diff --git a/src/ui/flutter/lib/common/misc.dart b/src/ui/flutter/lib/common/algorithm.dart
similarity index 99%
rename from src/ui/flutter/lib/common/misc.dart
rename to src/ui/flutter/lib/common/algorithm.dart
index 8f12475d..7a6e5e2b 100644
--- a/src/ui/flutter/lib/common/misc.dart
+++ b/src/ui/flutter/lib/common/algorithm.dart
@@ -20,7 +20,6 @@
 abs(value) => value > 0 ? value : -value;
 
 int binarySearch(List<int> array, int start, int end, int key) {
-  //
   if (start > end) return -1;
 
   if (array[start] == key) return start;
diff --git a/src/ui/flutter/lib/common/config.dart b/src/ui/flutter/lib/common/config.dart
index 995028da..702ea4bd 100644
--- a/src/ui/flutter/lib/common/config.dart
+++ b/src/ui/flutter/lib/common/config.dart
@@ -20,29 +20,26 @@
 import 'profile.dart';
 
 class Config {
-  //
   static bool bgmEnabled = false;
   static bool toneEnabled = true;
-  static int stepTime = 5000;
+  static int thinkingTime = 5000;
 
   static Future<void> loadProfile() async {
-    //
     final profile = await Profile.shared();
 
     Config.bgmEnabled = profile['bgm-enabled'] ?? false;
     Config.toneEnabled = profile['tone-enabled'] ?? true;
-    Config.stepTime = profile['step-time'] ?? 5000;
+    Config.thinkingTime = profile['thinking-time'] ?? 5000;
 
     return true;
   }
 
   static Future<bool> save() async {
-    //
     final profile = await Profile.shared();
 
     profile['bgm-enabled'] = Config.bgmEnabled;
     profile['tone-enabled'] = Config.toneEnabled;
-    profile['step-time'] = Config.stepTime;
+    profile['thinking-time'] = Config.thinkingTime;
 
     profile.commit();
 
diff --git a/src/ui/flutter/lib/common/profile.dart b/src/ui/flutter/lib/common/profile.dart
index fbd7867a..30ff2db7 100644
--- a/src/ui/flutter/lib/common/profile.dart
+++ b/src/ui/flutter/lib/common/profile.dart
@@ -23,18 +23,16 @@ import 'dart:io';
 import 'package:path_provider/path_provider.dart';
 
 class Profile {
-  //
-  static const DefaultFileName = 'default-profile.json';
+  static const defaultFileName = 'default-profile.json';
   static Profile _shared;
 
   File _file;
   Map<String, dynamic> _values = {};
 
   static shared() async {
-    //
     if (_shared == null) {
       _shared = Profile();
-      await _shared._load(DefaultFileName);
+      await _shared._load(defaultFileName);
     }
 
     return _shared;
@@ -45,7 +43,6 @@ class Profile {
   operator []=(String key, dynamic value) => _values[key] = value;
 
   Future<bool> commit() async {
-    //
     _file.create(recursive: true);
 
     try {
@@ -60,7 +57,6 @@ class Profile {
   }
 
   Future<bool> _load(String fileName) async {
-    //
     final docDir = await getApplicationDocumentsDirectory();
     _file = File('${docDir.path}/$fileName');
 
diff --git a/src/ui/flutter/lib/engine/analysis.dart b/src/ui/flutter/lib/engine/analyze.dart
similarity index 65%
rename from src/ui/flutter/lib/engine/analysis.dart
rename to src/ui/flutter/lib/engine/analyze.dart
index 9de1590b..c14aa6dc 100644
--- a/src/ui/flutter/lib/engine/analysis.dart
+++ b/src/ui/flutter/lib/engine/analyze.dart
@@ -17,41 +17,37 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-class AnalysisItem {
-  //
-  String move, stepName;
+class AnalyzeItem {
+  String move, moveName;
   int score;
-  double winrate;
+  double winRate;
 
-  AnalysisItem({this.move, this.score, this.winrate});
+  AnalyzeItem({this.move, this.score, this.winRate});
 
   @override
   String toString() {
-    return '{move: ${stepName ?? move}, score: $score, winrate: $winrate}';
+    return '{move: ${moveName ?? move}, score: $score, winRate: $winRate}';
   }
 }
 
-class AnalysisFetcher {
-  //
-  static List<AnalysisItem> fetch(String response, {limit = 5}) {
-    //
+class AnalyzeFetcher {
+  static List<AnalyzeItem> fetch(String response, {limit = 5}) {
     final segments = response.split('|');
 
-    List<AnalysisItem> result = [];
+    List<AnalyzeItem> result = [];
 
-    final regx = RegExp(r'move:(.{4}).+score:(\-?\d+).+winrate:(\d+.?\d*)');
+    final regExp = RegExp(r'move:(.{4}).+score:(\-?\d+).+winRate:(\d+.?\d*)');
 
     for (var segment in segments) {
-      //
-      final match = regx.firstMatch(segment);
+      final match = regExp.firstMatch(segment);
 
       if (match == null) break;
 
       final move = match.group(1);
       final score = int.parse(match.group(2));
-      final winrate = double.parse(match.group(3));
+      final winRate = double.parse(match.group(3));
 
-      result.add(AnalysisItem(move: move, score: score, winrate: winrate));
+      result.add(AnalyzeItem(move: move, score: score, winRate: winRate));
       if (result.length == limit) break;
     }
 
diff --git a/src/ui/flutter/lib/engine/engine.dart b/src/ui/flutter/lib/engine/engine.dart
index 42dff9e7..bad829a3 100644
--- a/src/ui/flutter/lib/engine/engine.dart
+++ b/src/ui/flutter/lib/engine/engine.dart
@@ -17,7 +17,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import '../mill/position.dart';
+import 'package:sanmill/mill/position.dart';
 
 enum EngineType { Cloud, Native }
 
@@ -28,10 +28,7 @@ class EngineResponse {
 }
 
 abstract class AiEngine {
-  //
   Future<void> startup() async {}
-
   Future<void> shutdown() async {}
-
   Future<EngineResponse> search(Position position, {bool byUser = true});
 }
diff --git a/src/ui/flutter/lib/engine/native_engine.dart b/src/ui/flutter/lib/engine/native_engine.dart
index da3d0419..54b72b69 100644
--- a/src/ui/flutter/lib/engine/native_engine.dart
+++ b/src/ui/flutter/lib/engine/native_engine.dart
@@ -18,30 +18,25 @@
 */
 
 import 'package:flutter/services.dart';
+import 'package:sanmill/mill/mill.dart';
+import 'package:sanmill/mill/position.dart';
 
-import '../mill/mill.dart';
-import '../mill/position.dart';
 import 'engine.dart';
 
 class NativeEngine extends AiEngine {
-  //
   static const platform = const MethodChannel('com.calcitem.sanmill/engine');
 
   Future<void> startup() async {
-    //
     try {
       await platform.invokeMethod('startup');
     } catch (e) {
       print('Native startup Error: $e');
     }
 
-    //await setBookFile();
-
     await waitResponse(['uciok'], sleep: 1, times: 30);
   }
 
   Future<void> send(String command) async {
-    //
     try {
       print("send: $command");
       await platform.invokeMethod('send', command);
@@ -51,7 +46,6 @@ class NativeEngine extends AiEngine {
   }
 
   Future<String> read() async {
-    //
     try {
       return await platform.invokeMethod('read');
     } catch (e) {
@@ -62,7 +56,6 @@ class NativeEngine extends AiEngine {
   }
 
   Future<void> shutdown() async {
-    //
     try {
       await platform.invokeMethod('shutdown');
     } catch (e) {
@@ -71,7 +64,6 @@ class NativeEngine extends AiEngine {
   }
 
   Future<bool> isReady() async {
-    //
     try {
       return await platform.invokeMethod('isReady');
     } catch (e) {
@@ -82,7 +74,6 @@ class NativeEngine extends AiEngine {
   }
 
   Future<bool> isThinking() async {
-    //
     try {
       return await platform.invokeMethod('isThinking');
     } catch (e) {
@@ -92,32 +83,11 @@ class NativeEngine extends AiEngine {
     return null;
   }
 
-/*
-  Future setBookFile() async {
-    //
-    final docDir = await getApplicationDocumentsDirectory();
-    final bookFile = File('${docDir.path}/book.dat');
-
-    try {
-      if (!await bookFile.exists()) {
-        await bookFile.create(recursive: true);
-        final bytes = await rootBundle.load("assets/book.dat");
-        await bookFile.writeAsBytes(bytes.buffer.asUint8List());
-      }
-    } catch (e) {
-      print(e);
-    }
-
-    await send("setoption bookfiles ${bookFile.path}");
-  }
-  */
-
   @override
   Future<EngineResponse> search(Position position, {bool byUser = true}) async {
-    //
     if (await isThinking()) await stopSearching();
 
-    send(buildPositionCommand(position));
+    send(getPositionFen(position));
     send('go');
 
     final response = await waitResponse(['bestmove', 'nobestmove']);
@@ -125,13 +95,12 @@ class NativeEngine extends AiEngine {
     print("response: $response");
 
     if (response.startsWith('bestmove')) {
-      //
-      var step = response.substring('bestmove'.length + 1);
+      var best = response.substring('bestmove'.length + 1);
 
-      final pos = step.indexOf(' ');
-      if (pos > -1) step = step.substring(0, pos);
+      final pos = best.indexOf(' ');
+      if (pos > -1) best = best.substring(0, pos);
 
-      return EngineResponse('move', value: Move.fromEngineMove(step));
+      return EngineResponse('move', value: Move.set(best));
     }
 
     if (response.startsWith('nobestmove')) {
@@ -143,7 +112,6 @@ class NativeEngine extends AiEngine {
 
   Future<String> waitResponse(List<String> prefixes,
       {sleep = 100, times = 100}) async {
-    //
     if (times <= 0) return '';
 
     final response = await read();
@@ -164,7 +132,7 @@ class NativeEngine extends AiEngine {
     await send('stop');
   }
 
-  String buildPositionCommand(Position position) {
+  String getPositionFen(Position position) {
     /*
     final startPosition = position.lastCapturedPosition;
     final moves = position.movesSinceLastCaptured();
diff --git a/src/ui/flutter/lib/main.dart b/src/ui/flutter/lib/main.dart
index f9cb5ad4..1d7fadce 100644
--- a/src/ui/flutter/lib/main.dart
+++ b/src/ui/flutter/lib/main.dart
@@ -22,9 +22,9 @@ import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
-import './routes/main_menu.dart';
 import 'services/audios.dart';
 import 'services/player.dart';
+import 'widgets/main_menu.dart';
 
 void main() {
   //
diff --git a/src/ui/flutter/lib/game/battle.dart b/src/ui/flutter/lib/mill/game.dart
similarity index 67%
rename from src/ui/flutter/lib/game/battle.dart
rename to src/ui/flutter/lib/mill/game.dart
index 6f97ff31..2caf220a 100644
--- a/src/ui/flutter/lib/game/battle.dart
+++ b/src/ui/flutter/lib/mill/game.dart
@@ -17,14 +17,13 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:sanmill/common/types.dart';
+import 'package:sanmill/mill/types.dart';
 
-import '../mill/mill.dart';
-import '../mill/position.dart';
+import 'mill.dart';
+import 'position.dart';
 
-class Battle {
-  //
-  static Battle _instance;
+class Game {
+  static Game _instance;
 
