Feature: Add Fill Tool command pipeline

lib/core/commands/command_factory/command_factory.dart

@@ -4,6 +4,7 @@ import 'dart:ui' as ui;
 import 'package:flutter/material.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/clipboard_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/delete_region_command.dart';
+import 'package:paintroid/core/commands/command_implementation/graphic/fill_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/text_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/line_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/path_command.dart';
@@ -136,4 +137,13 @@ class CommandFactory {
         Paint(),
         region,
       );
+
+  FillCommand createFillCommand(
+    Paint paint,
+    Uint8List imageData,
+  ) =>
+      FillCommand(
+        paint,
+        imageData,
+      );
 }

lib/core/commands/command_implementation/command.dart

@@ -1,6 +1,7 @@
 import 'package:equatable/equatable.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/clipboard_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/delete_region_command.dart';
+import 'package:paintroid/core/commands/command_implementation/graphic/fill_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/line_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/path_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/shape/ellipse_shape_command.dart';
@@ -34,6 +35,8 @@ abstract class Command with EquatableMixin {
         return DeleteRegionCommand.fromJson(json);
       case SerializerType.TEXT_COMMAND:
         return TextCommand.fromJson(json);
+      case SerializerType.FILL_COMMAND:
+        return FillCommand.fromJson(json);
       case SerializerType.HEART_SHAPE_COMMAND:
         return HeartShapeCommand.fromJson(json);
       case SerializerType.STAR_SHAPE_COMMAND:

lib/core/commands/command_implementation/graphic/fill_command.dart

@@ -0,0 +1,68 @@
+// ignore_for_file: must_be_immutable
+
+import 'dart:typed_data';
+import 'dart:ui' as ui;
+
+import 'package:paintroid/core/commands/command_implementation/graphic/graphic_command.dart';
+import 'package:paintroid/core/json_serialization/converter/paint_converter.dart';
+import 'package:paintroid/core/json_serialization/converter/uint8list_base64_converter.dart';
+import 'package:paintroid/core/json_serialization/versioning/serializer_version.dart';
+import 'package:paintroid/core/json_serialization/versioning/version_strategy.dart';
+
+class FillCommand extends GraphicCommand {
+  final Uint8List imageData;
+  final int version;
+  final String type;
+
+  ui.Image? _runtimeImage;
+
+  FillCommand(
+    super.paint,
+    this.imageData, {
+    int? version,
+    this.type = SerializerType.FILL_COMMAND,
+  }) : version =
+            version ?? VersionStrategyManager.strategy.getFillCommandVersion();
+
+  @override
+  Future<void> prepareForRuntime() async {
+    if (_runtimeImage != null || imageData.isEmpty) {
+      return;
+    }
+    final buffer = await ui.ImmutableBuffer.fromUint8List(imageData);
+    final descriptor = await ui.ImageDescriptor.encoded(buffer);
+    final codec = await descriptor.instantiateCodec();
+    final frameInfo = await codec.getNextFrame();
+    _runtimeImage = frameInfo.image;
+  }
+
+  @override
+  void call(ui.Canvas canvas) {
+    if (_runtimeImage == null) {
+      return;
+    }
+    canvas.drawImage(_runtimeImage!, ui.Offset.zero, ui.Paint());
+  }
+
+  @override
+  Map<String, dynamic> toJson() {
+    return {
+      'paint': const PaintConverter().toJson(paint),
+      'imageData': const Uint8ListBase64Converter().toJson(imageData),
+      'version': version,
+      'type': type,
+    };
+  }
+
+  factory FillCommand.fromJson(Map<String, dynamic> json) {
+    return FillCommand(
+      const PaintConverter().fromJson(json['paint'] as Map<String, dynamic>),
+      const Uint8ListBase64Converter().fromJson(json['imageData'] as String),
+      version: json['version'] as int? ?? Version.v1,
+      type: json['type'] as String? ?? SerializerType.FILL_COMMAND,
+    );
+  }
+
+  @override
+  List<Object?> get props => [paint, imageData, version, type];
+}

lib/core/commands/command_manager/command_manager.dart

@@ -2,6 +2,7 @@ import 'dart:ui';
 
 import 'package:paintroid/core/commands/command_implementation/command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/clipboard_command.dart';
+import 'package:paintroid/core/commands/command_implementation/graphic/fill_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/text_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/graphic_command.dart';
 import 'package:paintroid/core/commands/command_implementation/graphic/line_command.dart';
@@ -123,6 +124,8 @@ class CommandManager {
       return ToolData.TEXT;
     } else if (command.runtimeType == SprayCommand) {
       return ToolData.SPRAY;
+    } else if (command.runtimeType == FillCommand) {
+      return ToolData.FILL;
     } else if (command.runtimeType == StarShapeCommand) {
       return ToolData.SHAPES;
     } else if (command.runtimeType == HeartShapeCommand) {

