缩放显现
图像从中心放大,同一进度下可与裁剪范围的变化对照。
演示进度
向下滚动前进,向上滚动回退。
50% 示意。裁剪只露出中央,缩放则保留完整构图。
GSAP 未加载,请联网后刷新以操作示例。
使用场景
产品图的整体呈现。例如从小尺寸到原尺寸逐渐带出一幅完整插图。
行为定义
两幅图共用同一进度。50% 时裁剪侧显示原尺寸画面的中心,缩放侧显示半尺寸的完整画面。
实现要点
把 0 到 1 的进度分别映射到居中 scale 和四边 inset。滑杆与页面滚动各自在选中模式下提供进度。
原生 HTML / CSS / JS
完整示例,可另存为 HTML 直接打开。
打开示例查看源码
<!doctype html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>缩放显现 · 原生示例</title>
<script>
if (new URLSearchParams(location.search).get('theme') === 'dark') {
document.documentElement.dataset.theme = 'dark';
}
</script>
<style>
:root {
color-scheme: light;
--page: #fbfaf7;
--surface: #fff;
--surface-2: #edf3f6;
--plate: #f7fafb;
--text: #222c36;
--text-2: #434f5d;
--line-hi: #82939f;
--accent: #b8412c;
--accent-text: #963324;
background: var(--page);
}
:root[data-theme="dark"] {
color-scheme: dark;
--page: #19222d;
--surface: #222e3c;
--surface-2: #2b3c4d;
--plate: #233142;
--text: #f6f5f1;
--text-2: #d8dce1;
--line-hi: #8396a8;
--accent: #ff9d7c;
--accent-text: #ffb399;
}
*, *::before, *::after { box-sizing: border-box; }
body { max-width: 54rem; margin: 0 auto; padding: clamp(1rem, 4vw, 2rem); color: var(--text); font: 1rem/1.6 system-ui, sans-serif; }
h1 { margin-block: 0 .4rem; font-size: 1.75rem; }
p { margin: 0 0 1rem; }
button, input { font: inherit; }
[hidden] { display: none !important; }
.scale-reveal__mode p { margin: 0; }
.scale-reveal[data-mode="scroll"] + p { min-height: 100vh; padding-block-start: 1rem; }
.scale-reveal {
--scale-progress: .5;
--scale-sticky-top: calc(var(--nav-h, 0px) + 1rem);
color: var(--text);
}
.scale-reveal__panel {
padding: clamp(.65rem, 2vw, 1.35rem);
border: 1px solid var(--line-hi);
border-radius: 14px;
background: var(--plate);
}
.scale-reveal__pair {
display: grid;
grid-template-columns: repeat(2, minmax(0, 1fr));
gap: clamp(.65rem, 2vw, 1.25rem);
}
.scale-reveal__pair figure { margin: 0; }
.scale-reveal__well {
position: relative;
aspect-ratio: 760 / 430;
overflow: hidden;
border: 1px solid var(--line-hi);
border-radius: 8px;
background: var(--surface-2);
}
.scale-reveal__art { position: absolute; inset: 0; }
.scale-reveal__art svg { display: block; width: 100%; height: 100%; }
.scale-reveal__art--crop { clip-path: inset(calc((1 - var(--scale-progress)) * 50%)); }
.scale-reveal__art--zoom { transform: scale(var(--scale-progress)); transform-origin: center; }
.scale-reveal__pair figcaption {
display: grid;
gap: .18rem;
padding-block: .65rem .15rem;
line-height: 1.4;
}
.scale-reveal__pair figcaption strong { font-size: .875rem; font-weight: 650; }
.scale-reveal__pair figcaption span { color: var(--text-2); font-size: .75rem; }
.scale-reveal__controls {
display: grid;
gap: .65rem;
margin-top: clamp(.8rem, 2vw, 1.2rem);
}
.scale-reveal__progress {
display: grid;
grid-template-columns: max-content minmax(0, 1fr) 4ch;
align-items: center;
gap: .5rem clamp(.55rem, 2vw, 1.25rem);
padding: .2rem clamp(.55rem, 2vw, 1rem);
border-radius: 10px;
background: var(--surface-2);
font-size: .8125rem;
font-weight: 600;
}
.scale-reveal__progress input,
.scale-reveal__progress progress {
width: 100%;
min-width: 0;
accent-color: var(--accent);
}
.scale-reveal__progress input { height: 44px; cursor: pointer; }
.scale-reveal__progress progress { height: .75rem; }
.scale-reveal__value {
color: var(--accent-text);
font: 500 .8125rem/1 var(--font-mono, ui-monospace, monospace);
font-variant-numeric: tabular-nums;
text-align: right;
}
.scale-reveal__mode, .scale-reveal__steps {
display: flex;
flex-wrap: wrap;
align-items: center;
gap: .4rem .65rem;
}
.scale-reveal__controls button {
min-height: 44px;
padding: .45rem .72rem;
border: 1px solid var(--line-hi);
border-radius: 10px;
background: var(--surface);
color: var(--text);
font-size: .8125rem;
font-weight: 600;
cursor: pointer;
}
.scale-reveal__controls button:hover,
.scale-reveal__controls button[aria-pressed="true"] {
border-color: var(--accent-text);
color: var(--accent-text);
}
.scale-reveal__controls :is(button, input):focus-visible {
outline: 2px solid var(--accent);
outline-offset: 2px;
}
.scale-reveal__static, .scale-reveal__mode p { color: var(--text-2); font-size: .8125rem; }
.scale-reveal__static { margin: .85rem 0 0; }
.scale-reveal__distance { display: none; }
.scale-reveal[data-mode="scroll"] .scale-reveal__panel {
position: sticky;
top: var(--scale-sticky-top);
z-index: 1;
}
.scale-reveal[data-mode="scroll"] .scale-reveal__distance {
display: block;
height: clamp(22rem, 85vh, 55rem);
}
@media (max-width: 34rem) {
.scale-reveal__progress { grid-template-columns: minmax(0, 1fr) 4ch; padding-block: .35rem; gap: .2rem .55rem; }
.scale-reveal__progress > :first-child { grid-column: 1 / -1; }
.scale-reveal__pair figcaption { padding-block-start: .45rem; }
.scale-reveal__steps { gap: .3rem; }
.scale-reveal__steps button { padding-inline: .45rem; }
}
</style>
<style>.demo-guide {
display: flex;
align-items: center;
justify-content: space-between;
gap: .5rem .9rem;
min-inline-size: 0;
margin-block: 0 .75rem;
padding-block-end: .5rem;
border-block-end: 1px solid var(--line-hi, #b8c4cd);
color: var(--text-2, #434f5d);
font-size: .8125rem;
line-height: 1.5;
}
.trigger-stage > .demo-guide {
margin: .35rem clamp(.85rem, 2.2vw, 1.4rem) 0;
}
.demo-guide [data-guide-caption] { margin: 0; }
.demo-guide > button[data-guide-replay] {
flex: none;
min-block-size: 44px;
margin: 0;
padding: .35rem .65rem;
border: 1px solid var(--line-strong, #82939f);
border-radius: 7px;
background: var(--surface, #fff);
color: var(--text, #222c36);
font: inherit;
font-weight: 550;
cursor: pointer;
}
