X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/puzzles/blobdiff_plain/eb2ad6f1d0284c83b3cb5caf631c659441189d7d..5d8c6c556982ae44f786d14a6d641182ced15043:/midend.c

diff --git a/midend.c b/midend.c
index cafc8ea..dec0cc9 100644
--- a/midend.c
+++ b/midend.c
@@ -2,107 +2,251 @@
  * midend.c: general middle fragment sitting between the
  * platform-specific front end and game-specific back end.
  * Maintains a move list, takes care of Undo and Redo commands, and
- * processes standard keystrokes for undo/redo/new/restart/quit.
+ * processes standard keystrokes for undo/redo/new/quit.
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <assert.h>
+#include <stdlib.h>
+#include <ctype.h>
 
 #include "puzzles.h"
 
+enum { DEF_PARAMS, DEF_SEED, DEF_DESC };   /* for midend_game_id_int */
+
+struct midend_state_entry {
+    game_state *state;
+    int special;                       /* created by solve or restart */
+};
+
 struct midend_data {
     frontend *frontend;
-    char *seed;
+    random_state *random;
+    const game *ourgame;
+
+    char *desc, *seedstr;
+    game_aux_info *aux_info;
+    enum { GOT_SEED, GOT_DESC, GOT_NOTHING } genmode;
     int nstates, statesize, statepos;
 
     game_params **presets;
     char **preset_names;
     int npresets, presetsize;
 
-    game_params *params;
-    game_state **states;
+    game_params *params, *curparams;
+    struct midend_state_entry *states;
     game_drawstate *drawstate;
     game_state *oldstate;
+    game_ui *ui;
     float anim_time, anim_pos;
+    float flash_time, flash_pos;
+    int dir;
+
+    int timing;
+    float elapsed;
+    char *laststatus;
+
+    int pressed_mouse_button;
+
+    int winwidth, winheight;
 };
 
 #define ensure(me) do { \
     if ((me)->nstates >= (me)->statesize) { \
 	(me)->statesize = (me)->nstates + 128; \
-	(me)->states = sresize((me)->states, (me)->statesize, game_state *); \
+	(me)->states = sresize((me)->states, (me)->statesize, \
+                               struct midend_state_entry); \
     } \
 } while (0)
 
-midend_data *midend_new(frontend *frontend)
+midend_data *midend_new(frontend *fe, const game *ourgame)
 {
     midend_data *me = snew(midend_data);
+    void *randseed;
+    int randseedsize;
+
+    get_random_seed(&randseed, &randseedsize);
 
-    me->frontend = frontend;
+    me->frontend = fe;
+    me->ourgame = ourgame;
+    me->random = random_init(randseed, randseedsize);
     me->nstates = me->statesize = me->statepos = 0;
     me->states = NULL;
-    me->params = default_params();
-    me->seed = NULL;
+    me->params = ourgame->default_params();
+    me->curparams = NULL;
+    me->desc = NULL;
+    me->seedstr = NULL;
+    me->aux_info = NULL;
+    me->genmode = GOT_NOTHING;
     me->drawstate = NULL;
     me->oldstate = NULL;
     me->presets = NULL;
     me->preset_names = NULL;
     me->npresets = me->presetsize = 0;
+    me->anim_time = me->anim_pos = 0.0F;
+    me->flash_time = me->flash_pos = 0.0F;
+    me->dir = 0;
+    me->ui = NULL;
+    me->pressed_mouse_button = 0;
+    me->laststatus = NULL;
+    me->timing = FALSE;
+    me->elapsed = 0.0F;
+    me->winwidth = me->winheight = 0;
+
+    sfree(randseed);
 
     return me;
 }
 
+static void midend_free_game(midend_data *me)
+{
+    while (me->nstates > 0)
+	me->ourgame->free_game(me->states[--me->nstates].state);
+
+    if (me->drawstate)
+        me->ourgame->free_drawstate(me->drawstate);
+}
+
 void midend_free(midend_data *me)
 {
+    int i;
+
+    midend_free_game(me);
+
+    random_free(me->random);
     sfree(me->states);
-    sfree(me->seed);
-    free_params(me->params);
+    sfree(me->desc);
+    sfree(me->seedstr);
+    if (me->aux_info)
+	me->ourgame->free_aux_info(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->presets);
+	sfree(me->preset_names);
+    }
+    if (me->ui)
+        me->ourgame->free_ui(me->ui);
+    if (me->curparams)
+        me->ourgame->free_params(me->curparams);
+    sfree(me->laststatus);
     sfree(me);
 }
 
