chiark / gitweb /
changelog: document last change
[sgt-puzzles.git] / rect.c
diff --git a/rect.c b/rect.c
index f4ce74b8a9bda23c630d6a9fa85e95ff2d5e77b8..465e1436fac50b2cfc8b125224011316f3b83178 100644 (file)
--- a/rect.c
+++ b/rect.c
@@ -36,7 +36,8 @@ enum {
     COL_LINE,
     COL_TEXT,
     COL_GRID,
-    COL_DRAG,
+    COL_DRAG, COL_DRAGERASE,
+    COL_CURSOR,
     NCOLOURS
 };
 
@@ -60,7 +61,11 @@ struct game_params {
 
 #define PREFERRED_TILE_SIZE 24
 #define TILE_SIZE (ds->tilesize)
+#ifdef SMALL_SCREEN
+#define BORDER (2)
+#else
 #define BORDER (TILE_SIZE * 3 / 4)
+#endif
 
 #define CORNER_TOLERANCE 0.15F
 #define CENTRE_TOLERANCE 0.15F
@@ -76,6 +81,7 @@ struct game_state {
     unsigned char *vedge;             /* (w+1) x h */
     unsigned char *hedge;             /* w x (h+1) */
     int completed, cheated;
+    unsigned char *correct;
 };
 
 static game_params *default_params(void)
@@ -101,8 +107,10 @@ static int game_fetch_preset(int i, char **name, game_params **params)
       case 2: w = 11, h = 11; break;
       case 3: w = 13, h = 13; break;
       case 4: w = 15, h = 15; break;
+#ifndef SMALL_SCREEN
       case 5: w = 17, h = 17; break;
       case 6: w = 19, h = 19; break;
+#endif
       default: return FALSE;
     }
 
@@ -121,7 +129,7 @@ static void free_params(game_params *params)
     sfree(params);
 }
 
-static game_params *dup_params(game_params *params)
+static game_params *dup_params(const game_params *params)
 {
     game_params *ret = snew(game_params);
     *ret = *params;                   /* structure copy */
@@ -139,7 +147,7 @@ static void decode_params(game_params *ret, char const *string)
     }
     if (*string == 'e') {
        string++;
-       ret->expandfactor = atof(string);
+       ret->expandfactor = (float)atof(string);
        while (*string &&
               (*string == '.' || isdigit((unsigned char)*string))) string++;
     }
@@ -149,7 +157,7 @@ static void decode_params(game_params *ret, char const *string)
     }
 }
 
-static char *encode_params(game_params *params, int full)
+static char *encode_params(const game_params *params, int full)
 {
     char data[256];
 
@@ -162,7 +170,7 @@ static char *encode_params(game_params *params, int full)
     return dupstr(data);
 }
 
-static config_item *game_configure(game_params *params)
+static config_item *game_configure(const game_params *params)
 {
     config_item *ret;
     char buf[80];
@@ -200,19 +208,19 @@ static config_item *game_configure(game_params *params)
     return ret;
 }
 
-static game_params *custom_params(config_item *cfg)
+static game_params *custom_params(const config_item *cfg)
 {
     game_params *ret = snew(game_params);
 
     ret->w = atoi(cfg[0].sval);
     ret->h = atoi(cfg[1].sval);
-    ret->expandfactor = atof(cfg[2].sval);
+    ret->expandfactor = (float)atof(cfg[2].sval);
     ret->unique = cfg[3].ival;
 
     return ret;
 }
 
-static char *validate_params(game_params *params)
+static char *validate_params(const game_params *params, int full)
 {
     if (params->w <= 0 || params->h <= 0)
        return "Width and height must both be greater than zero";
@@ -322,6 +330,11 @@ static void remove_number_placement(int w, int h, struct numberdata *number,
     number->npoints--;
 }
 
+/*
+ * Returns 0 for failure to solve due to inconsistency; 1 for
+ * success; 2 for failure to complete a solution due to either
+ * ambiguity or it being too difficult.
+ */
 static int rect_solver(int w, int h, int nrects, struct numberdata *numbers,
                        unsigned char *hedge, unsigned char *vedge,
                       random_state *rs)
@@ -427,6 +440,14 @@ static int rect_solver(int w, int h, int nrects, struct numberdata *numbers,
      * Indexing of this array is by the formula
      * 
      *   overlaps[(rectindex * h + y) * w + x]
+     * 
+     * A positive or zero value indicates what it sounds as if it
+     * should; -1 indicates that this square _cannot_ be part of
+     * this rectangle; and -2 indicates that it _definitely_ is
+     * (which is distinct from 1, because one might very well know
+     * that _if_ square S is part of rectangle R then it must be
+     * because R is placed in a certain position without knowing
+     * that it definitely _is_).
      */
     overlaps = snewn(nrects * w * h, int);
     memset(overlaps, 0, nrects * w * h * sizeof(int));
@@ -519,7 +540,10 @@ static int rect_solver(int w, int h, int nrects, struct numberdata *numbers,
                 if (overlaps[(i * h + y) * w + x] >= -1) {
                     int j;
 
-                    assert(overlaps[(i * h + y) * w + x] > 0);
+                    if (overlaps[(i * h + y) * w + x] <= 0) {
+                        ret = 0;       /* inconsistency */
+                        goto cleanup;
+                    }
 #ifdef SOLVER_DIAGNOSTICS
                     printf("marking %d,%d as known for rect %d"
                            " (sole remaining number position)\n", x, y, i);
@@ -561,7 +585,10 @@ static int rect_solver(int w, int h, int nrects, struct numberdata *numbers,
             for (yy = miny; yy < maxy; yy++)
                 for (xx = minx; xx < maxx; xx++)
                     if (overlaps[(i * h + yy) * w + xx] >= -1) {
-                        assert(overlaps[(i * h + yy) * w + xx] > 0);
+                        if (overlaps[(i * h + yy) * w + xx] <= 0) {
+                            ret = 0;   /* inconsistency */
+                            goto cleanup;
+                        }
 #ifdef SOLVER_DIAGNOSTICS
                         printf("marking %d,%d as known for rect %d"
                                " (intersection of all placements)\n",
@@ -840,15 +867,17 @@ static int rect_solver(int w, int h, int nrects, struct numberdata *numbers,
         }
     }
 
