X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=midend.c;h=2edc1ec6ef4286a4124f7d2f440a0b2ed472dee2;hb=3aa4516a680f52e2e6c8a16234a7ecca0ec77233;hp=52299353ca6dcee96806c16c2f423e7cf8acbe18;hpb=1d661ec46b8d7216bc6f2e34a4d6b9cc9fdc6f96;p=sgt-puzzles.git

diff --git a/midend.c b/midend.c
index 5229935..2edc1ec 100644
--- a/midend.c
+++ b/midend.c
@@ -30,9 +30,9 @@ struct midend {
     random_state *random;
     const game *ourgame;
 
-    game_params **presets;
-    char **preset_names, **preset_encodings;
-    int npresets, presetsize;
+    struct preset_menu *preset_menu;
+    char **encoded_presets; /* for midend_which_preset to check against */
+    int n_encoded_presets;
 
     /*
      * `desc' and `privdesc' deserve a comment.
@@ -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)
 {
@@ -106,6 +132,25 @@ midend *midend_new(frontend *fe, const game *ourgame,
     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;
@@ -113,10 +158,7 @@ midend *midend_new(frontend *fe, const game *ourgame,
     me->genmode = GOT_NOTHING;
     me->drawstate = NULL;
     me->oldstate = NULL;
-    me->presets = NULL;
-    me->preset_names = NULL;
-    me->preset_encodings = NULL;
-    me->npresets = me->presetsize = 0;
+    me->preset_menu = NULL;
     me->anim_time = me->anim_pos = 0.0F;
     me->flash_time = me->flash_pos = 0.0F;
     me->dir = 0;
@@ -131,31 +173,27 @@ midend *midend_new(frontend *fe, const game *ourgame,
     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) {
@@ -168,10 +206,23 @@ static void midend_free_game(midend *me)
         me->ourgame->free_drawstate(me->drawing, me->drawstate);
 }
 
-void midend_free(midend *me)
+static void midend_free_preset_menu(midend *me, struct preset_menu *menu)
 {
-    int i;
+    if (menu) {
+        int i;
+        for (i = 0; i < menu->n_entries; i++) {
+            sfree(menu->entries[i].title);
+            if (menu->entries[i].params)
+                me->ourgame->free_params(menu->entries[i].params);
+            midend_free_preset_menu(me, menu->entries[i].submenu);
+        }
+        sfree(menu->entries);
+        sfree(menu);
+    }
+}
 
+void midend_free(midend *me)
+{
     midend_free_game(me);
 
     if (me->drawing)
@@ -183,16 +234,7 @@ void midend_free(midend *me)
     sfree(me->seedstr);
     sfree(me->aux_info);
     me->ourgame->free_params(me->params);
-    if (me->npresets) {
-	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);
-    }
+    midend_free_preset_menu(me, me->preset_menu);
     if (me->ui)
         me->ourgame->free_ui(me->ui);
     if (me->curparams)
@@ -278,6 +320,8 @@ void midend_size(midend *me, int *x, int *y, int user_size)
     *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);
@@ -312,6 +356,7 @@ void midend_force_redraw(midend *me)
 
 void midend_new_game(midend *me)
 {
+    midend_stop_anim(me);
     midend_free_game(me);
 
     assert(me->nstates == 0);
@@ -383,6 +428,25 @@ 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++;
@@ -391,11 +455,26 @@ 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)
@@ -471,8 +550,6 @@ 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! */
@@ -490,8 +567,7 @@ 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);
@@ -501,7 +577,7 @@ 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);
@@ -514,31 +590,40 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
     int type = MOVE, gottype = FALSE, ret = 1;
     float anim_time;
     game_state *s;
-    char *movestr;
-	
-    movestr =
-	me->ourgame->interpret_move(me->states[me->statepos-1].state,
-				    me->ui, me->drawstate, x, y, button);
+    char *movestr = NULL;
+
+    if (!IS_UI_FAKE_KEY(button)) {
+        movestr = me->ourgame->interpret_move(
+            me->states[me->statepos-1].state,
+            me->ui, me->drawstate, x, y, button);
+    }
 