-void midend_size(midend_data *me, int *x, int *y)
+void midend_size(midend_data *me, int *x, int *y, int expand)
 {
-    game_size(me->params, x, y);
+    me->ourgame->size(me->params, me->drawstate, x, y, expand);
+    me->winwidth = *x;
+    me->winheight = *y;
 }
 
 void midend_set_params(midend_data *me, game_params *params)
 {
-    free_params(me->params);
-    me->params = dup_params(params);
+    me->ourgame->free_params(me->params);
+    me->params = me->ourgame->dup_params(params);
 }
 
-void midend_new_game(midend_data *me, char *seed)
+static void midend_set_timer(midend_data *me)
 {
-    while (me->nstates > 0)
-	free_game(me->states[--me->nstates]);
+    me->timing = (me->ourgame->is_timed &&
+		  me->ourgame->timing_state(me->states[me->statepos-1].state));
+    if (me->timing || me->flash_time || me->anim_time)
+	activate_timer(me->frontend);
+    else
+	deactivate_timer(me->frontend);
+}
+
+static void midend_size_new_drawstate(midend_data *me)
+{
+    me->ourgame->size(me->params, me->drawstate, &me->winwidth, &me->winheight,
+                      TRUE);
+}
 
+void midend_force_redraw(midend_data *me)
+{
     if (me->drawstate)
-        game_free_drawstate(me->drawstate);
+        me->ourgame->free_drawstate(me->drawstate);
+    me->drawstate = me->ourgame->new_drawstate(me->states[0].state);
+    midend_size_new_drawstate(me);
+    midend_redraw(me);
+}
+
+void midend_new_game(midend_data *me)
+{
+    midend_free_game(me);
 
     assert(me->nstates == 0);
 
-    sfree(me->seed);
-    if (seed)
-	me->seed = dupstr(seed);
-    else
-	me->seed = new_game_seed(me->params);
+    if (me->genmode == GOT_DESC) {
+	me->genmode = GOT_NOTHING;
+    } else {
+        random_state *rs;
+
+        if (me->genmode == GOT_SEED) {
+            me->genmode = GOT_NOTHING;
+        } else {
+            /*
+             * Generate a new random seed. 15 digits comes to about
+             * 48 bits, which should be more than enough.
+             * 
+             * I'll avoid putting a leading zero on the number,
+             * just in case it confuses anybody who thinks it's
+             * processed as an integer rather than a string.
+             */
+            char newseed[16];
+            int i;
+            newseed[15] = '\0';
+            newseed[0] = '1' + random_upto(me->random, 9);
+            for (i = 1; i < 15; i++)
+                newseed[i] = '0' + random_upto(me->random, 10);
+            sfree(me->seedstr);
+            me->seedstr = dupstr(newseed);
+
+	    if (me->curparams)
+		me->ourgame->free_params(me->curparams);
+	    me->curparams = me->ourgame->dup_params(me->params);
+        }
+
+	sfree(me->desc);
+	if (me->aux_info)
+	    me->ourgame->free_aux_info(me->aux_info);
+	me->aux_info = NULL;
+
+        rs = random_init(me->seedstr, strlen(me->seedstr));
+        me->desc = me->ourgame->new_desc(me->curparams, rs,
+					 &me->aux_info, TRUE);
+        random_free(rs);
+    }
 
