ftp://ftp.krokus.ru/pub/OpenBSD/distfiles/xscreensaver-4.22.tar.gz
[xscreensaver] / hacks / maze.c
index aa2de92fcd36f337c76f687630415f28cf0b6153..ba80e835e399d43893942063531318d25123831e 100644 (file)
@@ -1,12 +1,45 @@
 /******************************************************************************
  * [ maze ] ...
  *
+ * modified:  [ 1-04-00 ]  Johannes Keukelaar <johannes@nada.kth.se>
+ *              Added -ignorant option (not the default) to remove knowlege
+ *              of the direction in which the exit lies.
+ *
+ * modified:  [ 6-28-98 ]  Zack Weinberg <zack@rabi.phys.columbia.edu>
+ *
+ *              Made the maze-solver somewhat more intelligent.  There are
+ *              three optimizations:
+ *
+ *              - Straight-line lookahead: the solver does not enter dead-end
+ *                corridors.  This is a win with all maze generators.
+ *
+ *              - First order direction choice: the solver knows where the
+ *                exit is in relation to itself, and will try paths leading in
+ *                that direction first. This is a major win on maze generator 1
+ *                which tends to offer direct routes to the exit.
+ *
+ *              - Dead region elimination: the solver already has a map of
+ *                all squares visited.  Whenever it starts to backtrack, it
+ *                consults this map and marks off all squares that cannot be
+ *                reached from the exit without crossing a square already
+ *                visited.  Those squares can never contribute to the path to
+ *                the exit, so it doesn't bother checking them.  This helps a
+ *                lot with maze generator 2 and somewhat less with generator 1.
+ *
+ *              Further improvements would require knowledge of the wall map
+ *              as well as the position of the exit and the squares visited.
+ *              I would consider that to be cheating.  Generator 0 makes
+ *              mazes which are remarkably difficult to solve mechanically --
+ *              even with these optimizations the solver generally must visit
+ *              at least two-thirds of the squares.  This is partially
+ *              because generator 0's mazes have longer paths to the exit.
+ *
  * modified:  [ 4-10-97 ]  Johannes Keukelaar <johannes@nada.kth.se>
  *              Added multiple maze creators. Robustified solver.
  *              Added bridge option.
  * modified:  [ 8-11-95 ] Ed James <james@mml.mmc.com>
  *              added fill of dead-end box to solve_maze while loop.
- * modified:  [ 3-7-93 ]  Jamie Zawinski <jwz@netscape.com>
+ * modified:  [ 3-7-93 ]  Jamie Zawinski <jwz@jwz.org>
  *             added the XRoger logo, cleaned up resources, made
  *             grid size a parameter.
  * modified:  [ 3-3-93 ]  Jim Randell <jmr@mddjmr.fc.hp.com>
  *****************************************************************************/
 
 #include "screenhack.h"
+#include "erase.h"
 
-#define XROGER
+#define XSCREENSAVER_LOGO
 
 static int solve_delay, pre_solve_delay, post_solve_delay;
 
 #include  <stdio.h>
 #include  <X11/Xlib.h>
 #include  <X11/Xutil.h>
-#ifndef VMS
-# include  <X11/bitmaps/gray1>
-#else  /* VMS */
-# include "sys$common:[decw$include.bitmaps]gray1.xbm"
-#endif /* VMS */
 
-#define MAX_MAZE_SIZE_X        500
-#define MAX_MAZE_SIZE_Y        500
+/* #include  <X11/bitmaps/gray1> */
+#define gray1_width  2
+#define gray1_height 2
+static char gray1_bits[] = { 0x01, 0x02 };
+
+
+#define MAX_MAZE_SIZE_X        1000
+#define MAX_MAZE_SIZE_Y        1000
 
 #define MOVE_LIST_SIZE  (MAX_MAZE_SIZE_X * MAX_MAZE_SIZE_Y)
 
-#define WALL_TOP       0x8000
-#define WALL_RIGHT     0x4000
-#define WALL_BOTTOM    0x2000
-#define WALL_LEFT      0x1000
+#define NOT_DEAD       0x8000
+#define SOLVER_VISIT    0x4000
+#define START_SQUARE   0x2000
+#define END_SQUARE     0x1000
+
+#define WALL_TOP       0x8
+#define WALL_RIGHT     0x4
+#define WALL_BOTTOM    0x2
+#define WALL_LEFT      0x1
+#define WALL_ANY       0xF
 
