Clear memory of erased position on variant switch

The Edit Position clear-board cycle would go from initial position to
last-erased position (if this is different), but the latter could have been
from another variant. In wich case we also want to clear.
  also print a message to alert people to the fact that they can click the
clock again to restore the position.

diff --git a/backend.c b/backend.c
index aea15b5..6dae63d 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -14593,7 +14593,8 @@ EditPositionMenuEvent (ChessSquare selection, int x, int y)
 {
     char buf[MSG_SIZ];
     ChessSquare piece = boards[0][y][x];
-    static Board erasedBoard, currentBoard, menuBoard;
+    static Board erasedBoard, currentBoard, menuBoard, nullBoard;
+    static int lastVariant;
 
     if (gameMode != EditPosition && gameMode != IcsExamining) return;
 
@@ -14632,13 +14633,16 @@ EditPositionMenuEvent (ChessSquare selection, int x, int y)
                    p = menuBoard[BOARD_HEIGHT-1][x];
                    for(y = x + 1; y < BOARD_RGHT; y++) if(menuBoard[BOARD_HEIGHT-1][y] == p) menuBoard[BOARD_HEIGHT-1][y] = EmptySquare;
                }
+               DisplayMessage("Clicking clock again restores position", "");
+               if(gameInfo.variant != lastVariant) lastVariant = gameInfo.variant, CopyBoard(erasedBoard, boards[0]);
                if(!nonEmpty) { // asked to clear an empty board
                    CopyBoard(boards[0], menuBoard);
                } else
                if(CompareBoards(currentBoard, menuBoard)) { // asked to clear an empty board
                    CopyBoard(boards[0], initialPosition);
                } else
-               if(CompareBoards(currentBoard, initialPosition) && !CompareBoards(currentBoard, erasedBoard)) {
+               if(CompareBoards(currentBoard, initialPosition) && !CompareBoards(currentBoard, erasedBoard)
+                                                                && !CompareBoards(nullBoard, erasedBoard)) {
                    CopyBoard(boards[0], erasedBoard);
                } else
                    CopyBoard(erasedBoard, currentBoard);