fix(core): the keyboard height reads the whole keyboard while Safari pans to a focused field

.changeset/keyboard-height-safari-pan.md

@@ -0,0 +1,7 @@
+---
+'@astryxdesign/core': patch
+---
+
+[fix] The on-screen keyboard's height reads the whole keyboard while Safari on iOS pans the page to a focused field. Safari reports `innerHeight` as the visual viewport's height during that pan, so the height read 0, as if no keyboard were up. At a visual-viewport scale of 1, where `innerHeight` equals the visual viewport's height and the root is as wide as the visual viewport, the layout viewport's height now takes the root's client height where it is larger.
+
+@vjeux

packages/core/src/Chat/useChatKeyboard.ts

@@ -23,6 +23,7 @@ import {
   claimTapFocus,
   findTextEntryControl,
   getKeyboardHeight,
+  getKeyboardViewportHeight,
   isTextEntryControl,
   refuseFocusReveal,
   subscribeKeyboardHeight,
@@ -38,7 +39,6 @@ import {
 } from '../keyboard/keyboardTarget';
 import type {KeyboardTransition} from '../keyboard/keyboardModel';
 import {rideKeyboard} from '../keyboard/rideKeyboard';
-import {layoutViewportHeight} from '../utils/layoutViewport';
 import {
   useInteractionModalityTrackingFor,
   type InteractionModality,
@@ -230,8 +230,9 @@ export function useChatKeyboard({
       if (inset <= 0) {
         return 0;
       }
-      // In layout px, as the root's rect is, under a pinch zoom too.
-      const viewportBottom = layoutViewportHeight(win);
+      // In layout px, as the root's rect is, under a pinch zoom too. The
+      // keyboard module measured it with the keyboard height.
+      const viewportBottom = getKeyboardViewportHeight(win);
       const bottom = isSelfScrolling
         ? root.getBoundingClientRect().bottom
         : viewportBottom;

packages/core/src/Layer/useLayerKeyboardClearance.ts

@@ -35,7 +35,10 @@ import {useIsomorphicLayoutEffect} from '../hooks/useIsomorphicLayoutEffect';
 // BottomSheet's keyboard hook. An import through it would put that hook's
 // on-demand code in every layered component.
 import {getKeyboardLayoutGuide} from '../keyboard/keyboardLayoutGuide';
-import {getKeyboardHeight} from '../keyboard/keyboardHeight';
+import {
+  getKeyboardHeight,
+  getKeyboardViewportHeight,
+} from '../keyboard/keyboardHeight';
 import {timing} from '../motion/uikit/timing';
 import {
   keyboardClearanceCap,
@@ -45,7 +48,6 @@ import {
 import {settledBox} from './settledBox';
 import {awaitBrowserClick} from '../utils/browserClickWait';
 import {subscribeInput} from '../utils/inputStream';
-import {layoutViewportHeight} from '../utils/layoutViewport';
 
 export {
   keyboardClearanceCap,
@@ -247,7 +249,7 @@ export function useLayerKeyboardClearance(
       }
       // In layout px, the box's and the keyboard's units: WebKit reports
       // `innerHeight` in the pinch-zoomed visual viewport's px.
-      const viewport = layoutViewportHeight(win);
+      const viewport = getKeyboardViewportHeight(win);
       const box = settledBox(layer);
       const height = keyboardClearanceCap(box, viewport, inset);
       if (height == null) {

