Implement entering gating moves with mouse

A move with a back-rank piece that starts when a piece in the holdings
is selected will be interpreted as a gating move in variant seirawan.
The front-end uses a 'gatingPiece' selected this way todisplay it on the
from square during animate dragging.

diff --git a/backend.c b/backend.c
index 05f7dfc..958c92e 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -6340,6 +6340,8 @@ Explode(Board board, int fromX, int fromY, int toX, int toY)
     return FALSE;
 }
 
+ChessSquare gatingPiece = EmptySquare; // exported to front-end, for dragging
+
 void LeftClick(ClickType clickType, int xPix, int yPix)
 {
     int x, y;
@@ -6396,6 +6398,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
     autoQueen = appData.alwaysPromoteToQueen;
 
     if (fromX == -1) {
+      gatingPiece = EmptySquare;
       if(!appData.oneClick || !OnlyMove(&x, &y, FALSE)) {
        if (clickType == Press) {
            /* First square */
@@ -6429,7 +6432,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
        /* Check if clicking again on the same color piece */
        fromP = boards[currentMove][fromY][fromX];
        toP = boards[currentMove][y][x];
-       frc = gameInfo.variant == VariantFischeRandom || gameInfo.variant == VariantCapaRandom;
+       frc = gameInfo.variant == VariantFischeRandom || gameInfo.variant == VariantCapaRandom || gameInfo.variant == VariantSChess;
        if ((WhitePawn <= fromP && fromP <= WhiteKing &&
             WhitePawn <= toP && toP <= WhiteKing &&
             !(fromP == WhiteKing && toP == WhiteRook && frc) &&
@@ -6447,6 +6450,11 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
                ClearHighlights();
            }
            if (OKToStartUserMove(x, y)) {
+               if(gameInfo.variant == VariantSChess && // S-Chess: back-rank piece selected after holdings means gating
+                 (fromX == BOARD_LEFT-2 || fromX == BOARD_RGHT+1) &&
+               y == (toP < BlackPawn ? 0 : BOARD_HEIGHT-1))
+                 gatingPiece = boards[currentMove][fromY][fromX];
+               else gatingPiece = EmptySquare;
                fromX = x;
                fromY = y; dragging = 1;
                MarkTargetSquares(0);
@@ -6470,6 +6478,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
            /* Second up/down in same square; just abort move */
            second = 0;
            fromX = fromY = -1;
+           gatingPiece = EmptySquare;
            ClearHighlights();
            gotPremove = 0;
            ClearPremoveHighlights();
@@ -6534,6 +6543,8 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
     // off-board moves should not be highlighted
     if(x < 0 || y < 0) ClearHighlights();
 
+    if(gatingPiece != EmptySquare) promoChoice = ToLower(PieceToChar(gatingPiece));
+
     if (HasPromotionChoice(fromX, fromY, toX, toY, &promoChoice)) {
        SetHighlights(fromX, fromY, toX, toY);
        if(gameInfo.variant == VariantSuper || gameInfo.variant == VariantGreat) {

diff --git a/backend.h b/backend.h
index 6da6323..7e5accd 100644 (file)
--- a/backend.h
+++ b/backend.h
@@ -274,6 +274,7 @@ typedef struct _ListGame {
     GameInfo gameInfo;      /*  Note that some entries may be NULL. */
 } ListGame;
  
+extern ChessSquare gatingPiece;
 extern List gameList;
 void ClearGameInfo P((GameInfo *));
 int GameListBuild P((FILE *));

diff --git a/winboard/winboard.c b/winboard/winboard.c
index e98e516..fcadd27 100644 (file)
--- a/winboard/winboard.c
+++ b/winboard/winboard.c
@@ -3505,7 +3505,7 @@ HDCDrawPosition(HDC hdc, BOOLEAN repaint, Board board)
             if(--board[dragInfo.from.y][dragInfo.from.x-1] == 0 )\r
         board[dragInfo.from.y][dragInfo.from.x] = EmptySquare;\r
     } else \r
-        board[dragInfo.from.y][dragInfo.from.x] = EmptySquare;\r
+        board[dragInfo.from.y][dragInfo.from.x] = gatingPiece;\r
   }\r
 \r
   /* Figure out which squares need updating by comparing the \r

diff --git a/xboard.c b/xboard.c
index d1d00a3..3a39fe0 100644 (file)
--- a/xboard.c
+++ b/xboard.c
@@ -9048,6 +9048,17 @@ DragPieceBegin(x, y)
            XCopyArea(xDisplay, xBoardWindow, player.saveBuf, player.blitGC,
                     corner.x, corner.y, squareSize, squareSize,
                     0, 0); // [HGM] zh: unstack in stead of grab
+           if(gatingPiece != EmptySquare) {
+               /* Kludge alert: When gating we want the introduced
+                  piece to appear on the from square. To generate an
+                  image of it, we draw it on the board, copy the image,
+                  and draw the original piece again. */
+               ChessSquare piece = boards[currentMove][boardY][boardX];
+               DrawSquare(boardY, boardX, gatingPiece, 0);
+               XCopyArea(xDisplay, xBoardWindow, player.saveBuf, player.blitGC,
+                    corner.x, corner.y, squareSize, squareSize, 0, 0);
+               DrawSquare(boardY, boardX, piece, 0);
+           }
        damage[0][boardY][boardX] = True;
     } else {
        player.dragActive = False;