   Position _position;
   int _focusIndex, _blurIndex;
@@ -32,21 +31,16 @@ class Battle {
   String sideToMove = Color.black;
 
   // 是否黑白反转
-  bool isInverted;
+  bool isColorInverted;
 
-  Map<String, bool> isAiPlayer = {Color.black: false, Color.white: true};
-  Map<String, bool> isAiSearching = {Color.black: false, Color.white: false};
-
-  Battle() {
-    //cmdlist = new List;
-  }
+  Map<String, bool> isAi = {Color.black: false, Color.white: true};
+  Map<String, bool> isSearching = {Color.black: false, Color.white: false};
 
   bool aiIsSearching() {
-    return isAiSearching[Color.black] == true ||
-        isAiSearching[Color.white] == true;
+    return isSearching[Color.black] == true || isSearching[Color.white] == true;
   }
 
-  void gameStart() {
+  void start() {
     position.start();
   }
 
@@ -60,7 +54,7 @@ class Battle {
   static bool hasSound = true;
 
   // 是否必败时认输
-  bool resignIfMostLose_ = false;
+  bool resignIfMostLose = false;
 
   // 是否自动交换先后手
   bool isAutoChangeFirstMove = false;
@@ -74,34 +68,34 @@ class Battle {
   // 提示语
   String tips;
 
-  List<String> cmdlist = [""];
+  List<String> moveHistory = [""];
 
   String getTips() => tips;
 
-  bool isAIsTurn() {
-    return isAiPlayer[sideToMove];
+  bool isAiToMove() {
+    return isAi[sideToMove];
   }
 
   static get shared {
-    _instance ??= Battle();
+    _instance ??= Game();
     return _instance;
   }
 
   init() {
     _position = Position();
-    _focusIndex = _blurIndex = Move.invalidValue;
+    _focusIndex = _blurIndex = Move.invalidMove;
   }
 
   newGame() {
-    Battle.shared.position.init();
-    _focusIndex = _blurIndex = Move.invalidValue;
-    cmdlist = [""];
+    Game.shared.position.init();
+    _focusIndex = _blurIndex = Move.invalidMove;
+    moveHistory = [""];
     sideToMove = Color.black;
   }
 
   select(int pos) {
     _focusIndex = pos;
-    _blurIndex = Move.invalidValue;
+    _blurIndex = Move.invalidMove;
     //Audios.playTone('click.mp3');
   }
 
@@ -112,30 +106,23 @@ class Battle {
     _blurIndex = from;
     _focusIndex = to;
 
-    /*
-    if (ChessRules.checked(position)) {
-      //Audios.playTone('check.mp3');
-    } else {
-      //Audios.playTone(captured != Piece.Empty ? 'capture.mp3' : 'move.mp3');
-    }
-     */
-
     return true;
   }
 
-  bool regret({steps = 2}) {
+  bool regret({moves = 2}) {
     //
     // 轮到自己走棋的时候，才能悔棋
+    // TODO
     if (_position.side != Color.white) {
       //Audios.playTone('invalid.mp3');
       return false;
     }
 
-    var regreted = false;
+    var regretted = false;
 
     /// 悔棋一回合（两步），才能撤回自己上一次的动棋
 
-    for (var i = 0; i < steps; i++) {
+    for (var i = 0; i < moves; i++) {
       //
       if (!_position.regret()) break;
 
@@ -148,13 +135,13 @@ class Battle {
         //
       } else {
         //
-        _blurIndex = _focusIndex = Move.invalidValue;
+        _blurIndex = _focusIndex = Move.invalidMove;
       }
 
-      regreted = true;
+      regretted = true;
     }
 
-    if (regreted) {
+    if (regretted) {
       //Audios.playTone('regret.mp3');
       return true;
     }
@@ -164,7 +151,7 @@ class Battle {
   }
 
   clear() {
-    _blurIndex = _focusIndex = Move.invalidValue;
+    _blurIndex = _focusIndex = Move.invalidMove;
   }
 
   GameResult scanBattleResult() {
@@ -196,12 +183,12 @@ class Battle {
 
     // 如果未开局则开局
     if (position.phase == Phase.ready) {
-      gameStart();
+      start();
     }
 
     print("Computer: $cmd");
 
-    cmdlist.add(cmd);
+    moveHistory.add(cmd);
 
     if (!position.command(cmd)) {
       return false;
@@ -209,30 +196,6 @@ class Battle {
 
     sideToMove = position.sideToMove();
 
-    String winner = position.winner;
-
-    if (winner != Color.nobody) {
-      //resumeAiThreads(position.sideToMove());
-      // TODO
-    } else {
-      // pauseThreads();
-
-      /*
-                  if (gameOptions.getAutoRestart()) {
-                saveScore();
-
-                gameReset();
-                gameStart();
-
-                if (isAiPlayer[BLACK]) {
-                    setEngine(BLACK, true);
-                }
-                if (isAiPlayer[WHITE]) {
-                    setEngine(WHITE, true);
-                }
-            }
-       */
-    }
     total = position.score[Color.black] +
         position.score[Color.white] +
         position.score[Color.draw];
@@ -247,7 +210,7 @@ class Battle {
       drawRate = position.score[Color.draw] * 100 / total;
     }
 
-    String outStr = "Score: " +
+    String stat = "Score: " +
         position.score[Color.black].toString() +
         " : " +
         position.score[Color.white].toString() +
@@ -264,7 +227,7 @@ class Battle {
         "%" +
         "\n";
 
-    print(outStr);
+    print(stat);
     return true;
   }
 }
diff --git a/src/ui/flutter/lib/mill/mill.dart b/src/ui/flutter/lib/mill/mill.dart
index 5686f1f9..9dda9c32 100644
--- a/src/ui/flutter/lib/mill/mill.dart
+++ b/src/ui/flutter/lib/mill/mill.dart
@@ -17,7 +17,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:sanmill/common/types.dart';
+import 'types.dart';
 
 Map<int, int> squareToIndex = {
   8: 17,
@@ -56,7 +56,6 @@ int makeSquare(int file, int rank) {
 enum GameResult { pending, win, lose, draw }
 
 class Color {
-  //
   static const none = '*';
   static const black = '@';
   static const white = 'O';
@@ -85,24 +84,19 @@ class Color {
 }
 
 class Piece {
-  //
-  static const noPiece = '*';
-  //
-  static const blackStone = '@';
-  static const whiteStone = 'O';
-  static const ban = 'X';
+  static const noPiece = Color.none;
+  static const blackStone = Color.black;
+  static const whiteStone = Color.white;
+  static const ban = Color.ban;
 
-  static bool isBlack(String c) => '@'.contains(c);
-
-  static bool isWhite(String c) => 'O'.contains(c);
-
-  static bool isBan(String c) => 'X'.contains(c);
-
-  static bool isEmpty(String c) => '*'.contains(c);
+  static bool isEmpty(String c) => noPiece.contains(c);
+  static bool isBlack(String c) => blackStone.contains(c);
+  static bool isWhite(String c) => whiteStone.contains(c);
+  static bool isBan(String c) => ban.contains(c);
 }
 
 class Move {
-  static const invalidValue = -1;
+  static const invalidMove = -1;
 
   // Square
   int from = 0;
@@ -118,7 +112,7 @@ class Move {
   int fromIndex = 0;
   int toIndex = 0;
 
-  String captured;
+  String removed;
 
   // 'move' is the UCI engine's move-string
   String move;
@@ -129,13 +123,13 @@ class Move {
   String counterMarks;
 
   parse() {
-    if (!validateEngineMove(move)) {
+    if (!legal(move)) {
       throw "Error: Invalid Move: $move";
     }
 
     if (move[0] == '-' && move.length == "-(1,2)".length) {
       type = MoveType.remove;
-      from = fromFile = fromRank = fromIndex = invalidValue;
+      from = fromFile = fromRank = fromIndex = invalidMove;
       toFile = int.parse(move[2]);
       toRank = int.parse(move[4]);
       //captured = Piece.noPiece;
@@ -147,13 +141,13 @@ class Move {
       fromIndex = squareToIndex[from];
       toFile = int.parse(move[8]);
       toRank = int.parse(move[10]);
-      captured = Piece.noPiece;
+      removed = Piece.noPiece;
     } else if (move.length == "(1,2)".length) {
       type = MoveType.place;
-      from = fromFile = fromRank = fromIndex = invalidValue;
+      from = fromFile = fromRank = fromIndex = invalidMove;
       toFile = int.parse(move[1]);
       toRank = int.parse(move[3]);
-      captured = Piece.noPiece;
+      removed = Piece.noPiece;
     } else if (move == "draw") {
       // TODO
       print("Computer request draw");
@@ -169,44 +163,24 @@ class Move {
     parse();
   }
 
-  /*
-  Move(this.from, this.to,
-      {this.captured = Piece.noPiece, this.counterMarks = '0 0'}) {
-    //
-    fx = from % 9;
-    fy = from ~/ 9;
-
-    tx = to % 9;
-    ty = to ~/ 9;
-
-    if (fx < 0 || fx > 8 || fy < 0 || fy > 9) {
-      throw "Error: Invalid Step (from:$from, to:$to)";
-    }
-
-    move = String.fromCharCode('a'.codeUnitAt(0) + fx) + (9 - fy).toString();
-    move += String.fromCharCode('a'.codeUnitAt(0) + tx) + (9 - ty).toString();
-  }
-  */
-
   /// 引擎返回的招法用是如此表示的，例如:
   /// 落子：(1,2)
   /// 吃子：-(1,2)
   /// 走子：(3,1)->(2,1)
 
-  Move.fromEngineMove(String move) {
-    //
+  Move.set(String move) {
     this.move = move;
     parse();
   }
 
-  static bool validateEngineMove(String move) {
+  static bool legal(String move) {
     if (move == "draw") {
       return true; // TODO
     }
 
     if (move == null || move.length > "(3,1)->(2,1)".length) return false;
 
-    String sets = "0123456789(,)->";
+    String range = "0123456789(,)->";
 
     if (!(move[0] == '(' || move[0] == '-')) {
       return false;
@@ -217,7 +191,13 @@ class Move {
     }
 
     for (int i = 0; i < move.length; i++) {
-      if (!sets.contains(move[i])) return false;
+      if (!range.contains(move[i])) return false;
+    }
+
+    if (move.length == "(3,1)->(2,1)".length) {
+      if (move.substring(0, 4) == move.substring(7, 11)) {
+        return false;
+      }
     }
 
     return true;
diff --git a/src/ui/flutter/lib/mill/position.dart b/src/ui/flutter/lib/mill/position.dart
index 8b13388a..aa5585bd 100644
--- a/src/ui/flutter/lib/mill/position.dart
+++ b/src/ui/flutter/lib/mill/position.dart
@@ -18,11 +18,11 @@
 */
 
 import 'package:flutter/cupertino.dart';
+import 'package:sanmill/mill/mill.dart';
+import 'package:sanmill/mill/recorder.dart';
+import 'package:sanmill/mill/rule.dart';
 
-import '../common/types.dart';
-import '../mill/mill.dart';
-import '../mill/recorder.dart';
-import '../mill/rule.dart';
+import 'types.dart';
 
 class StateInfo {
   /*
@@ -44,10 +44,10 @@ class Position {
 
   GameResult result = GameResult.pending;
 
-  List<String> board = List<String>(40);
-  List<String> _grid = List<String>(49); // 7  *  7
+  List<String> board = List<String>(sqNumber);
+  List<String> _grid = List<String>(7 * 7);
 
-  MillRecorder _recorder;
+  GameRecorder _recorder;
 
