feat(settings): reduce animations switch

src/components/AppearanceCard.jsx

@@ -31,6 +31,14 @@ export default function AppearanceCard() {
                     <Switch id="wideLayout" checked={appearance.wideLayout}
                             onCheckedChange={(wideLayout) => saveAppearance({wideLayout})}/>
                 </div>
+                <div className="flex items-center justify-between gap-4">
+                    <div className="space-y-1">
+                        <Label htmlFor="reduceMotion">{t('SETTINGS.REDUCE_MOTION')}</Label>
+                        <p className="text-xs text-muted-foreground">{t('SETTINGS.REDUCE_MOTION_HINT')}</p>
+                    </div>
+                    <Switch id="reduceMotion" checked={appearance.reduceMotion}
+                            onCheckedChange={(reduceMotion) => saveAppearance({reduceMotion})}/>
+                </div>
                 <div className="flex items-center justify-between gap-4">
                     <div className="space-y-1">
                         <Label id="background-label">{t('SETTINGS.BACKGROUND')}</Label>

src/components/Confetti.jsx

@@ -1,6 +1,7 @@
 import {useEffect, useRef, useState} from 'react';
 
 import {LOGO_COLORS} from './Logo.jsx';
+import {reduceMotion} from '../utils/appearance.js';
 
 const DURATION_MS = 2800;
 const PIECES = {small: 70, big: 240};
@@ -8,8 +9,6 @@ const GRAVITY = 0.12;
 // The speeds are per frame at 60 Hz; a faster screen moves the same distance in the same time.
 const FRAME_MS = 1000 / 60;
 
-const reducedMotion = () => window.matchMedia?.('(prefers-reduced-motion: reduce)').matches ?? false;
-
 // The logo colors of the chosen accent and the accent itself.
 function colors() {
     const style = getComputedStyle(document.documentElement);
@@ -48,7 +47,7 @@ function pieces(size, width, height) {
  */
 export default function Confetti({size, onDone}) {
     const canvasRef = useRef(null);
-    const [reduce] = useState(reducedMotion);
+    const [reduce] = useState(reduceMotion);
     // In a ref: a new function from a re-render must not restart the animation, and the latest one runs at the end.
     const onDoneRef = useRef(onDone);
     onDoneRef.current = onDone;

src/components/Confetti.test.jsx

@@ -34,4 +34,13 @@ describe('Confetti', () => {
 
         expect(container.querySelector('canvas')).toBeNull();
     });
+
+    it('draws nothing when the reduce animations setting is on', () => {
+        reducedMotion(false);
+        document.documentElement.setAttribute('data-reduce-motion', '');
+        const {container} = render(<Confetti size="small"/>);
+        document.documentElement.removeAttribute('data-reduce-motion');
+
+        expect(container.querySelector('canvas')).toBeNull();
+    });
 });

src/hooks/useSaveAppearance.test.jsx

@@ -54,7 +54,7 @@ describe('useSaveAppearance', () => {
         const [url, request] = fetch.mock.calls[0];
         expect(url).toContain('/api/users/settings/appearance');
         expect(request.method).toBe('PUT');
-        expect(JSON.parse(request.body)).toEqual({accent: 'blue', corners: 'default', wideLayout: false, backgroundAppid: null, bannerAppid: null, showBanner: true});
+        expect(JSON.parse(request.body)).toEqual({accent: 'blue', corners: 'default', wideLayout: false, backgroundAppid: null, bannerAppid: null, showBanner: true, reduceMotion: false});
     });
 
     it('puts the old value back when Auth refuses', async () => {
@@ -119,7 +119,7 @@ describe('useSaveAppearance', () => {
     });
 
     it('waits for a running load from Auth, then keeps its values for the fields not changed here', async () => {
-        const fromServer = {accent: 'green', corners: 'default', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: false};
+        const fromServer = {accent: 'green', corners: 'default', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: false, reduceMotion: false};
         let answerMe;
         fetchRoutes({
             [PUT]: json(204),
@@ -206,7 +206,7 @@ describe('useSaveAppearance', () => {
         });
 
