Accessibility: Show a message when monster is spotted

Adds a new boolean option, spot_monsters.  If on, every time
the hero notices a monster which was out of sight before,
a message is given.  Combine with accessiblemsg to get the
monster location:

(3north): You see a newt.

Breaks saves and bones.

src/allmain.c

@@ -705,6 +705,8 @@ newgame(void)
 {
     int i;
 
+    /* make sure welcome messages are given before noticing monsters */
+    notice_mon_off();
     disp.botlx = TRUE;
     gc.context.ident = 1;
     gc.context.warnlevel = 1;
@@ -765,6 +767,8 @@ newgame(void)
 
     /* Success! */
     welcome(TRUE);
+    notice_mon_on(); /* now we can notice monsters */
+    notice_all_mons(TRUE);
     return;
 }
 

src/do.c

@@ -1807,6 +1807,7 @@ goto_level(
     /* Reset the screen. */
     vision_reset(); /* reset the blockages */
     reset_glyphmap(gm_levelchange);
+    notice_mon_off(); /* not noticing monsters yet! */
     docrt(); /* does a full vision recalc */
     flush_screen(-1);
 
@@ -1923,6 +1924,8 @@ goto_level(
 #ifdef INSURANCE
     save_currentstate();
 #endif
+    notice_mon_on();
+    notice_all_mons(TRUE);
 
     print_level_annotation();
     /* give room entrance message, if any */

src/hack.c

@@ -12,6 +12,7 @@ static int moverock(void);
 static void dosinkfall(void);
 static boolean findtravelpath(int);
 static boolean trapmove(coordxy, coordxy, struct trap *);
+static int QSORTCALLBACK notice_mons_cmp(const genericptr, const genericptr);
 static schar u_simple_floortyp(coordxy, coordxy);
 static boolean swim_move_danger(coordxy, coordxy);
 static boolean domove_bump_mon(struct monst *, int) NONNULLARG1;
@@ -1601,6 +1602,80 @@ u_rooted(void)
     return FALSE;
 }
 
+void
+notice_mon(struct monst *mtmp)
+{
+    if (a11y.mon_notices && !a11y.mon_notices_blocked) {
+        boolean spot = canspotmon(mtmp)
+            && !(is_hider(mtmp->data)
+                 && (mtmp->mundetected
+                     || M_AP_TYPE(mtmp) == M_AP_FURNITURE
+                     || M_AP_TYPE(mtmp) == M_AP_OBJECT));
+
+        if (spot && !mtmp->mspotted && !DEADMONSTER(mtmp)) {
+            mtmp->mspotted = TRUE;
+            set_msg_xy(mtmp->mx, mtmp->my);
+            You("%s %s.", canseemon(mtmp) ? "see" : "notice",
+                x_monnam(mtmp,
+                     mtmp->mtame ? ARTICLE_YOUR
+                     : (!has_mgivenname(mtmp)
+                        && !type_is_pname(mtmp->data)) ? ARTICLE_A
+                     : ARTICLE_NONE,
+                     (mtmp->mpeaceful && !mtmp->mtame) ? "peaceful" : 0,
+                     has_mgivenname(mtmp) ? SUPPRESS_SADDLE : 0, FALSE));
+        } else if (!spot) {
+            mtmp->mspotted = FALSE;
+        }
+    }
+}
+
+static int QSORTCALLBACK
+notice_mons_cmp(const genericptr ptr1, const genericptr ptr2)
+{
+    const struct monst *m1 = *(const struct monst **) ptr1,
+        *m2 = *(const struct monst **) ptr2;
+
+    return (distu(m1->mx, m1->my) - distu(m2->mx, m2->my));
+}
+
+void
+notice_all_mons(boolean reset)
+{
+    if (a11y.mon_notices && !a11y.mon_notices_blocked) {
+        struct monst *mtmp;
+        struct monst **arr = NULL;
+        int i = 0, cnt = 0;
+
+        for (mtmp = fmon; mtmp; mtmp = mtmp->nmon)
+            if (canspotmon(mtmp))
+                cnt++;
+            else if (reset)
+                mtmp->mspotted = FALSE;
+
+        if (!cnt)
+            return;
+
+        arr = (struct monst **) alloc(cnt * sizeof(struct monst *));
+
+
+        for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
+            if (!canspotmon(mtmp))
+                mtmp->mspotted = FALSE;
+            else if (!DEADMONSTER(mtmp) && i < cnt)
+                arr[i++] = mtmp;
+        }
+
+        if (i) {
+            qsort((genericptr_t) arr, (size_t) i, sizeof *arr, notice_mons_cmp);
+
+            for (i = 0; i < cnt; i++)
+                notice_mon(arr[i]);
+        }
+
+        free(arr);
+    }
+}
+
 /* maybe disturb buried zombies when an object is dropped or thrown nearby */
 void
 impact_disturbs_zombies(struct obj *obj, boolean violent)

src/monmove.c

@@ -1307,6 +1307,8 @@ postmov(
     boolean canseeit = cansee(mtmp->mx, mtmp->my),
             didseeit = canseeit;
 
+    notice_mon(mtmp);
+
     if (mmoved == MMOVE_MOVED) {
         nix = mtmp->mx, niy = mtmp->my;
         /* sequencing issue:  when monster movement decides that a

src/teleport.c

@@ -513,6 +513,7 @@ teleds(coordxy nux, coordxy nuy, int teleds_flags)
     see_monsters();
     gv.vision_full_recalc = 1;
     nomul(0);
+    notice_mon_off();
     vision_recalc(0); /* vision before effects */
 
     /* this used to take place sooner, but if a --More-- prompt was issued
@@ -542,6 +543,8 @@ teleds(coordxy nux, coordxy nuy, int teleds_flags)
     /* possible shop entry message comes after guard's shrill whistle */
     spoteffects(TRUE);
     invocation_message();
+    notice_mon_on();
+    notice_all_mons(TRUE);
     return;
 }
 

src/vision.c

@@ -837,6 +837,8 @@ vision_recalc(int control)
     /* Set the new min and max pointers. */
     gv.viz_rmin = next_rmin;
     gv.viz_rmax = next_rmax;
+
+    notice_all_mons(TRUE);
 }
 
 /*