468 show captured pieces instead of material imbalance

lib/src/model/game/material_diff.dart

@@ -9,6 +9,7 @@ class MaterialDiffSide with _$MaterialDiffSide {
   const factory MaterialDiffSide({
     required IMap<Role, int> pieces,
     required int score,
+    required IMap<Role, int> capturedPieces,
   }) = _MaterialDiffSide;
 }
 
@@ -30,11 +31,32 @@ class MaterialDiff with _$MaterialDiff {
     required MaterialDiffSide white,
   }) = _MaterialDiff;
 
-  factory MaterialDiff.fromBoard(Board board) {
+  factory MaterialDiff.fromBoard(Board board, {Board? startingPosition}) {
     int score = 0;
     final IMap<Role, int> blackCount = board.materialCount(Side.black);
     final IMap<Role, int> whiteCount = board.materialCount(Side.white);
 
+    final IMap<Role, int> blackStartingCount =
+        startingPosition?.materialCount(Side.black) ??
+            Board.standard.materialCount(Side.black);
+    final IMap<Role, int> whiteStartingCount =
+        startingPosition?.materialCount(Side.white) ??
+            Board.standard.materialCount(Side.white);
+
+    IMap<Role, int> subtractPieceCounts(
+      IMap<Role, int> startingCount,
+      IMap<Role, int> subtractCount,
+    ) {
+      return startingCount.map(
+        (role, count) => MapEntry(role, count - (subtractCount.get(role) ?? 0)),
+      );
+    }
+
+    final IMap<Role, int> blackCapturedPieces =
+        subtractPieceCounts(whiteStartingCount, whiteCount);
+    final IMap<Role, int> whiteCapturedPieces =
+        subtractPieceCounts(blackStartingCount, blackCount);
+
     Map<Role, int> count;
     Map<Role, int> black;
     Map<Role, int> white;
@@ -80,8 +102,16 @@ class MaterialDiff with _$MaterialDiff {
     });
 
     return MaterialDiff(
-      black: MaterialDiffSide(pieces: black.toIMap(), score: -score),
-      white: MaterialDiffSide(pieces: white.toIMap(), score: score),
+      black: MaterialDiffSide(
+        pieces: black.toIMap(),
+        score: -score,
+        capturedPieces: blackCapturedPieces,
+      ),
+      white: MaterialDiffSide(
+        pieces: white.toIMap(),
+        score: score,
+        capturedPieces: whiteCapturedPieces,
+      ),
     );
   }
 

lib/src/model/settings/board_preferences.dart

@@ -1,6 +1,8 @@
 import 'package:chessground/chessground.dart';
+import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:freezed_annotation/freezed_annotation.dart';
+import 'package:lichess_mobile/l10n/l10n.dart';
 import 'package:lichess_mobile/src/model/settings/preferences_storage.dart';
 import 'package:lichess_mobile/src/styles/styles.dart';
 import 'package:lichess_mobile/src/utils/color_palette.dart';
@@ -84,9 +86,11 @@ class BoardPreferences extends _$BoardPreferences
     return save(state.copyWith(dragTargetKind: dragTargetKind));
   }
 
-  Future<void> toggleShowMaterialDifference() {
+  Future<void> setMaterialDifferenceFormat(
+    MaterialDifferenceFormat materialDifferenceFormat,
+  ) {
     return save(
-      state.copyWith(showMaterialDifference: !state.showMaterialDifference),
+      state.copyWith(materialDifferenceFormat: materialDifferenceFormat),
     );
   }
 
@@ -120,7 +124,7 @@ class BoardPrefs with _$BoardPrefs implements Serializable {
     required bool boardHighlights,
     required bool coordinates,
     required bool pieceAnimation,
-    required bool showMaterialDifference,
+    required MaterialDifferenceFormat materialDifferenceFormat,
     required ClockPosition clockPosition,
     @JsonKey(
       defaultValue: PieceShiftMethod.either,
@@ -150,7 +154,7 @@ class BoardPrefs with _$BoardPrefs implements Serializable {
     boardHighlights: true,
     coordinates: true,
     pieceAnimation: true,
-    showMaterialDifference: true,
+    materialDifferenceFormat: MaterialDifferenceFormat.materialDifference,
     clockPosition: ClockPosition.right,
     pieceShiftMethod: PieceShiftMethod.either,
     enableShapeDrawings: true,
@@ -317,6 +321,27 @@ enum BoardTheme {
         );
 }
 