-    ret = TRUE;
+    cleanup:
+    ret = 1;
     for (i = 0; i < nrects; i++) {
 #ifdef SOLVER_DIAGNOSTICS
         printf("rect %d has %d possible placements\n",
                i, rectpositions[i].n);
 #endif
-        assert(rectpositions[i].n > 0);
-        if (rectpositions[i].n > 1) {
-            ret = FALSE;
+        if (rectpositions[i].n <= 0) {
+            ret = 0;                   /* inconsistency */
+        } else if (rectpositions[i].n > 1) {
+            ret = 2;                   /* remaining uncertainty */
         } else if (hedge && vedge) {
             /*
              * Place the rectangle in its only possible position.
@@ -1117,9 +1146,11 @@ static void display_grid(game_params *params, int *grid, int *numbers, int all)
 }
 #endif
 
-static char *new_game_desc(game_params *params, random_state *rs,
+static char *new_game_desc(const game_params *params_in, random_state *rs,
                           char **aux, int interactive)
 {
+    game_params params_copy = *params_in; /* structure copy */
+    game_params *params = &params_copy;
     int *grid, *numbers = NULL;
     int x, y, y2, y2last, yx, run, i, nsquares;
     char *desc, *p;
@@ -1131,9 +1162,9 @@ static char *new_game_desc(game_params *params, random_state *rs,
          * Set up the smaller width and height which we will use to
          * generate the base grid.
          */
-        params2->w = params->w / (1.0F + params->expandfactor);
+        params2->w = (int)((float)params->w / (1.0F + params->expandfactor));
         if (params2->w < 2 && params->w >= 2) params2->w = 2;
-        params2->h = params->h / (1.0F + params->expandfactor);
+        params2->h = (int)((float)params->h / (1.0F + params->expandfactor));
         if (params2->h < 2 && params->h >= 2) params2->h = 2;
 
         grid = snewn(params2->w * params2->h, int);
@@ -1286,7 +1317,8 @@ static char *new_game_desc(game_params *params, random_state *rs,
                     if (ndirs > 0) {
                         int which, dir;
                         struct rect r1, r2;
-
+                        memset(&r1, 0, sizeof(struct rect));
+                        memset(&r2, 0, sizeof(struct rect));
                         which = random_upto(rs, ndirs);
                         dir = dirs[which];
 
@@ -1347,6 +1379,8 @@ static char *new_game_desc(game_params *params, random_state *rs,
                                 r1.x++;
                             r1.w--;
                             break;
+                          default:     /* should never happen */
+                            assert(!"invalid direction");
                         }
                         if (r1.h > 0 && r1.w > 0)
                             place_rect(params2, grid, r1);
@@ -1630,9 +1664,9 @@ static char *new_game_desc(game_params *params, random_state *rs,
                ret = rect_solver(params->w, params->h, nnumbers, nd,
                                  NULL, NULL, rs);
            else
-               ret = TRUE;            /* allow any number placement at all */
+               ret = 1;               /* allow any number placement at all */
 
-            if (ret) {
+            if (ret == 1) {
                 /*
                  * Now place the numbers according to the solver's
                  * recommendations.
@@ -1662,7 +1696,7 @@ static char *new_game_desc(game_params *params, random_state *rs,
             /*
              * If we've succeeded, then terminate the loop.
              */
-            if (ret)
+            if (ret == 1)
                 break;
         }
 
@@ -1745,7 +1779,7 @@ static char *new_game_desc(game_params *params, random_state *rs,
     return desc;
 }
 
-static char *validate_desc(game_params *params, char *desc)
+static char *validate_desc(const game_params *params, const char *desc)
 {
     int area = params->w * params->h;
     int squares = 0;
@@ -1773,7 +1807,101 @@ static char *validate_desc(game_params *params, char *desc)
     return NULL;
 }
 
-static game_state *new_game(midend_data *me, game_params *params, char *desc)
+static unsigned char *get_correct(game_state *state)
+{
+    unsigned char *ret;
+    int x, y;
+
+    ret = snewn(state->w * state->h, unsigned char);
+    memset(ret, 0xFF, state->w * state->h);
+
+    for (x = 0; x < state->w; x++)
+       for (y = 0; y < state->h; y++)
+           if (index(state,ret,x,y) == 0xFF) {
+               int rw, rh;
+               int xx, yy;
+               int num, area, valid;
+
+               /*
+                * Find a rectangle starting at this point.
+                */
+               rw = 1;
+               while (x+rw < state->w && !vedge(state,x+rw,y))
+                   rw++;
+               rh = 1;
+               while (y+rh < state->h && !hedge(state,x,y+rh))
+                   rh++;
+
+               /*
+                * We know what the dimensions of the rectangle
+                * should be if it's there at all. Find out if we
+                * really have a valid rectangle.
+                */
+               valid = TRUE;
+               /* Check the horizontal edges. */
+               for (xx = x; xx < x+rw; xx++) {
+                   for (yy = y; yy <= y+rh; yy++) {
+                       int e = !HRANGE(state,xx,yy) || hedge(state,xx,yy);
+                       int ec = (yy == y || yy == y+rh);
+                       if (e != ec)
+                           valid = FALSE;
+                   }
+               }
+               /* Check the vertical edges. */
+               for (yy = y; yy < y+rh; yy++) {
+                   for (xx = x; xx <= x+rw; xx++) {
+                       int e = !VRANGE(state,xx,yy) || vedge(state,xx,yy);
+                       int ec = (xx == x || xx == x+rw);
+                       if (e != ec)
+                           valid = FALSE;
+                   }
+               }
+
+               /*
+                * If this is not a valid rectangle with no other
+                * edges inside it, we just mark this square as not
+                * complete and proceed to the next square.
+                */
+               if (!valid) {
+                   index(state, ret, x, y) = 0;
+                   continue;
+               }
+
+               /*
+                * We have a rectangle. Now see what its area is,
+                * and how many numbers are in it.
+                */
+               num = 0;
+               area = 0;
+               for (xx = x; xx < x+rw; xx++) {
+                   for (yy = y; yy < y+rh; yy++) {
+                       area++;
+                       if (grid(state,xx,yy)) {
+                           if (num > 0)
+                               valid = FALSE;   /* two numbers */
+                           num = grid(state,xx,yy);
+                       }
+                   }
+               }
+               if (num != area)
+                   valid = FALSE;
+
+               /*
+                * Now fill in the whole rectangle based on the
+                * value of `valid'.
+                */
+               for (xx = x; xx < x+rw; xx++) {
+                   for (yy = y; yy < y+rh; yy++) {
+                       index(state, ret, xx, yy) = valid;
+                   }
+               }
+           }
+
+    return ret;
+}
+
+static game_state *new_game(midend *me, const game_params *params,
+                            const char *desc)
 {
     game_state *state = snew(game_state);
     int x, y, i, area;
@@ -1813,10 +1941,12 @@ static game_state *new_game(midend_data *me, game_params *params, char *desc)
        for (x = 0; x < state->w; x++)
            vedge(state,x,y) = hedge(state,x,y) = 0;
 
