BadNote/lib/editor/render/annotation_layer.dart

// lib/editor/render/annotation_layer.dart
//
// Composites the static committed-stroke layer and the live in-progress layer
// into a single widget. Wrap the page widget with this to get ink rendering.
//
// Layout:
//   RepaintBoundary
//     └─ Stack
//          ├─ CustomPaint(StaticInkPainter)   ← repaints only on revision bump
//          └─ CustomPaint(LiveInkPainter)      ← repaints on every pointer move

import 'package:flutter/material.dart';

import '../engine/stroke_model.dart';
import '../engine/stroke_store.dart';
import 'ink_picture_cache.dart';
import 'live_ink_painter.dart';
import 'static_ink_painter.dart';

/// A [StatelessWidget] that renders committed and live ink strokes over a
/// [pageSize]-sized area.
///
/// Place it as an overlay on top of the page content; it is fully transparent
/// where no strokes are drawn.
///
/// [hostId] identifies the ink host (e.g. page id) and is used as the cache
/// key prefix so multiple pages can share an [InkPictureCache] instance.
class AnnotationLayer extends StatelessWidget {
  const AnnotationLayer({
    super.key,
    required this.hostId,
    required this.store,
    required this.liveStroke,
    required this.pageSize,
    required this.cache,
  });

  final String hostId;
  final StrokeStore store;

  /// The stroke currently being drawn, or null when idle.
  final EditorStroke? liveStroke;
  final Size pageSize;
  final InkPictureCache cache;

  @override
  Widget build(BuildContext context) {
    return RepaintBoundary(
      child: Stack(
        children: [
          CustomPaint(
            size: pageSize,
            painter: StaticInkPainter(
              hostId: hostId,
              store: store,
              pageSize: pageSize,
              cache: cache,
            ),
          ),
          CustomPaint(
            size: pageSize,
            painter: LiveInkPainter(
              live: liveStroke,
              pageSize: pageSize,
            ),
          ),
        ],
      ),
    );
  }
}