.demo-guide > button[data-guide-replay]:hover { border-color: var(--accent-text, #963324); }
.demo-guide > button[data-guide-replay]:focus-visible { outline: 2px solid var(--accent-text, #963324); outline-offset: 2px; }
.demo-guide-cursor {
position: fixed;
z-index: 20;
inset: 0 auto auto 0;
inline-size: 20px;
block-size: 24px;
pointer-events: none;
}
.demo-guide-cursor svg { display: block; inline-size: 100%; block-size: 100%; }
.demo-guide-cursor::before {
position: absolute;
inset: -7px auto auto -7px;
inline-size: 18px;
block-size: 18px;
border: 2px solid var(--accent-text, #963324);
border-radius: 50%;
content: '';
opacity: 0;
}
.demo-guide-cursor[data-press]::before { opacity: 1; }
@media (prefers-reduced-motion: reduce) { .demo-guide-cursor { display: none; } }
</style>
</head>
<body>
<h1>缩放显现</h1>
<p>拖动同一条进度,观察裁剪与缩放怎样处理同一幅插图。</p>
<div class="scale-reveal" data-scale-reveal data-mode="manual">
<div class="scale-reveal__panel" data-scale-panel>
<div class="scale-reveal__pair">
<figure>
<div class="scale-reveal__well">
<div class="scale-reveal__art scale-reveal__art--crop" data-scale-crop><svg viewBox="0 0 760 430" aria-hidden="true" focusable="false">
<path fill="#e8f3fa" d="M0 0h760v430H0z"/>
<circle cx="454" cy="151" r="77" fill="#ef784d"/>
<path fill="#f7c98b" d="M0 228 93 198q59-19 127 9l72 30q56 25 112-5l102-57q50-27 103-6l151 63v198H0z"/>
<path fill="#7299b4" d="m0 294 137-77q54-29 111 5l106 68q40 26 94 9l135-43q89-30 177 11v163H0z"/>
<path fill="#e5a38a" d="m0 350 128-21q63-11 122 6l95 28q72 22 137-2l110-41q88-33 168 11v99H0z"/>
<path fill="#adcfdf" d="m0 379 115 9q89 7 174-19l72-22q59-19 119-3l134 34q69 18 146 3v49H0z"/>
<g fill="none" stroke="#fffdf8" stroke-linecap="round" opacity=".76">
<path d="M0 403q126 17 274-20m235-21 107 27q76 19 144 5M18 417q114 14 246-20"/>
<path d="M124 175h43m-12-10h29m377-31h47m-13 12h25" stroke-width="2"/>
</g>
</svg></div>
</div>
<figcaption><strong>裁剪展开</strong><span>原尺寸,打开可见区域</span></figcaption>
</figure>
<figure>
<div class="scale-reveal__well">
<div class="scale-reveal__art scale-reveal__art--zoom" data-scale-zoom><svg viewBox="0 0 760 430" aria-hidden="true" focusable="false">
<path fill="#e8f3fa" d="M0 0h760v430H0z"/>
<circle cx="454" cy="151" r="77" fill="#ef784d"/>
<path fill="#f7c98b" d="M0 228 93 198q59-19 127 9l72 30q56 25 112-5l102-57q50-27 103-6l151 63v198H0z"/>
<path fill="#7299b4" d="m0 294 137-77q54-29 111 5l106 68q40 26 94 9l135-43q89-30 177 11v163H0z"/>
<path fill="#e5a38a" d="m0 350 128-21q63-11 122 6l95 28q72 22 137-2l110-41q88-33 168 11v99H0z"/>
<path fill="#adcfdf" d="m0 379 115 9q89 7 174-19l72-22q59-19 119-3l134 34q69 18 146 3v49H0z"/>
<g fill="none" stroke="#fffdf8" stroke-linecap="round" opacity=".76">
<path d="M0 403q126 17 274-20m235-21 107 27q76 19 144 5M18 417q114 14 246-20"/>
<path d="M124 175h43m-12-10h29m377-31h47m-13 12h25" stroke-width="2"/>
</g>
</svg></div>
</div>
<figcaption><strong>缩放显现</strong><span>完整构图,从中心放大</span></figcaption>
</figure>
</div>
<div class="scale-reveal__controls" data-scale-controls hidden>
<div class="scale-reveal__progress">
<span id="scale-reveal-progress-label">演示进度</span>
<input type="range" min="0" max="100" value="50" aria-labelledby="scale-reveal-progress-label"
aria-valuetext="50%" data-scale-slider />
<progress max="100" value="50" aria-labelledby="scale-reveal-progress-label" data-scale-meter hidden></progress>
<div class="scale-reveal__steps" role="group" aria-labelledby="scale-reveal-progress-label" data-scale-steps hidden>
<button type="button" data-scale-step="0" aria-pressed="false">0%</button>
<button type="button" data-scale-step="50" aria-pressed="true">50%</button>
<button type="button" data-scale-step="100" aria-pressed="false">100%</button>
</div>
<span class="scale-reveal__value" data-scale-value aria-hidden="true">50%</span>
</div>
<div class="scale-reveal__mode" data-scale-mode>
<button type="button" aria-pressed="false" data-scale-toggle>跟随页面滚动</button>
<p data-scale-hint hidden>向下滚动前进,向上滚动回退。</p>
</div>
</div>
<p class="scale-reveal__static" data-scale-static>50% 示意。裁剪只露出中央,缩放则保留完整构图。</p>
<p class="scale-reveal__static" data-scale-error hidden>GSAP 未加载,请联网后刷新以操作示例。</p>
</div>
<div class="scale-reveal__distance" aria-hidden="true"></div>
</div>
<p>裁剪改变可见区域,缩放改变整幅图的大小。</p>
<script>
(() => {
/**
* @param {HTMLElement} root
* @param {(crop: HTMLElement, zoom: HTMLElement) => { progress(value: number): unknown }} [createTimeline]
*/
function bindScaleReveal(root, createTimeline) {
const panel = root.querySelector('[data-scale-panel]');
const controls = root.querySelector('[data-scale-controls]');
const slider = root.querySelector('[data-scale-slider]');
const meter = root.querySelector('[data-scale-meter]');
const steps = root.querySelector('[data-scale-steps]');
const stepButtons = [...steps.querySelectorAll('button')];
const value = root.querySelector('[data-scale-value]');
const mode = root.querySelector('[data-scale-mode]');
const toggle = root.querySelector('[data-scale-toggle]');
const hint = root.querySelector('[data-scale-hint]');
const motion = window.matchMedia('(prefers-reduced-motion: reduce)');
const timeline = createTimeline?.(root.querySelector('[data-scale-crop]'), root.querySelector('[data-scale-zoom]'));
let progress = slider.valueAsNumber / 100;
let scrollMode = false;
let start = 0;
let distance = 1;
let frame = 0;
function render(next) {
progress = next;
if (timeline) timeline.progress(next);
else root.style.setProperty('--scale-progress', String(next));
const percent = Math.round(next * 100);
const label = `${percent}%`;
slider.value = String(percent);