 #define DOOR_IN_TOP    0x800
 #define DOOR_IN_RIGHT  0x400
@@ -84,20 +125,18 @@ static int solve_delay, pre_solve_delay, post_solve_delay;
 #define DOOR_OUT_BOTTOM        0x20
 #define DOOR_OUT_LEFT  0x10
 
-#define SOLVER_VISIT    0x4
-#define START_SQUARE   0x2
-#define END_SQUARE     0x1
 
 #define        border_x        (0)
 #define        border_y        (0)
 
 #define        get_random(x)   (random() % (x))
-  
+
+
 static int logo_x, logo_y;
 
-#ifdef XROGER
-# define logo_width  128
-# define logo_height 128
+#ifdef XSCREENSAVER_LOGO
+# define logo_width  54
+# define logo_height 54
 #else
 # include  <X11/bitmaps/xlogo64>
 # define logo_width xlogo64_width
@@ -108,9 +147,9 @@ static int logo_x, logo_y;
 static unsigned short maze[MAX_MAZE_SIZE_X][MAX_MAZE_SIZE_Y];
 
 static struct {
-  unsigned char x;
-  unsigned char y;
-  unsigned char dir;
+  unsigned short x;
+  unsigned short y;
+  unsigned char dir, ways;
 } move_list[MOVE_LIST_SIZE], save_path[MOVE_LIST_SIZE], path[MOVE_LIST_SIZE];
 
 static int maze_size_x, maze_size_y;
@@ -121,11 +160,11 @@ static int bw;
 
 static Display *dpy;
 static Window  win;
-static GC      gc, cgc, tgc, logo_gc, erase_gc;
+static GC      gc, cgc, tgc, sgc, ugc, logo_gc, erase_gc;
 static Pixmap  logo_map;
 
 static int     x = 0, y = 0, restart = 0, stop = 1, state = 1, max_length;
-static int      sync_p, bridge_p;
+static int      sync_p, bridge_p, ignorant_p;
 
 static int
 check_events (void)                        /* X event handler [ rhess ] */
@@ -167,6 +206,9 @@ check_events (void)                        /* X event handler [ rhess ] */
     case Expose:
       restart = 1;
       break;
+    default:
+      screenhack_handle_event(dpy, &e);
+      break;
     }
     return(1);
   }
@@ -1087,14 +1129,35 @@ draw_maze_border (void)                         /* draw the maze outline */
       Window r;
       int x, y;
       unsigned int w, h, bw, d;
+
+      /* round up to grid size */
+      int ww = ((logo_width  / grid_width) + 1)  * grid_width;
+      int hh = ((logo_height / grid_height) + 1) * grid_height;
+
       XGetGeometry (dpy, logo_map, &r, &x, &y, &w, &h, &bw, &d);
-      XCopyPlane (dpy, logo_map, win, logo_gc,
-                 0, 0, w, h,
-                 border_x + 3 + grid_width * logo_x,
-                 border_y + 3 + grid_height * logo_y, 1);
+
+# ifdef XSCREENSAVER_LOGO
+      /* kludge: if the logo "hole" is around the same size as the logo,
+         don't center it (since the xscreensaver logo image is a little
+         off center...  But do center if if the hole/gridsize is large. */
+      if (ww < logo_width  + 5) ww = w; 
+      if (hh < logo_height + 5) hh = h; 
+# endif /* XSCREENSAVER_LOGO */
+
+      if (d == 1)
+        XCopyPlane (dpy, logo_map, win, logo_gc,
+                    0, 0, w, h,
+                    border_x + 3 + grid_width  * logo_x + ((ww - w) / 2),
+                    border_y + 3 + grid_height * logo_y + ((hh - h) / 2),
+                    1);
+      else
+        XCopyArea (dpy, logo_map, win, logo_gc,
+                   0, 0, w, h,
+                   border_x + 3 + grid_width  * logo_x + ((ww - w) / 2),
+                   border_y + 3 + grid_height * logo_y + ((hh - h) / 2));
     }
-  draw_solid_square (start_x, start_y, start_dir, tgc);
-  draw_solid_square (end_x, end_y, end_dir, tgc);
+  draw_solid_square (start_x, start_y, WALL_TOP >> start_dir, tgc);
+  draw_solid_square (end_x, end_y, WALL_TOP >> end_dir, tgc);
 }
 