+    state->correct = get_correct(state);
+
     return state;
 }
 
-static game_state *dup_game(game_state *state)
+static game_state *dup_game(const game_state *state)
 {
     game_state *ret = snew(game_state);
 
@@ -1826,6 +1956,7 @@ static game_state *dup_game(game_state *state)
     ret->vedge = snewn(state->w * state->h, unsigned char);
     ret->hedge = snewn(state->w * state->h, unsigned char);
     ret->grid = snewn(state->w * state->h, int);
+    ret->correct = snewn(ret->w * ret->h, unsigned char);
 
     ret->completed = state->completed;
     ret->cheated = state->cheated;
@@ -1834,6 +1965,8 @@ static game_state *dup_game(game_state *state)
     memcpy(ret->vedge, state->vedge, state->w*state->h*sizeof(unsigned char));
     memcpy(ret->hedge, state->hedge, state->w*state->h*sizeof(unsigned char));
 
+    memcpy(ret->correct, state->correct, state->w*state->h*sizeof(unsigned char));
+
     return ret;
 }
 
@@ -1842,11 +1975,12 @@ static void free_game(game_state *state)
     sfree(state->grid);
     sfree(state->vedge);
     sfree(state->hedge);
+    sfree(state->correct);
     sfree(state);
 }
 
-static char *solve_game(game_state *state, game_state *currstate,
-                       char *ai, char **error)
+static char *solve_game(const game_state *state, const game_state *currstate,
+                        const char *ai, char **error)
 {
     unsigned char *vedge, *hedge;
     int x, y, len;
@@ -1914,7 +2048,12 @@ static char *solve_game(game_state *state, game_state *currstate,
     return ret;
 }
 
-static char *game_text_format(game_state *state)
+static int game_can_format_as_text_now(const game_params *params)
+{
+    return TRUE;
+}
+
+static char *game_text_format(const game_state *state)
 {
     char *ret, *p, buf[80];
     int i, x, y, col, maxlen;
@@ -2007,99 +2146,6 @@ static char *game_text_format(game_state *state)
     return ret;
 }
 
-static unsigned char *get_correct(game_state *state)
-{
-    unsigned char *ret;
-    int x, y;
-
-    ret = snewn(state->w * state->h, unsigned char);
-    memset(ret, 0xFF, state->w * state->h);
-
-    for (x = 0; x < state->w; x++)
-       for (y = 0; y < state->h; y++)
-           if (index(state,ret,x,y) == 0xFF) {
-               int rw, rh;
-               int xx, yy;
-               int num, area, valid;
-
-               /*
-                * Find a rectangle starting at this point.
-                */
-               rw = 1;
-               while (x+rw < state->w && !vedge(state,x+rw,y))
-                   rw++;
-               rh = 1;
-               while (y+rh < state->h && !hedge(state,x,y+rh))
-                   rh++;
-
-               /*
-                * We know what the dimensions of the rectangle
-                * should be if it's there at all. Find out if we
-                * really have a valid rectangle.
-                */
-               valid = TRUE;
-               /* Check the horizontal edges. */
-               for (xx = x; xx < x+rw; xx++) {
-                   for (yy = y; yy <= y+rh; yy++) {
-                       int e = !HRANGE(state,xx,yy) || hedge(state,xx,yy);
-                       int ec = (yy == y || yy == y+rh);
-                       if (e != ec)
-                           valid = FALSE;
-                   }
-               }
-               /* Check the vertical edges. */
-               for (yy = y; yy < y+rh; yy++) {
-                   for (xx = x; xx <= x+rw; xx++) {
-                       int e = !VRANGE(state,xx,yy) || vedge(state,xx,yy);
-                       int ec = (xx == x || xx == x+rw);
-                       if (e != ec)
-                           valid = FALSE;
-                   }
-               }
-
-               /*
-                * If this is not a valid rectangle with no other
-                * edges inside it, we just mark this square as not
-                * complete and proceed to the next square.
-                */
-               if (!valid) {
-                   index(state, ret, x, y) = 0;
-                   continue;
-               }
-
-               /*
-                * We have a rectangle. Now see what its area is,
-                * and how many numbers are in it.
-                */
-               num = 0;
-               area = 0;
-               for (xx = x; xx < x+rw; xx++) {
-                   for (yy = y; yy < y+rh; yy++) {
-                       area++;
-                       if (grid(state,xx,yy)) {
-                           if (num > 0)
-                               valid = FALSE;   /* two numbers */
-                           num = grid(state,xx,yy);
-                       }
-                   }
-               }
-               if (num != area)
-                   valid = FALSE;
-
-               /*
-                * Now fill in the whole rectangle based on the
-                * value of `valid'.
-                */
-               for (xx = x; xx < x+rw; xx++) {
-                   for (yy = y; yy < y+rh; yy++) {
-                       index(state, ret, xx, yy) = valid;
-                   }
-               }
-           }
-
-    return ret;
-}
-
 struct game_ui {
     /*
      * These coordinates are 2 times the obvious grid coordinates.
@@ -2122,6 +2168,11 @@ struct game_ui {
      * treated as a small drag rather than a click.
      */
     int dragged;
+    /* This flag is set if we're doing an erase operation (i.e.
+     * removing edges in the centre of the rectangle without altering
+     * the outlines).
+     */
+    int erasing;
     /*
      * These are the co-ordinates of the top-left and bottom-right squares
      * in the drag box, respectively, or -1 otherwise.
@@ -2130,20 +2181,32 @@ struct game_ui {
     int y1;
     int x2;
     int y2;
+    /*
+     * These are the coordinates of a cursor, whether it's visible, and
+     * whether it was used to start a drag.
+     */
+    int cur_x, cur_y, cur_visible, cur_dragging;
 };
 
