feat(perf): RDP stroke simplification for storage/render compaction (R1/R10)

simplifyStroke reduces a stroke's points via Ramer–Douglas–Peucker at a normalized perpendicular-distance tolerance: a fast Surface-Pen stroke drops hundreds of near-collinear samples with no visible change, shrinking the DB row and speeding re-rasterization (R1/R10). Endpoints + significant vertices kept; pressure/tilt + color/width/tool/id preserved; <=2 points or tol<=0 are no-ops (returns the same instance). The commit path can call it before saveHost; the live in-progress stroke stays untouched. Pure geometry over EditorStroke; fully unit-tested (collinear collapse, peak retention, within-tolerance drop, metadata preservation). flutter analyze lib/editor clean; 198/198 tests (+7). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-23 03:33:39 +08:00
parent b359000991
commit 1e836d6e7d
2 changed files with 184 additions and 0 deletions
--- a/test/stroke_simplify_test.dart
+++ b/test/stroke_simplify_test.dart
@@ -0,0 +1,104 @@
+// Tests for RDP stroke simplification (R1/R10 perf).
+
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:badnote/editor/engine/stroke_model.dart';
+import 'package:badnote/editor/engine/stroke_simplify.dart';
+
+EditorStroke _stroke(List<List<double>> pts, {List<double?>? pressures}) =>
+    EditorStroke.create(
+      id: 's',
+      points: [
+        for (var i = 0; i < pts.length; i++)
+          EditorPoint(
+            x: pts[i][0],
+            y: pts[i][1],
+            pressure: pressures?[i],
+          ),
+      ],
+    );
+
+void main() {
+  test('collinear points collapse to the two endpoints', () {
+    final s = _stroke([
+      [0.0, 0.0],
+      [0.1, 0.1],
+      [0.2, 0.2],
+      [0.3, 0.3],
+    ]);
+    final out = simplifyStroke(s, tolerance: 0.0008);
+    expect(out.points.length, 2);
+    expect(out.points.first.x, 0.0);
+    expect(out.points.last.x, 0.3);
+  });
+
+  test('a perceptually significant peak is kept', () {
+    final s = _stroke([
+      [0.0, 0.0],
+      [0.5, 0.5], // far off the (0,0)-(1,0) line → kept
+      [1.0, 0.0],
+    ]);
+    final out = simplifyStroke(s, tolerance: 0.0008);
+    expect(out.points.length, 3);
+  });
+
+  test('a deviation within tolerance is dropped', () {
+    final s = _stroke([
+      [0.0, 0.0],
+      [0.5, 0.0001], // perp dist 0.0001 < 0.0008 → dropped
+      [1.0, 0.0],
+    ]);
+    final out = simplifyStroke(s, tolerance: 0.0008);
+    expect(out.points.length, 2);
+  });
+
+  test('<= 2 points are returned unchanged (same instance)', () {
+    final s = _stroke([
+      [0.1, 0.1],
+      [0.2, 0.2],
+    ]);
+    expect(identical(simplifyStroke(s), s), isTrue);
+  });
+
+  test('non-positive tolerance is a no-op', () {
+    final s = _stroke([
+      [0.0, 0.0],
+      [0.1, 0.11],
+      [0.2, 0.2],
+    ]);
+    expect(identical(simplifyStroke(s, tolerance: 0), s), isTrue);
+  });
+
+  test('pressure rides along on retained points', () {
+    final s = _stroke([
+      [0.0, 0.0],
+      [0.5, 0.5],
+      [1.0, 0.0],
+    ], pressures: [
+      0.2,
+      0.9,
+      0.3,
+    ]);
+    final out = simplifyStroke(s, tolerance: 0.0008);
+    expect(out.points.map((p) => p.pressure), [0.2, 0.9, 0.3]);
+  });
+
+  test('metadata (color/width/tool/id) is preserved', () {
+    final s = EditorStroke.create(
+      id: 'keep-me',
+      color: 0xFF112233,
+      width: 0.02,
+      tool: EditorTool.highlighter,
+      points: [
+        const EditorPoint(x: 0, y: 0),
+        const EditorPoint(x: 0.1, y: 0.1),
+        const EditorPoint(x: 0.2, y: 0.2),
+      ],
+    );
+    final out = simplifyStroke(s, tolerance: 0.0008);
+    expect(out.id, 'keep-me');
+    expect(out.color, 0xFF112233);
+    expect(out.width, 0.02);
+    expect(out.tool, EditorTool.highlighter);
+  });
+}