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hyperframes/packages/engine/src/services/screenshotService.ts
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// fallow-ignore-file code-duplication complexity
/**
* Screenshot Service
*
* BeginFrame-based deterministic screenshot capture and video frame injection.
*/
// fallow-ignore-file code-duplication
import { type Page } from "puppeteer-core";
import { type CaptureOptions } from "../types.js";
import { COLOR_GRADING_SOURCE_HIDDEN_ATTR } from "@hyperframes/core/color-grading";
import {
HF_COLOR_GRADING_CANVAS_ID_PREFIX,
MEDIA_VISUAL_STYLE_PROPERTIES,
} from "@hyperframes/core";
export const cdpSessionCache = new WeakMap<Page, import("puppeteer-core").CDPSession>();
export async function getCdpSession(page: Page): Promise<import("puppeteer-core").CDPSession> {
let client = cdpSessionCache.get(page);
if (!client) {
client = await page.createCDPSession();
cdpSessionCache.set(page, client);
}
return client;
}
export function shouldDefaultCaptureBeyondViewport(
browserVersion: string,
platform: NodeJS.Platform = process.platform,
): boolean {
// Regular Chrome's viewport-bound screenshot path can expose a compositor
// surface shorter than the page viewport on affected macOS builds. In that
// case Chrome fills the clipped area with the page background. Headless shell
// reports as HeadlessChrome and keeps the faster viewport-bound path.
return platform === "darwin" && browserVersion.startsWith("Chrome/");
}
/**
* BeginFrame result with screenshot data and damage detection.
*/
export interface BeginFrameResult {
buffer: Buffer;
hasDamage: boolean;
}
/**
* Issue a single no-output BeginFrame and race it against `timeoutMs`.
*
* On SwiftShader, compositions with many promoted layers (multi-group nested
* opacity caption animations) can stall the FIRST BeginFrame indefinitely —
* tested to 30 minutes without completion (style-7/8/10/15-prod). The
* auto-worker calibration path catches this with its own capped protocol
* timeout, but renders with an explicit `--workers N` skip calibration and
* would hang for the full protocol timeout (and never succeed). This probe
* gives the producer a cheap liveness signal right after session init:
* `false` means route the render through screenshot capture instead.
*
* Healthy comps complete the probe in well under a second on GPU and within
* a few seconds on SwiftShader. A protocol error also resolves `false` —
* the safe direction (screenshot capture always works).
*/
export async function probeBeginFrameLiveness(
page: Page,
timeoutMs: number,
// BeginFrame frameTimeTicks must be monotonic per session. The capture loop
// sends `session.beginFrameTimeTicks + frameIndex * interval`, where the
// base carries a 10-interval cushion above the warmup loop's last tick —
// callers probing an initialized session should pass a tick INSIDE that
// cushion (e.g. base 5·interval) so warmup < probe < first capture stays
// monotonic. Omit both params only for a session that will not issue
// further BeginFrames.
frameTimeTicks?: number,
intervalMs?: number,
): Promise<boolean> {
const client = await getCdpSession(page);
const params: { frameTimeTicks?: number; interval?: number } = {};
if (typeof frameTimeTicks === "number") params.frameTimeTicks = frameTimeTicks;
if (typeof intervalMs === "number") params.interval = intervalMs;
let timer: ReturnType<typeof setTimeout> | undefined;
try {
return await Promise.race([
client
.send("HeadlessExperimental.beginFrame", params)
.then(() => true)
.catch(() => false),
new Promise<boolean>((resolve) => {
timer = setTimeout(() => resolve(false), timeoutMs);
}),
]);
} finally {
if (timer) clearTimeout(timer);
}
}
/**
* Capture a frame using HeadlessExperimental.beginFrame.
*
* This is an atomic operation: one CDP call runs a single layout-paint-composite
* cycle and returns the screenshot + hasDamage boolean. Replaces the separate
* settle → screenshot pipeline with a single deterministic render cycle.
*
* Requires chrome-headless-shell with --enable-begin-frame-control and
* --deterministic-mode flags.
*/
// Cache the last valid screenshot buffer per page for hasDamage=false frames.