     ensure(me);
-    me->states[me->nstates++] = new_game(me->params, me->seed);
+    me->states[me->nstates].state =
+	me->ourgame->new_game(me, me->params, me->desc);
+    me->states[me->nstates].special = TRUE;
+    me->nstates++;
     me->statepos = 1;
-    me->drawstate = game_new_drawstate(me->states[0]);
-}
-
-void midend_restart_game(midend_data *me)
-{
-    while (me->nstates > 1)
-	free_game(me->states[--me->nstates]);
-    me->statepos = me->nstates;
+    me->drawstate = me->ourgame->new_drawstate(me->states[0].state);
+    midend_size_new_drawstate(me);
+    me->elapsed = 0.0F;
+    midend_set_timer(me);
+    if (me->ui)
+        me->ourgame->free_ui(me->ui);
+    me->ui = me->ourgame->new_ui(me->states[0].state);
+    me->pressed_mouse_button = 0;
 }
 
 static int midend_undo(midend_data *me)
 {
     if (me->statepos > 1) {
+        if (me->ui)
+            me->ourgame->changed_state(me->ui,
+                                       me->states[me->statepos-1].state,
+                                       me->states[me->statepos-2].state);
 	me->statepos--;
+        me->dir = -1;
         return 1;
     } else
         return 0;
@@ -111,79 +255,288 @@ static int midend_undo(midend_data *me)
 static int midend_redo(midend_data *me)
 {
     if (me->statepos < me->nstates) {
+        if (me->ui)
+            me->ourgame->changed_state(me->ui,
+                                       me->states[me->statepos-1].state,
+                                       me->states[me->statepos].state);
 	me->statepos++;
+        me->dir = +1;
         return 1;
     } else
         return 0;
 }
 
-int midend_process_key(midend_data *me, int x, int y, int button)
+static void midend_finish_move(midend_data *me)
 {
-    game_state *oldstate = dup_game(me->states[me->statepos - 1]);
-    float anim_time;
+    float flashtime;
+
+    /*
+     * We do not flash if the later of the two states is special.
+     * This covers both forward Solve moves and backward (undone)
+     * Restart moves.
+     */
+    if ((me->oldstate || me->statepos > 1) &&
+        ((me->dir > 0 && !me->states[me->statepos-1].special) ||
+         (me->dir < 0 && me->statepos < me->nstates &&
+          !me->states[me->statepos].special))) {
+	flashtime = me->ourgame->flash_length(me->oldstate ? me->oldstate :
+					      me->states[me->statepos-2].state,
+					      me->states[me->statepos-1].state,
+					      me->oldstate ? me->dir : +1,
+					      me->ui);
+	if (flashtime > 0) {
+	    me->flash_pos = 0.0F;
+	    me->flash_time = flashtime;
+	}
+    }
 
+    if (me->oldstate)
+	me->ourgame->free_game(me->oldstate);
+    me->oldstate = NULL;
+    me->anim_pos = me->anim_time = 0;
+    me->dir = 0;
+
+    midend_set_timer(me);
+}
+
+void midend_stop_anim(midend_data *me)
+{
     if (me->oldstate || me->anim_time) {
-        if (me->oldstate)
-            free_game(me->oldstate);
-        me->oldstate = NULL;
-        me->anim_pos = me->anim_time = 0;
-        deactivate_timer(me->frontend);
+	midend_finish_move(me);
         midend_redraw(me);
     }
+}
+
+void midend_restart_game(midend_data *me)
+{
+    game_state *s;
+
+    midend_stop_anim(me);
+
+    assert(me->statepos >= 1);
+    if (me->statepos == 1)
+        return;                        /* no point doing anything at all! */
+
+    s = me->ourgame->dup_game(me->states[0].state);
+
+    /*
+     * 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);
+    ensure(me);
+    me->states[me->nstates].state = s;
+    me->states[me->nstates].special = TRUE;   /* we just restarted */
+    me->statepos = ++me->nstates;
+    if (me->ui)
+        me->ourgame->changed_state(me->ui,
+                                   me->states[me->statepos-2].state,
+                                   me->states[me->statepos-1].state);
+    me->anim_time = 0.0;
+    midend_finish_move(me);
+    midend_redraw(me);
+    midend_set_timer(me);
+}
+
+static int midend_really_process_key(midend_data *me, int x, int y, int button)
+{
+    game_state *oldstate =
+        me->ourgame->dup_game(me->states[me->statepos - 1].state);
+    int special = FALSE, gotspecial = FALSE, ret = 1;
+    float anim_time;
 