lib/core/json_serialization/versioning/serializer_version.dart

@@ -11,6 +11,7 @@ class SerializerVersion {
   static const int SPRAY_COMMAND_VERSION = Version.v1;
   static const int CLIPBOARD_COMMAND_VERSION = Version.v1;
   static const int DELETE_REGION_COMMAND_VERSION = Version.v1;
+  static const int FILL_COMMAND_VERSION = Version.v1;
 }
 
 class Version {
@@ -33,4 +34,5 @@ class SerializerType {
   static const String SPRAY_COMMAND = 'SprayCommand';
   static const String CLIPBOARD_COMMAND = 'ClipboardCommand';
   static const String DELETE_REGION_COMMAND = 'DeleteRegionCommand';
+  static const String FILL_COMMAND = 'FillCommand';
 }

lib/core/json_serialization/versioning/version_strategy.dart

@@ -22,6 +22,8 @@ abstract class IVersionStrategy {
   int getClipboardCommandVersion();
 
   int getDeleteRegionCommandVersion();
+
+  int getFillCommandVersion();
 }
 
 class ProductionVersionStrategy implements IVersionStrategy {
@@ -63,6 +65,9 @@ class ProductionVersionStrategy implements IVersionStrategy {
   @override
   int getDeleteRegionCommandVersion() =>
       SerializerVersion.DELETE_REGION_COMMAND_VERSION;
+
+  @override
+  int getFillCommandVersion() => SerializerVersion.FILL_COMMAND_VERSION;
 }
 
 class VersionStrategyManager {

lib/core/providers/object/tools/fill_tool_provider.dart

@@ -0,0 +1,52 @@
+import 'dart:ui' as ui;
+
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'package:paintroid/core/commands/command_factory/command_factory_provider.dart';
+import 'package:paintroid/core/commands/command_manager/command_manager_provider.dart';
+import 'package:paintroid/core/commands/graphic_factory/graphic_factory_provider.dart';
+import 'package:paintroid/core/enums/tool_types.dart';
+import 'package:paintroid/core/providers/object/canvas_painter_provider.dart';
+import 'package:paintroid/core/providers/state/canvas_state_provider.dart';
+import 'package:paintroid/core/tools/implementation/fill_tool.dart';
+
+final fillToolProvider = Provider<FillTool>((ref) {
+  Future<ui.Image?> sourceImageProvider() async {
+    final canvasState = ref.read(canvasStateProvider);
+    final size = canvasState.size;
+    if (size.width <= 0 || size.height <= 0) {
+      return null;
+    }
+
+    final recorder = ref.read(graphicFactoryProvider).createPictureRecorder();
+    final canvas =
+        ref.read(graphicFactoryProvider).createCanvasWithRecorder(recorder);
+    final bounds = ui.Rect.fromLTWH(0, 0, size.width, size.height);
+    canvas.clipRect(bounds);
+
+    if (canvasState.backgroundImage != null) {
+      canvas.drawImage(
+          canvasState.backgroundImage!, ui.Offset.zero, ui.Paint());
+    }
+    if (canvasState.cachedImage != null) {
+      canvas.drawImage(canvasState.cachedImage!, ui.Offset.zero, ui.Paint());
+    }
+
+    final picture = recorder.endRecording();
+    return picture.toImage(size.width.toInt(), size.height.toInt());
+  }
+
+  Future<void> onFillApplied() async {
+    await ref.read(canvasStateProvider.notifier).updateCachedImage();
+    ref.read(canvasPainterProvider.notifier).repaint();
+  }
+
+  return FillTool(
+    commandManager: ref.watch(commandManagerProvider),
+    commandFactory: ref.watch(commandFactoryProvider),
+    graphicFactory: ref.watch(graphicFactoryProvider),
+    type: ToolType.FILL,
+    getSourceImage: sourceImageProvider,
+    onFillApplied: onFillApplied,
+  );
+});

lib/core/providers/state/toolbox_state_provider.dart

@@ -6,6 +6,7 @@ import 'package:paintroid/core/providers/object/canvas_painter_provider.dart';
 import 'package:paintroid/core/providers/object/tools/brush_tool_provider.dart';
 import 'package:paintroid/core/providers/object/tools/clipboard_tool_provider.dart';
 import 'package:paintroid/core/providers/object/tools/eraser_tool_provider.dart';
+import 'package:paintroid/core/providers/object/tools/fill_tool_provider.dart';
 import 'package:paintroid/core/providers/object/tools/hand_tool_provider.dart';
 import 'package:paintroid/core/providers/object/tools/line_tool_provider.dart';
 import 'package:paintroid/core/providers/object/tools/shapes_tool_provider.dart';
@@ -77,6 +78,9 @@ class ToolBoxStateProvider extends _$ToolBoxStateProvider {
         state = state.copyWith(currentTool: ref.read(shapesToolProvider));
         ref.read(canvasPainterProvider.notifier).repaint();
         break;
+      case ToolType.FILL:
+        state = state.copyWith(currentTool: ref.read(fillToolProvider));
+        break;
       case ToolType.TEXT:
         state = state.copyWith(currentTool: ref.read(textToolProvider));
         break;