   Map<String, int> pieceCountInHand = {Color.black: 12, Color.white: 12};
   Map<String, int> pieceCountOnBoard = {Color.black: 0, Color.white: 0};
@@ -64,6 +64,7 @@ class Position {
   String us = Color.black;
   String them = Color.white;
   String winner = Color.nobody;
+
   GameOverReason gameOverReason = GameOverReason.noReason;
 
   Phase phase = Phase.none;
@@ -145,57 +146,9 @@ class Position {
     return pieceOn(fromSq(move));
   }
 
-  bool selectPieceFR(int file, int rank) {
-    return selectPieceSQ(makeSquare(file, rank));
-  }
-
-  bool putPieceFR(int file, int rank) {
-    bool ret = putPieceSQ(makeSquare(file, rank));
-
-    if (ret) {
-      updateScore();
-    }
-
-    return ret;
-  }
-
-  bool movePieceFR(int file1, int rank1, int file2, int rank2) {
-    return movePieceSQ(makeSquare(file1, rank1), makeSquare(file2, rank2));
-  }
-
-  bool removePieceFR(int file, int rank) {
-    bool ret = removePieceSQ(makeSquare(file, rank));
-
-    if (ret) {
-      updateScore();
-    }
-
-    return ret;
-  }
-
-  bool selectPieceSQ(int sq) {
-    // TODO
-    return false;
-  }
-
-  bool putPieceSQ(int sq) {
-    // TODO
-    return false;
-  }
-
-  bool movePieceSQ(int fromSq, int toSq) {
-    // TODO
-    return false;
-  }
-
-  bool removePieceSQ(int sq) {
-    // TODO
-    return false;
-  }
-
-  bool movePiece(int fromSq, int toSq) {
-    if (selectPiece(fromSq)) {
-      return putPiece(toSq);
+  bool movePiece(int from, int to) {
+    if (selectPiece(from)) {
+      return putPiece(to);
     }
 
     return false;
@@ -219,7 +172,7 @@ class Position {
 
     // TODO
 
-    _recorder = MillRecorder(lastCapturedPosition: fen());
+    _recorder = GameRecorder(lastPositionWithRemove: fen());
   }
 
   Position() {
@@ -227,41 +180,6 @@ class Position {
     init();
   }
 
-  void set(String fenStr) {
-    /*
-       A FEN string defines a particular position using only the ASCII character set.
-
-       A FEN string contains six fields separated by a space. The fields are:
-
-       1) Piece placement. Each rank is described, starting
-          with rank 1 and ending with rank 8. Within each rank, the contents of each
-          square are described from file A through file C. Following the Standard
-          Algebraic Notation (SAN), each piece is identified by a single letter taken
-          from the standard English names. White pieces are designated using "O"
-          whilst Black uses "@". Blank uses "*". Banned uses "X".
-          noted using digits 1 through 8 (the number of blank squares), and "/"
-          separates ranks.
-
-       2) Active color. "w" means white moves next, "b" means black.
-
-       3) Phrase.
-
-       4) Action.
-
-       5) Black on board/Black in hand/White on board/White in hand/need to remove
-
-       6) Halfmove clock. This is the number of halfmoves since the last
-          capture. This is used to determine if a draw can be claimed under the
-          fifty-move rule.
-
-       7) Fullmove number. The number of the full move. It starts at 1, and is
-          incremented after Black's move.
-    */
-
-    // TODO
-    return;
-  }
-
   /// fen() returns a FEN representation of the position.
 
   String fen() {
@@ -354,19 +272,19 @@ class Position {
 
   /// Position::legal() tests whether a pseudo-legal move is legal
 
-  bool legal(int move) {
-    assert(isOk(move));
+  bool legal(Move move) {
+    if (!isOk(move.from) || !isOk(move.to)) return false;
 
     String us = _sideToMove;
-    int fromSQ = fromSq(move);
-    int toSQ = toSq(move);
 
-    if (fromSQ == toSQ) {
+    if (move.from == move.to) {
+      print("Move $move.move from == to");
       return false; // TODO: Same with is_ok(m)
     }
 
-    if (phase == Phase.moving && typeOf(move) != MoveType.remove) {
-      if (movedPiece(move) != us) {
+    if (move.type == MoveType.remove) {
+      if (movedPiece(move.to) != us) {
+        print("Move $move.to to != us");
         return false;
       }
     }
@@ -376,20 +294,10 @@ class Position {
     return true;
   }
 
-  /// Position::pseudo_legal() takes a random move and tests whether the move is
-  /// pseudo legal. It is used to validate moves from TT that can be corrupted
-  /// due to SMP concurrent access or hash position key aliasing.
-
-  bool pseudoLegal(int move) {
-    // TODO
-    return legal(move);
-  }
-
   void doMove(Move m) {
-    //
-    //if (!validateMove(m)) return null;
-
-    //final move = Move(m);
+    if (!legal(m)) {
+      return null;
+    }
 
     bool ret = false;
 
@@ -421,22 +329,11 @@ class Position {
 
     this.move = m;
 
-    //StepName.translate(this, move);
-    _recorder.stepIn(move, this);
-
-    // 交换走棋方
-    //_sideToMove = Color.opponent(_sideToMove);
-  }
-
-  void doNullMove() {
-    changeSideToMove();
-  }
-
-  void undoNullMove() {
-    changeSideToMove();
+    _recorder.moveIn(move, this);
   }
 
   bool posIsOk() {
+    // TODO
     return true;
   }
 
@@ -445,9 +342,9 @@ class Position {
   int piecesOnBoardCount() {
     pieceCountOnBoard[Color.black] = pieceCountOnBoard[Color.white] = 0;
 
-    for (int f = 1; f < 3 + 2; f++) {
-      for (int r = 0; r < 8; r++) {
-        int s = f * 8 + r;
+    for (int f = 1; f < fileExNumber; f++) {
+      for (int r = 0; r < rankNumber; r++) {
+        int s = f * rankNumber + r;
         if (board[s] == Piece.blackStone) {
           pieceCountOnBoard[Color.black]++;
         } else if (board[s] == Piece.whiteStone) {
@@ -473,6 +370,16 @@ class Position {
     return pieceCountOnBoard[Color.black] + pieceCountOnBoard[Color.white];
   }
 
+  void clearBoard() {
+    for (int i = 0; i < _grid.length; i++) {
+      _grid[i] = Piece.noPiece;
+    }
+
+    for (int i = 0; i < board.length; i++) {
+      board[i] = Piece.noPiece;
+    }
+  }
+
   int setPosition(Rule newRule) {
     result = GameResult.pending;
 
@@ -490,13 +397,7 @@ class Position {
 
     cmdline = "";
 
-    for (int i = 0; i < _grid.length; i++) {
-      _grid[i] = Piece.noPiece;
-    }
-
-    for (int i = 0; i < board.length; i++) {
-      board[i] = Piece.noPiece;
-    }
+    clearBoard();
 
     if (piecesOnBoardCount() == -1) {
       return -1;
@@ -509,6 +410,7 @@ class Position {
     createMoveTable();
     createMillTable();
     currentSquare = 0;
+
     return -1;
   }
 
@@ -523,13 +425,7 @@ class Position {
     winner = Color.nobody;
     gameOverReason = GameOverReason.noReason;
 
-    for (int i = 0; i < _grid.length; i++) {
-      _grid[i] = Piece.noPiece;
-    }
-
-    for (int i = 0; i < board.length; i++) {
-      board[i] = Piece.noPiece;
-    }
+    clearBoard();
 
     pieceCountOnBoard[Color.black] = pieceCountOnBoard[Color.white] = 0;
     pieceCountInHand[Color.black] =
@@ -761,13 +657,13 @@ class Position {
     return true;
   }
 
-  bool selectPiece(int s) {
+  bool selectPiece(int sq) {
     if (phase != Phase.moving) return false;
 
     if (action != Act.select && action != Act.place) return false;
 
-    if (board[s] == sideToMove()) {
-      currentSquare = s;
+    if (board[sq] == sideToMove()) {
+      currentSquare = sq;
       action = Act.place;
 
       return true;
@@ -793,18 +689,19 @@ class Position {
   bool command(String cmd) {
     // TODO
     /*
-  if (sscanf(cmd, "r%1u s%3d t%2u", &ruleIndex, &step, &t) == 3) {
-    if (ruleIndex <= 0 || ruleIndex > N_RULES) {
-      return false;
-    }
+    if (sscanf(cmd, "r%1u s%3d t%2u", &ruleIndex, &step, &t) == 3) {
+      if (ruleIndex <= 0 || ruleIndex > N_RULES) {
+        return false;
+      }
 
-    return set_position(&RULES[ruleIndex - 1]) >= 0 ? true : false;
-  }
+      return set_position(&RULES[ruleIndex - 1]) >= 0 ? true : false;
+    }
   */
     print("position: command = $cmd");
 
-    if (cmd.length > 6 && cmd.substring(0, 5) == "Player") {
-      if (cmd[6] == '1') {
+    if (cmd.length > "Player".length &&
+        cmd.substring(0, "Player".length - 1) == "Player") {
+      if (cmd["Player".length] == '1') {
         return resign(Color.black);
       } else {
         return resign(Color.white);
@@ -1449,7 +1346,7 @@ class Position {
 
   int inHowManyMills(int s, String c, {int squareSelected = 0}) {
     int n = 0;
-    String locbak = Piece.noPiece;
+    String ptBak = Piece.noPiece;
 
     assert(0 <= squareSelected && squareSelected < sqNumber);
 
@@ -1458,20 +1355,19 @@ class Position {
     }
 
     if (squareSelected != 0) {
-      locbak = board[squareSelected];
+      ptBak = board[squareSelected];
       board[squareSelected] =
           _grid[squareToIndex[squareSelected]] = Piece.noPiece;
     }
 
     for (int l = 0; l < lineDirectionNumber; l++) {
-      // TODO: right?
       if (c == board[millTable[s][l][0]] && c == board[millTable[s][l][1]]) {
         n++;
       }
     }
 
     if (squareSelected != 0) {
-      board[squareSelected] = _grid[squareToIndex[squareSelected]] = locbak;
+      board[squareSelected] = _grid[squareToIndex[squareSelected]] = ptBak;
     }
 
     return n;
@@ -1490,7 +1386,6 @@ class Position {
       idx[2] = millTable[s][i][1];
 
       // no mill
-      // TODO: right?
       if (!(m == board[idx[1]] && m == board[idx[2]])) {
         continue;
       }
@@ -1571,45 +1466,37 @@ class Position {
 
 ///////////////////////////////////////////////////////////////////////////////
 
-// 验证移动棋子的着法是否合法
-  bool validateMove(int from, int to) {
-    // 移动的棋子的选手，应该是当前方
-    //if (Color.of(_board[from]) != _sideToMove) return false;
-    return true;
-    //(StepValidate.validate(this, Move(from, to)));
-  }
-
   bool regret() {
     // TODO
     final lastMove = _recorder.removeLast();
     if (lastMove == null) return false;
 
     _grid[lastMove.from] = _grid[lastMove.to];
-    _grid[lastMove.to] = lastMove.captured;
+    _grid[lastMove.to] = lastMove.removed;
     board[lastMove.from] = board[lastMove.to];
-    board[lastMove.to] = lastMove.captured;
+    board[lastMove.to] = lastMove.removed;
 
     changeSideToMove();
 