-static game_ui *new_ui(game_state *state)
+static void reset_ui(game_ui *ui)
 {
-    game_ui *ui = snew(game_ui);
     ui->drag_start_x = -1;
     ui->drag_start_y = -1;
     ui->drag_end_x = -1;
     ui->drag_end_y = -1;
-    ui->dragged = FALSE;
     ui->x1 = -1;
     ui->y1 = -1;
     ui->x2 = -1;
     ui->y2 = -1;
+    ui->dragged = FALSE;
+}
+
+static game_ui *new_ui(const game_state *state)
+{
+    game_ui *ui = snew(game_ui);
+    reset_ui(ui);
+    ui->erasing = FALSE;
+    ui->cur_x = ui->cur_y = ui->cur_visible = ui->cur_dragging = 0;
     return ui;
 }
 
@@ -2152,12 +2215,12 @@ static void free_ui(game_ui *ui)
     sfree(ui);
 }
 
-char *encode_ui(game_ui *ui)
+static char *encode_ui(const game_ui *ui)
 {
     return NULL;
 }
 
-void decode_ui(game_ui *ui, char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding)
 {
 }
 
@@ -2248,9 +2311,9 @@ static void coord_round(float x, float y, int *xr, int *yr)
 /*
  * Returns TRUE if it has made any change to the grid.
  */
-static int grid_draw_rect(game_state *state,
+static int grid_draw_rect(const game_state *state,
                          unsigned char *hedge, unsigned char *vedge,
-                         int c, int really,
+                         int c, int really, int outline,
                          int x1, int y1, int x2, int y2)
 {
     int x, y;
@@ -2263,9 +2326,10 @@ static int grid_draw_rect(game_state *state,
         for (y = y1; y <= y2; y++)
             if (HRANGE(state,x,y)) {
                 int val = index(state,hedge,x,y);
-                if (y == y1 || y == y2)
+                if (y == y1 || y == y2) {
+                    if (!outline) continue;
                     val = c;
-                else if (c == 1)
+                else if (c == 1)
                     val = 0;
                changed = changed || (index(state,hedge,x,y) != val);
                if (really)
@@ -2279,9 +2343,10 @@ static int grid_draw_rect(game_state *state,
         for (x = x1; x <= x2; x++)
             if (VRANGE(state,x,y)) {
                 int val = index(state,vedge,x,y);
-                if (x == x1 || x == x2)
+                if (x == x1 || x == x2) {
+                    if (!outline) continue;
                     val = c;
-                else if (c == 1)
+                else if (c == 1)
                     val = 0;
                changed = changed || (index(state,vedge,x,y) != val);
                 if (really)
@@ -2291,16 +2356,16 @@ static int grid_draw_rect(game_state *state,
     return changed;
 }
 
-static int ui_draw_rect(game_state *state, game_ui *ui,
+static int ui_draw_rect(const game_state *state, const game_ui *ui,
                        unsigned char *hedge, unsigned char *vedge, int c,
-                       int really)
+                       int really, int outline)
 {
-    return grid_draw_rect(state, hedge, vedge, c, really,
+    return grid_draw_rect(state, hedge, vedge, c, really, outline,
                          ui->x1, ui->y1, ui->x2, ui->y2);
 }
 
-static void game_changed_state(game_ui *ui, game_state *oldstate,
-                               game_state *newstate)
+static void game_changed_state(game_ui *ui, const game_state *oldstate,
+                               const game_state *newstate)
 {
 }
 
@@ -2310,40 +2375,98 @@ struct game_drawstate {
     unsigned long *visible;
 };
 
-static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
-                           int x, int y, int button)
+static char *interpret_move(const game_state *from, game_ui *ui,
+                            const game_drawstate *ds,
+                            int x, int y, int button)
 {
     int xc, yc;
-    int startdrag = FALSE, enddrag = FALSE, active = FALSE;
+    int startdrag = FALSE, enddrag = FALSE, active = FALSE, erasing = FALSE;
     char buf[80], *ret;
 
     button &= ~MOD_MASK;
 
