gobang/lib/widgets/board_painter.dart

import 'package:flutter/cupertino.dart';
import 'package:gobang/models/position.dart';
import 'package:gobang/utils/constants.dart';

/// 棋盘 + 棋子绘制
class BoardPainter extends CustomPainter {
  BoardPainter({required this.pieces, required this.version});

  final List<Position> pieces;
  final int version;

  @override
  void paint(Canvas canvas, Size size) {
    final cell = size.width / (kBoardSize - 1);
    final bg = Paint()
      ..isAntiAlias = true
      ..style = PaintingStyle.fill
      ..color = const Color(0x77cdb175);
    canvas.drawRect(Offset.zero & size, bg);

    final line = Paint()
      ..style = PaintingStyle.stroke
      ..color = CupertinoColors.systemGrey6
      ..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);
    }

    final radius = cell / 2 - 2;
    final fill = Paint()..style = PaintingStyle.fill;
    for (final p in pieces) {
      fill.color = p.chess.color;
      final center = Offset(p.dx, p.dy);
      if (p.chessShape.shape == 1) {
        canvas.drawCircle(center, radius, fill);
      } else {
        canvas.drawRect(
          Rect.fromCircle(center: center, radius: radius),
          fill,
        );
      }
    }
  }

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