BadNote/test/pen_polish_test.dart

// test/pen_polish_test.dart
//
// Guards the pen-polish work (W1 configurable thinning + W3 tilt):
//  - the on-screen painter (ink_painters.buildStrokePath) and the export/engine
//    path (stroke_geometry.buildStrokeOutline) share ONE thinning default
//    (kDefaultPenThinning) and respond to it identically — the user's core
//    "thinning 写死" complaint, and the single-source-of-truth invariant the
//    Critic required;
//  - tilt survives the PenStroke -> EditorStroke adapter (W3 model fix).

import 'dart:ui';

import 'package:flutter_test/flutter_test.dart';

import 'package:badnote/editor/canvas/ink_painters.dart';
import 'package:badnote/editor/canvas/pen_stroke.dart';
import 'package:badnote/editor/engine/brush.dart';
import 'package:badnote/editor/engine/stroke_geometry.dart';
import 'package:badnote/editor/engine/stroke_model.dart';

PenStroke _pressuredPen() => PenStroke(
      // Varied pressure, deliberately NOT reaching full force, so that
      // thinning>0 (pressure-modulated, narrower) vs thinning=0 (constant full
      // width) produces a measurably different bounding box.
      points: const [
        PenPoint(0.10, 0.50, 0.10),
        PenPoint(0.30, 0.50, 0.25),
        PenPoint(0.50, 0.50, 0.40),
        PenPoint(0.70, 0.50, 0.55),
      ],
      color: 0xFF000000,
      width: 0.01,
      kind: PenStrokeKind.pen,
    );

void main() {
  const size = Size(1000, 1000);

  group('W1 — thinning is configurable and single-sourced', () {
    test('buildStrokePath default == explicit kDefaultPenThinning', () {
      final pen = _pressuredPen();
      final byDefault = buildStrokePath(pen, size, isComplete: true);
      final explicit = buildStrokePath(pen, size,
          isComplete: true, thinning: kDefaultPenThinning);
      expect(byDefault.getBounds(), explicit.getBounds());
    });

    test('brush thinning actually affects the outline (param is wired)', () {
      // After the brush-engine rebuild each brush owns its perfect_freehand
      // thinning (spec §4): fountainPen = 0.9 (pressure-modulated, pinched
      // middle) vs highlighter = 0.0 (constant full width). The bounding box is
      // thinning-INVARIANT (round caps at full size), so compare the outline
      // PERIMETER, which reflects the pinched middle.
      double perimeter(Path p) =>
          p.computeMetrics().fold(0.0, (sum, m) => sum + m.length);
      final pressured = _pressuredPen(); // fountainPen brush, thinning 0.9
      final flat = PenStroke(
        points: _pressuredPen().points,
        color: 0xFF000000,
        width: 0.01,
        kind: PenStrokeKind.highlighter,
        brush: BrushKind.highlighter, // highlighter brush, thinning 0.0
      );
      final strong =
          perimeter(buildStrokePath(pressured, size, isComplete: true));
      final none = perimeter(buildStrokePath(flat, size, isComplete: true));
      expect((strong - none).abs(), greaterThan(1.0),
          reason: 'brush thinning had no effect on the outline — not wired');
    });

    test('screen and export builders agree for the same stroke + thinning', () {
      final pen = _pressuredPen();
      final editor = EditorStroke.fromPenStroke(pen);
      for (final thinning in const [0.0, kDefaultPenThinning, 1.0]) {
        final screen =
            buildStrokePath(pen, size, isComplete: true, thinning: thinning)
                .getBounds();
        final export =
            buildStrokeOutline(editor, size, isComplete: true, thinning: thinning)
                .getBounds();
        expect(screen, export,
            reason: 'screen vs export diverged at thinning=$thinning');
      }
    });
  });

  group('W3 — tilt survives the PenStroke adapter', () {
    test('PenPoint.tilt maps into EditorPoint.tilt', () {
      const pen = PenStroke(
        points: [PenPoint(0.1, 0.2, 0.5, tilt: 23.5)],
        color: 0xFF112233,
        width: 0.01,
        kind: PenStrokeKind.pen,
      );
      final editor = EditorStroke.fromPenStroke(pen);
      expect(editor.points.single.tilt, 23.5);
    });

    test('null tilt stays null through the adapter', () {
      const pen = PenStroke(
        points: [PenPoint(0.1, 0.2, 0.5)],
        color: 0xFF112233,
        width: 0.01,
        kind: PenStrokeKind.pen,
      );
      final editor = EditorStroke.fromPenStroke(pen);
      expect(editor.points.single.tilt, isNull);
    });
  });
}