// When Chrome reports no visual change, we reuse the previous frame rather than
// attempting Page.captureScreenshot (which times out in beginFrame mode since
// the compositor is paused).
const lastFrameCache = new WeakMap<Page, Buffer>();
const PENDING_FRAME_RETRIES = 5;
async function sendBeginFrame(
client: import("puppeteer-core").CDPSession,
params: Parameters<typeof client.send<"HeadlessExperimental.beginFrame">>[1],
) {
for (let attempt = 0; ; attempt++) {
try {
return await client.send("HeadlessExperimental.beginFrame", params);
} catch (err: unknown) {
const msg = err instanceof Error ? err.message : String(err);
const isPending = msg.includes("Another frame is pending");
if (isPending && attempt < PENDING_FRAME_RETRIES) {
await new Promise((r) => setTimeout(r, 50 * 2 ** attempt));
continue;
}
if (isPending) {
throw new Error(
`[BeginFrame] Frame still pending after ${PENDING_FRAME_RETRIES} retries — CPU overloaded by parallel renders. ` +
`Reduce concurrent renders or use --docker for isolation.`,
);
}
throw err;
}
}
}
export async function beginFrameCapture(
page: Page,
options: CaptureOptions,
frameTimeTicks: number,
interval: number,
): Promise<BeginFrameResult> {
const client = await getCdpSession(page);
const isPng = options.format === "png";
const screenshot = {
format: isPng ? "png" : "jpeg",
quality: isPng ? undefined : (options.quality ?? 80),
optimizeForSpeed: true,
} as const;
const result = await sendBeginFrame(client, { frameTimeTicks, interval, screenshot });
let buffer: Buffer;
if (result.screenshotData) {
buffer = Buffer.from(result.screenshotData, "base64");
lastFrameCache.set(page, buffer);
} else {
const cached = lastFrameCache.get(page);
if (cached) {
buffer = cached;
} else {
// Frame 0 always has damage, so this path is near-unreachable.
// Force a composite with a tiny time advance.
const fallback = await sendBeginFrame(client, {
frameTimeTicks: frameTimeTicks + 0.001,
interval,
screenshot,
});
buffer = fallback.screenshotData
? Buffer.from(fallback.screenshotData, "base64")
: Buffer.alloc(0);
if (buffer.length > 0) lastFrameCache.set(page, buffer);
}
}
return {
buffer,
hasDamage: result.hasDamage,
};
}
/**
* True if the page's actual rendered content is taller than the requested
* capture height. `captureBeyondViewport` exists for exactly one reason
* (#1094): a native `<video>` surface whose content genuinely overflows the
* viewport-bound capture path clips its bottom edge to black. A video that
* fits entirely inside its composition's declared viewport doesn't have that
* problem — ground-truth measurement beats the coarser "has a video, so
* always request beyond-viewport" heuristic, which also unnecessarily routes
* every video render through a CDP capture path prone to producing phantom
* duplicate content on SwiftShader (#2550).
*
* Callers measure once after page settle. Hyperframes compositions have a
* fixed-height, overflow-clipped render surface; timeline animation may move
* pixels within that surface but must not grow document flow during capture.
*/
export async function pageContentExceedsCaptureHeight(
page: Page,
requestedHeight: number,
): Promise<boolean> {
const scrollHeight = await page.evaluate(() => document.documentElement.scrollHeight);
// Small tolerance for subpixel layout rounding, not a real overflow signal.
return scrollHeight > requestedHeight + 1;
}
/**
* Capture a screenshot using standard Page.captureScreenshot CDP call.
* Fallback for environments where BeginFrame is unavailable (macOS, Windows).
*
* For `format: "png"` captures we disable Chrome's `optimizeForSpeed` fast
* path. The fast path uses a zero-alpha-aware codec that crushes real alpha
* values to 0 or 255 (verified empirically; CDP docs don't document this) —
* exactly the same caveat called out on `captureScreenshotWithAlpha` /
* `captureAlphaPng`. Keeping the fast path for opaque jpeg captures is fine.
