From c487bc03058931c96f8358728286b8db0e711806 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Wed, 3 Jul 2013 16:27:47 +0200
Subject: [PATCH] Implement hover command

When the user hovers a dragged piece over a square marked as a legal
capture target (by R in the highlight command), the engine is notified
by a hover command indicating the square (at the moment the user enters it).
Only send hover when the engine has feature highlight=1.
---
 backend.c           |   22 ++++++++++++++++++++++
 backend.h           |    1 +
 dialogs.c           |    1 +
 winboard/winboard.c |    2 +-
 xboard2.h           |    2 +-
 5 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/backend.c b/backend.c
index abc4495..24ae75d 100644
--- a/backend.c
+++ b/backend.c
@@ -7111,6 +7111,28 @@ CanPromote (ChessSquare piece, int y)
 		piece == WhiteLance && y == BOARD_HEIGHT-2 );
 }
 
+void
+HoverEvent (int hiX, int hiY, int x, int y)
+{
+	static char baseMarker[BOARD_RANKS][BOARD_FILES], baseLegal[BOARD_RANKS][BOARD_FILES];
+	int r, f;
+	if(!first.highlight) return;
+	if(hiX == -1 && hiY == -1 && x == fromX && y == fromY) // record markings 
+	  for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++)
+	    baseMarker[r][f] = marker[r][f], baseLegal[r][f] = legal[r][f];
+	else if(hiX != x || hiY != y) {
+	  // [HGM] lift: entered new to-square; redraw arrow, and inform engine
+	  for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++)
+	    marker[r][f] = baseMarker[r][f], legal[r][f] = baseLegal[r][f];
+	  if(marker[y][x] == 2 && legal[y][x] == 1) {
+	    char buf[MSG_SIZ];
+	    snprintf(buf, MSG_SIZ, "hover %c%d\n", x + AAA, y + ONE - '0');
+	    SendToProgram(buf, &first);
+	  }
+	  SetHighlights(fromX, fromY, x, y);
+	}
+}
+
 void ReportClick(char *action, int x, int y)
 {
 	char buf[MSG_SIZ]; // Inform engine of what user does
diff --git a/backend.h b/backend.h
index edb615c..6b750df 100644
--- a/backend.h
+++ b/backend.h
@@ -241,6 +241,7 @@ int PromoScroll P((int x, int y));
 void EditBookEvent P((void));
 Boolean DisplayBook P((int moveNr));
 void SaveToBook P((char *text));
+void HoverEvent P((int hiX, int hiY, int x, int y));
 int PackGame P((Board board));
 Boolean ParseFEN P((Board board, int *blackPlaysFirst, char *fen));
 void ApplyMove P((int fromX, int fromY, int toX, int toY, int promoChar, Board board));
diff --git a/dialogs.c b/dialogs.c
index 96f85e2..a7d30f6 100644
--- a/dialogs.c
+++ b/dialogs.c
@@ -2144,6 +2144,7 @@ Exp (int n, int x, int y)
 	if(SeekGraphClick(Press, x, y, 1)) return NULL;
 	if(but1 && !PromoScroll(x, y)) DragPieceMove(x, y);
 	if(but3) MovePV(x, y, lineGap + BOARD_HEIGHT * (squareSize + lineGap));
+	if(appData.highlightDragging) HoverEvent(hi2X, hi2Y, x, y);
 	return NULL;
     }
     if(n != 10 && PopDown(PromoDlg)) fromX = fromY = -1; // user starts fiddling with board when promotion dialog is up
diff --git a/winboard/winboard.c b/winboard/winboard.c
index 7bd391d..2b13222 100644
--- a/winboard/winboard.c
+++ b/winboard/winboard.c
@@ -4302,7 +4302,7 @@ MouseEvent(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
 	dragInfo.pos = pt;
       }
       if (appData.highlightDragging) {
-	SetHighlights(fromX, fromY, x, y);
+	HoverEvent(highlightInfo.sq[1].x, highlightInfo.sq[1].y, x, y);
         if( IsDrawArrowEnabled() && (x < 0 || x >= BOARD_WIDTH || y < 0 || y >= BOARD_HEIGHT) ) {
             full_repaint = TRUE;
         }
diff --git a/xboard2.h b/xboard2.h
index 98aec80..825b0f2 100644
--- a/xboard2.h
+++ b/xboard2.h
@@ -6,4 +6,4 @@ extern int searchTime;
 extern int squareSize, lineGap, defaultLineGap;
 extern int startedFromPositionFile;
 extern char *icsTextMenuString;
-
+extern int hi2X, hi2Y;
-- 
1.7.0.4