     if (button == 'n' || button == 'N' || button == '\x0E') {
-	midend_new_game(me, NULL);
-        midend_redraw(me);
-        return 1;                      /* never animate */
-    } else if (button == 'r' || button == 'R') {
-	midend_restart_game(me);
+	midend_stop_anim(me);
+	midend_new_game(me);
         midend_redraw(me);
-        return 1;                      /* never animate */
+	goto done;		       /* never animate */
     } else if (button == 'u' || button == 'u' ||
                button == '\x1A' || button == '\x1F') {
+	midend_stop_anim(me);
+        special = me->states[me->statepos-1].special;
+        gotspecial = TRUE;
 	if (!midend_undo(me))
-            return 1;
-    } else if (button == '\x12') {
+	    goto done;
+    } else if (button == 'r' || button == 'R' ||
+               button == '\x12' || button == '\x19') {
+	midend_stop_anim(me);
 	if (!midend_redo(me))
-            return 1;
+            goto done;
     } else if (button == 'q' || button == 'Q' || button == '\x11') {
-	free_game(oldstate);
-        return 0;
+	ret = 0;
+	goto done;
     } else {
-        game_state *s = make_move(me->states[me->statepos-1], x, y, button);
-
-        if (s) {
+        game_state *s =
+            me->ourgame->make_move(me->states[me->statepos-1].state,
+                                   me->ui, me->drawstate, x, y, button);
+
+        if (s == me->states[me->statepos-1].state) {
+            /*
+             * make_move() is allowed to return its input state to
+             * indicate that although no move has been made, the UI
+             * state has been updated and a redraw is called for.
+             */
+            midend_redraw(me);
+            goto done;
+        } else if (s) {
+	    midend_stop_anim(me);
             while (me->nstates > me->statepos)
-                free_game(me->states[--me->nstates]);
+                me->ourgame->free_game(me->states[--me->nstates].state);
             ensure(me);
-            me->states[me->nstates] = s;
+            me->states[me->nstates].state = s;
+            me->states[me->nstates].special = FALSE;   /* normal move */
             me->statepos = ++me->nstates;
+            me->dir = +1;
         } else {
-            free_game(oldstate);
-            return 1;
+          goto done;
         }
     }
 
+    if (!gotspecial)
+        special = me->states[me->statepos-1].special;
+
     /*
      * See if this move requires an animation.
      */
-    anim_time = game_anim_length(oldstate, me->states[me->statepos-1]);
+    if (special) {
+        anim_time = 0;
+    } else {
+        anim_time = me->ourgame->anim_length(oldstate,
+                                             me->states[me->statepos-1].state,
+                                             me->dir, me->ui);
+    }
 
+    me->oldstate = oldstate; oldstate = NULL;
     if (anim_time > 0) {
-        me->oldstate = oldstate;
         me->anim_time = anim_time;
     } else {
-        free_game(oldstate);
-        me->oldstate = NULL;
         me->anim_time = 0.0;
+	midend_finish_move(me);
     }
     me->anim_pos = 0.0;
 
     midend_redraw(me);
 
