DroidFish: Improved "one touch move" behavior. Based on patch from Leo Mayer.

DroidFish/res/values/strings.xml

@@ -249,8 +249,8 @@ you are not actively using the program.\
     <string name="prefs_user_interface">User Interface</string>
     <string name="prefs_animateMoves_title">Animate Moves</string>
     <string name="prefs_animateMoves_summary">Animate piece movements</string>
-    <string name="prefs_oneTouchMoves_title">One Touch Moves</string>
+    <string name="prefs_quickMoveInput_title">Quick Move Input</string>
-    <string name="prefs_oneTouchMoves_summary">Touching a square that corresponds to one unique move makes that move immediately</string>
+    <string name="prefs_quickMoveInput_summary">From and To squares can be touched in any order. Move is played as soon as uniquely defined.</string>
     <string name="prefs_soundEnabled_title">Enable Sounds</string>
     <string name="prefs_soundEnabled_summary">Play sound when computer makes a move</string>
     <string name="prefs_vibrateEnabled_title">Enable Vibration</string>

DroidFish/res/xml/preferences.xml

@@ -125,8 +125,8 @@
         </CheckBoxPreference>
         <CheckBoxPreference
             android:key="oneTouchMoves"
-            android:title="@string/prefs_oneTouchMoves_title"
+            android:title="@string/prefs_quickMoveInput_title"
-            android:summary="@string/prefs_oneTouchMoves_summary"
+            android:summary="@string/prefs_quickMoveInput_summary"
             android:defaultValue="false">
         </CheckBoxPreference>
         <CheckBoxPreference

DroidFish/src/org/petero/droidfish/ChessBoard.java

@@ -24,6 +24,7 @@ import java.util.List;
 
 import org.petero.droidfish.gamelogic.Move;
 import org.petero.droidfish.gamelogic.MoveGen;
+import org.petero.droidfish.gamelogic.Pair;
 import org.petero.droidfish.gamelogic.Piece;
 import org.petero.droidfish.gamelogic.Position;
 import org.petero.droidfish.gamelogic.UndoInfo;
@@ -44,6 +45,8 @@ public class ChessBoard extends View {
     public Position pos;
 
     public int selectedSquare;
+    public boolean userSelectedSquare;  // True if selectedSquare was set by user tap/click,
+                                        // false if selectedSquare used to highlight last move
     public float cursorX, cursorY;
     public boolean cursorVisible;
     protected int x0, y0, sqSize;
@@ -88,6 +91,7 @@ public class ChessBoard extends View {
         super(context, attrs);
         pos = new Position();
         selectedSquare = -1;
+        userSelectedSquare = false;
         cursorX = cursorY = 0;
         cursorVisible = false;
         x0 = y0 = sqSize = 0;
@@ -344,6 +348,7 @@ public class ChessBoard extends View {
             selectedSquare = square;
             invalidate();
         }
+        userSelectedSquare = true;
     }
 
     protected int getWidth(int sqSize) { return sqSize * 8; }
@@ -592,13 +597,10 @@ public class ChessBoard extends View {
         if (sq < 0)
             return null;
         cursorVisible = false;
-        if (selectedSquare != -1) {
+        if ((selectedSquare != -1) && !userSelectedSquare)
-            int p = pos.getPiece(selectedSquare);
-            if (!myColor(p)) {
             setSelection(-1); // Remove selection of opponents last moving piece
-            }
-        }
 
+        if (!oneTouchMoves) {
             int p = pos.getPiece(sq);
             if (selectedSquare != -1) {
                 if (sq == selectedSquare)
@@ -606,36 +608,72 @@ public class ChessBoard extends View {
                 if (!myColor(p)) {
                     Move m = new Move(selectedSquare, sq, Piece.EMPTY);
                     setSelection(sq);
+                    userSelectedSquare = false;
                     return m;
+                } else
+                    setSelection(sq);
             } else {
+                if (myColor(p))
                     setSelection(sq);
             }
         } else {
-            if (oneTouchMoves) {
+            int prevSq = userSelectedSquare ? selectedSquare : -1;
+            if (prevSq == sq)
+                return null;
             ArrayList<Move> moves = new MoveGen().legalMoves(pos);
             Move matchingMove = null;
-                int toSq = -1;
+            if (prevSq >= 0)
+                matchingMove = matchingMove(prevSq, sq, moves).first;
+            boolean anyMatch = false;
+            if  (matchingMove == null) {
+                Pair<Move, Boolean> match = matchingMove(-1, sq, moves);
+                matchingMove = match.first;
+                anyMatch = match.second;
+            }
+            if (matchingMove != null) {
+                setSelection(matchingMove.to);
+                userSelectedSquare = false;
+                return matchingMove;
+            }
+            setSelection(anyMatch ? sq : -1);
+        }
+        return null;
+    }
+
+    /**
+     * Determine if there is a unique legal move corresponding to one or two selected squares.
+     * @param sq1   First square, or -1.
+     * @param sq2   Second square.
+     * @param moves List of legal moves.
+     * @return      Matching move if unique.
+     *              Boolean indicating if there was at least one match.
+     */
+    private final Pair<Move, Boolean> matchingMove(int sq1, int sq2, ArrayList<Move> moves) {
+        Move matchingMove = null;
+        boolean anyMatch = false;
         for (Move m : moves) {
-                    if ((m.from == sq) || (m.to == sq)) {
+            boolean match;
+            if (sq1 == -1)
+                match = (m.from == sq2) || (m.to == sq2);
+            else
+                match = (m.from == sq1) && (m.to == sq2) ||
+                        (m.from == sq2) && (m.to == sq1);
+            if (match) {
                 if (matchingMove == null) {
                     matchingMove = m;
-                            toSq = m.to;
+                    anyMatch = true;
+                } else {
+                    if ((matchingMove.from == m.from) &&
+                        (matchingMove.to == m.to)) {
+                        matchingMove.promoteTo = Piece.EMPTY;
                     } else {
                         matchingMove = null;
                         break;
                     }
                 }
             }
-                if (matchingMove != null) {
-                    setSelection(toSq);
-                    return matchingMove;
         }
-            }
+        return new Pair<Move, Boolean>(matchingMove, anyMatch);
-            if (myColor(p)) {
-                setSelection(sq);
-            }
-        }
-        return null;
     }
 
     public static class OnTrackballListener {

DroidFish/src/org/petero/droidfish/DroidFish.java

@@ -476,6 +476,7 @@ public class DroidFish extends Activity implements GUIInterface {
         cb.setDrawSquareLabels(oldCB.drawSquareLabels);
         cb.oneTouchMoves = oldCB.oneTouchMoves;
         setSelection(oldCB.selectedSquare);
+        cb.userSelectedSquare = oldCB.userSelectedSquare;
         setStatusString(statusStr);
         moveListUpdated();
         updateThinkingInfo();
@@ -1175,6 +1176,7 @@ public class DroidFish extends Activity implements GUIInterface {
     @Override
     public void setSelection(int sq) {
         cb.setSelection(sq);
+        cb.userSelectedSquare = false;
         setEgtbHints(sq);
     }
 

DroidFish/src/org/petero/droidfish/activities/EditBoard.java

@@ -91,6 +91,7 @@ public class EditBoard extends Activity {
         cb.cursorVisible = oldCB.cursorVisible;
         cb.setPosition(oldCB.pos);
         setSelection(oldCB.selectedSquare);
+        cb.userSelectedSquare = oldCB.userSelectedSquare;
         status.setText(statusStr);
     }