         expect(result.current.preferences.appearance.corners).toBe('round');
-        expect(puts()[2]).toEqual({accent: 'green', corners: 'round', wideLayout: true, backgroundAppid: null, bannerAppid: null, showBanner: true});
+        expect(puts()[2]).toEqual({accent: 'green', corners: 'round', wideLayout: true, backgroundAppid: null, bannerAppid: null, showBanner: true, reduceMotion: false});
     });
 
     it('sends nothing for a change that waited for the load when a reset came first', async () => {

src/pages/SettingsPage.test.jsx

@@ -187,11 +187,20 @@ describe('SettingsPage appearance', () => {
         fireEvent.click(appearanceCard().getByRole('button', {name: 'SETTINGS.CORNER_OPTIONS.ROUND'}));
 
         await waitFor(() => expect(appearancePuts()).toHaveLength(2));
-        expect(appearancePuts()[1]).toEqual({accent: 'green', corners: 'round', wideLayout: false, backgroundAppid: null, bannerAppid: null, showBanner: true});
+        expect(appearancePuts()[1]).toEqual({accent: 'green', corners: 'round', wideLayout: false, backgroundAppid: null, bannerAppid: null, showBanner: true, reduceMotion: false});
         expect(appearanceCard().getByRole('button', {name: 'SETTINGS.ACCENT_OPTIONS.GREEN'}).getAttribute('aria-pressed')).toBe('true');
         expect(appearanceCard().getByRole('button', {name: 'SETTINGS.ACCENT_OPTIONS.VIOLET'}).getAttribute('aria-pressed')).toBe('false');
     });
 
+    it('saves the reduce animations switch', async () => {
+        renderPage(profile());
+
+        fireEvent.click(await screen.findByRole('switch', {name: 'SETTINGS.REDUCE_MOTION'}));
+
+        await waitFor(() => expect(appearancePuts()).toHaveLength(1));
+        expect(appearancePuts()[0].reduceMotion).toBe(true);
+    });
+
     it('removes the background', async () => {
         localStorage.setItem('tbp_appearance', JSON.stringify({backgroundAppid: 620}));
         renderPage(profile());

src/utils/appearance.js

@@ -9,6 +9,7 @@ export const CORNERS = ['sharp', 'default', 'round'];
 // bannerAppid null: the dashboard banner shows the game played most in the last two weeks.
 export const DEFAULT_APPEARANCE = {
     accent: 'violet', corners: 'default', wideLayout: false, backgroundAppid: null, bannerAppid: null, showBanner: true,
+    reduceMotion: false,
 };
 
 export const appid = (value) => (Number.isInteger(value) && value > 0 ? value : null);
@@ -22,6 +23,7 @@ export const normalizeAppearance = (value) => ({
     backgroundAppid: appid(value?.backgroundAppid),
     bannerAppid: appid(value?.bannerAppid),
     showBanner: value?.showBanner !== false,
+    reduceMotion: value?.reduceMotion === true,
 });
 
 /**
@@ -41,8 +43,14 @@ export const cacheAppearance = (appearance) => storage.set(STORAGE_KEY, JSON.str
 export const applyAppearance = (appearance, accentOverride = null, root = document.documentElement) => {
     root.dataset.accent = accentOverride ?? appearance.accent;
     root.dataset.corners = appearance.corners;
+    root.toggleAttribute('data-reduce-motion', appearance.reduceMotion === true);
 };
 