 
@@ -1209,85 +1272,287 @@ draw_solid_square(int i, int j,          /* draw a solid square in a square */
                  int dir, GC gc)
 {
   switch (dir) {
-  case 0: XFillRectangle(dpy, win, gc,
-                        border_x + bw + grid_width * i, 
-                        border_y - bw + grid_height * j, 
-                        grid_width - (bw+bw), grid_height);
-    break;
-  case 1: XFillRectangle(dpy, win, gc,
-                        border_x + bw + grid_width * i, 
-                        border_y + bw + grid_height * j, 
-                        grid_width, grid_height - (bw+bw));
-    break;
-  case 2: XFillRectangle(dpy, win, gc,
-                        border_x + bw + grid_width * i, 
-                        border_y + bw + grid_height * j, 
-                        grid_width - (bw+bw), grid_height);
-    break;
-  case 3: XFillRectangle(dpy, win, gc,
-                        border_x - bw + grid_width * i, 
-                        border_y + bw + grid_height * j, 
-                        grid_width, grid_height - (bw+bw));
-    break;
+  case WALL_TOP:
+      XFillRectangle(dpy, win, gc,
+                    border_x + bw+(bw==0?1:0) + grid_width * i, 
+                    border_y - bw-(bw==0?1:0) + grid_height * j, 
+                    grid_width - (bw+bw+(bw==0?1:0)), grid_height);
+      break;
+  case WALL_RIGHT:
+      XFillRectangle(dpy, win, gc,
+                    border_x + bw+(bw==0?1:0) + grid_width * i, 
+                    border_y + bw+(bw==0?1:0) + grid_height * j, 
+                    grid_width, grid_height - (bw+bw+(bw==0?1:0)));
+      break;
+  case WALL_BOTTOM:
+      XFillRectangle(dpy, win, gc,
+                    border_x + bw+(bw==0?1:0) + grid_width * i, 
+                    border_y + bw+(bw==0?1:0) + grid_height * j, 
+                    grid_width - (bw+bw+(bw==0?1:0)), grid_height);
+      break;
+  case WALL_LEFT:
+      XFillRectangle(dpy, win, gc,
+                    border_x - bw-(bw==0?1:0) + grid_width * i, 
+                    border_y + bw+(bw==0?1:0) + grid_height * j, 
+                    grid_width, grid_height - (bw+bw+(bw==0?1:0)));
+      break;
   }
   XSync (dpy, False);
 }
 
+int
+longdeadend_p(int x1, int y1, int x2, int y2, int endwall)
+{
+    int dx = x2 - x1, dy = y2 - y1;
+    int sidewalls;
+
+    sidewalls = endwall | (endwall >> 2 | endwall << 2);
+    sidewalls = ~sidewalls & WALL_ANY;
+
+    while((maze[x2][y2] & WALL_ANY) == sidewalls)
+    {
+       x2 += dx;
+       y2 += dy;
+    }
+
+    if((maze[x2][y2] & WALL_ANY) == (sidewalls | endwall))
+    {
+       endwall = (endwall >> 2 | endwall << 2) & WALL_ANY;
+       while(x1 != x2 || y1 != y2)
+       {
+           x1 += dx;
+           y1 += dy;
+           draw_solid_square(x1, y1, endwall, sgc);
+           maze[x1][y1] |= SOLVER_VISIT;
+       }
+       return 1;
+    }
+    else
+       return 0;
+}
+
+/* Find all dead regions -- areas from which the goal cannot be reached --
+   and mark them visited. */
+void
+find_dead_regions(void)
+{
+    int x, y, flipped;
+
+    /* Find all not SOLVER_VISIT squares bordering NOT_DEAD squares
+       and mark them NOT_DEAD also.  Repeat until no more such squares. */
+    maze[start_x][start_y] |= NOT_DEAD;
+    
+    do
+    {
+       flipped = 0;
+       for(x = 0; x < maze_size_x; x++)
+           for(y = 0; y < maze_size_y; y++)
+               if(!(maze[x][y] & (SOLVER_VISIT | NOT_DEAD))
+                  && (   (x && (maze[x-1][y] & NOT_DEAD))
+                      || (y && (maze[x][y-1] & NOT_DEAD))))
+               {
+                   flipped = 1;
+                   maze[x][y] |= NOT_DEAD;
+               }
+       for(x = maze_size_x-1; x >= 0; x--)
+           for(y = maze_size_y-1; y >= 0; y--)
+               if(!(maze[x][y] & (SOLVER_VISIT | NOT_DEAD))
+                  && (   (x != maze_size_x-1 && (maze[x+1][y] & NOT_DEAD))
+                      || (y != maze_size_y-1 && (maze[x][y+1] & NOT_DEAD))))
+               {
+                   flipped = 1;
+                   maze[x][y] |= NOT_DEAD;
+               }
+    }
+    while(flipped);
+
+    for (y = 0; y < maze_size_y; y++)
+      for (x = 0; x < maze_size_x; x++)
+      {
+       if (maze[x][y] & NOT_DEAD)
+         maze[x][y] &= ~NOT_DEAD;
+       else if (!(maze[x][y] & SOLVER_VISIT))
+       {
+         maze[x][y] |= SOLVER_VISIT;
+         if((x < logo_x || x > logo_x + logo_width / grid_width) ||
+            (y < logo_y || y > logo_y + logo_height / grid_height))
+         {
+            /* if we are completely surrounded by walls, just draw the
+               inside part */
+            if ((maze[x][y] & WALL_ANY) == WALL_ANY)
+             XFillRectangle(dpy, win, ugc,
+                            border_x + bw + grid_width * x,
+                            border_y + bw + grid_height * y,
+                            grid_width - (bw+bw), grid_height - (bw+bw));
+           else
+           {
+             if (! (maze[x][y] & WALL_LEFT))
+               draw_solid_square(x, y, WALL_LEFT, ugc);
+             if (! (maze[x][y] & WALL_RIGHT))
+               draw_solid_square(x, y, WALL_RIGHT, ugc);
+             if (! (maze[x][y] & WALL_TOP))
+               draw_solid_square(x, y, WALL_TOP, ugc);
+             if (! (maze[x][y] & WALL_BOTTOM))
+               draw_solid_square(x, y, WALL_BOTTOM, ugc);
+           }
+         }
+       }
+      }
+    XSync(dpy, False);
+}
 