slider.setAttribute('aria-valuetext', label);
meter.value = percent;
value.textContent = label;
if (motion.matches) {
for (const button of stepButtons) {
button.setAttribute('aria-pressed', String(Number(button.dataset.scaleStep) === percent));
}
}
}
function updateFromScroll() {
if (!scrollMode || frame) return;
frame = requestAnimationFrame(() => {
frame = 0;
if (scrollMode) render(Math.max(0, Math.min(1, (window.scrollY - start) / distance)));
});
}
function measure() {
if (!scrollMode) return;
const top = Number.parseFloat(getComputedStyle(panel).top) || 0;
start = root.getBoundingClientRect().top + window.scrollY - top;
distance = Math.max(1, root.offsetHeight - panel.offsetHeight);
updateFromScroll();
}
function setMode(active, keepPanelInView = false) {
const returnToPanel = keepPanelInView && scrollMode && !active && window.scrollY > start;
scrollMode = active;
root.dataset.mode = active ? 'scroll' : 'manual';
slider.hidden = active || motion.matches;
meter.hidden = !active;
steps.hidden = !motion.matches;
mode.hidden = motion.matches;
toggle.setAttribute('aria-pressed', String(active));
hint.hidden = !active;
if (active) {
measure();
} else {
const stepsPerRange = motion.matches ? 2 : 100;
render(Math.round(progress * stepsPerRange) / stepsPerRange);
if (returnToPanel) window.scrollTo({ top: Math.max(0, start), behavior: 'instant' });
}
}
function syncMotion() {
const hadFocus = controls.contains(document.activeElement);
setMode(false, hadFocus);
if (hadFocus) {
const control = motion.matches ? steps.querySelector('[aria-pressed="true"]') : slider;
control?.focus({ preventScroll: true });
}
}
slider.addEventListener('input', () => {
if (!scrollMode && !motion.matches) render(slider.valueAsNumber / 100);
});
for (const button of stepButtons) {
button.addEventListener('click', () => render(Number(button.dataset.scaleStep) / 100));
}
toggle.addEventListener('click', () => setMode(!scrollMode, true));
root.addEventListener('formtempo:guide-reset', () => setMode(false));
window.addEventListener('scroll', updateFromScroll, { passive: true });
window.addEventListener('resize', measure);
window.addEventListener('pageshow', measure);
const resize = new ResizeObserver(measure);
resize.observe(root);
resize.observe(panel);
resize.observe(document.body);
motion.addEventListener('change', syncMotion);
syncMotion();
root.querySelector('[data-scale-static]').hidden = true;
controls.hidden = false;
}
const root = document.querySelector('[data-scale-reveal]');
bindScaleReveal(root);
})();
</script>
<script>
(() => {
/** @param {number} duration @param {AbortSignal} signal @param {(progress: number) => void} [render] */
function guideBeat(duration, signal, render) {
if (signal.aborted) return Promise.resolve();
if (duration === 0) {
render?.(1);
return Promise.resolve();
}
return new Promise((resolve) => {
let timer = 0;
let frame = 0;
const done = () => {
clearTimeout(timer);
cancelAnimationFrame(frame);
signal.removeEventListener('abort', done);
resolve(undefined);
};
signal.addEventListener('abort', done, { once: true });
if (!render) {
timer = window.setTimeout(done, duration);
return;
}
const start = performance.now();
const tick = (now) => {
const progress = Math.min(1, (now - start) / duration);
render(progress);
if (progress === 1) done();
else if (!signal.aborted) frame = requestAnimationFrame(tick);
};
frame = requestAnimationFrame(tick);
});
}
/** @param {HTMLElement} root @param {import('./demo-guide-cases').DemoGuide} guide */
function bindDemoGuide(root, guide) {
const view = root.querySelector(guide.view);
if (!view || root.dataset.guideState || guide.steps.some(({ target }) => !root.querySelector(target))) return;
const dock = guide.dock ? root.querySelector(guide.dock) : null;
const bar = document.createElement('div');
bar.className = 'demo-guide';
bar.innerHTML = '<p data-guide-caption></p><button type="button" data-guide-replay>重播导览</button>';
const caption = bar.querySelector('[data-guide-caption]');
const replay = bar.querySelector('button');
const heading = root === document.body ? root.querySelector('h1') : null;
if (dock) dock.prepend(bar);
else if (heading) heading.after(bar);
else root.prepend(bar);
const cursor = document.createElement('div');
cursor.className = 'demo-guide-cursor';
cursor.setAttribute('aria-hidden', 'true');
cursor.hidden = true;
cursor.innerHTML = '<svg viewBox="0 0 20 24" focusable="false"><path d="M2 2v17l4.8-4.5L10 21l3.2-1.6-3.2-6.2 6.6-.7L2 2Z" fill="#222c36" stroke="#fff" stroke-width="1.5" stroke-linejoin="round"/></svg>';
document.body.append(cursor);
const reduced = matchMedia('(prefers-reduced-motion: reduce)');
const threshold = .5;
const idleCaption = '导览在画面进入视口后播放一次。';
const reducedCaption = '可重播关键状态,或直接操作。';
const reset = guide.reset ? (root.matches(guide.reset) ? root : root.querySelector(guide.reset)) : null;
const releaseTarget = guide.release ? root.querySelector(guide.release) : null;
let autoPending = !reduced.matches;
let inView = false;
let playbackScroll = window.scrollY;
/** @type {AbortController | undefined} */
let run;
/** @type {[number, number] | undefined} */
let cursorPosition;
root.dataset.guideState = 'idle';
caption.textContent = reduced.matches ? reducedCaption : idleCaption;
function hideCursor() {
cursor.hidden = true;
delete cursor.dataset.press;
cursorPosition = undefined;
}
/** @param {PointerEvent} [pointer] */
function stop(pointer) {
autoPending = false;
if (!run) return;
run.abort();
run = undefined;
hideCursor();
if (releaseTarget) {
// A real pointer inside the target keeps its hover when the guide yields.