*/
export async function pageScreenshotCapture(page: Page, options: CaptureOptions): Promise<Buffer> {
const client = await getCdpSession(page);
const isPng = options.format === "png";
const dpr = options.deviceScaleFactor ?? 1;
const clip = { x: 0, y: 0, width: options.width, height: options.height, scale: dpr };
const result = await client.send("Page.captureScreenshot", {
format: isPng ? "png" : "jpeg",
quality: isPng ? undefined : (options.quality ?? 80),
fromSurface: true,
// Use Chrome's faster viewport-bound screenshot path by default. Callers
// opt into the beyond-viewport path only for known compositor edge cases,
// such as native video surfaces in tall portrait renders.
captureBeyondViewport: options.captureBeyondViewport ?? false,
optimizeForSpeed: !isPng,
clip,
});
return Buffer.from(result.data, "base64");
}
/**
* Capture a screenshot with transparent background (PNG + alpha channel).
*
* Used in the two-pass HDR compositing pipeline — captures DOM content
* (text, graphics, SDR overlays) with transparency where the background shows,
* so it can be overlaid on top of native HDR video frames in FFmpeg.
*
* Sets and restores the background color override on every call. For sessions
* that capture many frames, prefer calling initTransparentBackground() once
* at session init, then captureAlphaPng() per frame to avoid the 2× CDP
* round-trip overhead.
*/
export async function captureScreenshotWithAlpha(
page: Page,
width: number,
height: number,
): Promise<Buffer> {
const client = await getCdpSession(page);
// Force transparent background so the screenshot has a real alpha channel
await client.send("Emulation.setDefaultBackgroundColorOverride", {
color: { r: 0, g: 0, b: 0, a: 0 },
});
try {
const result = await client.send("Page.captureScreenshot", {
format: "png",
fromSurface: true,
// Preserve the #1094 tall-portrait edge-clipping guard on HDR alpha captures.
captureBeyondViewport: true,
optimizeForSpeed: false, // `true` uses a zero-alpha-aware fast path that crushes real alpha values — observed empirically, CDP docs don't spell it out
clip: { x: 0, y: 0, width, height, scale: 1 },
});
return Buffer.from(result.data, "base64");
} finally {
// Restore opaque background even if captureScreenshot throws, otherwise
// subsequent opaque captures keep a transparent background.
await client.send("Emulation.setDefaultBackgroundColorOverride", {}).catch(() => {});
}
}
/**
* Set the page background to transparent once for a dedicated HDR DOM session.
*
* Call this once after session initialization. Then use captureAlphaPng() per
* frame instead of captureScreenshotWithAlpha() to skip the per-frame CDP
* background override round-trips.
*
* Only use on sessions that are exclusively dedicated to transparent capture
* (e.g., the HDR two-pass DOM layer session) — the background will stay
* transparent for the lifetime of the session.
*
* NOTE on the injected stylesheet: `Emulation.setDefaultBackgroundColorOverride`
* only replaces the *default* page background. Compositions almost always set
* `body { background: ... }` and `#root { background: ... }`, which paint over
* the override and ruin alpha capture for layered HDR compositing — the
* composition root's full-frame background paints across the entire viewport
* and wipes out HDR content captured beneath it.
*
* We force `html`, `body`, and any element marked as a composition root
* (`[data-composition-id]`) to transparent. In HDR layered compositing the HDR
* video itself is the backdrop, so DOM layers must only contribute their
* foreground UI pixels — never a page-spanning solid backdrop.
*/
const TRANSPARENT_BG_STYLE_ID = "__hf_transparent_bg__";
export async function initTransparentBackground(page: Page): Promise<void> {
const client = await getCdpSession(page);
await client.send("Emulation.setDefaultBackgroundColorOverride", {
color: { r: 0, g: 0, b: 0, a: 0 },
});
await page.evaluate((styleId: string) => {
if (document.getElementById(styleId)) return;
const style = document.createElement("style");
style.id = styleId;
style.textContent =
"html,body,[data-composition-id]{background:transparent !important;background-color:transparent !important;background-image:none !important;}";
document.head.appendChild(style);
}, TRANSPARENT_BG_STYLE_ID);
}
/**
* Capture a transparent-background PNG screenshot without setting the
* background color override. Requires initTransparentBackground() to have
* been called once on this session.