     if (!movestr) {
-	if (button == 'n' || button == 'N' || button == '\x0E') {
-	    midend_stop_anim(me);
+	if (button == 'n' || button == 'N' || button == '\x0E' ||
+            button == UI_NEWGAME) {
 	    midend_new_game(me);
 	    midend_redraw(me);
 	    goto done;		       /* never animate */
-	} else if (button == 'u' || button == 'u' ||
-		   button == '\x1A' || button == '\x1F') {
+	} else if (button == 'u' || button == 'U' ||
+		   button == '\x1A' || button == '\x1F' ||
+                   button == UI_UNDO) {
 	    midend_stop_anim(me);
 	    type = me->states[me->statepos-1].movetype;
 	    gottype = TRUE;
 	    if (!midend_undo(me))
 		goto done;
 	} else if (button == 'r' || button == 'R' ||
-		   button == '\x12' || button == '\x19') {
+		   button == '\x12' || button == '\x19' ||
+                   button == UI_REDO) {
 	    midend_stop_anim(me);
 	    if (!midend_redo(me))
 		goto done;
-	} else if (button == 'q' || button == 'Q' || button == '\x11') {
+	} else if ((button == '\x13' || button == UI_SOLVE) &&
+                   me->ourgame->can_solve) {
+	    if (midend_solve(me))
+		goto done;
+	} else if (button == 'q' || button == 'Q' || button == '\x11' ||
+                   button == UI_QUIT) {
 	    ret = 0;
 	    goto done;
 	} else
@@ -563,8 +648,7 @@ static int midend_really_process_key(midend *me, int x, int y, int button)
             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;
@@ -728,6 +812,15 @@ int midend_process_key(midend *me, int x, int y, int button)
     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.
      */
@@ -842,40 +935,177 @@ float *midend_colours(midend *me, int *ncolours)
     return ret;
 }
 
-int midend_num_presets(midend *me)
+struct preset_menu *preset_menu_new(void)
 {
-    if (!me->npresets) {
-        char *name;
+    struct preset_menu *menu = snew(struct preset_menu);
+    menu->n_entries = 0;
+    menu->entries_size = 0;
+    menu->entries = NULL;
+    return menu;
+}
+
+static struct preset_menu_entry *preset_menu_add(struct preset_menu *menu,
+                                                 char *title)
+{
+    struct preset_menu_entry *toret;
+    if (menu->n_entries >= menu->entries_size) {
+        menu->entries_size = menu->n_entries * 5 / 4 + 10;
+        menu->entries = sresize(menu->entries, menu->entries_size,
+                                struct preset_menu_entry);
+    }
+    toret = &menu->entries[menu->n_entries++];
+    toret->title = title;
+    toret->params = NULL;
+    toret->submenu = NULL;
+    return toret;
+}
+
+struct preset_menu *preset_menu_add_submenu(struct preset_menu *parent,
+                                            char *title)
+{
+    struct preset_menu_entry *entry = preset_menu_add(parent, title);
+    entry->submenu = preset_menu_new();
+    return entry->submenu;
+}
+
+void preset_menu_add_preset(struct preset_menu *parent,
+                            char *title, game_params *params)
+{
+    struct preset_menu_entry *entry = preset_menu_add(parent, title);
+    entry->params = params;
+}
+
+game_params *preset_menu_lookup_by_id(struct preset_menu *menu, int id)
+{
+    int i;
+    game_params *retd;
+
+    for (i = 0; i < menu->n_entries; i++) {
+        if (id == menu->entries[i].id)
+            return menu->entries[i].params;
+        if (menu->entries[i].submenu &&
+            (retd = preset_menu_lookup_by_id(
+                 menu->entries[i].submenu, id)) != NULL)
+            return retd;
+    }
+
+    return NULL;
+}
+
+static char *preset_menu_add_from_user_env(
+    midend *me, struct preset_menu *menu, char *p, int top_level)
+{
+    while (*p) {
+        char *name, *val;
         game_params *preset;
 