if (pointer) sendPointer(releaseTarget, 'pointerenter', [pointer.clientX, pointer.clientY]);
else sendPointer(releaseTarget, 'pointerleave', [0, 0]);
}
reset?.dispatchEvent(new Event('formtempo:guide-cancel'));
root.dataset.guideState = 'interrupted';
caption.textContent = '导览已停止,可以继续手动操作。';
}
/** @param {[number, number]} position */
function moveCursor(position) {
cursor.hidden = false;
cursor.style.transform = `translate3d(${position[0]}px, ${position[1]}px, 0)`;
cursorPosition = position;
}
/** @param {Element} target @param {readonly [number, number]} point */
function location(target, [x, y]) {
const rect = target.getBoundingClientRect();
return /** @type {[number, number]} */ ([rect.left + rect.width * x, rect.top + rect.height * y]);
}
/** @param {Element} target @param {string} type @param {readonly [number, number]} position */
function sendPointer(target, type, [clientX, clientY]) {
target.dispatchEvent(new PointerEvent(type, { pointerType: 'mouse', clientX, clientY }));
}
/** @param {HTMLInputElement} slider @param {number} value */
function setProgress(slider, value) {
const next = Math.round(value);
if (slider.valueAsNumber === next) return;
slider.value = String(next);
slider.dispatchEvent(new Event('input', { bubbles: true }));
}
/** @param {number} value */
function showReducedProgress(value) {
const options = Array.from(root.querySelectorAll('button[data-driven-step], button[data-scale-step], button[data-progress-step], button[data-progress]'));
const percent = (button) => button.hasAttribute('data-progress')
? Number(button.getAttribute('data-progress')) * 100
: Number(button.getAttribute('data-driven-step') ?? button.getAttribute('data-scale-step') ?? button.getAttribute('data-progress-step'));
options.sort((a, b) => Math.abs(percent(a) - value) - Math.abs(percent(b) - value));
if (options[0] instanceof HTMLButtonElement) options[0].click();
}
/** @param {import('./demo-guide-cases').DemoGuide['steps'][number]} step @param {AbortSignal} signal */
async function playStep(step, signal) {
const target = root.querySelector(step.target);
if (!target) return;
caption.textContent = step.text;
const { action, value = 0, point = [.5, .5] } = step;
if (action === 'progress' && target instanceof HTMLInputElement) {
if (reduced.matches) {
showReducedProgress(value);
} else {
const from = target.valueAsNumber;
await guideBeat(step.duration ?? 0, signal, (progress) => {
const current = from + (value - from) * progress;
setProgress(target, current);
moveCursor(location(target, [.04 + .92 * current / 100, .65]));
});
}
} else {
if (!reduced.matches) {
const to = location(target, point);
const [x, y] = point;
const entry = x < .25 ? [-.08, y] : x > .75 ? [1.08, y] : [x, y < .5 ? -.08 : 1.08];
const from = action === 'enter' ? location(target, /** @type {[number, number]} */ (entry))
: cursorPosition ?? [to[0] + 26, to[1] + 19];
const duration = action === 'leave' ? 200 : 340;
await guideBeat(duration, signal, (progress) => {
const t = 1 - (1 - progress) ** 3;
const end = location(target, point);
const position = /** @type {[number, number]} */ ([
from[0] + (end[0] - from[0]) * t,
from[1] + (end[1] - from[1]) * t,
]);
moveCursor(position);
if (action === 'move') sendPointer(target, 'pointermove', position);
});
}
if (signal.aborted) return;
if (action === 'click' && target instanceof HTMLElement) {
if (!reduced.matches) {
cursor.dataset.press = '';
await guideBeat(125, signal);
if (signal.aborted) return;
}
target.click();
delete cursor.dataset.press;
} else if (action === 'enter' || action === 'leave') {
sendPointer(target, `pointer${action}`, location(target, point));
}
}
await guideBeat(reduced.matches ? 600 : step.hold ?? 500, signal);
}
function bringViewIntoFrame() {
const rect = view.getBoundingClientRect();
const visibleHeight = Math.min(rect.bottom, window.innerHeight) - Math.max(rect.top, 0);
if (visibleHeight < rect.height * threshold) view.scrollIntoView({ block: 'center', behavior: 'instant' });
}
async function start(replaying = false) {
stop();
const controller = new AbortController();
const { signal } = controller;
run = controller;
root.dataset.guideState = 'playing';
if (guide.ready) {
caption.textContent = '正在等待视频就绪…';
const deadline = performance.now() + 4000;
while (!signal.aborted && !root.querySelector(guide.ready) && performance.now() < deadline &&
!root.querySelector('[data-video-state="error"]')) {
await guideBeat(90, signal);
}
if (signal.aborted) return;
if (!root.querySelector(guide.ready)) {
run = undefined;
root.dataset.guideState = 'unavailable';
caption.textContent = '视频暂未就绪,可以查看关键帧或重播。';
return;
}
}
reset?.dispatchEvent(new Event('formtempo:guide-reset'));
if (replaying) bringViewIntoFrame();
playbackScroll = window.scrollY;
const steps = (reduced.matches && guide.reducedSteps) || guide.steps;
for (const step of steps) {
if (signal.aborted) return;
await playStep(step, signal);
}
if (signal.aborted) return;
run = undefined;
hideCursor();
root.dataset.guideState = 'complete';
caption.textContent = '导览结束,可以继续手动操作。';
}
function tryAutoplay() {
if (autoPending && inView && !document.hidden) void start();
}
if (typeof IntersectionObserver === 'function') {
const observer = new IntersectionObserver(([entry]) => {
inView = entry.intersectionRatio >= threshold;
if (!entry.isIntersecting && run) stop();
tryAutoplay();
}, { threshold: [0, threshold] });
observer.observe(view);
}
replay.addEventListener('click', () => {
bringViewIntoFrame();
void start(true);
});
const takeOver = (event) => {
if (!event.isTrusted || replay.contains(event.target)) return;
if (!run) {
if (event.type === 'wheel' || !(event.target instanceof Element)) return;
if (!event.target.closest('button, input') && !view.contains(event.target)) return;
}
const pointer = event instanceof PointerEvent && event.pointerType === 'mouse' && releaseTarget?.contains(event.target)
? event : undefined;
stop(pointer);
};
for (const event of ['pointerdown', 'keydown', 'focusin', 'input', 'click', 'wheel']) {
root.addEventListener(event, takeOver, { capture: true, passive: true });