-    activate_timer(me->frontend);
+    midend_set_timer(me);
+
+    done:
+    if (oldstate) me->ourgame->free_game(oldstate);
+    return ret;
+}
+
+int midend_process_key(midend_data *me, int x, int y, int button)
+{
+    int ret = 1;
+
+    /*
+     * Harmonise mouse drag and release messages.
+     * 
+     * Some front ends might accidentally switch from sending, say,
+     * RIGHT_DRAG messages to sending LEFT_DRAG, half way through a
+     * drag. (This can happen on the Mac, for example, since
+     * RIGHT_DRAG is usually done using Command+drag, and if the
+     * user accidentally releases Command half way through the drag
+     * then there will be trouble.)
+     * 
+     * It would be an O(number of front ends) annoyance to fix this
+     * in the front ends, but an O(number of back ends) annoyance
+     * to have each game capable of dealing with it. Therefore, we
+     * fix it _here_ in the common midend code so that it only has
+     * to be done once.
+     * 
+     * The possible ways in which things can go screwy in the front
+     * end are:
+     * 
+     *  - in a system containing multiple physical buttons button
+     *    presses can inadvertently overlap. We can see ABab (caps
+     *    meaning button-down and lowercase meaning button-up) when
+     *    the user had semantically intended AaBb.
+     * 
+     *  - in a system where one button is simulated by means of a
+     *    modifier key and another button, buttons can mutate
+     *    between press and release (possibly during drag). So we
+     *    can see Ab instead of Aa.
+     * 
+     * Definite requirements are:
+     * 
+     *  - button _presses_ must never be invented or destroyed. If
+     *    the user presses two buttons in succession, the button
+     *    presses must be transferred to the backend unchanged. So
+     *    if we see AaBb , that's fine; if we see ABab (the button
+     *    presses inadvertently overlapped) we must somehow
+     *    `correct' it to AaBb.
+     * 
+     *  - every mouse action must end up looking like a press, zero
+     *    or more drags, then a release. This allows back ends to
+     *    make the _assumption_ that incoming mouse data will be
+     *    sane in this regard, and not worry about the details.
+     * 
+     * So my policy will be:
+     * 
+     *  - treat any button-up as a button-up for the currently
+     *    pressed button, or ignore it if there is no currently
+     *    pressed button.
+     * 
+     *  - treat any drag as a drag for the currently pressed
+     *    button, or ignore it if there is no currently pressed
+     *    button.
+     * 
+     *  - if we see a button-down while another button is currently
+     *    pressed, invent a button-up for the first one and then
+     *    pass the button-down through as before.
+     * 
+     * 2005-05-31: An addendum to the above. Some games might want
+     * a `priority order' among buttons, such that if one button is
+     * pressed while another is down then a fixed one of the
+     * buttons takes priority no matter what order they're pressed
+     * in. Mines, in particular, wants to treat a left+right click
+     * 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.
+     */
+    if (IS_MOUSE_DRAG(button) || IS_MOUSE_RELEASE(button)) {
+        if (me->pressed_mouse_button) {
+            if (IS_MOUSE_DRAG(button)) {
+                button = me->pressed_mouse_button +
+                    (LEFT_DRAG - LEFT_BUTTON);
+            } else {
+                button = me->pressed_mouse_button +
+                    (LEFT_RELEASE - LEFT_BUTTON);
+            }
+        } else
+            return ret;                /* ignore it */
+    } else if (IS_MOUSE_DOWN(button) && me->pressed_mouse_button) {
+	/*
+	 * If the new button has lower priority than the old one,
+	 * don't bother doing this.
+	 */
+	if (me->ourgame->mouse_priorities &
+	    BUTTON_BEATS(me->pressed_mouse_button, button))
+	    return ret;		       /* just ignore it */
+
+        /*
+         * Fabricate a button-up for the previously pressed button.
+         */
+        ret = ret && midend_really_process_key
+            (me, x, y, (me->pressed_mouse_button +
+                        (LEFT_RELEASE - LEFT_BUTTON)));
+    }
+
+    /*
+     * Now send on the event we originally received.
+     */
+    ret = ret && midend_really_process_key(me, x, y, button);
+
+    /*
+     * And update the currently pressed button.
+     */
+    if (IS_MOUSE_RELEASE(button))
+        me->pressed_mouse_button = 0;
+    else if (IS_MOUSE_DOWN(button))
+        me->pressed_mouse_button = button;
 