 static void
 solve_maze (void)                     /* solve it with graphical feedback */
 {
-  int i;
-  int step_x[4] = { 0, 1, 0, -1 };
-  int step_y[4] = { -1, 0, 1, 0 };
+    int i, dir, from, x, y, ways, bt = 0;
+
+    /* plug up the surrounding wall */
+    maze[end_x][end_y] |= (WALL_TOP >> end_dir);
     
-  /* plug up the surrounding wall */
-  maze[start_x][start_y] |= (WALL_TOP >> start_dir);
-  maze[end_x][end_y] |= (WALL_TOP >> end_dir);
-  
-  /* initialize search path */
-  i = 0;
-  path[i].x = end_x;
-  path[i].y = end_y;
-  path[i].dir = -1;
-  maze[end_x][end_y] |= SOLVER_VISIT;
-  
-  /* do it */
-  while (1) {
-    if ( ++path[i].dir >= 4 ) {
-      XFillRectangle(dpy, win, cgc,
-                    border_x + bw + grid_width * (int)(path[i].x),
-                    border_y + bw + grid_height * (int)(path[i].y),
-                    grid_width - (bw+bw), grid_height - (bw+bw));
-      i--;
-      if(i<0) /* Can't solve this maze. */
+    /* initialize search path */
+    i = 0;
+    path[i].x = end_x;
+    path[i].y = end_y;
+    path[i].dir = 0;
+    maze[end_x][end_y] |= SOLVER_VISIT;
+    
+    /* do it */
+    while (1)
+    {
+       if ( maze[path[i].x][path[i].y] & START_SQUARE )
+           return;
+
+       /* Abort solve on expose - cheapo repaint strategy */
+       if (check_events()) return;
+       
+       if (solve_delay) usleep (solve_delay);
+       
+       if(!path[i].dir)
        {
-         printf("Unsolvable maze.\n");
-         return;
+           ways = 0;
+           /* First visit this square.  Which adjacent squares are open? */
+           for(dir = WALL_TOP; dir & WALL_ANY; dir >>= 1)
+           {
+               if(maze[path[i].x][path[i].y] & dir)
+                   continue;
+               
+               y = path[i].y - !!(dir & WALL_TOP) + !!(dir & WALL_BOTTOM);
+               x = path[i].x + !!(dir & WALL_RIGHT) - !!(dir & WALL_LEFT);
+               
+               if(maze[x][y] & SOLVER_VISIT)
+                   continue;
+               
+               from = (dir << 2 & WALL_ANY) | (dir >> 2 & WALL_ANY);
+               /* don't enter obvious dead ends */
+               if(((maze[x][y] & WALL_ANY) | from) != WALL_ANY)
+               {
+                   if(!longdeadend_p(path[i].x, path[i].y, x, y, dir))
+                       ways |= dir;
+               }
+               else
+               {
+                   draw_solid_square(x, y, from, sgc);
+                   maze[x][y] |= SOLVER_VISIT;
+               }
+           }
+       }
+       else
+           ways = path[i].ways;
+       /* ways now has a bitmask of open paths. */
+       
+       if(!ways)
+           goto backtrack;
+
+       if (!ignorant_p)
+         {
+           x = path[i].x - start_x;
+           y = path[i].y - start_y;
+           /* choice one */
+           if(abs(y) <= abs(x))
+             dir = (x > 0) ? WALL_LEFT : WALL_RIGHT;
+           else