}
if (guide.steps.some(({ action }) => action === 'enter' || action === 'move')) {
view.addEventListener('pointermove', takeOver, { capture: true, passive: true });
}
if (guide.pageScrollInput) {
window.addEventListener('scroll', () => {
if (run && window.scrollY !== playbackScroll) stop();
}, { passive: true });
}
document.addEventListener('visibilitychange', () => {
if (document.hidden && run) stop();
else tryAutoplay();
});
reduced.addEventListener('change', () => {
if (!reduced.matches) return;
const wasIdle = root.dataset.guideState === 'idle';
stop();
if (wasIdle) caption.textContent = reducedCaption;
});
}
bindDemoGuide(document.body, {"view":".scale-reveal__pair","dock":"[data-scale-panel]","reset":"[data-scale-reveal]","steps":[{"text":"从中心开始比较裁剪与缩放。","target":"input[type=\"range\"]","action":"progress","value":0,"duration":0,"hold":360},{"text":"到达一半时,左侧只露出原图中心,右侧显示缩小的完整画面。","target":"input[type=\"range\"]","action":"progress","value":50,"duration":600,"hold":600},{"text":"到达终点,两侧都是完整图像。","target":"input[type=\"range\"]","action":"progress","value":100,"duration":600,"hold":360},{"text":"退回一半,再看两种变化的差别。","target":"input[type=\"range\"]","action":"progress","value":50,"duration":600,"hold":360}]});
})();
</script>
</body>
</html>GSAP 3.15.0
完整示例,从 CDN 加载指定版本。
打开示例查看源码
<!doctype html>
<html lang="zh-CN">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>缩放显现 · GSAP示例</title>
<script>
if (new URLSearchParams(location.search).get('theme') === 'dark') {
document.documentElement.dataset.theme = 'dark';
}
</script>
<style>
:root {
color-scheme: light;
--page: #fbfaf7;
--surface: #fff;
--surface-2: #edf3f6;
--plate: #f7fafb;
--text: #222c36;
--text-2: #434f5d;
--line-hi: #82939f;
--accent: #b8412c;
--accent-text: #963324;
background: var(--page);
}
:root[data-theme="dark"] {
color-scheme: dark;
--page: #19222d;
--surface: #222e3c;
--surface-2: #2b3c4d;
--plate: #233142;
--text: #f6f5f1;
--text-2: #d8dce1;
--line-hi: #8396a8;
--accent: #ff9d7c;
--accent-text: #ffb399;
}
*, *::before, *::after { box-sizing: border-box; }
body { max-width: 54rem; margin: 0 auto; padding: clamp(1rem, 4vw, 2rem); color: var(--text); font: 1rem/1.6 system-ui, sans-serif; }
h1 { margin-block: 0 .4rem; font-size: 1.75rem; }
p { margin: 0 0 1rem; }
button, input { font: inherit; }
[hidden] { display: none !important; }
.scale-reveal__mode p { margin: 0; }
.scale-reveal[data-mode="scroll"] + p { min-height: 100vh; padding-block-start: 1rem; }
.scale-reveal {
--scale-progress: .5;
--scale-sticky-top: calc(var(--nav-h, 0px) + 1rem);
color: var(--text);
}
.scale-reveal__panel {
padding: clamp(.65rem, 2vw, 1.35rem);
border: 1px solid var(--line-hi);
border-radius: 14px;
background: var(--plate);
}
.scale-reveal__pair {
display: grid;
grid-template-columns: repeat(2, minmax(0, 1fr));
gap: clamp(.65rem, 2vw, 1.25rem);
}
.scale-reveal__pair figure { margin: 0; }
.scale-reveal__well {
position: relative;
aspect-ratio: 760 / 430;
overflow: hidden;
border: 1px solid var(--line-hi);
border-radius: 8px;
background: var(--surface-2);
}
.scale-reveal__art { position: absolute; inset: 0; }
.scale-reveal__art svg { display: block; width: 100%; height: 100%; }
.scale-reveal__art--crop { clip-path: inset(calc((1 - var(--scale-progress)) * 50%)); }
.scale-reveal__art--zoom { transform: scale(var(--scale-progress)); transform-origin: center; }
.scale-reveal__pair figcaption {
display: grid;
gap: .18rem;
padding-block: .65rem .15rem;
line-height: 1.4;
}
.scale-reveal__pair figcaption strong { font-size: .875rem; font-weight: 650; }
.scale-reveal__pair figcaption span { color: var(--text-2); font-size: .75rem; }
.scale-reveal__controls {
display: grid;
gap: .65rem;
margin-top: clamp(.8rem, 2vw, 1.2rem);
}
.scale-reveal__progress {
display: grid;
grid-template-columns: max-content minmax(0, 1fr) 4ch;
align-items: center;
gap: .5rem clamp(.55rem, 2vw, 1.25rem);
padding: .2rem clamp(.55rem, 2vw, 1rem);
border-radius: 10px;
background: var(--surface-2);
font-size: .8125rem;
font-weight: 600;
}
.scale-reveal__progress input,
.scale-reveal__progress progress {
width: 100%;
min-width: 0;
accent-color: var(--accent);
}
.scale-reveal__progress input { height: 44px; cursor: pointer; }
.scale-reveal__progress progress { height: .75rem; }
.scale-reveal__value {
color: var(--accent-text);
font: 500 .8125rem/1 var(--font-mono, ui-monospace, monospace);
font-variant-numeric: tabular-nums;
text-align: right;
}
.scale-reveal__mode, .scale-reveal__steps {
display: flex;
flex-wrap: wrap;
align-items: center;
gap: .4rem .65rem;
}
.scale-reveal__controls button {
min-height: 44px;
padding: .45rem .72rem;
border: 1px solid var(--line-hi);
border-radius: 10px;
background: var(--surface);
color: var(--text);
font-size: .8125rem;
font-weight: 600;
cursor: pointer;
}
.scale-reveal__controls button:hover,
.scale-reveal__controls button[aria-pressed="true"] {
border-color: var(--accent-text);
color: var(--accent-text);
}
.scale-reveal__controls :is(button, input):focus-visible {
outline: 2px solid var(--accent);
outline-offset: 2px;
}
.scale-reveal__static, .scale-reveal__mode p { color: var(--text-2); font-size: .8125rem; }
.scale-reveal__static { margin: .85rem 0 0; }
.scale-reveal__distance { display: none; }
.scale-reveal[data-mode="scroll"] .scale-reveal__panel {
position: sticky;
top: var(--scale-sticky-top);
z-index: 1;
}
.scale-reveal[data-mode="scroll"] .scale-reveal__distance {
display: block;
height: clamp(22rem, 85vh, 55rem);
}
@media (max-width: 34rem) {
.scale-reveal__progress { grid-template-columns: minmax(0, 1fr) 4ch; padding-block: .35rem; gap: .2rem .55rem; }
.scale-reveal__progress > :first-child { grid-column: 1 / -1; }
.scale-reveal__pair figcaption { padding-block-start: .45rem; }
.scale-reveal__steps { gap: .3rem; }
.scale-reveal__steps button { padding-inline: .45rem; }
}
</style>
<style>.demo-guide {
display: flex;
align-items: center;
justify-content: space-between;
gap: .5rem .9rem;
min-inline-size: 0;
margin-block: 0 .75rem;
padding-block-end: .5rem;