packages/core/src/keyboard/README.md

@@ -17,7 +17,11 @@ that times motion with it. Everything here is internal to
   `innerWidth` matching the visual viewport's width tells apart. A classic
   horizontal scrollbar, which `innerHeight` counts and the visual viewport
   does not, is taken out, so a desktop page wider than its window reads no
-  keyboard. BottomSheet's obstruction reads it too.
+  keyboard. While Safari pans the page to a focused field, it reports
+  `innerHeight` as the visual viewport's height; the root's client height
+  keeps the layout viewport's. At a scale of 1, where the two heights are
+  equal and the root is as wide as the visual viewport, the function takes the
+  larger. BottomSheet's obstruction reads it too.
 - **Where it measures (FR6, FR7, DEC-4):** `isKeyboardMeasurable(window)` is
   true for a top-level document with a visual viewport, a browser with its own
   keyboard geometry API (`navigator.virtualKeyboard`, Chrome on Android)
@@ -33,8 +37,10 @@ that times motion with it. Everything here is internal to
   resize, and with `{focus: true}` focus moves, whose input-stream
   subscriptions exist only while such a subscriber does) from one set of listeners per window,
   however many components subscribe, and `getKeyboardHeight(window)` gives a reader the
-  height that report measured. No other code in core listens to the visual
-  viewport for the keyboard.
+  height that report measured. `getKeyboardViewportHeight(window)` gives the
+  layout viewport's height that report measured it against, so a reader lays
+  out with no second read of the visual viewport. No other code in core
+  listens to the visual viewport for the keyboard.
 - **Focus (FR4):** `refuseFocusReveal(document, {claim, park, isActive})`
   delivers every focus move a surface claims with `preventScroll`, on the
   capture-phase `blur` before the browser's own focus step, so the browser
@@ -170,7 +176,7 @@ that times motion with it. Everything here is internal to
 
 Layout follows the height (FR3), through a functional style on your own
 element, so it is right with no animation running; for an element docked at
-the bottom, `lift = height > 0 ? max(0, restingBottom − (innerHeight − height)) : 0`.
+the bottom, `lift = height > 0 ? max(0, restingBottom − (getKeyboardViewportHeight(window) − height)) : 0`.
 An animation that rides the keyboard is optional polish on top, timed by the
 guide:
 

packages/core/src/keyboard/keyboardHeight.test.ts

@@ -36,6 +36,7 @@ import {
   watchRevealPan,
   type KeyboardHeightEvent,
 } from './keyboardHeight';
+import {coveredBy} from './keyboardTarget';
 
 type FakeViewport = EventTarget & {
   height: number;
@@ -138,6 +139,17 @@ describe('the layout viewport WebKit reports under a pinch zoom (FR2)', () => {
     expect(Math.abs(measureKeyboardHeight(window) - 337)).toBeLessThan(1);
   });
 
+  // The root's client box. Safari keeps its height at the layout viewport's,
+  // and its width at the visual viewport's.
+  function rootHeight(clientHeight: number, clientWidth = 402) {
+    for (const [key, value] of Object.entries({clientHeight, clientWidth})) {
+      Object.defineProperty(document.documentElement, key, {
+        configurable: true,
+        value,
+      });
+    }
+  }
+
   it('follows the layout viewport WebKit clamps to the document after a scroll', () => {
     safari({
       innerHeight: 666,
@@ -146,9 +158,107 @@ describe('the layout viewport WebKit reports under a pinch zoom (FR2)', () => {
       scale: 1,
       offsetTop: 120,
     });
+    rootHeight(714);
     expect(measureKeyboardHeight(window)).toBe(289);
   });
 
