https://shimtimultimedia.com/assets/scripts/shared/mobile-animations.js

1/* Mobile SVG motion without one compositor layer per transformed SVG node. */
2(function () {
3  'use strict';
4  if (!window.matchMedia || !window.matchMedia('(pointer: coarse)').matches) return;
5  if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) return;
6
7  const motions = new Map();
8  let previousFrame = 0;
9
10  function specification(element) {
11    if (element.classList.contains('ring-spin-cw')) {
12      return { duration: parseFloat(element.style.animationDuration) || 60, direction: 1 };
13    }
14    if (element.classList.contains('ring-spin-ccw')) {
15      return { duration: parseFloat(element.style.animationDuration) || 60, direction: -1 };
16    }
17    if (element.classList.contains('ring-marker-spin')) return { duration: 6, direction: 1 };
18    if (element.classList.contains('rotating-squares')) return { duration: 60, direction: 1 };
19    if (element.classList.contains('rotating-square')) return { duration: 2, direction: -1 };
20    if (element.matches('.segmented-ring.ring-0')) return { duration: 100, direction: 1 };
21    if (element.matches('.segmented-ring.ring-1')) return { duration: 80, direction: -1 };
22    if (element.matches('.segmented-ring.ring-2')) return { duration: 60, direction: -1 };
23    return null;
24  }
25
26  function register(root) {
27    root.querySelectorAll([
28      '.ring-spin-cw', '.ring-spin-ccw', '.ring-marker-spin',
29      '.rotating-squares', '.rotating-square', '.segmented-ring'
30    ].join(',')).forEach(function (element) {
31      if (motions.has(element)) return;
32      const motion = specification(element);
33      if (!motion) return;
34      motion.delay = parseFloat(element.style.animationDelay) || 0;
35      // CSS animation time begins when the element itself enters the document. Dynamic
36      // wheel rings are added about a second after navigation, so a page-global clock
37      // shifts their pose relative to desktop even when speed and axis are correct.
38      motion.start = performance.now() / 1000;
39      motions.set(element, motion);
40    });
41  }
42
43  function draw(now) {
44    if (now - previousFrame >= 1000 / 30) {
45      previousFrame = now;
46      motions.forEach(function (motion, element) {
47        if (!element.isConnected) {
48          motions.delete(element);
49          return;
50        }
51        const elapsed = now / 1000 - motion.start - motion.delay;
52        const angle = motion.direction * (elapsed % motion.duration) / motion.duration * 360;
53        // Use the same CSS property as desktop so transform-box and transform-origin
54        // retain the exact axis defined by the existing stylesheet.
55        element.style.transform = 'rotate(' + angle + 'deg)';
56      });
57    }
58    window.requestAnimationFrame(draw);
59  }
60
61  register(document);
62  if (typeof MutationObserver === 'function') {
63    new MutationObserver(function (records) {
64      records.forEach(record => record.addedNodes.forEach(node => {
65        if (node.nodeType === 1) register(node.parentElement || document);
66      }));
67    }).observe(document.getElementById('stage'), { childList: true, subtree: true });
68  }
69  window.requestAnimationFrame(draw);
70})();