-        while (me->ourgame->fetch_preset(me->npresets, &name, &preset)) {
-            if (me->presetsize <= me->npresets) {
-                me->presetsize = me->npresets + 10;
-                me->presets = sresize(me->presets, me->presetsize,
-                                      game_params *);
-                me->preset_names = sresize(me->preset_names, me->presetsize,
-                                           char *);
-                me->preset_encodings = sresize(me->preset_encodings,
-					       me->presetsize, char *);
+        name = p;
+        while (*p && *p != ':') p++;
+        if (*p) *p++ = '\0';
+        val = p;
+        while (*p && *p != ':') p++;
+        if (*p) *p++ = '\0';
+
+        if (!strcmp(val, "#")) {
+            /*
+             * Special case: either open a new submenu with the given
+             * title, or terminate the current submenu.
+             */
+            if (*name) {
+                struct preset_menu *submenu =
+                    preset_menu_add_submenu(menu, dupstr(name));
+                p = preset_menu_add_from_user_env(me, submenu, p, FALSE);
+            } else {
+                /*
+                 * If we get a 'close submenu' indication at the top
+                 * level, there's not much we can do but quietly
+                 * ignore it.
+                 */
+                if (!top_level)
+                    return p;
             }
+            continue;
+        }
+
+        preset = me->ourgame->default_params();
+        me->ourgame->decode_params(preset, val);
 
-            me->presets[me->npresets] = preset;
-            me->preset_names[me->npresets] = name;
-            me->preset_encodings[me->npresets] =
-		me->ourgame->encode_params(preset, TRUE);;
-            me->npresets++;
+        if (me->ourgame->validate_params(preset, TRUE)) {
+            /* Drop this one from the list. */
+            me->ourgame->free_params(preset);
+            continue;
         }
+
+        preset_menu_add_preset(menu, dupstr(name), preset);
+    }
+
+    return p;
+}
+
+static void preset_menu_alloc_ids(midend *me, struct preset_menu *menu)
+{
+    int i;
+
+    for (i = 0; i < menu->n_entries; i++)
+        menu->entries[i].id = me->n_encoded_presets++;
+
+    for (i = 0; i < menu->n_entries; i++)
+        if (menu->entries[i].submenu)
+            preset_menu_alloc_ids(me, menu->entries[i].submenu);
+}
+
+static void preset_menu_encode_params(midend *me, struct preset_menu *menu)
+{
+    int i;
+
+    for (i = 0; i < menu->n_entries; i++) {
+        if (menu->entries[i].params) {
+            me->encoded_presets[menu->entries[i].id] =
+                me->ourgame->encode_params(menu->entries[i].params, TRUE);
+        } else {
+            preset_menu_encode_params(me, menu->entries[i].submenu);
+        }
+    }
+}
+
+struct preset_menu *midend_get_presets(midend *me, int *id_limit)
+{
+    int i;
+
+    if (me->preset_menu)
+        return me->preset_menu;
+
+#if 0
+    /* Expect the game to implement exactly one of the two preset APIs */
+    assert(me->ourgame->fetch_preset || me->ourgame->preset_menu);
+    assert(!(me->ourgame->fetch_preset && me->ourgame->preset_menu));
+#endif
+
+    if (me->ourgame->fetch_preset) {
+        char *name;
+        game_params *preset;
+
+        /* Simple one-level menu */
+        assert(!me->ourgame->preset_menu);
+        me->preset_menu = preset_menu_new();
+        for (i = 0; me->ourgame->fetch_preset(i, &name, &preset); i++)
+            preset_menu_add_preset(me->preset_menu, name, preset);
+
+    } else {
+        /* Hierarchical menu provided by the game backend */
+        me->preset_menu = me->ourgame->preset_menu();
     }
 
     {
         /*
-         * Allow environment-based extensions to the preset list by
-         * defining a variable along the lines of `SOLO_PRESETS=2x3
-         * Advanced:2x3da'. Colon-separated list of items,
-         * alternating between textual titles in the menu and
-         * encoded parameter strings.
+         * Allow user extensions to the preset list by defining an
+         * environment variable <gamename>_PRESETS whose value is a
+         * colon-separated list of items, alternating between textual
+         * titles in the menu and encoded parameter strings. For
+         * example, "SOLO_PRESETS=2x3 Advanced:2x3da" would define
+         * just one additional preset for Solo.
          */
-        char buf[80], *e, *p;
+        char buf[80], *e;
         int j, k;
 
