flutter: 没点击到棋盘点位上则不落子

顺带:
* 人工落子时，黑白交替落子改为只落黑子;
* 解决棋盘初始化位置函数找不到的问题。

src/ui/flutter/lib/game/battle.dart

@@ -38,7 +38,7 @@ class Battle {
   }
 
   newGame() {
-    Battle.shared.position.initDefaultPosition();
+    Battle.shared.position.init();
     _focusIndex = _blurIndex = Move.invalidIndex;
   }
 

src/ui/flutter/lib/mill/position.dart

@@ -94,6 +94,10 @@ class Position {
     _recorder = MillRecorder(lastCapturedPosition: fen());
   }
 
+  init() {
+    Position.init();
+  }
+
   Position.boardToGrid() {
     _grid = List<String>();
     for (int sq = 0; sq < _board.length; sq++) {
@@ -164,9 +168,20 @@ class Position {
     return selectPieceSQ(makeSquare(file, rank));
   }
 
-  void putPiece(var pt, int index) {
+  bool putPiece(var pt, int index) {
+    var sq = indexToSquare[index];
+
+    if (sq == null) {
+      print("putPiece skip index: $index");
+      return false;
+    }
+
     _grid[index] = pt;
-    _board[indexToSquare[index]] = pt;
+    _board[sq] = pt;
+
+    print("putPiece: pt = $pt, index = $index, sq = $sq");
+
+    return true;
   }
 
   bool putPieceFR(int file, int rank) {

src/ui/flutter/lib/routes/battle_page.dart

@@ -51,7 +51,7 @@ class _BattlePageState extends State<BattlePage> {
   String _status = '';
   bool _analysising = false;
 
-  static int flag = 0;
+  //static int flag = 0;
 
   @override
   void initState() {
@@ -72,8 +72,11 @@ class _BattlePageState extends State<BattlePage> {
     final position = Battle.shared.position;
 
     //position
-    flag++;
-    position.putPiece(flag % 2 == 0 ? '@' : 'O', index);
+    //flag++;
+    //position.putPiece(flag % 2 == 0 ? '@' : 'O', index);
+    if (position.putPiece('@', index) == false) {
+      return;
+    }
 
     // 仅 Position 中的 side 指示一方能动棋
     if (position.side != Color.black) return;