*
* Faster than captureScreenshotWithAlpha() for per-frame use in the HDR
* two-pass compositing loop.
*/
export async function captureAlphaPng(page: Page, width: number, height: number): Promise<Buffer> {
const client = await getCdpSession(page);
const result = await client.send("Page.captureScreenshot", {
format: "png",
fromSurface: true,
// Preserve the #1094 tall-portrait edge-clipping guard on HDR alpha captures.
captureBeyondViewport: true,
optimizeForSpeed: false, // must be false to preserve alpha
clip: { x: 0, y: 0, width, height, scale: 1 },
});
return Buffer.from(result.data, "base64");
}
/**
* Stylesheet ID used by applyDomLayerMask / removeDomLayerMask. Exposed so
* tests can assert presence/absence of the mask between captures.
*/
export const DOM_LAYER_MASK_STYLE_ID = "__hf_dom_layer_mask__";
const DOM_LAYER_MASK_HIDDEN_ATTR = "data-hf-dom-layer-mask-hidden";
const DOM_LAYER_MASK_PREV_VISIBILITY_ATTR = "data-hf-dom-layer-mask-prev-visibility";
const DOM_LAYER_MASK_PREV_PRIORITY_ATTR = "data-hf-dom-layer-mask-prev-priority";
/**
* Mask the DOM so a single layer screenshot captures ONLY the layer's pixels.
*
* The HDR layered compositor walks z-ordered layers and blits each one over a
* shared canvas. DOM layers are full-page screenshots — a naive screenshot
* captures every painted pixel on the page, which means root background +
* static overlays + sibling-scene content all overwrite previously composited
* HDR content beneath. The mask narrows each screenshot to the elements that
* actually belong to this layer.
*
* Strategy:
*
* 1. Inject a stylesheet that hides every body descendant
* (`body * { visibility: hidden !important }`) and re-shows the layer's
* elements (and their descendants, injected `__render_frame_*` siblings,
* and media color-grading canvases) via `visibility: visible !important`. CSS `visibility: visible`
* on a descendant overrides an ancestor's `visibility: hidden`, so deep
* layer elements remain visible even though intermediate parents are
* hidden by the mass-hide rule.
* 2. Inline-hide each `extraHideId` (and its render-frame/color-grading siblings) with
* `visibility: hidden !important`, while first recording its previous
* inline visibility. Inline `!important` beats stylesheet `!important`,
* so this overrides the show rule for elements that fall under a show
* selector but should NOT paint — typically other-layer elements that are
* descendants of a container layer (for example HDR videos and other-layer
* SDR videos are descendants of `#root` when we capture the root DOM layer).
* 3. Inline-hide timed descendants of shown elements that were hidden before
* the mask was installed. This covers idless child clips and same-layer
* descendants that the `extraHideIds` id list cannot represent.
*
* Only `visibility` is set on extraHideIds — never `opacity`. CSS opacity is
* multiplicative through the descendant chain and a descendant cannot escape
* an ancestor's `opacity: 0`. If `#root` is in `extraHideIds` and we set
* `opacity: 0` on it, every descendant — including `#vid-5-b` and its
* `__render_frame_vid-5-b__` IMG — becomes invisible even with
* `visibility: visible !important`. `visibility` does NOT have this problem:
* a descendant with `visibility: visible` overrides an ancestor's
* `visibility: hidden`.
*
* Layout is preserved (visibility doesn't trigger reflow), so border-radius
* clipping, overflow:hidden, and absolute positioning continue to apply to
* the visible layer elements. Opacity is also preserved — an ancestor at
* `opacity: 0` (e.g. an inactive scene during a transition) still
* propagates to its descendants, which is the desired behavior during
* cross-scene blends.
*
* Idempotent across calls: an existing mask stylesheet is removed before a
* new one is installed, so consecutive `applyDomLayerMask` invocations leave
* exactly one stylesheet attached.