+enum MaterialDifferenceFormat {
+  materialDifference(label: 'Material difference'),
+  capturedPieces(label: 'Captured pieces'),
+  hidden(label: 'Hidden');
+
+  const MaterialDifferenceFormat({
+    required this.label,
+  });
+
+  final String label;
+
+  bool get visible => this != MaterialDifferenceFormat.hidden;
+
+  String l10n(AppLocalizations l10n) => switch (this) {
+        //TODO: Add l10n
+        MaterialDifferenceFormat.materialDifference => materialDifference.label,
+        MaterialDifferenceFormat.capturedPieces => capturedPieces.label,
+        MaterialDifferenceFormat.hidden => hidden.label,
+      };
+}
+
 enum ClockPosition {
   left,
   right;

lib/src/view/correspondence/offline_correspondence_game_screen.dart

@@ -142,9 +142,9 @@ class _BodyState extends ConsumerState<_Body> {
 
   @override
   Widget build(BuildContext context) {
-    final shouldShowMaterialDiff = ref.watch(
+    final materialDifference = ref.watch(
       boardPreferencesProvider.select(
-        (prefs) => prefs.showMaterialDifference,
+        (prefs) => prefs.materialDifferenceFormat,
       ),
     );
 
@@ -157,9 +157,10 @@ class _BodyState extends ConsumerState<_Body> {
 
     final black = GamePlayer(
       player: game.black,
-      materialDiff: shouldShowMaterialDiff
+      materialDiff: materialDifference.visible
           ? game.materialDiffAt(stepCursor, Side.black)
           : null,
+      materialDifferenceFormat: materialDifference,
       shouldLinkToUserProfile: false,
       mePlaying: youAre == Side.black,
       confirmMoveCallbacks: youAre == Side.black && moveToConfirm != null
@@ -179,9 +180,10 @@ class _BodyState extends ConsumerState<_Body> {
     );
     final white = GamePlayer(
       player: game.white,
-      materialDiff: shouldShowMaterialDiff
+      materialDiff: materialDifference.visible
           ? game.materialDiffAt(stepCursor, Side.white)
           : null,
+      materialDifferenceFormat: materialDifference,
       shouldLinkToUserProfile: false,
       mePlaying: youAre == Side.white,
       confirmMoveCallbacks: youAre == Side.white && moveToConfirm != null

lib/src/view/game/game_body.dart

@@ -122,9 +122,10 @@ class GameBody extends ConsumerWidget {
 
         final black = GamePlayer(
           player: gameState.game.black,
-          materialDiff: boardPreferences.showMaterialDifference
+          materialDiff: boardPreferences.materialDifferenceFormat.visible
               ? gameState.game.materialDiffAt(gameState.stepCursor, Side.black)
               : null,
+          materialDifferenceFormat: boardPreferences.materialDifferenceFormat,
           timeToMove: gameState.game.sideToMove == Side.black
               ? gameState.timeToMove
               : null,
@@ -174,9 +175,10 @@ class GameBody extends ConsumerWidget {
         );
         final white = GamePlayer(
           player: gameState.game.white,
-          materialDiff: boardPreferences.showMaterialDifference
+          materialDiff: boardPreferences.materialDifferenceFormat.visible
               ? gameState.game.materialDiffAt(gameState.stepCursor, Side.white)
               : null,
+          materialDifferenceFormat: boardPreferences.materialDifferenceFormat,
           timeToMove: gameState.game.sideToMove == Side.white
               ? gameState.timeToMove
               : null,

lib/src/view/game/game_player.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:dartchess/dartchess.dart';
+import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
@@ -28,6 +29,7 @@ class GamePlayer extends StatelessWidget {
     required this.player,
     this.clock,
     this.materialDiff,
+    this.materialDifferenceFormat,
     this.confirmMoveCallbacks,
     this.timeToMove,
     this.shouldLinkToUserProfile = true,
@@ -40,6 +42,7 @@ class GamePlayer extends StatelessWidget {
   final Player player;
   final Widget? clock;
   final MaterialDiffSide? materialDiff;
+  final MaterialDifferenceFormat? materialDifferenceFormat;
 