border-block-end: 1px solid var(--line-hi, #b8c4cd);
color: var(--text-2, #434f5d);
font-size: .8125rem;
line-height: 1.5;
}
.trigger-stage > .demo-guide {
margin: .35rem clamp(.85rem, 2.2vw, 1.4rem) 0;
}
.demo-guide [data-guide-caption] { margin: 0; }
.demo-guide > button[data-guide-replay] {
flex: none;
min-block-size: 44px;
margin: 0;
padding: .35rem .65rem;
border: 1px solid var(--line-strong, #82939f);
border-radius: 7px;
background: var(--surface, #fff);
color: var(--text, #222c36);
font: inherit;
font-weight: 550;
cursor: pointer;
}
.demo-guide > button[data-guide-replay]:hover { border-color: var(--accent-text, #963324); }
.demo-guide > button[data-guide-replay]:focus-visible { outline: 2px solid var(--accent-text, #963324); outline-offset: 2px; }
.demo-guide-cursor {
position: fixed;
z-index: 20;
inset: 0 auto auto 0;
inline-size: 20px;
block-size: 24px;
pointer-events: none;
}
.demo-guide-cursor svg { display: block; inline-size: 100%; block-size: 100%; }
.demo-guide-cursor::before {
position: absolute;
inset: -7px auto auto -7px;
inline-size: 18px;
block-size: 18px;
border: 2px solid var(--accent-text, #963324);
border-radius: 50%;
content: '';
opacity: 0;
}
.demo-guide-cursor[data-press]::before { opacity: 1; }
@media (prefers-reduced-motion: reduce) { .demo-guide-cursor { display: none; } }
</style>
</head>
<body>
<h1>缩放显现</h1>
<p>拖动同一条进度,观察裁剪与缩放怎样处理同一幅插图。</p>
<div class="scale-reveal" data-scale-reveal data-mode="manual">
<div class="scale-reveal__panel" data-scale-panel>
<div class="scale-reveal__pair">
<figure>
<div class="scale-reveal__well">
<div class="scale-reveal__art scale-reveal__art--crop" data-scale-crop><svg viewBox="0 0 760 430" aria-hidden="true" focusable="false">
<path fill="#e8f3fa" d="M0 0h760v430H0z"/>
<circle cx="454" cy="151" r="77" fill="#ef784d"/>
<path fill="#f7c98b" d="M0 228 93 198q59-19 127 9l72 30q56 25 112-5l102-57q50-27 103-6l151 63v198H0z"/>
<path fill="#7299b4" d="m0 294 137-77q54-29 111 5l106 68q40 26 94 9l135-43q89-30 177 11v163H0z"/>
<path fill="#e5a38a" d="m0 350 128-21q63-11 122 6l95 28q72 22 137-2l110-41q88-33 168 11v99H0z"/>
<path fill="#adcfdf" d="m0 379 115 9q89 7 174-19l72-22q59-19 119-3l134 34q69 18 146 3v49H0z"/>
<g fill="none" stroke="#fffdf8" stroke-linecap="round" opacity=".76">
<path d="M0 403q126 17 274-20m235-21 107 27q76 19 144 5M18 417q114 14 246-20"/>
<path d="M124 175h43m-12-10h29m377-31h47m-13 12h25" stroke-width="2"/>
</g>
</svg></div>
</div>
<figcaption><strong>裁剪展开</strong><span>原尺寸,打开可见区域</span></figcaption>
</figure>
<figure>
<div class="scale-reveal__well">
<div class="scale-reveal__art scale-reveal__art--zoom" data-scale-zoom><svg viewBox="0 0 760 430" aria-hidden="true" focusable="false">
<path fill="#e8f3fa" d="M0 0h760v430H0z"/>
<circle cx="454" cy="151" r="77" fill="#ef784d"/>
<path fill="#f7c98b" d="M0 228 93 198q59-19 127 9l72 30q56 25 112-5l102-57q50-27 103-6l151 63v198H0z"/>
<path fill="#7299b4" d="m0 294 137-77q54-29 111 5l106 68q40 26 94 9l135-43q89-30 177 11v163H0z"/>
<path fill="#e5a38a" d="m0 350 128-21q63-11 122 6l95 28q72 22 137-2l110-41q88-33 168 11v99H0z"/>
<path fill="#adcfdf" d="m0 379 115 9q89 7 174-19l72-22q59-19 119-3l134 34q69 18 146 3v49H0z"/>
<g fill="none" stroke="#fffdf8" stroke-linecap="round" opacity=".76">
<path d="M0 403q126 17 274-20m235-21 107 27q76 19 144 5M18 417q114 14 246-20"/>
<path d="M124 175h43m-12-10h29m377-31h47m-13 12h25" stroke-width="2"/>
</g>
</svg></div>
</div>
<figcaption><strong>缩放显现</strong><span>完整构图,从中心放大</span></figcaption>
</figure>
</div>
<div class="scale-reveal__controls" data-scale-controls hidden>
<div class="scale-reveal__progress">
<span id="scale-reveal-progress-label">演示进度</span>
<input type="range" min="0" max="100" value="50" aria-labelledby="scale-reveal-progress-label"
aria-valuetext="50%" data-scale-slider />
<progress max="100" value="50" aria-labelledby="scale-reveal-progress-label" data-scale-meter hidden></progress>
<div class="scale-reveal__steps" role="group" aria-labelledby="scale-reveal-progress-label" data-scale-steps hidden>
<button type="button" data-scale-step="0" aria-pressed="false">0%</button>
<button type="button" data-scale-step="50" aria-pressed="true">50%</button>
<button type="button" data-scale-step="100" aria-pressed="false">100%</button>
</div>
<span class="scale-reveal__value" data-scale-value aria-hidden="true">50%</span>
</div>
<div class="scale-reveal__mode" data-scale-mode>
<button type="button" aria-pressed="false" data-scale-toggle>跟随页面滚动</button>
<p data-scale-hint hidden>向下滚动前进,向上滚动回退。</p>
</div>
</div>
<p class="scale-reveal__static" data-scale-static>50% 示意。裁剪只露出中央,缩放则保留完整构图。</p>
<p class="scale-reveal__static" data-scale-error hidden>GSAP 未加载,请联网后刷新以操作示例。</p>
</div>
<div class="scale-reveal__distance" aria-hidden="true"></div>
</div>
<p>裁剪改变可见区域,缩放改变整幅图的大小。</p>
<script src="https://cdn.jsdelivr.net/npm/gsap@3.15.0/dist/gsap.min.js"></script>
<script>
(() => {
/**
* @param {HTMLElement} root
* @param {(crop: HTMLElement, zoom: HTMLElement) => { progress(value: number): unknown }} [createTimeline]
*/
function bindScaleReveal(root, createTimeline) {
const panel = root.querySelector('[data-scale-panel]');
const controls = root.querySelector('[data-scale-controls]');
const slider = root.querySelector('[data-scale-slider]');
const meter = root.querySelector('[data-scale-meter]');
const steps = root.querySelector('[data-scale-steps]');
const stepButtons = [...steps.querySelectorAll('button')];
const value = root.querySelector('[data-scale-value]');
const mode = root.querySelector('[data-scale-mode]');
const toggle = root.querySelector('[data-scale-toggle]');
const hint = root.querySelector('[data-scale-hint]');
const motion = window.matchMedia('(prefers-reduced-motion: reduce)');
const timeline = createTimeline?.(root.querySelector('[data-scale-crop]'), root.querySelector('[data-scale-zoom]'));
let progress = slider.valueAsNumber / 100;
let scrollMode = false;
let start = 0;
let distance = 1;
let frame = 0;
function render(next) {
progress = next;
if (timeline) timeline.progress(next);