+             dir = (y > 0) ? WALL_TOP : WALL_BOTTOM;
+           
+           if(dir & ways)
+             goto found;
+           
+           /* choice two */
+           switch(dir)
+             {
+             case WALL_LEFT:
+             case WALL_RIGHT:
+               dir = (y > 0) ? WALL_TOP : WALL_BOTTOM; break;
+             case WALL_TOP:
+             case WALL_BOTTOM:
+               dir = (x > 0) ? WALL_LEFT : WALL_RIGHT;
+             }
+           
+           if(dir & ways)
+             goto found;
+           
+           /* choice three */
+           
+           dir = (dir << 2 & WALL_ANY) | (dir >> 2 & WALL_ANY);
+           if(dir & ways)
+             goto found;
+           
+           /* choice four */
+           dir = ways;
+           if(!dir)
+             goto backtrack;
+           
+         found: ;
+         }
+       else
+         {
+           if(ways&WALL_TOP)
+             dir = WALL_TOP;
+           else if(ways&WALL_LEFT)
+             dir = WALL_LEFT;
+           else if(ways&WALL_BOTTOM)
+             dir = WALL_BOTTOM;
+           else if(ways&WALL_RIGHT)
+             dir = WALL_RIGHT;
+           else
+             goto backtrack;
+         }
+       bt = 0;
+       ways &= ~dir;  /* tried this one */
+       
+       y = path[i].y - !!(dir & WALL_TOP) + !!(dir & WALL_BOTTOM);
+       x = path[i].x + !!(dir & WALL_RIGHT) - !!(dir & WALL_LEFT);
+       
+       /* advance in direction dir */
+       path[i].dir = dir;
+       path[i].ways = ways;
+       draw_solid_square(path[i].x, path[i].y, dir, tgc);
+       
+       i++;
+       path[i].dir = 0;
+       path[i].ways = 0;
+       path[i].x = x;
+       path[i].y = y;
+       maze[x][y] |= SOLVER_VISIT;
+       continue;
+
+    backtrack:
+       if(i == 0)
+       {
+           printf("Unsolvable maze.\n");
+           return;
        }
-      draw_solid_square( (int)(path[i].x), (int)(path[i].y), 
-                       (int)(path[i].dir), cgc);
+
+       if(!bt && !ignorant_p)
+           find_dead_regions();
+       bt = 1;
+       from = path[i-1].dir;
+       from = (from << 2 & WALL_ANY) | (from >> 2 & WALL_ANY);
+       
+       draw_solid_square(path[i].x, path[i].y, from, cgc);
+       i--;
     }
-    else if ( (! (maze[path[i].x][path[i].y] & (WALL_TOP >> path[i].dir))) && 
-            (!( maze[path[i].x+step_x[path[i].dir]]
-                   [path[i].y+step_y[path[i].dir]]&SOLVER_VISIT)) ) {
-      path[i+1].x = path[i].x+step_x[path[i].dir];
-      path[i+1].y = path[i].y+step_y[path[i].dir];
-      path[i+1].dir = -1;
-      draw_solid_square(path[i].x, path[i].y, path[i].dir, tgc);
-      i++;
-      maze[path[i].x][path[i].y] |= SOLVER_VISIT;
-      if ( maze[path[i].x][path[i].y] & START_SQUARE ) {
-       return;
-      }
-    } 
-    if (check_events()) return;
-    /* Abort solve on expose - cheapo repaint strategy */
-    if (solve_delay) usleep (solve_delay);
-  }
 } 
 