-    final counterMarks = MillRecorder.fromCounterMarks(lastMove.counterMarks);
+    final counterMarks = GameRecorder.fromCounterMarks(lastMove.counterMarks);
     _recorder.halfMove = counterMarks.halfMove;
     _recorder.fullMove = counterMarks.fullMove;
 
-    if (lastMove.captured != Piece.noPiece) {
+    if (lastMove.removed != Piece.noPiece) {
       //
       // 查找上一个吃子局面（或开局），NativeEngine 需要
       final tempPosition = Position.clone(this);
 
-      final moves = _recorder.reverseMovesToPrevCapture();
+      final moves = _recorder.reverseMovesToPrevRemove();
       moves.forEach((move) {
         //
         tempPosition._grid[move.from] = tempPosition._grid[move.to];
-        tempPosition._grid[move.to] = move.captured;
+        tempPosition._grid[move.to] = move.removed;
 
         tempPosition._sideToMove = Color.opponent(tempPosition._sideToMove);
       });
 
-      _recorder.lastCapturedPosition = tempPosition.fen();
+      _recorder.lastPositionWithRemove = tempPosition.fen();
     }
 
     result = GameResult.pending;
@@ -1617,20 +1504,20 @@ class Position {
     return true;
   }
 
-  String movesSinceLastCaptured() {
+  String movesSinceLastRemove() {
     //
-    var steps = '', posAfterLastCaptured = 0;
+    var moves = '', posAfterLastRemove = 0;
 
-    for (var i = _recorder.stepsCount - 1; i >= 0; i--) {
-      if (_recorder.stepAt(i).captured != Piece.noPiece) break;
-      posAfterLastCaptured = i;
+    for (var i = _recorder.movesCount - 1; i >= 0; i--) {
+      if (_recorder.stepAt(i).removed != Piece.noPiece) break;
+      posAfterLastRemove = i;
     }
 
-    for (var i = posAfterLastCaptured; i < _recorder.stepsCount; i++) {
-      steps += ' ${_recorder.stepAt(i).move}';
+    for (var i = posAfterLastRemove; i < _recorder.movesCount; i++) {
+      moves += ' ${_recorder.stepAt(i).move}';
     }
 
-    return steps.length > 0 ? steps.substring(1) : '';
+    return moves.length > 0 ? moves.substring(1) : '';
   }
 
   get manualText => _recorder.buildManualText();
@@ -1649,5 +1536,5 @@ class Position {
 
   get lastMove => _recorder.last;
 
-  get lastCapturedPosition => _recorder.lastCapturedPosition;
+  get lastPositionWithRemove => _recorder.lastPositionWithRemove;
 }
diff --git a/src/ui/flutter/lib/mill/recorder.dart b/src/ui/flutter/lib/mill/recorder.dart
index 0b6d9358..a65427d2 100644
--- a/src/ui/flutter/lib/mill/recorder.dart
+++ b/src/ui/flutter/lib/mill/recorder.dart
@@ -20,16 +20,16 @@
 import 'mill.dart';
 import 'position.dart';
 
-class MillRecorder {
+class GameRecorder {
   //
   // 无吃子步数、总回合数
   int halfMove, fullMove;
-  String lastCapturedPosition;
+  String lastPositionWithRemove;
   final _history = <Move>[];
 
-  MillRecorder(
-      {this.halfMove = 0, this.fullMove = 0, this.lastCapturedPosition});
-  MillRecorder.fromCounterMarks(String marks) {
+  GameRecorder(
+      {this.halfMove = 0, this.fullMove = 0, this.lastPositionWithRemove});
+  GameRecorder.fromCounterMarks(String marks) {
     //
     var segments = marks.split(' ');
     if (segments.length != 2) {
@@ -43,9 +43,9 @@ class MillRecorder {
       throw 'Error: Invalid Counter Marks: $marks';
     }
   }
-  void stepIn(Move move, Position position) {
+  void moveIn(Move move, Position position) {
     //
-    if (move.captured != Piece.noPiece) {
+    if (move.removed != Piece.noPiece) {
       halfMove = 0;
     } else {
       halfMove++;
@@ -59,8 +59,8 @@ class MillRecorder {
 
     _history.add(move);
 
-    if (move.captured != Piece.noPiece) {
-      lastCapturedPosition = position.fen();
+    if (move.removed != Piece.noPiece) {
+      lastPositionWithRemove = position.fen();
     }
   }
 
@@ -71,12 +71,12 @@ class MillRecorder {
 
   get last => _history.isEmpty ? null : _history.last;
 
-  List<Move> reverseMovesToPrevCapture() {
+  List<Move> reverseMovesToPrevRemove() {
     //
     List<Move> moves = [];
 
     for (var i = _history.length - 1; i >= 0; i--) {
-      if (_history[i].captured != Piece.noPiece) break;
+      if (_history[i].removed != Piece.noPiece) break;
       moves.add(_history[i]);
     }
 
@@ -101,7 +101,7 @@ class MillRecorder {
 
   Move stepAt(int index) => _history[index];
 
-  get stepsCount => _history.length;
+  get movesCount => _history.length;
 
   @override
   String toString() {
diff --git a/src/ui/flutter/lib/common/types.dart b/src/ui/flutter/lib/mill/types.dart
similarity index 84%
rename from src/ui/flutter/lib/common/types.dart
rename to src/ui/flutter/lib/mill/types.dart
index a6b7aedc..7f0abb1a 100644
--- a/src/ui/flutter/lib/common/types.dart
+++ b/src/ui/flutter/lib/mill/types.dart
@@ -17,7 +17,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-import 'package:sanmill/common/misc.dart';
+import 'package:sanmill/common/algorithm.dart';
 
 enum MoveType { place, move, remove }
 
@@ -91,13 +91,20 @@ const lineDirectionNumber = 3;
 enum File { A, B, C }
 
 const fileNumber = 3;
+const fileExNumber = fileNumber + 2;
 
 enum Rank { rank_1, rank_2, rank_3, rank_4, rank_5, rank_6, rank_7, rank_8 }
 
 const rankNumber = 8;
 
 bool isOk(int sq) {
-  return sq == 0 || (sq >= 8 && sq <= 31); // TODO: SQ_NONE?
+  bool ret = (sq == 0 || (sq >= 8 && sq <= 31));
+
+  if (ret == false) {
+    print("$sq is not OK");
+  }
+
+  return ret; // TODO: SQ_NONE?
 }
 
 int fileOf(int sq) {
@@ -118,20 +125,6 @@ int toSq(int move) {
   return (move & 0x00FF);
 }
 
-MoveType typeOf(int move) {
-  if (move < 0) {
-    return MoveType.remove;
-  } else if (move & 0x1f00 > 0) {
-    return MoveType.move;
-  }
-
-  return MoveType.place; // m & 0x00ff
-}
-
-int makeMove(int fromSq, int toSq) {
-  return (fromSq << 8) + toSq;
-}
-
-int reverseMove(int move) {
-  return makeMove(toSq(move), fromSq(move));
+int makeMove(int from, int to) {
+  return (from << 8) + to;
 }
diff --git a/src/ui/flutter/lib/board/board_painter.dart b/src/ui/flutter/lib/painting/board_painter.dart
similarity index 92%
rename from src/ui/flutter/lib/board/board_painter.dart
rename to src/ui/flutter/lib/painting/board_painter.dart
index 9cc8821c..2a6ef351 100644
--- a/src/ui/flutter/lib/board/board_painter.dart
+++ b/src/ui/flutter/lib/painting/board_painter.dart
@@ -18,25 +18,23 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/style/colors.dart';
+import 'package:sanmill/widgets/board.dart';
 
-import '../board/painter_base.dart';
-import '../common/properties.dart';
-import 'board_widget.dart';
+import 'painter_base.dart';
 
-class BoardPainter extends PainterBase {
-  //
+class BoardPainter extends PiecesBasePainter {
   BoardPainter({@required double width}) : super(width: width);
 
   @override
   void paint(Canvas canvas, Size size) {
-    //
     doPaint(
       canvas,
       thePaint,
       gridWidth,
       squareWidth,
-      offsetX: BoardWidget.padding + squareWidth / 2,
-      offsetY: BoardWidget.padding + BoardWidget.digitsHeight + squareWidth / 2,
+      offsetX: Board.padding + squareWidth / 2,
+      offsetY: Board.padding + Board.digitsHeight + squareWidth / 2,
     );
   }
 
@@ -53,8 +51,7 @@ class BoardPainter extends PainterBase {
     double offsetX,
     double offsetY,
   }) {
-    //
-    paint.color = Properties.boardLineColor;
+    paint.color = UIColors.boardLineColor;
     paint.style = PaintingStyle.stroke;
 
     const double borderLineWidth = 2.0;
diff --git a/src/ui/flutter/lib/board/painter_base.dart b/src/ui/flutter/lib/painting/painter_base.dart
similarity index 79%
rename from src/ui/flutter/lib/board/painter_base.dart
rename to src/ui/flutter/lib/painting/painter_base.dart
index c7fc73c8..58856ff9 100644
--- a/src/ui/flutter/lib/board/painter_base.dart
+++ b/src/ui/flutter/lib/painting/painter_base.dart
@@ -18,18 +18,16 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/widgets/board.dart';
 
-import 'board_widget.dart';
-
-abstract class PainterBase extends CustomPainter {
-  //
+abstract class PiecesBasePainter extends CustomPainter {
   final double width;
 
   final thePaint = Paint();
   final gridWidth;
   final squareWidth;
 
-  PainterBase({@required this.width})
-      : gridWidth = (width - BoardWidget.padding * 2),
-        squareWidth = (width - BoardWidget.padding * 2) / 7;
+  PiecesBasePainter({@required this.width})
+      : gridWidth = (width - Board.padding * 2),
+        squareWidth = (width - Board.padding * 2) / 7;
 }
diff --git a/src/ui/flutter/lib/board/pieces_painter.dart b/src/ui/flutter/lib/painting/pieces_painter.dart
similarity index 70%
rename from src/ui/flutter/lib/board/pieces_painter.dart
rename to src/ui/flutter/lib/painting/pieces_painter.dart
index b722cc44..6e33995d 100644
--- a/src/ui/flutter/lib/board/pieces_painter.dart
+++ b/src/ui/flutter/lib/painting/pieces_painter.dart
@@ -18,21 +18,20 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/mill/mill.dart';
+import 'package:sanmill/mill/position.dart';
+import 'package:sanmill/style/colors.dart';
+import 'package:sanmill/widgets/board.dart';
 
-import '../board/painter_base.dart';
-import '../common/properties.dart';
-import '../mill/mill.dart';
-import '../mill/position.dart';
-import 'board_widget.dart';
+import 'painter_base.dart';
 
-class PiecePaintStub {
+class PiecePaintPair {
   final String piece;
   final Offset pos;
-  PiecePaintStub({this.piece, this.pos});
+  PiecePaintPair({this.piece, this.pos});
 }
 
-class PiecesPainter extends PainterBase {
-  //
+class PiecesPainter extends PiecesBasePainter {
   final Position position;
   final int focusIndex, blurIndex;
 
@@ -41,8 +40,8 @@ class PiecesPainter extends PainterBase {
   PiecesPainter({
     @required double width,
     @required this.position,
-    this.focusIndex = Move.invalidValue,
-    this.blurIndex = Move.invalidValue,
+    this.focusIndex = Move.invalidMove,
+    this.blurIndex = Move.invalidMove,
   }) : super(width: width) {
     //
     pieceWidth = squareWidth * 0.9; // 棋子大小
@@ -50,7 +49,6 @@ class PiecesPainter extends PainterBase {
 