+  it('reads no keyboard on a layout wider than the screen at a scale of 1', () => {
+    // A width=1024 page at initial-scale=1: the root spans the whole layout.
+    safari({innerHeight: 714, innerWidth: 402, height: 714, scale: 1});
+    rootHeight(1819, 1024);
+    expect(measureKeyboardHeight(window)).toBe(0);
+  });
+
+  it('reads no keyboard on a zoomed-out page with none shown', () => {
+    // No width=device-width viewport: a 980 px layout viewport at a scale of
+    // 402 / 980.
+    safari({
+      innerHeight: 1741,
+      innerWidth: 980,
+      height: 1741,
+      scale: 402 / 980,
+    });
+    rootHeight(1741);
+    expect(measureKeyboardHeight(window)).toBeCloseTo(0);
+  });
+
+  it('reads the keyboard while Safari pans the page to a focused field, where innerHeight follows the visual viewport', () => {
+    safari({
+      innerHeight: 377,
+      innerWidth: 402,
+      height: 377,
+      scale: 1,
+      offsetTop: 337,
+    });
+    rootHeight(714);
+    expect(measureKeyboardHeight(window)).toBe(337);
+  });
+
+  it('reads the visual viewport height once while Safari pans, the pan check included (INV11)', () => {
+    safari({
+      innerHeight: 377,
+      innerWidth: 402,
+      height: 377,
+      scale: 1,
+      offsetTop: 337,
+    });
+    rootHeight(714);
+    let height = viewport.height;
+    let reads = 0;
+    Object.defineProperty(viewport, 'height', {
+      configurable: true,
+      get: () => {
+        reads += 1;
+        return height;
+      },
+      set: (value: number) => {
+        height = value;
+      },
+    });
+    expect(measureKeyboardHeight(window)).toBe(337);
+    expect(reads).toBe(1);
+  });
+
+  it('reads the visual viewport height once per report while Safari pans, a reader laying out included (INV11)', () => {
+    safari({innerHeight: 714, innerWidth: 402, height: 714, scale: 1});
+    rootHeight(714);
+    const covered: number[] = [];
+    const stop = subscribeKeyboardHeight(window, event => {
+      if (event.type === 'viewport') {
+        covered.push(coveredBy(700, event.height, 0, window));
+      }
+    });
+    let height = viewport.height;
+    let reads = 0;
+    Object.defineProperty(viewport, 'height', {
+      configurable: true,
+      get: () => {
+        reads += 1;
+        return height;
+      },
+      set: (value: number) => {
+        height = value;
+      },
+    });
+    try {
+      vi.stubGlobal('innerHeight', 377);
+      reads = 0;
+      report({height: 377, offsetTop: 337});
+      // A 337 px keyboard under a 714 px layout viewport covers 323 px of a
+      // bottom edge at 700.
+      expect(covered).toEqual([323]);
+      expect(reads).toBe(1);
+    } finally {
+      stop();
+    }
+  });
+
+  it('reads none where the layout viewport truly shrinks for the keyboard, as under resizes-content', () => {
+    safari({innerHeight: 377, innerWidth: 402, height: 377, scale: 1});
+    rootHeight(377);
+    expect(measureKeyboardHeight(window)).toBe(0);
+  });
+
   it('reads the same keyboard scrolled and pinch-zoomed', () => {
     safari({
       innerHeight: 536,

packages/core/src/keyboard/keyboardHeight.ts

@@ -8,7 +8,8 @@
  *   resize, scroll and touch), and the layout viewport's height
  * @output The on-screen keyboard module: measureKeyboardHeight,
  *   isKeyboardMeasurable, hasVirtualKeyboard, subscribeKeyboardHeight,
- *   getKeyboardHeight, isTextEntryControl, findTextEntryControl,
+ *   getKeyboardHeight, getKeyboardViewportHeight, isTextEntryControl,
+ *   findTextEntryControl,
  *   refuseFocusReveal and watchRevealPan
  * @position Core's one source for the on-screen keyboard. It is internal to
  *   core and never exported from the package.
@@ -70,13 +71,29 @@ export function isKeyboardMeasurable(win: Window): boolean {
  * `isKeyboardMeasurable` is false.
  */
 export function measureKeyboardHeight(win: Window): number {
+  return measureKeyboard(win).height;
+}
+
+/**
+ * The keyboard height, and the layout viewport's height it is measured
+ * against (null where the keyboard is not measurable). It reads the visual
+ * viewport's height once.
+ */
+function measureKeyboard(win: Window): {
+  height: number;
+  viewportHeight: number | null;
+} {
   const viewport = win.visualViewport;
   if (viewport == null || !isKeyboardMeasurable(win)) {
-    return 0;
+    return {height: 0, viewportHeight: null};
   }
-  const height =
-    layoutViewportHeight(win) - viewport.height * (viewport.scale ?? 1);
-  return height > KEYBOARD_EPSILON ? Math.round(height * 100) / 100 : 0;
+  const visualHeight = viewport.height;
+  const viewportHeight = layoutViewportHeight(win, visualHeight);
+  const height = viewportHeight - visualHeight * (viewport.scale ?? 1);
+  return {
+    height: height > KEYBOARD_EPSILON ? Math.round(height * 100) / 100 : 0,
+    viewportHeight,
+  };
 }
 
