From 66fd3db23545caa404030583316767b938c4f739 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Fri, 8 Jan 2010 13:59:57 +0100
Subject: [PATCH] Indicate squares a lifted piece can legally move to

Under control of the new option -showTargetSquares when
-highlightDragging and -testLegality are on, the squares a piece can
move to are marked by fat dots in the highlightColor (non-captures) and
premoveHighlightColor (captures), as soon as you grab it for dragging.
In variants with mandatory capture, the capture target of other pieces
is marked with the highlightColor (as non-captures are then not allowed).
---
 args.h              |    1 +
 backend.c           |   41 +++++++++++++++++++++++++++++++++++++++++
 backend.h           |    1 +
 common.h            |    3 ++-
 winboard/winboard.c |   14 ++++++++++++++
 xboard.c            |    8 +++++++-
 6 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/args.h b/args.h
index ea1af0e..ff9b55b 100644
--- a/args.h
+++ b/args.h
@@ -573,6 +573,7 @@ ArgDescriptor argDescriptors[] = {
   { "keepAlive", ArgInt, (void *) &appData.keepAlive, FALSE, INVALID },
   { "icstype", ArgInt, (void *) &ics_type, FALSE, INVALID },
   { "forceIllegalMoves", ArgTrue, (void *) &appData.forceIllegal, FALSE, INVALID },
+  { "showTargetSquares", ArgBoolean, (void *) &appData.markers, TRUE, FALSE },
 
 #ifdef ZIPPY
   { "zippyTalk", ArgBoolean, (void *) &appData.zippyTalk, FALSE, (ArgIniType) ZIPPY_TALK },
diff --git a/backend.c b/backend.c
index e65421c..e1b7d9d 100644
--- a/backend.c
+++ b/backend.c
@@ -249,6 +249,7 @@ int lastSavedGame; /* [HGM] save: ID of game */
 char chatPartner[MAX_CHAT][MSG_SIZ]; /* [HGM] chat: list of chatting partners */
 extern int chatCount;
 int chattingPartner;
+char marker[BOARD_RANKS][BOARD_FILES]; /* [HGM] marks for target squares */
 
 /* States for ics_getting_history */
 #define H_FALSE 0
@@ -5634,6 +5635,43 @@ if(appData.debugMode) fprintf(debugFP, "moveType 4 = %d, promochar = %x\n", move
         FinishMove(moveType, fromX, fromY, toX, toY, promoChar);
 }
 
+void
+Mark(board, flags, kind, rf, ff, rt, ft, closure)
+     Board board;
+     int flags;
+     ChessMove kind;
+     int rf, ff, rt, ft;
+     VOIDSTAR closure;
+{
+    typedef char Markers[BOARD_RANKS][BOARD_FILES];
+    Markers *m = (Markers *) closure;
+    if(rf == fromY && ff == fromX)
+	(*m)[rt][ft] = 1 + (board[rt][ft] != EmptySquare
+			 || kind == WhiteCapturesEnPassant
+			 || kind == BlackCapturesEnPassant);
+    else if(flags & F_MANDATORY_CAPTURE && board[rt][ft] != EmptySquare) (*m)[rt][ft] = 3;
+}
+
+void
+MarkTargetSquares(int clear)
+{
+  int x, y;
+  if(!appData.markers || !appData.highlightDragging || 
+     !appData.testLegality || gameMode == EditPosition) return;
+  if(clear) {
+    for(x=0; x<BOARD_WIDTH; x++) for(y=0; y<BOARD_HEIGHT; y++) marker[y][x] = 0;
+  } else {
+    int capt = 0;
+    GenLegal(boards[currentMove], PosFlags(currentMove), Mark, (void*) marker);
+    if(PosFlags(0) & F_MANDATORY_CAPTURE) {
+      for(x=0; x<BOARD_WIDTH; x++) for(y=0; y<BOARD_HEIGHT; y++) if(marker[y][x]>1) capt++;
+      if(capt)
+      for(x=0; x<BOARD_WIDTH; x++) for(y=0; y<BOARD_HEIGHT; y++) if(marker[y][x] == 1) marker[y][x] = 0;
+    }
+  }
+  DrawPosition(TRUE, NULL);
+}
+
 void LeftClick(ClickType clickType, int xPix, int yPix)
 {
     int x, y;
@@ -5642,6 +5680,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
     char promoChoice = NULLCHAR;
 
     if (clickType == Press) ErrorPopDown();
+    MarkTargetSquares(1);
 
     x = EventToSquare(xPix, BOARD_WIDTH);
     y = EventToSquare(yPix, BOARD_HEIGHT);
@@ -5687,6 +5726,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
 		fromX = x;
 		fromY = y;
 		second = 0;
+		MarkTargetSquares(0);
 		DragPieceBegin(xPix, yPix);
 		if (appData.highlightDragging) {
 		    SetHighlights(x, y, -1, -1);
@@ -5727,6 +5767,7 @@ void LeftClick(ClickType clickType, int xPix, int yPix)
 	    if (OKToStartUserMove(x, y)) {
 		fromX = x;
 		fromY = y;
+		MarkTargetSquares(0);
 		DragPieceBegin(xPix, yPix);
 	    }
 	    return;
diff --git a/backend.h b/backend.h
index e310321..18f5c58 100644
--- a/backend.h
+++ b/backend.h
@@ -101,6 +101,7 @@ extern FILE *debugFP;
 extern char* programVersion;
 extern ProcRef firstProgramPR, secondProgramPR;
 extern Board boards[];
+extern char marker[BOARD_RANKS][BOARD_FILES];
 