   @override
   void paint(Canvas canvas, Size size) {
-    //
     doPaint(
       canvas,
       thePaint,
@@ -59,8 +57,8 @@ class PiecesPainter extends PainterBase {
       squareWidth: squareWidth,
       pieceWidth: pieceWidth,
       // 棋子放在线上中央
-      offsetX: BoardWidget.padding + squareWidth / 2,
-      offsetY: BoardWidget.padding + BoardWidget.digitsHeight + squareWidth / 2,
+      offsetX: Board.padding + squareWidth / 2,
+      offsetY: Board.padding + Board.digitsHeight + squareWidth / 2,
       focusIndex: focusIndex,
       blurIndex: blurIndex,
     );
@@ -81,19 +79,18 @@ class PiecesPainter extends PainterBase {
     double pieceWidth,
     double offsetX,
     double offsetY,
-    int focusIndex = Move.invalidValue,
-    int blurIndex = Move.invalidValue,
+    int focusIndex = Move.invalidMove,
+    int blurIndex = Move.invalidMove,
   }) {
     //
     final left = offsetX;
     final top = offsetY;
 
     final shadowPath = Path();
-    final piecesToDraw = <PiecePaintStub>[];
+    final piecesToDraw = <PiecePaintPair>[];
 
     // 在棋盘上画棋子
     for (var row = 0; row < 7; row++) {
-      //
       for (var col = 0; col < 7; col++) {
         //
         final piece = position.pieceOnGrid(row * 7 + col); // 初始状态无棋子
@@ -102,7 +99,7 @@ class PiecesPainter extends PainterBase {
 
         var pos = Offset(left + squareWidth * col, top + squareWidth * row);
 
-        piecesToDraw.add(PiecePaintStub(piece: piece, pos: pos));
+        piecesToDraw.add(PiecePaintPair(piece: piece, pos: pos));
 
         shadowPath.addOval(
           Rect.fromCenter(center: pos, width: pieceWidth, height: pieceWidth),
@@ -130,22 +127,22 @@ class PiecesPainter extends PainterBase {
       // 绘制棋子边界
       switch (pps.piece) {
         case Piece.blackStone:
-          paint.color = Properties.blackPieceBorderColor;
+          paint.color = UIColors.blackPieceBorderColor;
           canvas.drawCircle(pps.pos, pieceRadius, paint); // 临时调试用
-          paint.color = Properties.blackPieceColor;
+          paint.color = UIColors.blackPieceColor;
           canvas.drawCircle(pps.pos, pieceInnerRadius, paint);
           break;
         case Piece.whiteStone:
-          paint.color = Properties.whitePieceBorderColor;
+          paint.color = UIColors.whitePieceBorderColor;
           canvas.drawCircle(pps.pos, pieceRadius, paint); // 临时调试用
-          paint.color = Properties.whitePieceColor;
+          paint.color = UIColors.whitePieceColor;
           canvas.drawCircle(pps.pos, pieceInnerRadius, paint);
           break;
         case Piece.ban:
           print("pps.piece is Ban");
-          paint.color = Properties.banBorderColor;
+          paint.color = UIColors.banBorderColor;
           // TODO
-          paint.color = Properties.banColor;
+          paint.color = UIColors.banColor;
           canvas.drawLine(new Offset(0, 0),
               new Offset(pieceInnerRadius, pieceInnerRadius), paint);
           canvas.drawLine(new Offset(pieceInnerRadius, 0),
@@ -155,33 +152,15 @@ class PiecesPainter extends PainterBase {
           assert(false);
           break;
       }
-
-      /*
-      final textSpan = TextSpan(text: Piece.Names[pps.piece], style: textStyle);
-
-      final textPainter = TextPainter(
-        text: textSpan,
-        textDirection: TextDirection.ltr,
-      )..layout();
-
-
-      final metric = textPainter.computeLineMetrics()[0];
-      final textSize = textPainter.size;
-
-      // 从顶上算，文字的 Baseline 在 2/3 高度线上
-      final textOffset = pps.pos - Offset(textSize.width / 2, metric.baseline - textSize.height / 3);
-
-      textPainter.paint(canvas, textOffset);
-      */
     });
 
     // draw focus and blur position
 
-    if (focusIndex != Move.invalidValue) {
+    if (focusIndex != Move.invalidMove) {
       //
       final int row = focusIndex ~/ 7, column = focusIndex % 7;
 
-      paint.color = Properties.focusPositionColor;
+      paint.color = UIColors.focusPositionColor;
       paint.style = PaintingStyle.stroke;
       paint.strokeWidth = 2;
 
@@ -192,11 +171,10 @@ class PiecesPainter extends PainterBase {
       );
     }
 
-    if (blurIndex != Move.invalidValue) {
-      //
+    if (blurIndex != Move.invalidMove) {
       final row = blurIndex ~/ 7, column = blurIndex % 7;
 
-      paint.color = Properties.blurPositionColor;
+      paint.color = UIColors.blurPositionColor;
       paint.style = PaintingStyle.fill;
 
       canvas.drawCircle(
diff --git a/src/ui/flutter/lib/services/audios.dart b/src/ui/flutter/lib/services/audios.dart
index e810dd64..eaf237f7 100644
--- a/src/ui/flutter/lib/services/audios.dart
+++ b/src/ui/flutter/lib/services/audios.dart
@@ -29,7 +29,6 @@ class Audios {
     //
     try {
       if (_bgmPlayer == null) {
-        //
         _fixedBgmPlayer = AudioPlayer();
         _bgmPlayer =
             AudioCache(prefix: 'audios/', fixedPlayer: _fixedBgmPlayer);
@@ -43,7 +42,6 @@ class Audios {
   }
 
   static playTone(String fileName) async {
-    //
     try {
       if (_tonePlayer == null) {
         //
diff --git a/src/ui/flutter/lib/services/player.dart b/src/ui/flutter/lib/services/player.dart
index 1b402a58..e6df3e0f 100644
--- a/src/ui/flutter/lib/services/player.dart
+++ b/src/ui/flutter/lib/services/player.dart
@@ -32,7 +32,6 @@ class Player extends RankItem {
   static get shared => _instance;
 
   static Future<Player> loadProfile() async {
-    //
     if (_instance == null) {
       _instance = Player();
       await _instance._load();
@@ -42,7 +41,6 @@ class Player extends RankItem {
   }
 
   _load() async {
-    //
     final profile = await Profile.shared();
 
     _uuid = profile['player-uuid'];
@@ -56,14 +54,14 @@ class Player extends RankItem {
 
       name = values['name'] ?? '无名英雄';
       winCloudEngine = values['win_cloud_engine'] ?? 0;
-      winPhoneAi = values['win_phone_ai'] ?? 0;
+      winAi = values['win_ai'] ?? 0;
     }
   }
 
   Player() : super.empty();
 
-  Future<void> increaseWinPhoneAi() async {
-    winPhoneAi++;
+  Future<void> increaseWinAi() async {
+    winAi++;
     await saveAndUpload();
   }
 
diff --git a/src/ui/flutter/lib/services/ranks.dart b/src/ui/flutter/lib/services/ranks.dart
index f4169638..c494fa3b 100644
--- a/src/ui/flutter/lib/services/ranks.dart
+++ b/src/ui/flutter/lib/services/ranks.dart
@@ -23,33 +23,33 @@ import 'dart:io';
 class RankItem {
   //
   String name;
-  int winCloudEngine, winPhoneAi;
+  int winCloudEngine, winAi;
 
   RankItem(Map<String, dynamic> values) {
     name = values['name'] ?? '无名英雄';
     winCloudEngine = values['win_cloud_engine'] ?? 0;
-    winPhoneAi = values['win_phone_ai'] ?? 0;
+    winAi = values['win_ai'] ?? 0;
   }
 
   RankItem.empty() {
     name = '无名英雄';
     winCloudEngine = 0;
-    winPhoneAi = 0;
+    winAi = 0;
   }
 
   RankItem.mock() {
     name = '我是英雄';
     winCloudEngine = 3;
-    winPhoneAi = 12;
+    winAi = 12;
   }
 
   Map<String, dynamic> toMap() => {
         'name': name,
         'win_cloud_engine': winCloudEngine,
-        'win_phone_ai': winPhoneAi,
+        'win_ai': winAi,
       };
 
-  get score => winCloudEngine * 30 + winPhoneAi * 5;
+  get score => winCloudEngine * 30 + winAi * 5;
 }
 
 class Ranks {
@@ -113,7 +113,7 @@ class Ranks {
           'uuid': uuid,
           'name': rank.name,
           'win_cloud_engine': '${rank.winCloudEngine}',
-          'win_phone_ai': '${rank.winPhoneAi}',
+          'win_ai': '${rank.winAi}',
         });
 
     final httpClient = HttpClient();
diff --git a/src/ui/flutter/lib/common/properties.dart b/src/ui/flutter/lib/style/colors.dart
similarity index 99%
rename from src/ui/flutter/lib/common/properties.dart
rename to src/ui/flutter/lib/style/colors.dart
index bb957e77..da4af433 100644
--- a/src/ui/flutter/lib/common/properties.dart
+++ b/src/ui/flutter/lib/style/colors.dart
@@ -19,7 +19,7 @@
 
 import 'package:flutter/material.dart';
 
-class Properties {
+class UIColors {
   //
   static const logoColor = Color(0xFF6D000D);
 
diff --git a/src/ui/flutter/lib/common/toast.dart b/src/ui/flutter/lib/style/toast.dart
similarity index 100%
rename from src/ui/flutter/lib/common/toast.dart
rename to src/ui/flutter/lib/style/toast.dart
diff --git a/src/ui/flutter/lib/board/board_widget.dart b/src/ui/flutter/lib/widgets/board.dart
similarity index 83%
rename from src/ui/flutter/lib/board/board_widget.dart
rename to src/ui/flutter/lib/widgets/board.dart
index bea1a07c..7ac20546 100644
--- a/src/ui/flutter/lib/board/board_widget.dart
+++ b/src/ui/flutter/lib/widgets/board.dart
@@ -18,14 +18,14 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/mill/game.dart';
+import 'package:sanmill/painting/board_painter.dart';
+import 'package:sanmill/painting/pieces_painter.dart';
+import 'package:sanmill/style/colors.dart';
 
-import '../common/properties.dart';
-import '../game/battle.dart';
-import 'board_painter.dart';
-import 'pieces_painter.dart';
 import 'words_on_board.dart';
 
-class BoardWidget extends StatelessWidget {
+class Board extends StatelessWidget {
   //
   static const padding = 5.0;
   static const digitsHeight = 0.0;
@@ -36,8 +36,7 @@ class BoardWidget extends StatelessWidget {
   final double height;
   final Function(BuildContext, int) onBoardTap;
 
-  BoardWidget({@required this.width, @required this.onBoardTap})
-      : height = width;
+  Board({@required this.width, @required this.onBoardTap}) : height = width;
 
