goban plugin: hoshi locations for more board sizes

Hoshi locations were hardcoded and only for board sizes 9, 13 and 19.

This new way has identical results for those board sizes, but
also places hoshi on other size boards.

There are no real standards for where hoshi should go on boards other
than 9, 13 and 19, but I think the results obtained are aesthetically
pleasing (and certainly better than not having any hoshi at all).

Change-Id: I08e449f17d782d212d5b1e16ebd7df52aec9ffb9
Reviewed-on: http://gerrit.rockbox.org/68
Reviewed-by: Björn Stenberg <bjorn@haxx.se>
Reviewed-by: Frank Gevaerts <frank@gevaerts.be>

1 files changed, 41 insertions, 26 deletions

diff --git a/apps/plugins/goban/display.c b/apps/plugins/goban/display.c
index 64b3adebb4..f701dbb315 100644
--- a/apps/plugins/goban/display.c
+++ b/apps/plugins/goban/display.c
@@ -1041,44 +1041,59 @@ draw_hoshi (unsigned short pos)
 static void
 draw_all_hoshi (void)
 {
-    if (board_width != board_height)
+    if (board_width != board_height ||
+        board_width <= 2 ||
+        board_width == 4 ||
+        board_width == 6)
     {
         return;
     }
 
-    if (board_width == 19)
+    if (board_width == 3)
     {
-        draw_hoshi (POS (3, 3));
-        draw_hoshi (POS (3, 9));
-        draw_hoshi (POS (3, 15));
-
-        draw_hoshi (POS (9, 3));
-        draw_hoshi (POS (9, 9));
-        draw_hoshi (POS (9, 15));
-
-        draw_hoshi (POS (15, 3));
-        draw_hoshi (POS (15, 9));
-        draw_hoshi (POS (15, 15));
+        draw_hoshi (POS (1, 1));
+        return;
     }
-    else if (board_width == 9)
+
+    if (board_width == 5)
     {
+        draw_hoshi (POS (1, 1));
+        draw_hoshi (POS (1, 3));
         draw_hoshi (POS (2, 2));
-        draw_hoshi (POS (2, 6));
+        draw_hoshi (POS (3, 1));
+        draw_hoshi (POS (3, 3));
+        return;
+    }
 
-        draw_hoshi (POS (4, 4));
+    /* special case boards taken care of, handle the general case
+     *
+     * Note: board_width == board_height here (or we bailed out) so the two
+     * are interchangeable */
+    int low_edge = (board_width < 12) ? 2 : 3;
+    int high_edge = board_width - low_edge - 1;
+    int mid = board_width / 2;
 
-        draw_hoshi (POS (6, 2));
-        draw_hoshi (POS (6, 6));
-    }
-    else if (board_width == 13)
+    /* corner hoshi, for big enough boards */
+    if (board_width > 7)
     {
-        draw_hoshi (POS (3, 3));
-        draw_hoshi (POS (3, 9));
-
-        draw_hoshi (POS (6, 6));
+        draw_hoshi (POS (low_edge, low_edge));
+        draw_hoshi (POS (low_edge, high_edge));
+        draw_hoshi (POS (high_edge, low_edge));
+        draw_hoshi (POS (high_edge, high_edge));
+    }
 
-        draw_hoshi (POS (9, 3));
-        draw_hoshi (POS (9, 9));
+    /* side hoshi, for big enough boards (only makes sense on odd) */
+    if (board_width > 12 && board_width % 2 == 1)
+    {
+        draw_hoshi (POS (low_edge, mid));
+        draw_hoshi (POS (mid, low_edge));
+        draw_hoshi (POS (high_edge, mid));
+        draw_hoshi (POS (mid, high_edge));
+    }
 
+    /* center hoshi */
+    if (board_width % 2 == 1)
+    {
+        draw_hoshi (POS (mid, mid));
     }
 }