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strokeBounds (tight AABB over normalized points, null for empty, zero-size for a single point), strokesBounds (union), and strokeIntersects (does a stroke's box overlap a viewport rect — touching edges count). Broad-phase primitive for the infinite board: skip painting/erasing/hit-testing strokes off-screen (R1 perf), and a cheap pre-filter before the exact per-point eraser test. Pure geometry over EditorStroke; fully unit-tested. flutter analyze lib/editor clean; 191/191 tests (+10). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
51 lines
1.7 KiB
Dart
51 lines
1.7 KiB
Dart
// lib/editor/engine/stroke_bounds.dart
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//
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// Axis-aligned bounds of strokes in normalized content coordinates. Used for
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// broad-phase culling (don't paint/erase/hit-test strokes whose box is off the
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// viewport — the infinite board's R1 perf primitive), and as a cheap pre-filter
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// before the exact per-point eraser test.
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//
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// Pure geometry over EditorStroke; no widgets/storage; fully unit-tested.
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import 'dart:ui' show Rect;
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import 'stroke_model.dart';
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/// Tight axis-aligned bounds of [stroke] in normalized coords, or null when the
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/// stroke has no points. A single-point stroke yields a zero-size rect at that
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/// point.
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Rect? strokeBounds(EditorStroke stroke) {
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if (stroke.points.isEmpty) return null;
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var minX = double.infinity, minY = double.infinity;
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var maxX = double.negativeInfinity, maxY = double.negativeInfinity;
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for (final p in stroke.points) {
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if (p.x < minX) minX = p.x;
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if (p.y < minY) minY = p.y;
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if (p.x > maxX) maxX = p.x;
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if (p.y > maxY) maxY = p.y;
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}
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return Rect.fromLTRB(minX, minY, maxX, maxY);
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}
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/// Union bounds of [strokes], or null when none have points.
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Rect? strokesBounds(Iterable<EditorStroke> strokes) {
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Rect? acc;
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for (final stroke in strokes) {
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final b = strokeBounds(stroke);
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if (b == null) continue;
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acc = acc == null ? b : acc.expandToInclude(b);
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}
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return acc;
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}
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/// Whether [stroke]'s bounds overlap [viewport] (broad-phase visibility test).
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/// Empty strokes are never visible. Touching edges count as overlapping.
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bool strokeIntersects(EditorStroke stroke, Rect viewport) {
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final b = strokeBounds(stroke);
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if (b == null) return false;
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return b.left <= viewport.right &&
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b.right >= viewport.left &&
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b.top <= viewport.bottom &&
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b.bottom >= viewport.top;
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}
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