-
 #if 0
 static void
 enter_square (int n)                      /* move into a neighboring square */
@@ -1315,7 +1580,7 @@ enter_square (int n)                      /* move into a neighboring square */
 
 
 /*
- *  jmr additions for Jamie Zawinski's <jwz@netscape.com> screensaver stuff,
+ *  jmr additions for Jamie Zawinski's <jwz@jwz.org> screensaver stuff,
  *  note that the code above this has probably been hacked about in some
  *  arbitrary way.
  */
@@ -1323,31 +1588,36 @@ enter_square (int n)                      /* move into a neighboring square */
 char *progclass = "Maze";
 
 char *defaults[] = {
-  "Maze.background:    black",         /* to placate SGI */
-  "Maze.foreground:    white",         /* to placate SGI */
+  ".background:        black",
+  ".foreground:        white",
   "*gridSize:  0",
   "*solveDelay:        5000",
   "*preDelay:  2000000",
   "*postDelay: 4000000",
   "*liveColor: green",
   "*deadColor: red",
+  "*skipColor:  orange",
+  "*surroundColor: slateblue",
   "*generator:  -1",
   "*maxLength:  5",
   "*syncDraw:   False",
   "*bridge:     False",
-#ifdef XROGER
-  "*logoColor: red3",
-#endif
   0
 };
 
 XrmOptionDescRec options[] = {
+  { "-ignorant",        ".ignorant",    XrmoptionNoArg, "True" },
+  { "-no-ignorant",     ".ignorant",    XrmoptionNoArg, "False" },
   { "-grid-size",      ".gridSize",    XrmoptionSepArg, 0 },
   { "-solve-delay",    ".solveDelay",  XrmoptionSepArg, 0 },
   { "-pre-delay",      ".preDelay",    XrmoptionSepArg, 0 },
   { "-post-delay",     ".postDelay",   XrmoptionSepArg, 0 },
+  { "-bg-color",       ".background",  XrmoptionSepArg, 0 },
+  { "-fg-color",       ".foreground",  XrmoptionSepArg, 0 },
   { "-live-color",     ".liveColor",   XrmoptionSepArg, 0 },
   { "-dead-color",     ".deadColor",   XrmoptionSepArg, 0 },
+  { "-skip-color",     ".skipColor",   XrmoptionSepArg, 0 },
+  { "-surround-color", ".surroundColor",XrmoptionSepArg, 0 },
   { "-generator",       ".generator",   XrmoptionSepArg, 0 },
   { "-max-length",      ".maxLength",   XrmoptionSepArg, 0 },
   { "-bridge",          ".bridge",      XrmoptionNoArg, "True" },
@@ -1355,17 +1625,13 @@ XrmOptionDescRec options[] = {
   { 0, 0, 0, 0 }
 };
 
-#ifdef XROGER
-extern void skull (Display *, Window, GC, GC, int, int, int, int);
-#endif
-
 void
 screenhack(Display *display, Window window)
 {
   Pixmap gray;
   int size, root, generator, this_gen;
   XWindowAttributes xgwa;
-  unsigned long bg, fg, pfg, pbg, lfg;
+  unsigned long bg, fg, pfg, pbg, sfg, ufg;
 
   size = get_integer_resource ("gridSize", "Dimension");
   root = get_boolean_resource("root", "Boolean");
@@ -1375,6 +1641,7 @@ screenhack(Display *display, Window window)
   generator = get_integer_resource("generator", "Integer");
   max_length = get_integer_resource("maxLength", "Integer");
   bridge_p = get_boolean_resource("bridge", "Boolean");
+  ignorant_p = get_boolean_resource("ignorant", "Boolean");
 
   if (size < 2) size = 7 + (random () % 30);
   grid_width = grid_height = size;
@@ -1390,11 +1657,18 @@ screenhack(Display *display, Window window)
   set_maze_sizes (xgwa.width, xgwa.height);
 
   if (! root)
-    XSelectInput (dpy, win, ExposureMask|ButtonPressMask|StructureNotifyMask);
+    {
+      XWindowAttributes xgwa;
+      XGetWindowAttributes (dpy, window, &xgwa);
+      XSelectInput (dpy, win,
+                    xgwa.your_event_mask | ExposureMask | ButtonPressMask);
+    }
   