else root.style.setProperty('--scale-progress', String(next));
const percent = Math.round(next * 100);
const label = `${percent}%`;
slider.value = String(percent);
slider.setAttribute('aria-valuetext', label);
meter.value = percent;
value.textContent = label;
if (motion.matches) {
for (const button of stepButtons) {
button.setAttribute('aria-pressed', String(Number(button.dataset.scaleStep) === percent));
}
}
}
function updateFromScroll() {
if (!scrollMode || frame) return;
frame = requestAnimationFrame(() => {
frame = 0;
if (scrollMode) render(Math.max(0, Math.min(1, (window.scrollY - start) / distance)));
});
}
function measure() {
if (!scrollMode) return;
const top = Number.parseFloat(getComputedStyle(panel).top) || 0;
start = root.getBoundingClientRect().top + window.scrollY - top;
distance = Math.max(1, root.offsetHeight - panel.offsetHeight);
updateFromScroll();
}
function setMode(active, keepPanelInView = false) {
const returnToPanel = keepPanelInView && scrollMode && !active && window.scrollY > start;
scrollMode = active;
root.dataset.mode = active ? 'scroll' : 'manual';
slider.hidden = active || motion.matches;
meter.hidden = !active;
steps.hidden = !motion.matches;
mode.hidden = motion.matches;
toggle.setAttribute('aria-pressed', String(active));
hint.hidden = !active;
if (active) {
measure();
} else {
const stepsPerRange = motion.matches ? 2 : 100;
render(Math.round(progress * stepsPerRange) / stepsPerRange);
if (returnToPanel) window.scrollTo({ top: Math.max(0, start), behavior: 'instant' });
}
}
function syncMotion() {
const hadFocus = controls.contains(document.activeElement);
setMode(false, hadFocus);
if (hadFocus) {
const control = motion.matches ? steps.querySelector('[aria-pressed="true"]') : slider;
control?.focus({ preventScroll: true });
}
}
slider.addEventListener('input', () => {
if (!scrollMode && !motion.matches) render(slider.valueAsNumber / 100);
});
for (const button of stepButtons) {
button.addEventListener('click', () => render(Number(button.dataset.scaleStep) / 100));
}
toggle.addEventListener('click', () => setMode(!scrollMode, true));
root.addEventListener('formtempo:guide-reset', () => setMode(false));
window.addEventListener('scroll', updateFromScroll, { passive: true });
window.addEventListener('resize', measure);
window.addEventListener('pageshow', measure);
const resize = new ResizeObserver(measure);
resize.observe(root);
resize.observe(panel);
resize.observe(document.body);
motion.addEventListener('change', syncMotion);
syncMotion();
root.querySelector('[data-scale-static]').hidden = true;
controls.hidden = false;
}
const root = document.querySelector('[data-scale-reveal]');
if (!window.gsap) {
root.querySelector('[data-scale-error]').hidden = false;
return;
}
bindScaleReveal(root, (crop, zoom) => gsap.timeline({ paused: true })
.fromTo(crop, { clipPath: 'inset(50%)' }, { clipPath: 'inset(0%)', ease: 'none' }, 0)
.fromTo(zoom, { scale: 0 }, { scale: 1, ease: 'none' }, 0));
})();
</script>
<script>
(() => {
/** @param {number} duration @param {AbortSignal} signal @param {(progress: number) => void} [render] */
function guideBeat(duration, signal, render) {
if (signal.aborted) return Promise.resolve();
if (duration === 0) {
render?.(1);
return Promise.resolve();
}
return new Promise((resolve) => {
let timer = 0;
let frame = 0;
const done = () => {
clearTimeout(timer);
cancelAnimationFrame(frame);
signal.removeEventListener('abort', done);
resolve(undefined);
};
signal.addEventListener('abort', done, { once: true });
if (!render) {
timer = window.setTimeout(done, duration);
return;
}
const start = performance.now();
const tick = (now) => {
const progress = Math.min(1, (now - start) / duration);
render(progress);
if (progress === 1) done();
else if (!signal.aborted) frame = requestAnimationFrame(tick);
};
frame = requestAnimationFrame(tick);
});
}
/** @param {HTMLElement} root @param {import('./demo-guide-cases').DemoGuide} guide */
function bindDemoGuide(root, guide) {
const view = root.querySelector(guide.view);
if (!view || root.dataset.guideState || guide.steps.some(({ target }) => !root.querySelector(target))) return;
const dock = guide.dock ? root.querySelector(guide.dock) : null;
const bar = document.createElement('div');
bar.className = 'demo-guide';
bar.innerHTML = '<p data-guide-caption></p><button type="button" data-guide-replay>重播导览</button>';
const caption = bar.querySelector('[data-guide-caption]');
const replay = bar.querySelector('button');
const heading = root === document.body ? root.querySelector('h1') : null;
if (dock) dock.prepend(bar);
else if (heading) heading.after(bar);
else root.prepend(bar);
const cursor = document.createElement('div');
cursor.className = 'demo-guide-cursor';
cursor.setAttribute('aria-hidden', 'true');
cursor.hidden = true;
cursor.innerHTML = '<svg viewBox="0 0 20 24" focusable="false"><path d="M2 2v17l4.8-4.5L10 21l3.2-1.6-3.2-6.2 6.6-.7L2 2Z" fill="#222c36" stroke="#fff" stroke-width="1.5" stroke-linejoin="round"/></svg>';
document.body.append(cursor);
const reduced = matchMedia('(prefers-reduced-motion: reduce)');
const threshold = .5;
const idleCaption = '导览在画面进入视口后播放一次。';
const reducedCaption = '可重播关键状态,或直接操作。';
const reset = guide.reset ? (root.matches(guide.reset) ? root : root.querySelector(guide.reset)) : null;
const releaseTarget = guide.release ? root.querySelector(guide.release) : null;
let autoPending = !reduced.matches;
let inView = false;
let playbackScroll = window.scrollY;
/** @type {AbortController | undefined} */
let run;
/** @type {[number, number] | undefined} */
let cursorPosition;
root.dataset.guideState = 'idle';
caption.textContent = reduced.matches ? reducedCaption : idleCaption;
function hideCursor() {
cursor.hidden = true;
delete cursor.dataset.press;
cursorPosition = undefined;
}
/** @param {PointerEvent} [pointer] */
function stop(pointer) {
autoPending = false;
if (!run) return;
run.abort();
run = undefined;
hideCursor();
if (releaseTarget) {
// A real pointer inside the target keeps its hover when the guide yields.