-    return 1;
+    return ret;
 }
 
 void midend_redraw(midend_data *me)
@@ -192,11 +545,14 @@ void midend_redraw(midend_data *me)
         start_draw(me->frontend);
         if (me->oldstate && me->anim_time > 0 &&
             me->anim_pos < me->anim_time) {
-            game_redraw(me->frontend, me->drawstate, me->oldstate,
-                        me->states[me->statepos-1], me->anim_pos);
+            assert(me->dir != 0);
+            me->ourgame->redraw(me->frontend, me->drawstate, me->oldstate,
+				me->states[me->statepos-1].state, me->dir,
+				me->ui, me->anim_pos, me->flash_pos);
         } else {
-            game_redraw(me->frontend, me->drawstate, NULL,
-                        me->states[me->statepos-1], 0.0);
+            me->ourgame->redraw(me->frontend, me->drawstate, NULL,
+				me->states[me->statepos-1].state, +1 /*shrug*/,
+				me->ui, 0.0, me->flash_pos);
         }
         end_draw(me->frontend);
     }
@@ -207,13 +563,25 @@ void midend_timer(midend_data *me, float tplus)
     me->anim_pos += tplus;
     if (me->anim_pos >= me->anim_time ||
         me->anim_time == 0 || !me->oldstate) {
-        if (me->oldstate)
-            free_game(me->oldstate);
-        me->oldstate = NULL;
-        me->anim_pos = me->anim_time = 0;
-        deactivate_timer(me->frontend);
+	if (me->anim_time > 0)
+	    midend_finish_move(me);
+    }
+
+    me->flash_pos += tplus;
+    if (me->flash_pos >= me->flash_time || me->flash_time == 0) {
+	me->flash_pos = me->flash_time = 0;
     }
+
     midend_redraw(me);
+
+    if (me->timing) {
+	float oldelapsed = me->elapsed;
+	me->elapsed += tplus;
+	if ((int)oldelapsed != (int)me->elapsed)
+	    status_bar(me->frontend, me->laststatus ? me->laststatus : "");
+    }
+
+    midend_set_timer(me);
 }
 
 float *midend_colours(midend_data *me, int *ncolours)
@@ -222,16 +590,46 @@ float *midend_colours(midend_data *me, int *ncolours)
     float *ret;
 
     if (me->nstates == 0) {
-        char *seed = new_game_seed(me->params);
-        state = new_game(me->params, seed);
-        sfree(seed);
+	game_aux_info *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);
+	if (aux)
+	    me->ourgame->free_aux_info(aux);
     } else
-        state = me->states[0];
-
-    ret = game_colours(me->frontend, state, ncolours);
+        state = me->states[0].state;
+
+    ret = me->ourgame->colours(me->frontend, state, ncolours);
+
+    {
+        int i;
+
+        /*
+         * Allow environment-based overrides for the standard
+         * colours by defining variables along the lines of
+         * `NET_COLOUR_4=6000c0'.
+         */
+
+        for (i = 0; i < *ncolours; i++) {
+            char buf[80], *e;
+            unsigned int r, g, b;
+            int j;
+
+            sprintf(buf, "%s_COLOUR_%d", me->ourgame->name, i);
+            for (j = 0; buf[j]; j++)
+                buf[j] = toupper((unsigned char)buf[j]);
+            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;
+            }
+        }
+    }
 
     if (me->nstates == 0)
-        free_game(state);
+        me->ourgame->free_game(state);
 
     return ret;
 }
@@ -242,7 +640,7 @@ int midend_num_presets(midend_data *me)
         char *name;
         game_params *preset;
 
-        while (game_fetch_preset(me->npresets, &name, &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,
@@ -257,6 +655,59 @@ int midend_num_presets(midend_data *me)
         }
     }
 
+    {
+        /*
+         * 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.
+         */
+        char buf[80], *e, *p;
+        int j;
+
+        sprintf(buf, "%s_PRESETS", me->ourgame->name);
+        for (j = 0; buf[j]; j++)
+            buf[j] = toupper((unsigned char)buf[j]);
+
+        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)) {
+		    /* 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->presets[me->npresets] = preset;
+                me->preset_names[me->npresets] = name;
+                me->npresets++;
+            }
+        }
+    }
+
     return me->npresets;
 }
 
