fix(camera): hold the globe recovery until every pointer is released

The held-pointer guard was one flag, so with two fingers down, lifting one cleared it and the recovery turned the view down under the other (pitch -42° to -90°). It now tracks each pressed pointer by id and defers until the last is released.

A release outside the window that the page never sees could leave the recovery deferred for good. A lost window focus, a hidden page or a lost pointer capture now releases every held pointer, and a pointer that moves with no button down is released.

src/app/application.test.mjs

@@ -811,6 +811,102 @@ test('the recovery waits while a pointer is held on the globe', () => {
   assert.equal(timers.pending(), 0, 'disposed recovery holds no listeners');
 });
 
+/** A held-pointer recovery over a canvas in a document in a window. */
+function heldPointerRecovery() {
+  const timers = fakeTimers();
+  const { camera, scene, viewer } = realCamera({ width: 1225, height: 923 });
+  const window = new EventTarget();
+  const document = Object.assign(new EventTarget(), {
+    defaultView: window,
+    visibilityState: 'visible',
+  });
+  scene.canvas = Object.assign(new EventTarget(), {
+    clientWidth: 1225,
+    clientHeight: 923,
+    ownerDocument: document,
+  });
+  const dispose = installGlobeInViewRecovery(viewer, timers);
+  const pointer = (target, type, pointerId, init = {}) =>
+    target.dispatchEvent(
+      Object.assign(new Event(type), { pointerId, ...init }),
+    );
+  /** Press, move and hold still: the check defers while a pointer is held. */
+  const holdStill = () => {
+    aim(camera, reportedStuckView);
+    camera.moveStart.raiseEvent();
+    for (let i = 0; i < 8; i += 1) timers.tick();
+    camera.moveEnd.raiseEvent();
+    for (let i = 0; i < 8; i += 1) timers.tick();
+  };
+  const settle = () => {
+    for (let i = 0; i < 3; i += 1) timers.tick();
+  };
+  const recovered = () =>
+    Cesium.Math.equalsEpsilon(camera.pitch, -Math.PI / 2, 1e-6);
+  return {
+    camera,
+    document,
+    window,
+    dispose,
+    pointer,
+    holdStill,
+    settle,
+    recovered,
+    canvas: scene.canvas,
+  };
+}
+
+// Releasing one of two fingers cleared the held flag, and the recovery
+// turned the view down under the finger still on the glass.
+test('the recovery waits until every held pointer is released', () => {
+  const h = heldPointerRecovery();
+  h.pointer(h.canvas, 'pointerdown', 1);
+  h.pointer(h.canvas, 'pointerdown', 2);
+  h.holdStill();
+  h.pointer(h.document, 'pointerup', 1);
+  h.settle();
+  assert.equal(h.recovered(), false, 'left alone under the second finger');
+  assert.equal(globeOutOfFrame(h.camera), true);
+  h.pointer(h.document, 'pointercancel', 2);
+  h.settle();
+  assert.equal(h.recovered(), true, 'recovered once both are released');
+  h.dispose();
+});
+
+// A release the page never sees (the pointer let go outside the window)
+// must not hold the recovery off for good.
+for (const [label, lose] of [
+  ['the window loses focus', (h) => h.window.dispatchEvent(new Event('blur'))],
+  [
+    'the page is hidden',
+    (h) => {
+      h.document.visibilityState = 'hidden';
+      h.document.dispatchEvent(new Event('visibilitychange'));
+    },
+  ],
+  [
+    'the canvas loses the pointer capture',
+    (h) => h.pointer(h.canvas, 'lostpointercapture', 1),
+  ],
+  [
+    'the pointer moves with no button down',
+    (h) => h.pointer(h.document, 'pointermove', 1, { buttons: 0 }),
+  ],
+]) {
+  test(`a held pointer whose release is lost stops deferring when ${label}`, () => {
+    const h = heldPointerRecovery();
+    h.pointer(h.canvas, 'pointerdown', 1);
+    h.holdStill();
+    h.pointer(h.document, 'pointermove', 1, { buttons: 1 });
+    h.settle();
+    assert.equal(h.recovered(), false, 'left alone while held');
+    lose(h);
+    h.settle();
+    assert.equal(h.recovered(), true, 'recovered once the hold is let go');
+    h.dispose();
+  });
+}
+
 function fakeTimers() {
   let next = 1;
   const pending = new Map();

src/app/viewer.js

@@ -207,26 +207,43 @@ export function installGlobeInViewRecovery(
     throw new TypeError('A complete Cesium viewer is required');
 
   // A pointer held on the globe is a gesture in progress, even when it holds
-  // still for half a second: the check waits for its release.
+  // still for half a second: the check waits until every pointer pressed on
+  // it (each finger of a pinch) is released. A release the page never sees,
+  // outside the window, is taken as given when the window loses focus, the
+  // page is hidden, the canvas loses the pointer's capture, or the pointer
+  // moves with no button down.
   const canvas = scene.canvas;
   const releaseTarget = canvas?.ownerDocument ?? canvas;
-  let pointerHeld = false;
-  const onPointerDown = () => {
-    pointerHeld = true;
+  const releaseWindow = canvas?.ownerDocument?.defaultView;
+  const heldPointers = new Set();
+  const onPointerDown = (event) => heldPointers.add(event?.pointerId);
+  const onPointerUp = (event) => heldPointers.delete(event?.pointerId);
+  const onPointerMove = (event) => {
+    if (event?.buttons === 0) heldPointers.delete(event.pointerId);
   };
-  const onPointerUp = () => {
-    pointerHeld = false;
+  const releaseAll = () => heldPointers.clear();
+  const onVisibilityChange = () => {
+    if (canvas.ownerDocument.visibilityState === 'hidden') releaseAll();
   };
-  canvas?.addEventListener?.('pointerdown', onPointerDown);
-  releaseTarget?.addEventListener?.('pointerup', onPointerUp);
-  releaseTarget?.addEventListener?.('pointercancel', onPointerUp);
+  const listeners = [
+    [canvas, 'pointerdown', onPointerDown],
+    [canvas, 'lostpointercapture', onPointerUp],
+    [releaseTarget, 'pointerup', onPointerUp],
+    [releaseTarget, 'pointercancel', onPointerUp],
+    [releaseTarget, 'pointermove', onPointerMove],
+    [canvas?.ownerDocument, 'visibilitychange', onVisibilityChange],
+    [releaseWindow, 'blur', releaseAll],
+  ];
+  for (const [target, type, listener] of listeners)
+    target?.addEventListener?.(type, listener);
 
   // Returns false while a flight, a paused scene or a held pointer defers the
   // check, so the caller can try again once it ends.
   const recover = () => {
     if (!isFreeGlobeCamera(viewer)) return true;
     // Cesium has no public running-flight flag.
-    if (camera._currentFlight || paused() || pointerHeld) return false;
+    if (camera._currentFlight || paused() || heldPointers.size > 0)
+      return false;
     const height = camera.positionCartographic?.height;
     if (
       !(height > minHeight) ||
@@ -310,9 +327,9 @@ export function installGlobeInViewRecovery(
     stopSettling();
     removeMoveEnd();
     removeMoveStart();
-    canvas?.removeEventListener?.('pointerdown', onPointerDown);
-    releaseTarget?.removeEventListener?.('pointerup', onPointerUp);
-    releaseTarget?.removeEventListener?.('pointercancel', onPointerUp);
+    for (const [target, type, listener] of listeners)
+      target?.removeEventListener?.(type, listener);
+    heldPointers.clear();
   };
 }