-    if (button == LEFT_BUTTON) {
+    coord_round(FROMCOORD((float)x), FROMCOORD((float)y), &xc, &yc);
+
+    if (button == LEFT_BUTTON || button == RIGHT_BUTTON) {
+        if (ui->drag_start_x >= 0 && ui->cur_dragging)
+            reset_ui(ui); /* cancel keyboard dragging */
         startdrag = TRUE;
-    } else if (button == LEFT_RELEASE) {
+        ui->cur_visible = ui->cur_dragging = FALSE;
+        active = TRUE;
+        erasing = (button == RIGHT_BUTTON);
+    } else if (button == LEFT_RELEASE || button == RIGHT_RELEASE) {
+        /* We assert we should have had a LEFT_BUTTON first. */
+        if (ui->cur_visible) {
+            ui->cur_visible = FALSE;
+            active = TRUE;
+        }
+        assert(!ui->cur_dragging);
         enddrag = TRUE;
-    } else if (button != LEFT_DRAG) {
+        erasing = (button == RIGHT_RELEASE);
+    } else if (IS_CURSOR_MOVE(button)) {
+        move_cursor(button, &ui->cur_x, &ui->cur_y, from->w, from->h, 0);
+        ui->cur_visible = TRUE;
+        active = TRUE;
+        if (!ui->cur_dragging) return "";
+        coord_round((float)ui->cur_x + 0.5F, (float)ui->cur_y + 0.5F, &xc, &yc);
+    } else if (IS_CURSOR_SELECT(button)) {
+        if (ui->drag_start_x >= 0 && !ui->cur_dragging) {
+            /*
+             * If a mouse drag is in progress, ignore attempts to
+             * start a keyboard one.
+             */
+            return NULL;
+        }
+        if (!ui->cur_visible) {
+            assert(!ui->cur_dragging);
+            ui->cur_visible = TRUE;
+            return "";
+        }
+        coord_round((float)ui->cur_x + 0.5F, (float)ui->cur_y + 0.5F, &xc, &yc);
+        erasing = (button == CURSOR_SELECT2);
+        if (ui->cur_dragging) {
+            ui->cur_dragging = FALSE;
+            enddrag = TRUE;
+            active = TRUE;
+        } else {
+            ui->cur_dragging = TRUE;
+            startdrag = TRUE;
+            active = TRUE;
+        }
+    } else if (button == '\b' || button == 27) {
+        if (!ui->cur_dragging) {
+            ui->cur_visible = FALSE;
+        } else {
+            assert(ui->cur_visible);
+            reset_ui(ui); /* cancel keyboard dragging */
+            ui->cur_dragging = FALSE;
+        }
+        return "";
+    } else if (button != LEFT_DRAG && button != RIGHT_DRAG) {
         return NULL;
     }
 
-    coord_round(FROMCOORD((float)x), FROMCOORD((float)y), &xc, &yc);
+    if (startdrag &&
+       xc >= 0 && xc <= 2*from->w &&
+       yc >= 0 && yc <= 2*from->h) {
 
-    if (startdrag) {
         ui->drag_start_x = xc;
         ui->drag_start_y = yc;
-        ui->drag_end_x = xc;
-        ui->drag_end_y = yc;
+        ui->drag_end_x = -1;
+        ui->drag_end_y = -1;
         ui->dragged = FALSE;
+        ui->erasing = erasing;
         active = TRUE;
     }
 
-    if (xc != ui->drag_end_x || yc != ui->drag_end_y) {
+    if (ui->drag_start_x >= 0 &&
+       (xc != ui->drag_end_x || yc != ui->drag_end_y)) {
        int t;
 
+       if (ui->drag_end_x != -1 && ui->drag_end_y != -1)
+           ui->dragged = TRUE;
         ui->drag_end_x = xc;
         ui->drag_end_y = yc;
-        ui->dragged = TRUE;
         active = TRUE;
 
        if (xc >= 0 && xc <= 2*from->w &&
@@ -2370,14 +2493,16 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
 
     ret = NULL;
 
-    if (enddrag) {
+    if (enddrag && (ui->drag_start_x >= 0)) {
        if (xc >= 0 && xc <= 2*from->w &&
-           yc >= 0 && yc <= 2*from->h) {
+           yc >= 0 && yc <= 2*from->h &&
+            erasing == ui->erasing) {
 
            if (ui->dragged) {
                if (ui_draw_rect(from, ui, from->hedge,
-                                from->vedge, 1, FALSE)) {
-                   sprintf(buf, "R%d,%d,%d,%d",
+                                from->vedge, 1, FALSE, !ui->erasing)) {
+                   sprintf(buf, "%c%d,%d,%d,%d",
+                           (int)(ui->erasing ? 'E' : 'R'),
                            ui->x1, ui->y1, ui->x2 - ui->x1, ui->y2 - ui->y1);
                    ret = dupstr(buf);
                }
@@ -2393,15 +2518,7 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
            }
        }
 
-       ui->drag_start_x = -1;
-       ui->drag_start_y = -1;
-       ui->drag_end_x = -1;
-       ui->drag_end_y = -1;
-       ui->x1 = -1;
-       ui->y1 = -1;
-       ui->x2 = -1;
-       ui->y2 = -1;
-       ui->dragged = FALSE;
+        reset_ui(ui);
        active = TRUE;
     }
 
@@ -2413,13 +2530,13 @@ static char *interpret_move(game_state *from, game_ui *ui, game_drawstate *ds,
        return NULL;
 }
 
-static game_state *execute_move(game_state *from, char *move)
+static game_state *execute_move(const game_state *from, const char *move)
 {
     game_state *ret;
     int x1, y1, x2, y2, mode;
 
     if (move[0] == 'S') {
-       char *p = move+1;
+       const char *p = move+1;
        int x, y;
 
        ret = dup_game(from);
@@ -2436,9 +2553,12 @@ static game_state *execute_move(game_state *from, char *move)
                if (*p) p++;
            }
 
+       sfree(ret->correct);
+       ret->correct = get_correct(ret);
+
        return ret;
 
-    } else if (move[0] == 'R' &&
+    } else if ((move[0] == 'R' || move[0] == 'E') &&
        sscanf(move+1, "%d,%d,%d,%d", &x1, &y1, &x2, &y2) == 4 &&
        x1 >= 0 && x2 >= 0 && x1+x2 <= from->w &&
        y1 >= 0 && y2 >= 0 && y1+y2 <= from->h) {
@@ -2455,30 +2575,31 @@ static game_state *execute_move(game_state *from, char *move)
 
     ret = dup_game(from);
 