@@ -267,3 +718,288 @@ void midend_fetch_preset(midend_data *me, int n,
     *name = me->preset_names[n];
     *params = me->presets[n];
 }
+
+int midend_wants_statusbar(midend_data *me)
+{
+    return me->ourgame->wants_statusbar();
+}
+
+void midend_supersede_game_desc(midend_data *me, char *desc)
+{
+    sfree(me->desc);
+    me->desc = dupstr(desc);
+}
+
+config_item *midend_get_config(midend_data *me, int which, char **wintitle)
+{
+    char *titlebuf, *parstr, *rest;
+    config_item *ret;
+    char sep;
+
+    assert(wintitle);
+    titlebuf = snewn(40 + strlen(me->ourgame->name), char);
+
+    switch (which) {
+      case CFG_SETTINGS:
+	sprintf(titlebuf, "%s configuration", me->ourgame->name);
+	*wintitle = titlebuf;
+	return me->ourgame->configure(me->params);
+      case CFG_SEED:
+      case CFG_DESC:
+        if (!me->curparams) {
+          sfree(titlebuf);
+          return NULL;
+        }
+        sprintf(titlebuf, "%s %s selection", me->ourgame->name,
+                which == CFG_SEED ? "random" : "game");
+        *wintitle = titlebuf;
+
+	ret = snewn(2, config_item);
+
+	ret[0].type = C_STRING;
+        if (which == CFG_SEED)
+            ret[0].name = "Game random seed";
+        else
+            ret[0].name = "Game ID";
+	ret[0].ival = 0;
+        /*
+         * For CFG_DESC the text going in here will be a string
+         * encoding of the restricted parameters, plus a colon,
+         * plus the game description. For CFG_SEED it will be the
+         * full parameters, plus a hash, plus the random seed data.
+         * Either of these is a valid full game ID (although only
+         * the former is likely to persist across many code
+         * changes).
+         */
+        parstr = me->ourgame->encode_params(me->curparams, which == CFG_SEED);
+        assert(parstr);
+        if (which == CFG_DESC) {
+            rest = me->desc ? me->desc : "";
+            sep = ':';
+        } else {
+            rest = me->seedstr ? me->seedstr : "";
+            sep = '#';
+        }
+        ret[0].sval = snewn(strlen(parstr) + strlen(rest) + 2, char);
+        sprintf(ret[0].sval, "%s%c%s", parstr, sep, rest);
+        sfree(parstr);
+
+	ret[1].type = C_END;
+	ret[1].name = ret[1].sval = NULL;
+	ret[1].ival = 0;
+
+	return ret;
+    }
+
+    assert(!"We shouldn't be here");
+    return NULL;
+}
+
+static char *midend_game_id_int(midend_data *me, char *id, int defmode)
+{
+    char *error, *par, *desc, *seed;
+
+    seed = strchr(id, '#');
+    desc = strchr(id, ':');
+
+    if (desc && (!seed || desc < seed)) {
+        /*
+         * We have a colon separating parameters from game
+         * description. So `par' now points to the parameters
+         * string, and `desc' to the description string.
+         */
+        *desc++ = '\0';
+        par = id;
+        seed = NULL;
+    } else if (seed && (!desc || seed < desc)) {
+        /*
+         * We have a hash separating parameters from random seed.
+         * So `par' now points to the parameters string, and `seed'
+         * to the seed string.
+         */
+        *seed++ = '\0';
+        par = id;
+        desc = NULL;
+    } else {
+        /*
+         * We only have one string. Depending on `defmode', we take
+         * it to be either parameters, seed or description.
+         */
+        if (defmode == DEF_SEED) {
+            seed = id;
+            par = desc = NULL;
+        } else if (defmode == DEF_DESC) {
+            desc = id;
+            par = seed = NULL;
+        } else {
+            par = id;
+            seed = desc = NULL;
+        }
+    }
+
+    if (par) {
+        game_params *tmpparams;
+        tmpparams = me->ourgame->dup_params(me->params);
+        me->ourgame->decode_params(tmpparams, par);
+        error = me->ourgame->validate_params(tmpparams);
+        if (error) {
+            me->ourgame->free_params(tmpparams);
+            return error;