   @override
   Widget build(BuildContext context) {
@@ -47,15 +46,15 @@ class BoardWidget extends StatelessWidget {
       height: height,
       decoration: BoxDecoration(
         borderRadius: BorderRadius.circular(boardBorderRadius),
-        color: Properties.boardBackgroundColor,
+        color: UIColors.boardBackgroundColor,
       ),
       child: CustomPaint(
         painter: BoardPainter(width: width),
         foregroundPainter: PiecesPainter(
           width: width,
-          position: Battle.shared.position,
-          focusIndex: Battle.shared.focusIndex,
-          blurIndex: Battle.shared.blurIndex,
+          position: Game.shared.position,
+          focusIndex: Game.shared.focusIndex,
+          blurIndex: Game.shared.blurIndex,
         ),
         child: Container(
           margin: EdgeInsets.symmetric(
diff --git a/src/ui/flutter/lib/routes/edit_page.dart b/src/ui/flutter/lib/widgets/edit_page.dart
similarity index 92%
rename from src/ui/flutter/lib/routes/edit_page.dart
rename to src/ui/flutter/lib/widgets/edit_page.dart
index dd836054..4ec45a06 100644
--- a/src/ui/flutter/lib/routes/edit_page.dart
+++ b/src/ui/flutter/lib/widgets/edit_page.dart
@@ -18,8 +18,7 @@
 */
 
 import 'package:flutter/material.dart';
-
-import '../common/properties.dart';
+import 'package:sanmill/style/colors.dart';
 
 class EditPage extends StatefulWidget {
   //
@@ -58,7 +57,7 @@ class _EditPageState extends State<EditPage> {
     //
     final inputBorder = OutlineInputBorder(
       borderRadius: BorderRadius.circular(25),
-      borderSide: BorderSide(color: Properties.secondaryColor),
+      borderSide: BorderSide(color: UIColors.secondaryColor),
     );
 
     return Scaffold(
@@ -72,7 +71,7 @@ class _EditPageState extends State<EditPage> {
           )
         ],
       ),
-      backgroundColor: Properties.lightBackgroundColor,
+      backgroundColor: UIColors.lightBackgroundColor,
       body: Container(
         margin: EdgeInsets.all(16),
         child: Column(
@@ -86,7 +85,7 @@ class _EditPageState extends State<EditPage> {
                 focusedBorder: inputBorder,
               ),
               style: TextStyle(
-                  color: Properties.primaryColor, fontSize: 16, fontFamily: ''),
+                  color: UIColors.primaryColor, fontSize: 16, fontFamily: ''),
               onSubmitted: (input) => onSubmit(input),
               focusNode: _commentFocus,
             ),
diff --git a/src/ui/flutter/lib/routes/battle_page.dart b/src/ui/flutter/lib/widgets/game_page.dart
similarity index 61%
rename from src/ui/flutter/lib/routes/battle_page.dart
rename to src/ui/flutter/lib/widgets/game_page.dart
index 20fb1613..fdfff7cf 100644
--- a/src/ui/flutter/lib/routes/battle_page.dart
+++ b/src/ui/flutter/lib/widgets/game_page.dart
@@ -18,53 +18,49 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/engine/analyze.dart';
+import 'package:sanmill/engine/engine.dart';
+import 'package:sanmill/engine/native_engine.dart';
+import 'package:sanmill/main.dart';
+import 'package:sanmill/mill/game.dart';
+import 'package:sanmill/mill/mill.dart';
+import 'package:sanmill/mill/types.dart';
+import 'package:sanmill/services/player.dart';
+import 'package:sanmill/style/colors.dart';
+import 'package:sanmill/style/toast.dart';
 
-import '../board/board_widget.dart';
-import '../common/properties.dart';
-import '../common/toast.dart';
-import '../common/types.dart';
-import '../engine/analysis.dart';
-import '../engine/engine.dart';
-import '../engine/native_engine.dart';
-import '../game/battle.dart';
-import '../main.dart';
-import '../mill/mill.dart';
-import '../services/player.dart';
+import 'board.dart';
 import 'settings_page.dart';
 
-class BattlePage extends StatefulWidget {
+class GamePage extends StatefulWidget {
   //
   static double boardMargin = 10.0, screenPaddingH = 10.0;
 
   final EngineType engineType;
   final AiEngine engine;
 
-  BattlePage(this.engineType) : engine = NativeEngine();
+  GamePage(this.engineType) : engine = NativeEngine();
 
   @override
-  _BattlePageState createState() => _BattlePageState();
+  _GamePageState createState() => _GamePageState();
 }
 
-class _BattlePageState extends State<BattlePage> {
+class _GamePageState extends State<GamePage> {
   //
   String _status = '';
-  bool _analysising = false;
-
-  //static int flag = 0;
+  bool _searching = false;
 
   @override
   void initState() {
-    //
     super.initState();
-    Battle.shared.init();
-
+    Game.shared.init();
     widget.engine.startup();
   }
 
   changeStatus(String status) => setState(() => _status = status);
 
   onBoardTap(BuildContext context, int index) {
-    final position = Battle.shared.position;
+    final position = Game.shared.position;
 
     int sq = indexToSquare[index];
 
@@ -75,13 +71,13 @@ class _BattlePageState extends State<BattlePage> {
     }
 
     // AI 走棋或正在搜索时，点击无效
-    if (Battle.shared.isAIsTurn() || Battle.shared.aiIsSearching()) {
+    if (Game.shared.isAiToMove() || Game.shared.aiIsSearching()) {
       return false;
     }
 
     // 如果未开局则开局
     if (position.phase == Phase.ready) {
-      Battle.shared.gameStart();
+      Game.shared.start();
     }
 
     // 判断执行选子、落子或去子
@@ -92,11 +88,11 @@ class _BattlePageState extends State<BattlePage> {
         if (position.putPiece(sq)) {
           if (position.action == Act.remove) {
             // 播放成三音效
-            //playSound(GAME_SOUND_MILL, position.side_to_move());
+            //Audios.playTone('mill.mp3');
             changeStatus('请吃子');
           } else {
             // 播放移动棋子音效
-            //playSound(GAME_SOUND_DROG, position.side_to_move());
+            //Audios.playTone('put.mp3');
             changeStatus('已落子');
           }
           result = true;
@@ -112,19 +108,16 @@ class _BattlePageState extends State<BattlePage> {
         continue select;
       select:
       case Act.select:
-        //piece = qgraphicsitem_cast<PieceItem *>(item);
-        //if (!piece)
-        //break;
         if (position.selectPiece(sq)) {
           // 播放选子音效
-          //playSound(GAME_SOUND_SELECT, position.side_to_move());
-          Battle.shared.select(index);
+          //Audios.playTone('select.mp3');
+          Game.shared.select(index);
           result = true;
           print("selectPiece: [$sq]");
           changeStatus('请落子');
         } else {
           // 播放禁止音效
-          //playSound(GAME_SOUND_BANNED, position.side_to_move());
+          //Audios.playTone('banned.mp3');
           print("selectPiece: skip [$sq]");
           changeStatus('选择的子不对');
         }
@@ -133,13 +126,13 @@ class _BattlePageState extends State<BattlePage> {
       case Act.remove:
         if (position.removePiece(sq)) {
           // 播放音效
-          //playSound(GAME_SOUND_REMOVE, position.side_to_move());
+          //Audios.playTone('remove.mp3');
           result = true;
           print("removePiece: [$sq]");
           changeStatus('已吃子');
         } else {
           // 播放禁止音效
-          //playSound(GAME_SOUND_BANNED, position.side_to_move());
+          //Audios.playTone('banned.mp3');
           print("removePiece: skip [$sq]");
           changeStatus('不能吃这个子');
         }
@@ -151,135 +144,46 @@ class _BattlePageState extends State<BattlePage> {
     }
 
     if (result) {
-      Battle.shared.cmdlist.add(position.cmdline);
+      Game.shared.moveHistory.add(position.cmdline);
 
       // 发信号更新状态栏
       setState(() {});
-      //message = QString::fromStdString(getTips());
-      //emit statusBarChanged(message);
-
-      // 将新增的棋谱行插入到ListModel
-      /*
-    currentRow = manualListModel.rowCount() - 1;
-    int k = 0;
-
-    // 输出命令行
-    for (const auto & i : *(cmd_list())) {
-    // 跳过已添加的，因标准list容器没有下标
-    if (k++ <= currentRow)
-    continue;
-    manualListModel.insertRow(++currentRow);
-    manualListModel.setData(manualListModel.index(currentRow), i.c_str());
-    }
-     */
-
-      // 播放胜利或失败音效
-      /*
-      String winner = position.winner;
-      if (winner != Color.nobody &&
-          (manualListModel.data(manualListModel.index(currentRow - 1)))
-              .toString()
-              .contains("Time over.")) playSound(GAME_SOUND_WIN, winner);
-       */
 
       // AI设置
       // 如果还未决出胜负
       if (position.winner == Color.nobody) {
-        // Color.black is TODO
-        //resumeAiThreads(position.sideToMove());
         engineToGo();
       }
     }
 
-    Battle.shared.sideToMove = position.sideToMove();
+    Game.shared.sideToMove = position.sideToMove();
 
     setState(() {});
 
     return result;
-
-    // TODO:
-
-    // 仅 Position 中的 side 指示一方能动棋
-    //if (position.side != Color.black) return;
-
-    final tapedPiece = position.pieceOnGrid(index);
-    print("Tap piece $tapedPiece at <$index>");
-
-    switch (position.phase) {
-      case Phase.placing:
-        engineToGo();
-        break;
-      case Phase.moving:
-        // 之前已经有棋子被选中了
-        if (Battle.shared.focusIndex != Move.invalidValue &&
-            Color.of(position.pieceOnGrid(Battle.shared.focusIndex)) ==
-                Color.black) {
-          //
-          // 当前点击的棋子和之前已经选择的是同一个位置
-          if (Battle.shared.focusIndex == index) return;
-
-          // 之前已经选择的棋子和现在点击的棋子是同一边的，说明是选择另外一个棋子
-          final focusPiece = position.pieceOnGrid(Battle.shared.focusIndex);
-
-          if (Color.isSameColor(focusPiece, tapedPiece)) {
-            //
-            Battle.shared.select(index);
-            //
-          } else if (Battle.shared.move(Battle.shared.focusIndex, index)) {
-            // 现在点击的棋子和上一次选择棋子不同边，要么是吃子，要么是移动棋子到空白处
-            final result = Battle.shared.scanBattleResult();
-
-            switch (result) {
-              case GameResult.pending:
-                engineToGo();
-                break;
-              case GameResult.win:
-                gotWin();
-                break;
-              case GameResult.lose:
-                gotLose();
-                break;
-              case GameResult.draw:
-                gotDraw();
-                break;
-            }
-          }
-          //
-        } else {
-          // 之前未选择棋子，现在点击就是选择棋子
-          if (tapedPiece != Piece.noPiece) Battle.shared.select(index);
-        }
-
-        break;
-      default:
-        break;
-    }
-
-    setState(() {});
   }
 
   engineToGo() async {
     // TODO
-    while (Battle.shared.position.sideToMove() == Color.white) {
-      changeStatus('电脑思考中...');
+    while (Game.shared.position.sideToMove() == Color.white) {
+      changeStatus('对方思考中...');
 
-      final response = await widget.engine.search(Battle.shared.position);
+      final response = await widget.engine.search(Game.shared.position);
 
       if (response.type == 'move') {
-        //
         Move mv = response.value;
         final Move move = new Move(mv.move);
 
         //Battle.shared.move = move;
-        Battle.shared.command(move.move);
+        Game.shared.command(move.move);
 