+/** True when the system asks for reduced motion or the "Reduce animations" setting is on. */
+export const reduceMotion = () =>
+    (window.matchMedia?.('(prefers-reduced-motion: reduce)').matches ?? false)
+    || document.documentElement.hasAttribute('data-reduce-motion');
+
 /**
  * PUT /api/users/settings/appearance on Auth. The caller handles the response status.
  */

src/utils/appearance.test.js

@@ -1,22 +1,23 @@
 // @vitest-environment jsdom
-import {afterEach, describe, expect, it} from 'vitest';
+import {afterEach, describe, expect, it, vi} from 'vitest';
 import {
     applyAppearance,
     cacheAppearance,
     DEFAULT_APPEARANCE,
     normalizeAppearance,
     readCachedAppearance,
+    reduceMotion,
 } from './appearance.js';
 
 describe('normalizeAppearance', () => {
     it('keeps known values', () => {
-        const appearance = {accent: 'blue', corners: 'round', wideLayout: true, backgroundAppid: 620, bannerAppid: 1086940, showBanner: false};
+        const appearance = {accent: 'blue', corners: 'round', wideLayout: true, backgroundAppid: 620, bannerAppid: 1086940, showBanner: false, reduceMotion: true};
 
         expect(normalizeAppearance(appearance)).toEqual(appearance);
     });
 
     it('replaces unknown or missing values with the defaults', () => {
-        expect(normalizeAppearance({accent: 'red;x', corners: 'pointy', wideLayout: 'yes', backgroundAppid: -1, bannerAppid: '620', showBanner: 'no'}))
+        expect(normalizeAppearance({accent: 'red;x', corners: 'pointy', wideLayout: 'yes', backgroundAppid: -1, bannerAppid: '620', showBanner: 'no', reduceMotion: 'yes'}))
             .toEqual(DEFAULT_APPEARANCE);
         expect(normalizeAppearance(null)).toEqual(DEFAULT_APPEARANCE);
         expect(normalizeAppearance({backgroundAppid: 1.5})).toEqual(DEFAULT_APPEARANCE);
@@ -27,9 +28,9 @@ describe('appearance cache', () => {
     afterEach(() => localStorage.clear());
 
     it('reads back what was cached', () => {
-        cacheAppearance({accent: 'green', corners: 'sharp', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: true});
+        cacheAppearance({accent: 'green', corners: 'sharp', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: true, reduceMotion: false});
 
-        expect(readCachedAppearance()).toEqual({accent: 'green', corners: 'sharp', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: true});
+        expect(readCachedAppearance()).toEqual({accent: 'green', corners: 'sharp', wideLayout: false, backgroundAppid: null, bannerAppid: 620, showBanner: true, reduceMotion: false});
     });
 
     it('falls back to the defaults for a broken or empty cache', () => {
@@ -58,3 +59,41 @@ describe('applyAppearance', () => {
         expect(root.dataset.accent).toBe('gold');
     });
 });
+
+describe('reduce motion', () => {
+    afterEach(() => {
+        document.documentElement.removeAttribute('data-reduce-motion');
+        vi.unstubAllGlobals();
+    });
+
+    const mediaQuery = (matches) => vi.stubGlobal('matchMedia', () => ({matches}));
+
+    it('is set on the root by applyAppearance and removed again', () => {
+        const root = document.createElement('html');
+
+        applyAppearance({accent: 'blue', corners: 'default', reduceMotion: true}, null, root);
+        expect(root.hasAttribute('data-reduce-motion')).toBe(true);
+
+        applyAppearance({accent: 'blue', corners: 'default', reduceMotion: false}, null, root);
+        expect(root.hasAttribute('data-reduce-motion')).toBe(false);
+    });
+
+    it('is on for the system media query', () => {
+        mediaQuery(true);
+
+        expect(reduceMotion()).toBe(true);
+    });
+
+    it('is on for the setting', () => {
+        mediaQuery(false);
+        document.documentElement.setAttribute('data-reduce-motion', '');
+
+        expect(reduceMotion()).toBe(true);
+    });
+
+    it('is off for neither', () => {
+        mediaQuery(false);
+
+        expect(reduceMotion()).toBe(false);
+    });
+});