-    if (mode == 'R') {
-       grid_draw_rect(ret, ret->hedge, ret->vedge, 1, TRUE, x1, y1, x2, y2);
+    if (mode == 'R' || mode == 'E') {
+       grid_draw_rect(ret, ret->hedge, ret->vedge, 1, TRUE,
+                       mode == 'R', x1, y1, x2, y2);
     } else if (mode == 'H') {
        hedge(ret,x1,y1) = !hedge(ret,x1,y1);
     } else if (mode == 'V') {
        vedge(ret,x1,y1) = !vedge(ret,x1,y1);
     }
 
+    sfree(ret->correct);
+    ret->correct = get_correct(ret);
+
     /*
      * We've made a real change to the grid. Check to see
      * if the game has been completed.
      */
     if (!ret->completed) {
        int x, y, ok;
-       unsigned char *correct = get_correct(ret);
 
        ok = TRUE;
        for (x = 0; x < ret->w; x++)
            for (y = 0; y < ret->h; y++)
-               if (!index(ret, correct, x, y))
+               if (!index(ret, ret->correct, x, y))
                    ok = FALSE;
 
-       sfree(correct);
-
        if (ok)
            ret->completed = TRUE;
     }
@@ -2491,35 +2612,29 @@ static game_state *execute_move(game_state *from, char *move)
  */
 
 #define CORRECT (1L<<16)
+#define CURSOR  (1L<<17)
 
-#define COLOUR(k) ( (k)==1 ? COL_LINE : COL_DRAG )
+#define COLOUR(k) ( (k)==1 ? COL_LINE : (k)==2 ? COL_DRAG : COL_DRAGERASE )
 #define MAX4(x,y,z,w) ( max(max(x,y),max(z,w)) )
 
-static void game_size(game_params *params, game_drawstate *ds,
-                      int *x, int *y, int expand)
+static void game_compute_size(const game_params *params, int tilesize,
+                              int *x, int *y)
 {
-    int tsx, tsy, ts;
-    /*
-     * Each window dimension equals the tile size times 1.5 more
-     * than the grid dimension (the border is 3/4 the width of the
-     * tiles).
-     * 
-     * We must cast to unsigned before multiplying by two, because
-     * *x might be INT_MAX.
-     */
-    tsx = 2 * (unsigned)*x / (2 * params->w + 3);
-    tsy = 2 * (unsigned)*y / (2 * params->h + 3);
-    ts = min(tsx, tsy);
-    if (expand)
-        ds->tilesize = ts;
-    else
-        ds->tilesize = min(ts, PREFERRED_TILE_SIZE);
+    /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+    struct { int tilesize; } ads, *ds = &ads;
+    ads.tilesize = tilesize;
 
     *x = params->w * TILE_SIZE + 2*BORDER + 1;
     *y = params->h * TILE_SIZE + 2*BORDER + 1;
 }
 
-static float *game_colours(frontend *fe, game_state *state, int *ncolours)
+static void game_set_size(drawing *dr, game_drawstate *ds,
+                          const game_params *params, int tilesize)
+{
+    ds->tilesize = tilesize;
+}
+
+static float *game_colours(frontend *fe, int *ncolours)
 {
     float *ret = snewn(3 * NCOLOURS, float);
 
@@ -2533,6 +2648,10 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_DRAG * 3 + 1] = 0.0F;
     ret[COL_DRAG * 3 + 2] = 0.0F;
 
+    ret[COL_DRAGERASE * 3 + 0] = 0.2F;
+    ret[COL_DRAGERASE * 3 + 1] = 0.2F;
+    ret[COL_DRAGERASE * 3 + 2] = 1.0F;
+
     ret[COL_CORRECT * 3 + 0] = 0.75F * ret[COL_BACKGROUND * 3 + 0];
     ret[COL_CORRECT * 3 + 1] = 0.75F * ret[COL_BACKGROUND * 3 + 1];
     ret[COL_CORRECT * 3 + 2] = 0.75F * ret[COL_BACKGROUND * 3 + 2];
@@ -2545,11 +2664,15 @@ static float *game_colours(frontend *fe, game_state *state, int *ncolours)
     ret[COL_TEXT * 3 + 1] = 0.0F;
     ret[COL_TEXT * 3 + 2] = 0.0F;
 
+    ret[COL_CURSOR * 3 + 0] = 1.0F;
+    ret[COL_CURSOR * 3 + 1] = 0.5F;
+    ret[COL_CURSOR * 3 + 2] = 0.5F;
+
     *ncolours = NCOLOURS;
     return ret;
 }
 
-static game_drawstate *game_new_drawstate(game_state *state)
+static game_drawstate *game_new_drawstate(drawing *dr, const game_state *state)
 {
     struct game_drawstate *ds = snew(struct game_drawstate);
     int i;
@@ -2565,26 +2688,27 @@ static game_drawstate *game_new_drawstate(game_state *state)
     return ds;
 }
 
-static void game_free_drawstate(game_drawstate *ds)
+static void game_free_drawstate(drawing *dr, game_drawstate *ds)
 {
     sfree(ds->visible);
     sfree(ds);
 }
 
-static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
+static void draw_tile(drawing *dr, game_drawstate *ds, const game_state *state,
                       int x, int y, unsigned char *hedge, unsigned char *vedge,
-                      unsigned char *corners, int correct)
+                      unsigned char *corners, unsigned long bgflags)
 {
     int cx = COORD(x), cy = COORD(y);
     char str[80];
 
-    draw_rect(fe, cx, cy, TILE_SIZE+1, TILE_SIZE+1, COL_GRID);
-    draw_rect(fe, cx+1, cy+1, TILE_SIZE-1, TILE_SIZE-1,
-             correct ? COL_CORRECT : COL_BACKGROUND);
+    draw_rect(dr, cx, cy, TILE_SIZE+1, TILE_SIZE+1, COL_GRID);
+    draw_rect(dr, cx+1, cy+1, TILE_SIZE-1, TILE_SIZE-1,
+             (bgflags & CURSOR) ? COL_CURSOR :
+              (bgflags & CORRECT) ? COL_CORRECT : COL_BACKGROUND);
 
     if (grid(state,x,y)) {
        sprintf(str, "%d", grid(state,x,y));
-       draw_text(fe, cx+TILE_SIZE/2, cy+TILE_SIZE/2, FONT_VARIABLE,
+       draw_text(dr, cx+TILE_SIZE/2, cy+TILE_SIZE/2, FONT_VARIABLE,
                  TILE_SIZE/2, ALIGN_HCENTRE | ALIGN_VCENTRE, COL_TEXT, str);
     }
 
