+            if (started)
+            goto cleanup;
+        }
+        val[len] = '\0';
+
+        if (!started) {
+            if (strcmp(key, "SAVEFILE") || strcmp(val, SERIALISE_MAGIC)) {
+                /* ret already has the right message in it */
+                goto cleanup;
+            }
+            /* Now most errors are this one, unless otherwise specified */
+            ret = "Saved data ended unexpectedly";
+            started = TRUE;
+        } else {
+            if (!strcmp(key, "VERSION")) {
+                if (strcmp(val, SERIALISE_VERSION)) {
+                    ret = "Cannot handle this version of the saved game"
+                        " file format";
+                    goto cleanup;
+                }
+            } else if (!strcmp(key, "GAME")) {
+                *name = dupstr(val);
+                ret = NULL;
+                goto cleanup;
+            }
+        }
+
+        sfree(val);
+        val = NULL;
+    }
+
+    cleanup:
+    sfree(val);
+    return ret;
+}
+
 char *midend_print_puzzle(midend *me, document *doc, int with_soln)
 {
     game_state *soln = NULL;