gobang/lib/widgets/board_painter.dart

import 'package:flutter/material.dart';
import 'package:gobang/models/chess.dart';
import 'package:gobang/models/position.dart';
import 'package:gobang/themes/app_colors.dart';
import 'package:gobang/utils/constants.dart';

/// 棋盘 + 棋子绘制；最后一手支持缩放入场与高亮光圈。
class BoardPainter extends CustomPainter {
  BoardPainter({
    required this.pieces,
    required this.version,
    this.lastMoveScale = 1,
    this.lastMovePulse = 0,
  });

  final List<Position> pieces;
  final int version;
  final double lastMoveScale;
  final double lastMovePulse;

  @override
  void paint(Canvas canvas, Size size) {
    final cell = size.width / (kBoardSize - 1);

    final bg = Paint()
      ..shader = const LinearGradient(
        begin: Alignment.topLeft,
        end: Alignment.bottomRight,
        colors: [
          AppColors.woodLight,
          AppColors.woodMid,
          AppColors.woodDark,
        ],
      ).createShader(Offset.zero & size);
    final rrect = RRect.fromRectAndRadius(
      Offset.zero & size,
      const Radius.circular(12),
    );
    canvas.drawRRect(rrect, bg);

    final line = Paint()
      ..style = PaintingStyle.stroke
      ..color = const Color(0x66FFFFFF)
      ..strokeWidth = 1;
    for (var i = 0; i < kBoardSize; i++) {
      final o = cell * i;
      canvas.drawLine(Offset(0, o), Offset(size.width, o), line);
      canvas.drawLine(Offset(o, 0), Offset(o, size.height), line);
    }

    // 星位
    final star = Paint()..color = const Color(0xFF3D2B1F);
    for (final p in const [
      Offset(3, 3),
      Offset(3, 11),
      Offset(7, 7),
      Offset(11, 3),
      Offset(11, 11),
    ]) {
      canvas.drawCircle(
        Offset(p.dx * cell, p.dy * cell),
        3,
        star,
      );
    }

    final radius = cell / 2 - 2;
    final fill = Paint()..style = PaintingStyle.fill;
    final lastIndex = pieces.length - 1;

    for (var i = 0; i < pieces.length; i++) {
      final p = pieces[i];
      final isLast = i == lastIndex;
      final center = Offset(p.dx, p.dy);
      final scale = isLast ? lastMoveScale.clamp(0.0, 1.2) : 1.0;
      final r = radius * scale;

      if (isLast && lastMovePulse > 0) {
        final ring = Paint()
          ..style = PaintingStyle.stroke
          ..strokeWidth = 2.5
          ..color = AppColors.lastMark.withValues(
            alpha: 0.85 * lastMovePulse,
          );
        canvas.drawCircle(center, radius * (1.15 + 0.45 * lastMovePulse), ring);
      }

      // 棋子阴影
      canvas.drawCircle(
        center.translate(1.2, 1.8),
        r,
        Paint()..color = const Color(0x44000000),
      );

      final isWhite = p.chess is WhiteChess;
      fill.shader = RadialGradient(
        center: const Alignment(-0.35, -0.4),
        radius: 0.95,
        colors: isWhite
            ? const [Color(0xFFFFFFFF), Color(0xFFD8D8D8)]
            : const [Color(0xFF4A4A4A), Color(0xFF111111)],
      ).createShader(Rect.fromCircle(center: center, radius: r));

      if (p.chessShape.shape == 1) {
        canvas.drawCircle(center, r, fill);
      } else {
        canvas.drawRRect(
          RRect.fromRectAndRadius(
            Rect.fromCircle(center: center, radius: r),
            Radius.circular(r * 0.2),
          ),
          fill,
        );
      }
      fill.shader = null;

      if (isLast && scale > 0.85) {
        final mark = Paint()
          ..style = PaintingStyle.fill
          ..color = AppColors.lastMark;
        final s = radius * 0.28;
        final path = Path()
          ..moveTo(center.dx, center.dy - s)
          ..lineTo(center.dx - s * 0.9, center.dy + s * 0.7)
          ..lineTo(center.dx + s * 0.9, center.dy + s * 0.7)
          ..close();
        canvas.drawPath(path, mark);
      }
    }
  }

  @override
  bool shouldRepaint(covariant BoardPainter oldDelegate) {
    return oldDelegate.version != version ||
        oldDelegate.lastMoveScale != lastMoveScale ||
        oldDelegate.lastMovePulse != lastMovePulse;
  }
}