@@ -2592,19 +2716,19 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
      * Draw edges.
      */
     if (!HRANGE(state,x,y) || index(state,hedge,x,y))
-       draw_rect(fe, cx, cy, TILE_SIZE+1, 2,
+       draw_rect(dr, cx, cy, TILE_SIZE+1, 2,
                   HRANGE(state,x,y) ? COLOUR(index(state,hedge,x,y)) :
                   COL_LINE);
     if (!HRANGE(state,x,y+1) || index(state,hedge,x,y+1))
-       draw_rect(fe, cx, cy+TILE_SIZE-1, TILE_SIZE+1, 2,
+       draw_rect(dr, cx, cy+TILE_SIZE-1, TILE_SIZE+1, 2,
                   HRANGE(state,x,y+1) ? COLOUR(index(state,hedge,x,y+1)) :
                   COL_LINE);
     if (!VRANGE(state,x,y) || index(state,vedge,x,y))
-       draw_rect(fe, cx, cy, 2, TILE_SIZE+1,
+       draw_rect(dr, cx, cy, 2, TILE_SIZE+1,
                   VRANGE(state,x,y) ? COLOUR(index(state,vedge,x,y)) :
                   COL_LINE);
     if (!VRANGE(state,x+1,y) || index(state,vedge,x+1,y))
-       draw_rect(fe, cx+TILE_SIZE-1, cy, 2, TILE_SIZE+1,
+       draw_rect(dr, cx+TILE_SIZE-1, cy, 2, TILE_SIZE+1,
                   VRANGE(state,x+1,y) ? COLOUR(index(state,vedge,x+1,y)) :
                   COL_LINE);
 
@@ -2612,37 +2736,35 @@ static void draw_tile(frontend *fe, game_drawstate *ds, game_state *state,
      * Draw corners.
      */
     if (index(state,corners,x,y))
-       draw_rect(fe, cx, cy, 2, 2,
+       draw_rect(dr, cx, cy, 2, 2,
                   COLOUR(index(state,corners,x,y)));
     if (x+1 < state->w && index(state,corners,x+1,y))
-       draw_rect(fe, cx+TILE_SIZE-1, cy, 2, 2,
+       draw_rect(dr, cx+TILE_SIZE-1, cy, 2, 2,
                   COLOUR(index(state,corners,x+1,y)));
     if (y+1 < state->h && index(state,corners,x,y+1))
-       draw_rect(fe, cx, cy+TILE_SIZE-1, 2, 2,
+       draw_rect(dr, cx, cy+TILE_SIZE-1, 2, 2,
                   COLOUR(index(state,corners,x,y+1)));
     if (x+1 < state->w && y+1 < state->h && index(state,corners,x+1,y+1))
-       draw_rect(fe, cx+TILE_SIZE-1, cy+TILE_SIZE-1, 2, 2,
+       draw_rect(dr, cx+TILE_SIZE-1, cy+TILE_SIZE-1, 2, 2,
                   COLOUR(index(state,corners,x+1,y+1)));
 
-    draw_update(fe, cx, cy, TILE_SIZE+1, TILE_SIZE+1);
+    draw_update(dr, cx, cy, TILE_SIZE+1, TILE_SIZE+1);
 }
 
-static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
-                 game_state *state, int dir, game_ui *ui,
-                 float animtime, float flashtime)
+static void game_redraw(drawing *dr, game_drawstate *ds,
+                        const game_state *oldstate, const game_state *state,
+                        int dir, const game_ui *ui,
+                        float animtime, float flashtime)
 {
     int x, y;
-    unsigned char *correct;
     unsigned char *hedge, *vedge, *corners;
 
-    correct = get_correct(state);
-
     if (ui->dragged) {
         hedge = snewn(state->w*state->h, unsigned char);
         vedge = snewn(state->w*state->h, unsigned char);
         memcpy(hedge, state->hedge, state->w*state->h);
         memcpy(vedge, state->vedge, state->w*state->h);
-        ui_draw_rect(state, ui, hedge, vedge, 2, TRUE);
+        ui_draw_rect(state, ui, hedge, vedge, ui->erasing ? 3 : 2, TRUE, TRUE);
     } else {
         hedge = state->hedge;
         vedge = state->vedge;
@@ -2671,13 +2793,13 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
        }
 
     if (!ds->started) {
-       draw_rect(fe, 0, 0,
+       draw_rect(dr, 0, 0,
                  state->w * TILE_SIZE + 2*BORDER + 1,
                  state->h * TILE_SIZE + 2*BORDER + 1, COL_BACKGROUND);
-       draw_rect(fe, COORD(0)-1, COORD(0)-1,
+       draw_rect(dr, COORD(0)-1, COORD(0)-1,
                  ds->w*TILE_SIZE+3, ds->h*TILE_SIZE+3, COL_LINE);
        ds->started = TRUE;
-       draw_update(fe, 0, 0,
+       draw_update(dr, 0, 0,
                    state->w * TILE_SIZE + 2*BORDER + 1,
                    state->h * TILE_SIZE + 2*BORDER + 1);
     }
@@ -2702,12 +2824,14 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
            if (x+1 < state->w && y+1 < state->h)
                /* cast to prevent 2<<14 sign-extending on promotion to long */
                c |= (unsigned long)index(state,corners,x+1,y+1) << 14;
-           if (index(state, correct, x, y) && !flashtime)
+           if (index(state, state->correct, x, y) && !flashtime)
                c |= CORRECT;
+            if (ui->cur_visible && ui->cur_x == x && ui->cur_y == y)
+                c |= CURSOR;
 
            if (index(ds,ds->visible,x,y) != c) {
-               draw_tile(fe, ds, state, x, y, hedge, vedge, corners,
-                          (c & CORRECT) ? 1 : 0);
+               draw_tile(dr, ds, state, x, y, hedge, vedge, corners,
+                          (c & (CORRECT|CURSOR)) );
                index(ds,ds->visible,x,y) = c;
            }
        }
@@ -2715,7 +2839,8 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
     {
        char buf[256];
 