-  gc = XCreateGC(dpy, win, 0, 0);
+  gc  = XCreateGC(dpy, win, 0, 0);
   cgc = XCreateGC(dpy, win, 0, 0);
-  tgc = XCreateGC(dpy,win,0,0);
+  tgc = XCreateGC(dpy, win, 0, 0);
+  sgc = XCreateGC(dpy, win, 0, 0);
+  ugc = XCreateGC(dpy, win, 0, 0);
   logo_gc = XCreateGC(dpy, win, 0, 0);
   erase_gc = XCreateGC(dpy, win, 0, 0);
   
@@ -1402,15 +1676,10 @@ screenhack(Display *display, Window window)
 
   bg  = get_pixel_resource ("background","Background", dpy, xgwa.colormap);
   fg  = get_pixel_resource ("foreground","Foreground", dpy, xgwa.colormap);
-  lfg = get_pixel_resource ("logoColor", "Foreground", dpy, xgwa.colormap);
   pfg = get_pixel_resource ("liveColor", "Foreground", dpy, xgwa.colormap);
   pbg = get_pixel_resource ("deadColor", "Foreground", dpy, xgwa.colormap);
-  if (mono_p) lfg = pfg = fg;
-
-  if (lfg == bg)
-    lfg = ((bg == WhitePixel (dpy, DefaultScreen (dpy)))
-          ? BlackPixel (dpy, DefaultScreen (dpy))
-          : WhitePixel (dpy, DefaultScreen (dpy)));
+  sfg = get_pixel_resource ("skipColor", "Foreground", dpy, xgwa.colormap);
+  ufg = get_pixel_resource ("surroundColor", "Foreground", dpy, xgwa.colormap);
 
   XSetForeground (dpy, gc, fg);
   XSetBackground (dpy, gc, bg);
@@ -1418,31 +1687,30 @@ screenhack(Display *display, Window window)
   XSetBackground (dpy, cgc, bg);
   XSetForeground (dpy, tgc, pfg);
   XSetBackground (dpy, tgc, bg);
-  XSetForeground (dpy, logo_gc, lfg);
+  XSetForeground (dpy, sgc, sfg);
+  XSetBackground (dpy, sgc, bg);
+  XSetForeground (dpy, ugc, ufg);
+  XSetBackground (dpy, ugc, bg);
+  XSetForeground (dpy, logo_gc, fg);
   XSetBackground (dpy, logo_gc, bg);
   XSetForeground (dpy, erase_gc, bg);
   XSetBackground (dpy, erase_gc, bg);
 
   XSetStipple (dpy, cgc, gray);
   XSetFillStyle (dpy, cgc, FillOpaqueStippled);
+  XSetStipple (dpy, sgc, gray);
+  XSetFillStyle (dpy, sgc, FillOpaqueStippled);
+  XSetStipple (dpy, ugc, gray);
+  XSetFillStyle (dpy, ugc, FillOpaqueStippled);
   
-#ifdef XROGER
+#ifdef XSCREENSAVER_LOGO
   {
-    int w, h;
-    XGCValues gcv;
-    GC draw_gc, erase_gc;
-    /* round up to grid size */
-    w = ((logo_width  / grid_width) + 1)  * grid_width;
-    h = ((logo_height / grid_height) + 1) * grid_height;
-    logo_map = XCreatePixmap (dpy, win, w, h, 1);
-    gcv.foreground = 1L;
-    draw_gc = XCreateGC (dpy, logo_map, GCForeground, &gcv);
-    gcv.foreground = 0L;
-    erase_gc= XCreateGC (dpy, logo_map, GCForeground, &gcv);
-    XFillRectangle (dpy, logo_map, erase_gc, 0, 0, w, h);
-    skull (dpy, logo_map, draw_gc, erase_gc, 5, 0, w-10, h-10);
-    XFreeGC (dpy, draw_gc);
-    XFreeGC (dpy, erase_gc);
+    unsigned long *pixels; /* ignored - unfreed */
+    int npixels;
+    logo_map = xscreensaver_logo (xgwa.screen, xgwa.visual, win,
+                                  xgwa.colormap, bg,
+                                  &pixels, &npixels, 0,
+                                  logo_width > 150);
   }
 #else
   if  (!(logo_map = XCreateBitmapFromData (dpy, win, logo_bits,
@@ -1498,6 +1766,7 @@ screenhack(Display *display, Window window)
       XSync (dpy, False);
       usleep (post_solve_delay);
       state = 0 ;
+      erase_full_window(display, window);
       break;
     default:
       abort ();