   /// if confirm move preference is enabled, used to display confirmation buttons
   final ({VoidCallback confirm, VoidCallback cancel})? confirmMoveCallbacks;
@@ -148,33 +151,12 @@ class GamePlayer extends StatelessWidget {
         if (timeToMove != null)
           MoveExpiration(timeToMove: timeToMove!, mePlaying: mePlaying)
         else if (materialDiff != null)
-          Row(
-            mainAxisAlignment: clockPosition == ClockPosition.right
-                ? MainAxisAlignment.start
-                : MainAxisAlignment.end,
-            children: [
-              for (final role in Role.values)
-                for (int i = 0; i < materialDiff!.pieces[role]!; i++)
-                  Icon(
-                    _iconByRole[role],
-                    size: 13,
-                    color: Colors.grey,
-                  ),
-              const SizedBox(width: 3),
-              Text(
-                style: const TextStyle(
-                  fontSize: 13,
-                  color: Colors.grey,
-                ),
-                materialDiff != null && materialDiff!.score > 0
-                    ? '+${materialDiff!.score}'
-                    : '',
-              ),
-            ],
-          )
-        else
-          // to avoid shifts use an empty text widget
-          const Text('', style: TextStyle(fontSize: 13)),
+          MaterialDifferenceDisplay(
+            materialDiff: materialDiff!,
+            materialDifferenceFormat: materialDifferenceFormat,
+          ),
+        // to avoid shifts use an empty text widget
+        const Text('', style: TextStyle(fontSize: 13)),
       ],
     );
 
@@ -347,6 +329,46 @@ class _MoveExpirationState extends ConsumerState<MoveExpiration> {
   }
 }
 
+class MaterialDifferenceDisplay extends StatelessWidget {
+  const MaterialDifferenceDisplay({
+    required this.materialDiff,
+    this.materialDifferenceFormat = MaterialDifferenceFormat.materialDifference,
+  });
+
+  final MaterialDiffSide materialDiff;
+  final MaterialDifferenceFormat? materialDifferenceFormat;
+
+  @override
+  Widget build(BuildContext context) {
+    final IMap<Role, int> piecesToRender =
+        (materialDifferenceFormat == MaterialDifferenceFormat.capturedPieces
+            ? materialDiff.capturedPieces
+            : materialDiff.pieces);
+
+    return materialDifferenceFormat?.visible ?? true
+        ? Row(
+            children: [
+              for (final role in Role.values)
+                for (int i = 0; i < piecesToRender[role]!; i++)
+                  Icon(
+                    _iconByRole[role],
+                    size: 13,
+                    color: Colors.grey,
+                  ),
+              const SizedBox(width: 3),
+              Text(
+                style: const TextStyle(
+                  fontSize: 13,
+                  color: Colors.grey,
+                ),
+                materialDiff.score > 0 ? '+${materialDiff.score}' : '',
+              ),
+            ],
+          )
+        : const SizedBox.shrink();
+  }
+}
+
 const Map<Role, IconData> _iconByRole = {
   Role.king: LichessIcons.chess_king,
   Role.queen: LichessIcons.chess_queen,

lib/src/view/game/game_settings.dart

@@ -10,7 +10,6 @@ import 'package:lichess_mobile/src/view/settings/board_settings_screen.dart';
 import 'package:lichess_mobile/src/widgets/adaptive_bottom_sheet.dart';
 import 'package:lichess_mobile/src/widgets/list.dart';
 import 'package:lichess_mobile/src/widgets/settings.dart';
-
 import 'game_screen_providers.dart';
 
 class GameSettings extends ConsumerWidget {

lib/src/view/over_the_board/over_the_board_screen.dart

@@ -301,9 +301,10 @@ class _Player extends ConsumerWidget {
             name: side.name.capitalize(),
           ),
         ),
-        materialDiff: boardPreferences.showMaterialDifference
+        materialDiff: boardPreferences.materialDifferenceFormat.visible
             ? gameState.currentMaterialDiff(side)
             : null,
+        materialDifferenceFormat: boardPreferences.materialDifferenceFormat,
         shouldLinkToUserProfile: false,
         clock: clock.timeIncrement.isInfinite
             ? null