-       if (ui->x1 >= 0 && ui->y1 >= 0 &&
+       if (ui->dragged &&
+           ui->x1 >= 0 && ui->y1 >= 0 &&
            ui->x2 >= 0 && ui->y2 >= 0) {
            sprintf(buf, "%dx%d ",
                    ui->x2-ui->x1,
@@ -2729,7 +2854,7 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
         else if (state->completed)
             strcat(buf, "COMPLETED!");
 
-        status_bar(fe, buf);
+        status_bar(dr, buf);
     }
 
     if (hedge != state->hedge) {
@@ -2738,17 +2863,16 @@ static void game_redraw(frontend *fe, game_drawstate *ds, game_state *oldstate,
     }
 
     sfree(corners);
-    sfree(correct);
 }
 
-static float game_anim_length(game_state *oldstate,
-                             game_state *newstate, int dir, game_ui *ui)
+static float game_anim_length(const game_state *oldstate,
+                              const game_state *newstate, int dir, game_ui *ui)
 {
     return 0.0F;
 }
 
-static float game_flash_length(game_state *oldstate,
-                              game_state *newstate, int dir, game_ui *ui)
+static float game_flash_length(const game_state *oldstate,
+                               const game_state *newstate, int dir, game_ui *ui)
 {
     if (!oldstate->completed && newstate->completed &&
        !oldstate->cheated && !newstate->cheated)
@@ -2756,24 +2880,89 @@ static float game_flash_length(game_state *oldstate,
     return 0.0F;
 }
 
-static int game_wants_statusbar(void)
+static int game_status(const game_state *state)
 {
-    return TRUE;
+    return state->completed ? +1 : 0;
 }
 
-static int game_timing_state(game_state *state)
+static int game_timing_state(const game_state *state, game_ui *ui)
 {
     return TRUE;
 }
 
+static void game_print_size(const game_params *params, float *x, float *y)
+{
+    int pw, ph;
+
+    /*
+     * I'll use 5mm squares by default.
+     */
+    game_compute_size(params, 500, &pw, &ph);
+    *x = pw / 100.0F;
+    *y = ph / 100.0F;
+}
+
+static void game_print(drawing *dr, const game_state *state, int tilesize)
+{
+    int w = state->w, h = state->h;
+    int ink = print_mono_colour(dr, 0);
+    int x, y;
+
+    /* Ick: fake up `ds->tilesize' for macro expansion purposes */
+    game_drawstate ads, *ds = &ads;
+    game_set_size(dr, ds, NULL, tilesize);
+
+    /*
+     * Border.
+     */
+    print_line_width(dr, TILE_SIZE / 10);
+    draw_rect_outline(dr, COORD(0), COORD(0), w*TILE_SIZE, h*TILE_SIZE, ink);
+
+    /*
+     * Grid. We have to make the grid lines particularly thin,
+     * because users will be drawing lines _along_ them and we want
+     * those lines to be visible.
+     */
+    print_line_width(dr, TILE_SIZE / 256);
+    for (x = 1; x < w; x++)
+       draw_line(dr, COORD(x), COORD(0), COORD(x), COORD(h), ink);
+    for (y = 1; y < h; y++)
+       draw_line(dr, COORD(0), COORD(y), COORD(w), COORD(y), ink);
+
+    /*
+     * Solution.
+     */
+    print_line_width(dr, TILE_SIZE / 10);
+    for (y = 0; y <= h; y++)
+       for (x = 0; x <= w; x++) {
+           if (HRANGE(state,x,y) && hedge(state,x,y))
+               draw_line(dr, COORD(x), COORD(y), COORD(x+1), COORD(y), ink);
+           if (VRANGE(state,x,y) && vedge(state,x,y))
+               draw_line(dr, COORD(x), COORD(y), COORD(x), COORD(y+1), ink);
+       }
+
+    /*
+     * Clues.
+     */
+    for (y = 0; y < h; y++)
+       for (x = 0; x < w; x++)
+           if (grid(state,x,y)) {
+               char str[80];
+               sprintf(str, "%d", grid(state,x,y));
+               draw_text(dr, COORD(x)+TILE_SIZE/2, COORD(y)+TILE_SIZE/2,
+                         FONT_VARIABLE, TILE_SIZE/2,
+                         ALIGN_HCENTRE | ALIGN_VCENTRE, ink, str);
+           }
+}
+
 #ifdef COMBINED
 #define thegame rect
 #endif
 
 const struct game thegame = {
-    "Rectangles", "games.rectangles",
+    "Rectangles", "games.rectangles", "rect",
     default_params,
-    game_fetch_preset,
+    game_fetch_preset, NULL,
     decode_params,
     encode_params,
     free_params,
@@ -2786,7 +2975,7 @@ const struct game thegame = {
     dup_game,
     free_game,
     TRUE, solve_game,
-    TRUE, game_text_format,
+    TRUE, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
     encode_ui,
@@ -2794,14 +2983,18 @@ const struct game thegame = {
     game_changed_state,
     interpret_move,
     execute_move,
-    game_size,
+    PREFERRED_TILE_SIZE, game_compute_size, game_set_size,
     game_colours,
     game_new_drawstate,
     game_free_drawstate,
     game_redraw,
     game_anim_length,
     game_flash_length,
-    game_wants_statusbar,
+    game_status,
+    TRUE, FALSE, game_print_size, game_print,
+    TRUE,                             /* wants_statusbar */
     FALSE, game_timing_state,
-    0,                                /* mouse_priorities */
+    0,                                /* flags */
 };
+
+/* vim: set shiftwidth=4 tabstop=8: */