         sprintf(buf, "%s_PRESETS", me->ourgame->name);
@@ -885,56 +1115,27 @@ int midend_num_presets(midend *me)
 	buf[k] = '\0';
 
         if ((e = getenv(buf)) != NULL) {
-            p = e = dupstr(e);
-
-            while (*p) {
-                char *name, *val;
-                game_params *preset;
-
-                name = p;
-                while (*p && *p != ':') p++;
-                if (*p) *p++ = '\0';
-                val = p;
-                while (*p && *p != ':') p++;
-                if (*p) *p++ = '\0';
-
-                preset = me->ourgame->default_params();
-                me->ourgame->decode_params(preset, val);
-
-		if (me->ourgame->validate_params(preset, TRUE)) {
-		    /* Drop this one from the list. */
-		    me->ourgame->free_params(preset);
-		    continue;
-		}
-
-                if (me->presetsize <= me->npresets) {
-                    me->presetsize = me->npresets + 10;
-                    me->presets = sresize(me->presets, me->presetsize,
-                                          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++;
-            }
+            e = dupstr(e);
+            preset_menu_add_from_user_env(me, me->preset_menu, e, TRUE);
+            sfree(e);
         }
     }
 
-    return me->npresets;
-}
-
-void midend_fetch_preset(midend *me, int n,
-                         char **name, game_params **params)
-{
-    assert(n >= 0 && n < me->npresets);
-    *name = me->preset_names[n];
-    *params = me->presets[n];
+    /*
+     * Finalise the menu: allocate an integer id to each entry, and
+     * store string encodings of the presets' parameters in
+     * me->encoded_presets.
+     */
+    me->n_encoded_presets = 0;
+    preset_menu_alloc_ids(me, me->preset_menu);
+    me->encoded_presets = snewn(me->n_encoded_presets, char *);
+    for (i = 0; i < me->n_encoded_presets; i++)
+        me->encoded_presets[i] = NULL;
+    preset_menu_encode_params(me, me->preset_menu);
+
+    if (id_limit)
+        *id_limit = me->n_encoded_presets;
+    return me->preset_menu;
 }
 
 int midend_which_preset(midend *me)
@@ -943,8 +1144,9 @@ int midend_which_preset(midend *me)
     int i, ret;
 
     ret = -1;
-    for (i = 0; i < me->npresets; i++)
-	if (!strcmp(encoding, me->preset_encodings[i])) {
+    for (i = 0; i < me->n_encoded_presets; i++)
+	if (me->encoded_presets[i] &&
+            !strcmp(encoding, me->encoded_presets[i])) {
 	    ret = i;
 	    break;
 	}
@@ -958,12 +1160,20 @@ int midend_wants_statusbar(midend *me)
     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)
 {
     sfree(me->desc);
     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)
@@ -1085,7 +1295,45 @@ 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) {
@@ -1183,6 +1431,21 @@ 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;
@@ -1258,11 +1521,7 @@ 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;
@@ -1284,11 +1543,29 @@ 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)
 {
     /*
@@ -1340,7 +1617,9 @@ void midend_serialise(midend *me,
 #define wr(h,s) do { \
     char hbuf[80]; \
     char *str = (s); \
-    sprintf(hbuf, "%-8.8s:%d:", (h), (int)strlen(str)); \
+    char lbuf[9];                               \
+    copy_left_justified(lbuf, sizeof(lbuf), h); \
+    sprintf(hbuf, "%s:%d:", lbuf, (int)strlen(str)); \
     write(wctx, hbuf, strlen(hbuf)); \
     write(wctx, str, strlen(str)); \
     write(wctx, "\n", 1); \
@@ -1787,6 +2066,8 @@ char *midend_deserialise(midend *me,
         me->ourgame->new_drawstate(me->drawing,
 				   me->states[me->statepos-1].state);
     midend_size_new_drawstate(me);
+    if (me->game_id_change_notify_function)
+        me->game_id_change_notify_function(me->game_id_change_notify_ctx);
 
     ret = NULL;                        /* success! */
 
@@ -1819,6 +2100,111 @@ 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;