fix(capture): align masked tape calibration with #99

frontend/src/capture/tapeCalibration.test.ts

@@ -0,0 +1,57 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  CALIBRATION_FRAME,
+  applyApprovedMask,
+  cropTickPositions,
+  pinchPhotoTransform,
+  photoToStage,
+  stageToPhoto,
+  tapeLineFromStageTicks,
+} from './tapeCalibration.ts';
+
+test('the reference line is fixed at the center of the calibration frame', () => {
+  assert.equal(CALIBRATION_FRAME.width, 480);
+  assert.equal(CALIBRATION_FRAME.height, 640);
+  assert.equal(CALIBRATION_FRAME.width / 2, 240);
+  const [top, bottom] = cropTickPositions(90);
+  assert.ok(Math.abs(top - 32) < 1e-9);
+  assert.ok(Math.abs(bottom - 608) < 1e-9);
+  const transform = { tiltDeg: 21, zoom: 1.4, panX: -18, panY: 11 };
+  const tape = tapeLineFromStageTicks(100, 530, 2400, 1800, transform);
+  const start = photoToStage(tape.start, 2400, 1800, transform);
+  const end = photoToStage(tape.end, 2400, 1800, transform);
+  assert.ok(Math.abs(start[0] - 240) < 1e-8 && Math.abs(start[1] - 100) < 1e-8);
+  assert.ok(Math.abs(end[0] - 240) < 1e-8 && Math.abs(end[1] - 530) < 1e-8);
+});
+
+test('pan, zoom, and tilt change the photo under the fixed reference line without losing source coordinates', () => {
+  const transform = { tiltDeg: 31, zoom: 1.7, panX: 15, panY: -24 };
+  const sourcePoint: [number, number] = [317, 218];
+  const stagePoint = photoToStage(sourcePoint, 1200, 900, transform);
+  const restored = stageToPhoto(stagePoint, 1200, 900, transform);
+  assert.ok(Math.abs(restored[0] - sourcePoint[0]) < 1e-8);
+  assert.ok(Math.abs(restored[1] - sourcePoint[1]) < 1e-8);
+});
+
+test('approved-mask rendering removes background pixels but preserves slab pixels', () => {
+  const rgba = new Uint8ClampedArray([
+    180, 90, 30, 255,
+    20, 200, 40, 255,
+  ]);
+  const masked = applyApprovedMask(rgba, Uint8Array.of(1, 0));
+  assert.deepEqual([...masked.slice(0, 4)], [180, 90, 30, 255]);
+  assert.deepEqual([...masked.slice(4, 8)], [20, 200, 40, 0]);
+});
+
+test('pinch zoom keeps the photo point under the moving pinch midpoint', () => {
+  const transform = { tiltDeg: 17, zoom: 1.2, panX: 11, panY: -8 };
+  const anchor: [number, number] = [420, 530];
+  const before = photoToStage(anchor, 1200, 900, transform);
+  const midpoint: [number, number] = [before[0] + 18, before[1] - 12];
+  const next = pinchPhotoTransform(transform, anchor, midpoint, 1.5, 1200, 900);
+  const after = photoToStage(anchor, 1200, 900, next);
+  assert.ok(Math.abs(after[0] - midpoint[0]) < 1e-8);
+  assert.ok(Math.abs(after[1] - midpoint[1]) < 1e-8);
+  assert.ok(Math.abs(next.zoom - 1.8) < 1e-12);
+});