-        final winner = Battle.shared.position.winner;
+        final winner = Game.shared.position.winner;
 
         switch (winner) {
           case Color.nobody:
-            if (Battle.shared.position.phase == Phase.placing) {
+            if (Game.shared.position.phase == Phase.placing) {
               changeStatus('请摆子');
-            } else if (Battle.shared.position.phase == Phase.moving) {
+            } else if (Game.shared.position.phase == Phase.moving) {
               changeStatus('请走子');
             }
             break;
@@ -296,28 +200,22 @@ class _BattlePageState extends State<BattlePage> {
             gotDraw();
             break;
         }
-        //
       } else {
-        //
         changeStatus('Error: ${response.type}');
       }
     }
   }
 
   newGame() {
-    //
     confirm() {
       Navigator.of(context).pop();
-      Battle.shared.newGame();
-      //setState(() {});
+      Game.shared.newGame();
       changeStatus('新游戏');
 
-      if (Battle.shared.isAIsTurn()) {
+      if (Game.shared.isAiToMove()) {
         print("New Game: AI's turn.");
         engineToGo();
       }
-
-      //setState(() {});
     }
 
     cancel() => Navigator.of(context).pop();
@@ -326,7 +224,7 @@ class _BattlePageState extends State<BattlePage> {
       context: context,
       builder: (BuildContext context) {
         return AlertDialog(
-          title: Text('新局？', style: TextStyle(color: Properties.primaryColor)),
+          title: Text('新局？', style: TextStyle(color: UIColors.primaryColor)),
           content: SingleChildScrollView(child: Text('开始新局？')),
           actions: <Widget>[
             FlatButton(child: Text('确定'), onPressed: confirm),
@@ -337,33 +235,32 @@ class _BattlePageState extends State<BattlePage> {
     );
   }
 
-  analysisPosition() async {
+  analyzePosition() async {
     //
     Toast.toast(context, msg: '正在分析局面...', position: ToastPostion.bottom);
 
-    setState(() => _analysising = true);
+    setState(() => _searching = true);
 
     try {} catch (e) {
       Toast.toast(context, msg: '错误: $e', position: ToastPostion.bottom);
     } finally {
-      setState(() => _analysising = false);
+      setState(() => _searching = false);
     }
   }
 
-  showAnalysisItems(
+  showAnalyzeItems(
     BuildContext context, {
     String title,
-    List<AnalysisItem> items,
-    Function(AnalysisItem item) callback,
+    List<AnalyzeItem> items,
+    Function(AnalyzeItem item) callback,
   }) {
-    //
     final List<Widget> children = [];
 
     for (var item in items) {
       children.add(
         ListTile(
-          title: Text(item.stepName, style: TextStyle(fontSize: 18)),
-          subtitle: Text('胜率：${item.winrate}%'),
+          title: Text(item.moveName, style: TextStyle(fontSize: 18)),
+          subtitle: Text('胜率：${item.winRate}%'),
           trailing: Text('分数：${item.score}'),
           onTap: () => callback(item),
         ),
@@ -384,7 +281,7 @@ class _BattlePageState extends State<BattlePage> {
 
   void gotWin() {
     //
-    Battle.shared.position.result = GameResult.win;
+    Game.shared.position.result = GameResult.win;
     //Audios.playTone('win.mp3');
 
     showDialog(
@@ -392,7 +289,7 @@ class _BattlePageState extends State<BattlePage> {
       barrierDismissible: false,
       builder: (BuildContext context) {
         return AlertDialog(
-          title: Text('赢了', style: TextStyle(color: Properties.primaryColor)),
+          title: Text('赢了', style: TextStyle(color: UIColors.primaryColor)),
           content: Text('恭喜您取得了伟大的胜利！'),
           actions: <Widget>[
             FlatButton(child: Text('再来一盘'), onPressed: newGame),
@@ -407,12 +304,12 @@ class _BattlePageState extends State<BattlePage> {
     if (widget.engineType == EngineType.Cloud)
       Player.shared.increaseWinCloudEngine();
     else
-      Player.shared.increaseWinPhoneAi();
+      Player.shared.increaseWinAi();
   }
 
   void gotLose() {
     //
-    Battle.shared.position.result = GameResult.lose;
+    Game.shared.position.result = GameResult.lose;
     //Audios.playTone('lose.mp3');
 
     showDialog(
@@ -420,7 +317,7 @@ class _BattlePageState extends State<BattlePage> {
       barrierDismissible: false,
       builder: (BuildContext context) {
         return AlertDialog(
-          title: Text('输了', style: TextStyle(color: Properties.primaryColor)),
+          title: Text('输了', style: TextStyle(color: UIColors.primaryColor)),
           content: Text('勇士！坚定战斗，虽败犹荣！'),
           actions: <Widget>[
             FlatButton(child: Text('再来一盘'), onPressed: newGame),
@@ -435,14 +332,14 @@ class _BattlePageState extends State<BattlePage> {
 
   void gotDraw() {
     //
-    Battle.shared.position.result = GameResult.draw;
+    Game.shared.position.result = GameResult.draw;
 
     showDialog(
       context: context,
       barrierDismissible: false,
       builder: (BuildContext context) {
         return AlertDialog(
-          title: Text('和���', style: TextStyle(color: Properties.primaryColor)),
+          title: Text('和棋', style: TextStyle(color: UIColors.primaryColor)),
           content: Text('您用自己的力量捍卫了和平！'),
           actions: <Widget>[
             FlatButton(child: Text('再来一盘'), onPressed: newGame),
@@ -463,17 +360,17 @@ class _BattlePageState extends State<BattlePage> {
 
     if (height / width < 16.0 / 9.0) {
       width = height * 9 / 16;
-      BattlePage.screenPaddingH =
-          (windowSize.width - width) / 2 - BattlePage.boardMargin;
+      GamePage.screenPaddingH =
+          (windowSize.width - width) / 2 - GamePage.boardMargin;
     }
   }
 
   Widget createPageHeader() {
     //
     final titleStyle =
-        TextStyle(fontSize: 28, color: Properties.darkTextPrimaryColor);
+        TextStyle(fontSize: 28, color: UIColors.darkTextPrimaryColor);
     final subTitleStyle =
-        TextStyle(fontSize: 16, color: Properties.darkTextSecondaryColor);
+        TextStyle(fontSize: 16, color: UIColors.darkTextSecondaryColor);
 
     return Container(
       margin: EdgeInsets.only(top: SanmillApp.StatusBarHeight),
@@ -483,7 +380,7 @@ class _BattlePageState extends State<BattlePage> {
             children: <Widget>[
               IconButton(
                 icon: Icon(Icons.arrow_back,
-                    color: Properties.darkTextPrimaryColor),
+                    color: UIColors.darkTextPrimaryColor),
                 onPressed: () => Navigator.of(context).pop(),
               ),
               Expanded(child: SizedBox()),
@@ -493,8 +390,8 @@ class _BattlePageState extends State<BattlePage> {
                   style: titleStyle),
               Expanded(child: SizedBox()),
               IconButton(
-                icon: Icon(Icons.settings,
-                    color: Properties.darkTextPrimaryColor),
+                icon:
+                    Icon(Icons.settings, color: UIColors.darkTextPrimaryColor),
                 onPressed: () => Navigator.of(context).push(
                   MaterialPageRoute(builder: (context) => SettingsPage()),
                 ),
@@ -506,7 +403,7 @@ class _BattlePageState extends State<BattlePage> {
             width: 180,
             margin: EdgeInsets.only(bottom: 10),
             decoration: BoxDecoration(
-              color: Properties.boardBackgroundColor,
+              color: UIColors.boardBackgroundColor,
               borderRadius: BorderRadius.circular(2),
             ),
           ),
@@ -523,12 +420,11 @@ class _BattlePageState extends State<BattlePage> {
     //
     return Container(
       margin: EdgeInsets.symmetric(
-        horizontal: BattlePage.screenPaddingH,
-        vertical: BattlePage.boardMargin,
+        horizontal: GamePage.screenPaddingH,
+        vertical: GamePage.boardMargin,
       ),
-      child: BoardWidget(
-        width:
-            MediaQuery.of(context).size.width - BattlePage.screenPaddingH * 2,
+      child: Board(
+        width: MediaQuery.of(context).size.width - GamePage.screenPaddingH * 2,
         onBoardTap: onBoardTap,
       ),
     );
@@ -536,14 +432,14 @@ class _BattlePageState extends State<BattlePage> {
 
   Widget createOperatorBar() {
     //
-    final buttonStyle = TextStyle(color: Properties.primaryColor, fontSize: 20);
+    final buttonStyle = TextStyle(color: UIColors.primaryColor, fontSize: 20);
 
     return Container(
       decoration: BoxDecoration(
         borderRadius: BorderRadius.circular(5),
-        color: Properties.boardBackgroundColor,
+        color: UIColors.boardBackgroundColor,
       ),
-      margin: EdgeInsets.symmetric(horizontal: BattlePage.screenPaddingH),
+      margin: EdgeInsets.symmetric(horizontal: GamePage.screenPaddingH),
       padding: EdgeInsets.symmetric(vertical: 2),
       child: Row(children: <Widget>[
         Expanded(child: SizedBox()),
@@ -552,14 +448,14 @@ class _BattlePageState extends State<BattlePage> {
         FlatButton(
           child: Text('悔棋', style: buttonStyle),
           onPressed: () {
-            Battle.shared.regret(steps: 2);
+            Game.shared.regret(steps: 2);
             setState(() {});
           },
         ),
         Expanded(child: SizedBox()),
         FlatButton(
           child: Text('分析', style: buttonStyle),
-          onPressed: _analysising ? null : analysisPosition,
+          onPressed: _searching ? null : analyzePosition,
         ),
         Expanded(child: SizedBox()),
       ]),
@@ -570,12 +466,12 @@ class _BattlePageState extends State<BattlePage> {
     //
     final size = MediaQuery.of(context).size;
 
-    final manualText = Battle.shared.position.manualText;
+    final manualText = Game.shared.position.manualText;
 
     if (size.height / size.width > 16 / 9) {
       return buildManualPanel(manualText);
     } else {
-      return buildExpandableManaulPanel(manualText);
+      return buildExpandableRecordPanel(manualText);
     }
   }
 
@@ -583,7 +479,7 @@ class _BattlePageState extends State<BattlePage> {
     //
     final manualStyle = TextStyle(
       fontSize: 18,
-      color: Properties.darkTextSecondaryColor,
+      color: UIColors.darkTextSecondaryColor,
       height: 1.5,
     );
 
@@ -595,20 +491,19 @@ class _BattlePageState extends State<BattlePage> {
     );
   }
 
-  Widget buildExpandableManaulPanel(String text) {
+  Widget buildExpandableRecordPanel(String text) {
     //
     final manualStyle = TextStyle(fontSize: 18, height: 1.5);
 
     return Expanded(
       child: IconButton(
-        icon: Icon(Icons.expand_less, color: Properties.darkTextPrimaryColor),
+        icon: Icon(Icons.expand_less, color: UIColors.darkTextPrimaryColor),
         onPressed: () => showDialog(
           context: context,
           barrierDismissible: false,
           builder: (BuildContext context) {
             return AlertDialog(
-              title:
-                  Text('棋谱', style: TextStyle(color: Properties.primaryColor)),
+              title: Text('棋谱', style: TextStyle(color: UIColors.primaryColor)),
               content:
                   SingleChildScrollView(child: Text(text, style: manualStyle)),
               actions: <Widget>[
@@ -635,7 +530,7 @@ class _BattlePageState extends State<BattlePage> {
     final footer = buildFooter();
 
     return Scaffold(
-      backgroundColor: Properties.darkBackgroundColor,
+      backgroundColor: UIColors.darkBackgroundColor,
       body: Column(children: <Widget>[header, board, operatorBar, footer]),
     );
   }
diff --git a/src/ui/flutter/lib/routes/main_menu.dart b/src/ui/flutter/lib/widgets/main_menu.dart
similarity index 91%
rename from src/ui/flutter/lib/routes/main_menu.dart
rename to src/ui/flutter/lib/widgets/main_menu.dart
index 63ed5311..db1485cf 100644
--- a/src/ui/flutter/lib/routes/main_menu.dart
+++ b/src/ui/flutter/lib/widgets/main_menu.dart
@@ -18,11 +18,11 @@
 */
 
 import 'package:flutter/material.dart';
+import 'package:sanmill/engine/engine.dart';
+import 'package:sanmill/main.dart';
+import 'package:sanmill/style/colors.dart';
 