+        }
+        if (me->curparams)
+            me->ourgame->free_params(me->curparams);
+        me->curparams = tmpparams;
+
+        /*
+         * Now filter only the persistent parts of this state into
+         * the long-term params structure, unless we've _only_
+         * received a params string in which case the whole lot is
+         * persistent.
+         */
+        if (seed || desc) {
+            char *tmpstr = me->ourgame->encode_params(tmpparams, FALSE);
+            me->ourgame->decode_params(me->params, tmpstr);
+            sfree(tmpstr);
+        } else {
+            me->ourgame->free_params(me->params);
+            me->params = me->ourgame->dup_params(tmpparams);
+        }
+    }
+
+    sfree(me->desc);
+    me->desc = NULL;
+    sfree(me->seedstr);
+    me->seedstr = NULL;
+
+    if (desc) {
+        error = me->ourgame->validate_desc(me->params, desc);
+        if (error)
+            return error;
+
+        me->desc = dupstr(desc);
+        me->genmode = GOT_DESC;
+	if (me->aux_info)
+	    me->ourgame->free_aux_info(me->aux_info);
+	me->aux_info = NULL;
+    }
+
+    if (seed) {
+        me->seedstr = dupstr(seed);
+        me->genmode = GOT_SEED;
+    }
+
+    return NULL;
+}
+
+char *midend_game_id(midend_data *me, char *id)
+{
+    return midend_game_id_int(me, id, DEF_PARAMS);
+}
+
+char *midend_set_config(midend_data *me, int which, config_item *cfg)
+{
+    char *error;
+    game_params *params;
+
+    switch (which) {
+      case CFG_SETTINGS:
+	params = me->ourgame->custom_params(cfg);
+	error = me->ourgame->validate_params(params);
+
+	if (error) {
+	    me->ourgame->free_params(params);
+	    return error;
+	}
+
+	me->ourgame->free_params(me->params);
+	me->params = params;
+	break;
+
+      case CFG_SEED:
+      case CFG_DESC:
+        error = midend_game_id_int(me, cfg[0].sval,
+                                   (which == CFG_SEED ? DEF_SEED : DEF_DESC));
+	if (error)
+	    return error;
+	break;
+    }
+
+    return NULL;
+}
+
+char *midend_text_format(midend_data *me)
+{
+    if (me->ourgame->can_format_as_text && me->statepos > 0)
+	return me->ourgame->text_format(me->states[me->statepos-1].state);
+    else
+	return NULL;
+}
+
+char *midend_solve(midend_data *me)
+{
+    game_state *s;
+    char *msg;
+
+    if (!me->ourgame->can_solve)
+	return "This game does not support the Solve operation";
+
+    if (me->statepos < 1)
+	return "No game set up to solve";   /* _shouldn't_ happen! */
+
+    msg = "Solve operation failed";    /* game _should_ overwrite on error */
+    s = me->ourgame->solve(me->states[0].state,
+			   me->states[me->statepos-1].state,
+			   me->aux_info, &msg);
+    if (!s)
+	return msg;
+
+    /*
+     * 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);
+    ensure(me);
+    me->states[me->nstates].state = s;
+    me->states[me->nstates].special = TRUE;   /* created using solve */
+    me->statepos = ++me->nstates;
+    if (me->ui)
+        me->ourgame->changed_state(me->ui,
+                                   me->states[me->statepos-2].state,
+                                   me->states[me->statepos-1].state);
+    me->anim_time = 0.0;
+    midend_finish_move(me);
+    midend_redraw(me);
+    midend_set_timer(me);
+    return NULL;
+}
+
+char *midend_rewrite_statusbar(midend_data *me, char *text)
+{
+    /*
+     * An important special case is that we are occasionally called
+     * with our own laststatus, to update the timer.
+     */
+    if (me->laststatus != text) {
+	sfree(me->laststatus);
+	me->laststatus = dupstr(text);
+    }
+
+    if (me->ourgame->is_timed) {
+	char timebuf[100], *ret;
+	int min, sec;
+
+	sec = me->elapsed;
+	min = sec / 60;
+	sec %= 60;
+	sprintf(timebuf, "[%d:%02d] ", min, sec);
+
+	ret = snewn(strlen(timebuf) + strlen(text) + 1, char);
+	strcpy(ret, timebuf);
+	strcat(ret, text);
+	return ret;
+
+    } else {
+	return dupstr(text);
+    }
+}