From 9c7cb89d6ae88edc97bc99e51fb6779ddf6e33b8 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Sat, 13 Nov 2010 20:02:31 +0100
Subject: [PATCH] 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.
---
 backend.c           |   13 ++++++++++++-
 backend.h           |    1 +
 winboard/winboard.c |    2 +-
 xboard.c            |   11 +++++++++++
 4 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/backend.c b/backend.c
index 05f7dfc..958c92e 100644
--- 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
--- 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
--- 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 )
         board[dragInfo.from.y][dragInfo.from.x] = EmptySquare;
     } else 
-        board[dragInfo.from.y][dragInfo.from.x] = EmptySquare;
+        board[dragInfo.from.y][dragInfo.from.x] = gatingPiece;
   }
 
   /* Figure out which squares need updating by comparing the 
diff --git a/xboard.c b/xboard.c
index d1d00a3..3a39fe0 100644
--- 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;
-- 
1.7.0.4