 char *CmailMsg P((void));
 /* Tord: Added the useFEN960 parameter in PositionToFEN() below */
diff --git a/common.h b/common.h
index 6622a55..0950811 100644
--- a/common.h
+++ b/common.h
@@ -636,7 +636,8 @@ typedef struct {
     Boolean useInternalWrap; /* use internal wrapping -- noJoin usurps this if set */
     Boolean pasteSelection; /* paste X selection instead of clipboard */
     int nrVariations;   /* [HGM] multivar  */
-    Boolean dropMenu;
+    Boolean dropMenu;   /* [HGM] pv        */
+    Boolean markers;    /* [HGM] markers   */
 } AppData, *AppDataPtr;
 
 /* [AS] PGN tags (for showing in the game list) */
diff --git a/winboard/winboard.c b/winboard/winboard.c
index c3dcf97..24edde8 100644
--- a/winboard/winboard.c
+++ b/winboard/winboard.c
@@ -191,6 +191,7 @@ static HBITMAP pieceBitmap[3][(int) BlackPawn]; /* [HGM] nr of bitmaps referred
 static HBRUSH lightSquareBrush, darkSquareBrush,
   blackSquareBrush, /* [HGM] for band between board and holdings */
   explodeBrush,     /* [HGM] atomic */
+  markerBrush,      /* [HGM] markers */
   whitePieceBrush, blackPieceBrush, iconBkgndBrush /*, outlineBrush*/;
 static POINT gridEndpoints[(BOARD_RANKS + BOARD_FILES + 2) * 2];
 static DWORD gridVertexCounts[BOARD_RANKS + BOARD_FILES + 2];
@@ -1853,6 +1854,7 @@ InitDrawingColors()
   blackPieceBrush = CreateSolidBrush(blackPieceColor);
   iconBkgndBrush = CreateSolidBrush(GetSysColor(COLOR_BACKGROUND));
   explodeBrush = CreateSolidBrush(highlightSquareColor); // [HGM] atomic
+  markerBrush = CreateSolidBrush(premoveHighlightColor); // [HGM] markers
   /* [AS] Force rendering of the font-based pieces */
   if( fontBitmapSquareSize > 0 ) {
     fontBitmapSquareSize = 0;
@@ -3312,6 +3314,18 @@ HDCDrawPosition(HDC hdc, BOOLEAN repaint, Board board)
     DrawHighlightsOnDC(hdcmem);
     DrawBoardOnDC(hdcmem, board, tmphdc);
   }
+  for (row = 0; row < BOARD_HEIGHT; row++) {
+    for (column = 0; column < BOARD_WIDTH; column++) {
+	if (marker[row][column]) { // marker changes only occur with full repaint!
+	    HBRUSH oldBrush = SelectObject(hdcmem, 
+			marker[row][column] == 2 ? markerBrush : explodeBrush);
+	    SquareToPos(row, column, &x, &y);
+	    Ellipse(hdcmem, x + squareSize/4, y + squareSize/4,
+		  	  x + 3*squareSize/4, y + 3*squareSize/4);
+	    SelectObject(hdcmem, oldBrush);
+	}
+    }
+  }
   if(logoHeight) {
 	HBITMAP whiteLogo = (HBITMAP) first.programLogo, blackLogo = (HBITMAP) second.programLogo;
 	if(appData.autoLogo) {
diff --git a/xboard.c b/xboard.c
index 840ac50..c2910a3 100644
--- a/xboard.c
+++ b/xboard.c
@@ -49,6 +49,8 @@
  *------------------------------------------------------------------------
  ** See the file ChangeLog for a revision history.  */
 
+#define HIGHDRAG 1
+
 #include "config.h"
 
 #include <stdio.h>
@@ -4197,6 +4199,10 @@ void DrawSquare(row, column, piece, do_flash)
 			x + 2, y + font_ascent + 1, string, 1);
 	}
     }
+    if(marker[row][column]) {
+	XFillArc(xDisplay, xBoardWindow, marker[row][column] == 2 ? prelineGC : highlineGC, 
+		x + squareSize/4, y+squareSize/4, squareSize/2, squareSize/2, 0, 64*360);
+    }
 }
 
 
@@ -8632,7 +8638,7 @@ DragPieceMove(x, y)
     corner.x = x - player.mouseDelta.x;
     corner.y = y - player.mouseDelta.y;
     AnimationFrame(&player, &corner, player.dragPiece);
-#if HIGHDRAG
+#if HIGHDRAG*0
     if (appData.highlightDragging) {
 	int boardX, boardY;
 	BoardSquare(x, y, &boardX, &boardY);
-- 
1.7.0.4