-import '../common/properties.dart';
-import '../engine/engine.dart';
-import '../main.dart';
-import 'battle_page.dart';
+import 'game_page.dart';
 import 'settings_page.dart';
 
 class MainMenu extends StatefulWidget {
@@ -31,13 +31,11 @@ class MainMenu extends StatefulWidget {
 }
 
 class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
-  //
   AnimationController inController, shadowController;
   Animation inAnimation, shadowAnimation;
 
   @override
   void initState() {
-    //
     super.initState();
 
     inController = AnimationController(
@@ -78,7 +76,6 @@ class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
   }
 
   navigateTo(Widget page) async {
-    //
     await Navigator.of(context)
         .push(MaterialPageRoute(builder: (context) => page));
 
@@ -108,7 +105,7 @@ class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
     );
     final menuItemStyle = TextStyle(
       fontSize: 28,
-      color: Properties.primaryColor,
+      color: UIColors.primaryColor,
       shadows: [menuItemShadow],
     );
 
@@ -123,7 +120,7 @@ class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
           Expanded(child: SizedBox()),
           FlatButton(
             child: Text('人机对战', style: menuItemStyle),
-            onPressed: () => navigateTo(BattlePage(EngineType.Native)),
+            onPressed: () => navigateTo(GamePage(EngineType.Native)),
           ),
           Expanded(child: SizedBox()),
           Text('Calcitem',
@@ -134,7 +131,7 @@ class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
     );
 
     return Scaffold(
-      backgroundColor: Properties.lightBackgroundColor,
+      backgroundColor: UIColors.lightBackgroundColor,
       body: Stack(
         children: <Widget>[
           menuItems,
@@ -142,7 +139,7 @@ class _MainMenuState extends State<MainMenu> with TickerProviderStateMixin {
             top: SanmillApp.StatusBarHeight,
             left: 10,
             child: IconButton(
-              icon: Icon(Icons.settings, color: Properties.primaryColor),
+              icon: Icon(Icons.settings, color: UIColors.primaryColor),
               onPressed: () => Navigator.of(context).push(
                 MaterialPageRoute(builder: (context) => SettingsPage()),
               ),
diff --git a/src/ui/flutter/lib/routes/settings_page.dart b/src/ui/flutter/lib/widgets/settings_page.dart
similarity index 82%
rename from src/ui/flutter/lib/routes/settings_page.dart
rename to src/ui/flutter/lib/widgets/settings_page.dart
index 19e576e9..b498795a 100644
--- a/src/ui/flutter/lib/routes/settings_page.dart
+++ b/src/ui/flutter/lib/widgets/settings_page.dart
@@ -20,12 +20,12 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:package_info/package_info.dart';
+import 'package:sanmill/common/config.dart';
+import 'package:sanmill/services/audios.dart';
+import 'package:sanmill/services/player.dart';
+import 'package:sanmill/style/colors.dart';
+import 'package:sanmill/style/toast.dart';
 
-import '../common/config.dart';
-import '../common/properties.dart';
-import '../common/toast.dart';
-import '../services/audios.dart';
-import '../services/player.dart';
 import 'edit_page.dart';
 
 class SettingsPage extends StatefulWidget {
@@ -34,8 +34,7 @@ class SettingsPage extends StatefulWidget {
 }
 
 class _SettingsPageState extends State<SettingsPage> {
-  //
-  String _version = 'Ver 1.00';
+  String _version = "";
 
   @override
   void initState() {
@@ -53,12 +52,12 @@ class _SettingsPageState extends State<SettingsPage> {
 
   changeDifficult() {
     //
-    callback(int stepTime) async {
+    callback(int thinkingTime) async {
       //
       Navigator.of(context).pop();
 
       setState(() {
-        Config.stepTime = stepTime;
+        Config.thinkingTime = thinkingTime;
       });
 
       Config.save();
@@ -71,25 +70,25 @@ class _SettingsPageState extends State<SettingsPage> {
         children: <Widget>[
           SizedBox(height: 10),
           RadioListTile(
-            activeColor: Properties.primaryColor,
+            activeColor: UIColors.primaryColor,
             title: Text('初级'),
-            groupValue: Config.stepTime,
+            groupValue: Config.thinkingTime,
             value: 5000,
             onChanged: callback,
           ),
           Divider(),
           RadioListTile(
-            activeColor: Properties.primaryColor,
+            activeColor: UIColors.primaryColor,
             title: Text('中级'),
-            groupValue: Config.stepTime,
+            groupValue: Config.thinkingTime,
             value: 15000,
             onChanged: callback,
           ),
           Divider(),
           RadioListTile(
-            activeColor: Properties.primaryColor,
+            activeColor: UIColors.primaryColor,
             title: Text('高级'),
-            groupValue: Config.stepTime,
+            groupValue: Config.thinkingTime,
             value: 30000,
             onChanged: callback,
           ),
@@ -150,8 +149,7 @@ class _SettingsPageState extends State<SettingsPage> {
       context: context,
       barrierDismissible: false,
       builder: (context) => AlertDialog(
-        title:
-            Text('关于「直棋 」', style: TextStyle(color: Properties.primaryColor)),
+        title: Text('关于「直棋 」', style: TextStyle(color: UIColors.primaryColor)),
         content: Column(
           mainAxisSize: MainAxisSize.min,
           crossAxisAlignment: CrossAxisAlignment.start,
@@ -187,11 +185,11 @@ class _SettingsPageState extends State<SettingsPage> {
   Widget build(BuildContext context) {
     //
     final TextStyle headerStyle =
-        TextStyle(color: Properties.secondaryColor, fontSize: 20.0);
-    final TextStyle itemStyle = TextStyle(color: Properties.primaryColor);
+        TextStyle(color: UIColors.secondaryColor, fontSize: 20.0);
+    final TextStyle itemStyle = TextStyle(color: UIColors.primaryColor);
 
     return Scaffold(
-      backgroundColor: Properties.lightBackgroundColor,
+      backgroundColor: UIColors.lightBackgroundColor,
       appBar: AppBar(title: Text('设置')),
       body: SingleChildScrollView(
         padding: const EdgeInsets.all(16),
@@ -202,7 +200,7 @@ class _SettingsPageState extends State<SettingsPage> {
             Text("人机难度", style: headerStyle),
             const SizedBox(height: 10.0),
             Card(
-              color: Properties.boardBackgroundColor,
+              color: UIColors.boardBackgroundColor,
               elevation: 0.5,
               margin: const EdgeInsets.symmetric(vertical: 4.0, horizontal: 0),
               child: Column(
@@ -211,11 +209,13 @@ class _SettingsPageState extends State<SettingsPage> {
                     title: Text("游戏难度", style: itemStyle),
                     trailing:
                         Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
-                      Text(Config.stepTime <= 5000
+                      Text(Config.thinkingTime <= 5000
                           ? '初级'
-                          : Config.stepTime <= 15000 ? '中级' : '高级'),
+                          : Config.thinkingTime <= 15000
+                              ? '中级'
+                              : '高级'),
                       Icon(Icons.keyboard_arrow_right,
-                          color: Properties.secondaryColor),
+                          color: UIColors.secondaryColor),
                     ]),
                     onTap: changeDifficult,
                   ),
@@ -225,19 +225,19 @@ class _SettingsPageState extends State<SettingsPage> {
             const SizedBox(height: 16),
             Text("声音", style: headerStyle),
             Card(
-              color: Properties.boardBackgroundColor,
+              color: UIColors.boardBackgroundColor,
               margin: const EdgeInsets.symmetric(vertical: 10),
               child: Column(
                 children: <Widget>[
                   SwitchListTile(
-                    activeColor: Properties.primaryColor,
+                    activeColor: UIColors.primaryColor,
                     value: Config.bgmEnabled,
                     title: Text("背景音乐", style: itemStyle),
                     onChanged: switchMusic,
                   ),
                   _buildDivider(),
                   SwitchListTile(
-                    activeColor: Properties.primaryColor,
+                    activeColor: UIColors.primaryColor,
                     value: Config.toneEnabled,
                     title: Text("提示音效", style: itemStyle),
                     onChanged: switchTone,
@@ -248,7 +248,7 @@ class _SettingsPageState extends State<SettingsPage> {
             const SizedBox(height: 16),
             Text("排行榜", style: headerStyle),
             Card(
-              color: Properties.boardBackgroundColor,
+              color: UIColors.boardBackgroundColor,
               margin: const EdgeInsets.symmetric(vertical: 10),
               child: Column(
                 children: <Widget>[
@@ -258,7 +258,7 @@ class _SettingsPageState extends State<SettingsPage> {
                         Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                       Text(Player.shared.name),
                       Icon(Icons.keyboard_arrow_right,
-                          color: Properties.secondaryColor),
+                          color: UIColors.secondaryColor),
                     ]),
                     onTap: changeName,
                   ),
@@ -268,7 +268,7 @@ class _SettingsPageState extends State<SettingsPage> {
             const SizedBox(height: 16),
             Text("关于", style: headerStyle),
             Card(
-              color: Properties.boardBackgroundColor,
+              color: UIColors.boardBackgroundColor,
               margin: const EdgeInsets.symmetric(vertical: 10),
               child: Column(
                 children: <Widget>[
@@ -278,7 +278,7 @@ class _SettingsPageState extends State<SettingsPage> {
                         Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
                       Text(_version ?? ''),
                       Icon(Icons.keyboard_arrow_right,
-                          color: Properties.secondaryColor),
+                          color: UIColors.secondaryColor),
                     ]),
                     onTap: showAbout,
                   ),
@@ -297,7 +297,7 @@ class _SettingsPageState extends State<SettingsPage> {
       margin: const EdgeInsets.symmetric(horizontal: 16),
       width: double.infinity,
       height: 1.0,
-      color: Properties.lightLineColor,
+      color: UIColors.lightLineColor,
     );
   }
 }
diff --git a/src/ui/flutter/lib/board/words_on_board.dart b/src/ui/flutter/lib/widgets/words_on_board.dart
similarity index 93%
rename from src/ui/flutter/lib/board/words_on_board.dart
rename to src/ui/flutter/lib/widgets/words_on_board.dart
index 0dbee8ea..ffe2fe69 100644
--- a/src/ui/flutter/lib/board/words_on_board.dart
+++ b/src/ui/flutter/lib/widgets/words_on_board.dart
@@ -18,8 +18,7 @@
 */
 
 import 'package:flutter/material.dart';
-
-import '../common/properties.dart';
+import 'package:sanmill/style/colors.dart';
 
 class WordsOnBoard extends StatelessWidget {
   //
@@ -45,7 +44,7 @@ class WordsOnBoard extends StatelessWidget {
           Row(children: rChildren),
         ],
       ),
-      style: TextStyle(color: Properties.boardTipsColor),
+      style: TextStyle(color: UIColors.boardTipsColor),
     );
   }
 }