BlockSeasons/lib/ui/widgets/piece_painter.dart

import 'package:flutter/material.dart';

import '../../game/models/piece.dart';
import '../theme/palette.dart';

/// Draws a piece as rounded tiles at a given cell size; reused by the tray,
/// the drag overlay, and ghost previews.
void paintPiece(
  Canvas canvas,
  Piece piece, {
  required double cellSize,
  Offset origin = Offset.zero,
  Color? overrideColor,
}) {
  final paint = Paint()
    ..color = overrideColor ?? GamePalette.tile(piece.colorId);
  final inset = cellSize * 0.05;
  final radius = Radius.circular(cellSize * 0.18);
  for (final (dx, dy) in piece.offsets) {
    final rect = Rect.fromLTWH(
      origin.dx + dx * cellSize + inset,
      origin.dy + dy * cellSize + inset,
      cellSize - inset * 2,
      cellSize - inset * 2,
    );
    canvas.drawRRect(RRect.fromRectAndRadius(rect, radius), paint);
    if (overrideColor == null) {
      // Subtle top highlight for depth.
      final highlight = Paint()..color = Colors.white.withValues(alpha: 0.18);
      canvas.drawRRect(
        RRect.fromRectAndRadius(
          Rect.fromLTWH(rect.left, rect.top, rect.width, rect.height * 0.32),
          radius,
        ),
        highlight,
      );
    }
  }
}

/// Bounding size of a piece in cells.
(int, int) pieceCellBounds(Piece piece) {
  var w = 0;
  var h = 0;
  for (final (dx, dy) in piece.offsets) {
    if (dx + 1 > w) w = dx + 1;
    if (dy + 1 > h) h = dy + 1;
  }
  return (w, h);
}

class PieceWidget extends StatelessWidget {
  const PieceWidget({super.key, required this.piece, required this.cellSize});

  final Piece piece;
  final double cellSize;

  @override
  Widget build(BuildContext context) {
    final (w, h) = pieceCellBounds(piece);
    return CustomPaint(
      size: Size(w * cellSize, h * cellSize),
      painter: _PiecePainter(piece, cellSize),
    );
  }
}

class _PiecePainter extends CustomPainter {
  const _PiecePainter(this.piece, this.cellSize);

  final Piece piece;
  final double cellSize;

  @override
  void paint(Canvas canvas, Size size) {
    paintPiece(canvas, piece, cellSize: cellSize);
  }

  @override
  bool shouldRepaint(_PiecePainter old) =>
      old.piece != piece || old.cellSize != cellSize;
}