 /** A report from the keyboard module, in the order the window raised them. */
@@ -100,6 +117,8 @@ export type KeyboardHeightEvent =
 
 interface KeyboardStore {
   height: number;
+  /** The layout viewport's height that `height` was measured against. */
+  viewportHeight: number | null;
   listeners: Set<(event: KeyboardHeightEvent) => void>;
   /** The subscribers that asked for focus moves too (the layout guide). */
   focusListeners: Set<(event: KeyboardHeightEvent) => void>;
@@ -114,6 +133,7 @@ function storeOf(win: Window): KeyboardStore {
   if (store == null) {
     store = {
       height: 0,
+      viewportHeight: null,
       listeners: new Set(),
       focusListeners: new Set(),
       detach: null,
@@ -146,21 +166,28 @@ function isHideStep(win: Window, shown: number, height: number): boolean {
 
 function attach(win: Window, store: KeyboardStore): () => void {
   const viewport = win.visualViewport;
-  store.height = measureKeyboardHeight(win);
+  const first = measureKeyboard(win);
+  store.height = first.height;
+  store.viewportHeight = first.viewportHeight;
   // Set while a step of a hide waits. The store keeps the height it reported,
   // so every reader lays out once, when the keyboard comes to rest.
   let stepTimer: ReturnType<typeof setTimeout> | null = null;
   let stepHeight = 0;
   let stepLimit = 0;
-  const deliver = (height: number, timeStamp: number) => {
+  const deliver = (
+    {height, viewportHeight}: ReturnType<typeof measureKeyboard>,
+    timeStamp: number,
+  ) => {
     store.height = height;
+    store.viewportHeight = viewportHeight;
     const report: KeyboardHeightEvent = {type: 'viewport', height, timeStamp};
     for (const listener of [...store.listeners]) {
       listener(report);
     }
   };
   const onViewport = (event: Event) => {
-    const height = measureKeyboardHeight(win);
+    const measured = measureKeyboard(win);
+    const {height} = measured;
     if (isHideStep(win, store.height, height)) {
       // A pan reports the same step again, and leaves the wait as it is.
       if (
@@ -180,7 +207,7 @@ function attach(win: Window, store: KeyboardStore): () => void {
       stepTimer = setTimeout(
         () => {
           stepTimer = null;
-          deliver(measureKeyboardHeight(win), win.performance.now());
+          deliver(measureKeyboard(win), win.performance.now());
         },
         Math.min(HIDE_STEP_WAIT_MS, stepLimit - now),
       );
@@ -190,7 +217,7 @@ function attach(win: Window, store: KeyboardStore): () => void {
       clearTimeout(stepTimer);
       stepTimer = null;
     }
-    deliver(height, event.timeStamp);
+    deliver(measured, event.timeStamp);
   };
   viewport?.addEventListener('resize', onViewport);
   viewport?.addEventListener('scroll', onViewport);
@@ -295,6 +322,18 @@ export function getKeyboardHeight(win: Window): number {
   return store?.detach != null ? store.height : measureKeyboardHeight(win);
 }
 
+/**
+ * The layout viewport's height, CSS px, that `getKeyboardHeight` was
+ * measured against. A reader that lays out against the keyboard reads both
+ * from the module, so a keyboard change reads the visual viewport once.
+ */
+export function getKeyboardViewportHeight(win: Window): number {
+  const store = stores.get(win);
+  return store?.detach != null && store.viewportHeight != null
+    ? store.viewportHeight
+    : layoutViewportHeight(win);
+}
+
 /**
  * Whether focusing `element` brings up a keyboard for typing text. A control
  * with `inputmode="none"` brings up none.