lib/core/tools/implementation/fill_tool.dart

@@ -0,0 +1,167 @@
+import 'dart:async';
+import 'dart:collection';
+import 'dart:typed_data';
+import 'dart:ui' as ui;
+
+import 'package:paintroid/core/commands/graphic_factory/graphic_factory.dart';
+import 'package:paintroid/core/tools/tool.dart';
+
+class FillTool extends Tool {
+  final GraphicFactory graphicFactory;
+  final Future<ui.Image?> Function() getSourceImage;
+  final Future<void> Function() onFillApplied;
+  bool _isFilling = false;
+
+  FillTool({
+    required super.commandFactory,
+    required super.commandManager,
+    required super.type,
+    required this.graphicFactory,
+    required this.getSourceImage,
+    required this.onFillApplied,
+    super.hasAddFunctionality = false,
+    super.hasFinalizeFunctionality = false,
+  });
+
+  @override
+  void onDown(ui.Offset point, ui.Paint paint) {
+    if (_isFilling) {
+      return;
+    }
+    _isFilling = true;
+    unawaited(_fill(point, paint));
+  }
+
+  Future<void> _fill(ui.Offset point, ui.Paint paint) async {
+    try {
+      final sourceImage = await getSourceImage();
+      if (sourceImage == null) {
+        return;
+      }
+
+      final width = sourceImage.width;
+      final height = sourceImage.height;
+      if (width <= 0 || height <= 0) {
+        return;
+      }
+
+      final startX = point.dx.floor();
+      final startY = point.dy.floor();
+      if (startX < 0 || startX >= width || startY < 0 || startY >= height) {
+        return;
+      }
+
+      final sourceData =
+          await sourceImage.toByteData(format: ui.ImageByteFormat.rawRgba);
+      if (sourceData == null) {
+        return;
+      }
+      final pixels = sourceData.buffer.asUint8List();
+
+      final startIndex = (startY * width + startX) * 4;
+      final sourceR = pixels[startIndex];
+      final sourceG = pixels[startIndex + 1];
+      final sourceB = pixels[startIndex + 2];
+      final sourceA = pixels[startIndex + 3];
+
+      final targetColor = paint.color;
+      final targetR = (targetColor.r * 255).round();
+      final targetG = (targetColor.g * 255).round();
+      final targetB = (targetColor.b * 255).round();
+      final targetA = (targetColor.a * 255).round();
+
+      if (sourceR == targetR &&
+          sourceG == targetG &&
+          sourceB == targetB &&
+          sourceA == targetA) {
+        return;
+      }
+
+      final queue = Queue<int>()..add(startY * width + startX);
+      while (queue.isNotEmpty) {
+        final pixelPos = queue.removeFirst();
+        final x = pixelPos % width;
+        final y = pixelPos ~/ width;
+        final index = pixelPos * 4;
+
+        if (pixels[index] != sourceR ||
+            pixels[index + 1] != sourceG ||
+            pixels[index + 2] != sourceB ||
+            pixels[index + 3] != sourceA) {
+          continue;
+        }
+
+        pixels[index] = targetR;
+        pixels[index + 1] = targetG;
+        pixels[index + 2] = targetB;
+        pixels[index + 3] = targetA;
+
+        if (x > 0) queue.add(pixelPos - 1);
+        if (x < width - 1) queue.add(pixelPos + 1);
+        if (y > 0) queue.add(pixelPos - width);
+        if (y < height - 1) queue.add(pixelPos + width);
+      }
+
+      final filledImage = await _decodeFromRgba(
+        Uint8List.fromList(pixels),
+        width,
+        height,
+      );
+      final pngData =
+          await filledImage.toByteData(format: ui.ImageByteFormat.png);
+      if (pngData == null) {
+        return;
+      }
+
+      final savedPaint = graphicFactory.copyPaint(paint);
+      final command = commandFactory.createFillCommand(
+        savedPaint,
+        pngData.buffer.asUint8List(),
+      );
+      await command.prepareForRuntime();
+      commandManager.addGraphicCommand(command);
+      await onFillApplied();
+    } finally {
+      _isFilling = false;
+    }
+  }
+
+  Future<ui.Image> _decodeFromRgba(Uint8List rgba, int width, int height) {
+    final completer = Completer<ui.Image>();
+    ui.decodeImageFromPixels(
+      rgba,
+      width,
+      height,
+      ui.PixelFormat.rgba8888,
+      completer.complete,
+    );
+    return completer.future;
+  }
+
+  @override
+  void onDrag(ui.Offset point, ui.Paint paint) {}
+
+  @override
+  void onUp(ui.Offset point, ui.Paint paint) {}
+
+  @override
+  void onCancel() {
+    _isFilling = false;
+  }
+
+  @override
+  void onCheckmark(ui.Paint paint) {}
+
+  @override
+  void onPlus() {}
+
+  @override
+  void onUndo() {
+    commandManager.undo();
+  }
+
+  @override
+  void onRedo() {
+    commandManager.redo();
+  }
+}