if (pointer) sendPointer(releaseTarget, 'pointerenter', [pointer.clientX, pointer.clientY]);
else sendPointer(releaseTarget, 'pointerleave', [0, 0]);
}
reset?.dispatchEvent(new Event('formtempo:guide-cancel'));
root.dataset.guideState = 'interrupted';
caption.textContent = '导览已停止,可以继续手动操作。';
}
/** @param {[number, number]} position */
function moveCursor(position) {
cursor.hidden = false;
cursor.style.transform = `translate3d(${position[0]}px, ${position[1]}px, 0)`;
cursorPosition = position;
}
/** @param {Element} target @param {readonly [number, number]} point */
function location(target, [x, y]) {
const rect = target.getBoundingClientRect();
return /** @type {[number, number]} */ ([rect.left + rect.width * x, rect.top + rect.height * y]);
}
/** @param {Element} target @param {string} type @param {readonly [number, number]} position */
function sendPointer(target, type, [clientX, clientY]) {
target.dispatchEvent(new PointerEvent(type, { pointerType: 'mouse', clientX, clientY }));
}
/** @param {HTMLInputElement} slider @param {number} value */
function setProgress(slider, value) {
const next = Math.round(value);
if (slider.valueAsNumber === next) return;
slider.value = String(next);
slider.dispatchEvent(new Event('input', { bubbles: true }));
}
/** @param {number} value */
function showReducedProgress(value) {
const options = Array.from(root.querySelectorAll('button[data-driven-step], button[data-scale-step], button[data-progress-step], button[data-progress]'));
const percent = (button) => button.hasAttribute('data-progress')
? Number(button.getAttribute('data-progress')) * 100
: Number(button.getAttribute('data-driven-step') ?? button.getAttribute('data-scale-step') ?? button.getAttribute('data-progress-step'));
options.sort((a, b) => Math.abs(percent(a) - value) - Math.abs(percent(b) - value));
if (options[0] instanceof HTMLButtonElement) options[0].click();
}
/** @param {import('./demo-guide-cases').DemoGuide['steps'][number]} step @param {AbortSignal} signal */
async function playStep(step, signal) {
const target = root.querySelector(step.target);
if (!target) return;
caption.textContent = step.text;
const { action, value = 0, point = [.5, .5] } = step;
if (action === 'progress' && target instanceof HTMLInputElement) {
if (reduced.matches) {
showReducedProgress(value);
} else {
const from = target.valueAsNumber;
await guideBeat(step.duration ?? 0, signal, (progress) => {
const current = from + (value - from) * progress;
setProgress(target, current);
moveCursor(location(target, [.04 + .92 * current / 100, .65]));
});
}
} else {
if (!reduced.matches) {
const to = location(target, point);
const [x, y] = point;
const entry = x < .25 ? [-.08, y] : x > .75 ? [1.08, y] : [x, y < .5 ? -.08 : 1.08];
const from = action === 'enter' ? location(target, /** @type {[number, number]} */ (entry))
: cursorPosition ?? [to[0] + 26, to[1] + 19];
const duration = action === 'leave' ? 200 : 340;
await guideBeat(duration, signal, (progress) => {
const t = 1 - (1 - progress) ** 3;
const end = location(target, point);
const position = /** @type {[number, number]} */ ([
from[0] + (end[0] - from[0]) * t,
from[1] + (end[1] - from[1]) * t,
]);
moveCursor(position);
if (action === 'move') sendPointer(target, 'pointermove', position);
});
}
if (signal.aborted) return;
if (action === 'click' && target instanceof HTMLElement) {
if (!reduced.matches) {
cursor.dataset.press = '';
await guideBeat(125, signal);
if (signal.aborted) return;
}
target.click();
delete cursor.dataset.press;
} else if (action === 'enter' || action === 'leave') {
sendPointer(target, `pointer${action}`, location(target, point));
}
}
await guideBeat(reduced.matches ? 600 : step.hold ?? 500, signal);
}
function bringViewIntoFrame() {
const rect = view.getBoundingClientRect();
const visibleHeight = Math.min(rect.bottom, window.innerHeight) - Math.max(rect.top, 0);
if (visibleHeight < rect.height * threshold) view.scrollIntoView({ block: 'center', behavior: 'instant' });
}
async function start(replaying = false) {
stop();
const controller = new AbortController();
const { signal } = controller;
run = controller;
root.dataset.guideState = 'playing';
if (guide.ready) {
caption.textContent = '正在等待视频就绪…';
const deadline = performance.now() + 4000;
while (!signal.aborted && !root.querySelector(guide.ready) && performance.now() < deadline &&
!root.querySelector('[data-video-state="error"]')) {
await guideBeat(90, signal);
}
if (signal.aborted) return;
if (!root.querySelector(guide.ready)) {
run = undefined;
root.dataset.guideState = 'unavailable';
caption.textContent = '视频暂未就绪,可以查看关键帧或重播。';
return;
}
}
reset?.dispatchEvent(new Event('formtempo:guide-reset'));
if (replaying) bringViewIntoFrame();
playbackScroll = window.scrollY;
const steps = (reduced.matches && guide.reducedSteps) || guide.steps;
for (const step of steps) {
if (signal.aborted) return;
await playStep(step, signal);
}
if (signal.aborted) return;
run = undefined;
hideCursor();
root.dataset.guideState = 'complete';
caption.textContent = '导览结束,可以继续手动操作。';
}
function tryAutoplay() {
if (autoPending && inView && !document.hidden) void start();
}
if (typeof IntersectionObserver === 'function') {
const observer = new IntersectionObserver(([entry]) => {
inView = entry.intersectionRatio >= threshold;
if (!entry.isIntersecting && run) stop();
tryAutoplay();
}, { threshold: [0, threshold] });
observer.observe(view);
}
replay.addEventListener('click', () => {
bringViewIntoFrame();
void start(true);
});
const takeOver = (event) => {
if (!event.isTrusted || replay.contains(event.target)) return;
if (!run) {
if (event.type === 'wheel' || !(event.target instanceof Element)) return;
if (!event.target.closest('button, input') && !view.contains(event.target)) return;
}
const pointer = event instanceof PointerEvent && event.pointerType === 'mouse' && releaseTarget?.contains(event.target)
? event : undefined;
stop(pointer);
};
for (const event of ['pointerdown', 'keydown', 'focusin', 'input', 'click', 'wheel']) {
root.addEventListener(event, takeOver, { capture: true, passive: true });
}
if (guide.steps.some(({ action }) => action === 'enter' || action === 'move')) {
view.addEventListener('pointermove', takeOver, { capture: true, passive: true });
}
if (guide.pageScrollInput) {
window.addEventListener('scroll', () => {
if (run && window.scrollY !== playbackScroll) stop();
}, { passive: true });
}
document.addEventListener('visibilitychange', () => {
if (document.hidden && run) stop();
else tryAutoplay();
});
reduced.addEventListener('change', () => {
if (!reduced.matches) return;
const wasIdle = root.dataset.guideState === 'idle';
stop();
if (wasIdle) caption.textContent = reducedCaption;
});
}
bindDemoGuide(document.body, {"view":".scale-reveal__pair","dock":"[data-scale-panel]","reset":"[data-scale-reveal]","steps":[{"text":"从中心开始比较裁剪与缩放。","target":"input[type=\"range\"]","action":"progress","value":0,"duration":0,"hold":360},{"text":"到达一半时,左侧只露出原图中心,右侧显示缩小的完整画面。","target":"input[type=\"range\"]","action":"progress","value":50,"duration":600,"hold":600},{"text":"到达终点,两侧都是完整图像。","target":"input[type=\"range\"]","action":"progress","value":100,"duration":600,"hold":360},{"text":"退回一半,再看两种变化的差别。","target":"input[type=\"range\"]","action":"progress","value":50,"duration":600,"hold":360}]});
})();
</script>
</body>
</html>