*/
export async function applyDomLayerMask(
page: Page,
showIds: string[],
extraHideIds: string[],
): Promise<void> {
await page.evaluate(
// fallow-ignore-next-line complexity
(args: {
show: string[];
hide: string[];
styleId: string;
hiddenAttr: string;
prevVisibilityAttr: string;
prevPriorityAttr: string;
canvasIdPrefix: string;
}) => {
const existing = document.getElementById(args.styleId);
if (existing) existing.remove();
const restoreMaskedElements = () => {
const masked = document.querySelectorAll(`[${args.hiddenAttr}="1"]`);
for (const node of masked) {
if (!(node instanceof HTMLElement)) continue;
const prevVisibility = node.getAttribute(args.prevVisibilityAttr);
const prevPriority = node.getAttribute(args.prevPriorityAttr);
if (prevVisibility === null) {
node.style.removeProperty("visibility");
} else {
node.style.setProperty("visibility", prevVisibility, prevPriority ?? "");
}
node.removeAttribute(args.hiddenAttr);
node.removeAttribute(args.prevVisibilityAttr);
node.removeAttribute(args.prevPriorityAttr);
}
};
restoreMaskedElements();
const rememberAndHideElement = (el: HTMLElement) => {
if (el.getAttribute(args.hiddenAttr) !== "1") {
const prevVisibility = el.style.getPropertyValue("visibility");
const prevPriority =
typeof el.style.getPropertyPriority === "function"
? el.style.getPropertyPriority("visibility")
: "";
if (prevVisibility) {
el.setAttribute(args.prevVisibilityAttr, prevVisibility);
} else {
el.removeAttribute(args.prevVisibilityAttr);
}
if (prevPriority) {
el.setAttribute(args.prevPriorityAttr, prevPriority);
} else {
el.removeAttribute(args.prevPriorityAttr);
}
el.setAttribute(args.hiddenAttr, "1");
}
el.style.setProperty("visibility", "hidden", "important");
};
const hiddenTimedDescendants: HTMLElement[] = [];
const rememberHiddenTimedDescendants = (root: Element) => {
for (const node of root.querySelectorAll("[data-start]")) {
if (!(node instanceof HTMLElement)) continue;
const computed = window.getComputedStyle(node);
if (computed.visibility !== "hidden" && computed.display !== "none") continue;
hiddenTimedDescendants.push(node);
}
};
const showSelectors: string[] = [];
for (const id of args.show) {
const el = document.getElementById(id);
if (el) rememberHiddenTimedDescendants(el);
const escaped = CSS.escape(id);
showSelectors.push(`#${escaped}`, `#${escaped} *`);
const renderEscaped = CSS.escape(`__render_frame_${id}__`);
showSelectors.push(`#${renderEscaped}`, `#${renderEscaped} *`);
const colorGradingEscaped = CSS.escape(`${args.canvasIdPrefix}${id}`);
showSelectors.push(`#${colorGradingEscaped}`, `#${colorGradingEscaped} *`);
}
const massHideRule = "body *{visibility:hidden !important;}";
const showRule =
showSelectors.length === 0
? ""
: `${showSelectors.join(",")}{visibility:visible !important;}`;
const style = document.createElement("style");
style.id = args.styleId;
style.textContent = `${massHideRule}\n${showRule}`;
document.head.appendChild(style);
for (const el of hiddenTimedDescendants) {
rememberAndHideElement(el);
}
for (const id of args.hide) {
const el = document.getElementById(id);
if (el) {
rememberAndHideElement(el);
}
const img = document.getElementById(`__render_frame_${id}__`);
if (img) {
rememberAndHideElement(img);
}
const colorGradingCanvas = document.getElementById(`${args.canvasIdPrefix}${id}`);
if (colorGradingCanvas instanceof HTMLElement) {
rememberAndHideElement(colorGradingCanvas);
}
}
},
{
show: showIds,
hide: extraHideIds,
styleId: DOM_LAYER_MASK_STYLE_ID,
hiddenAttr: DOM_LAYER_MASK_HIDDEN_ATTR,
prevVisibilityAttr: DOM_LAYER_MASK_PREV_VISIBILITY_ATTR,
prevPriorityAttr: DOM_LAYER_MASK_PREV_PRIORITY_ATTR,
canvasIdPrefix: HF_COLOR_GRADING_CANVAS_ID_PREFIX,
},
);
}
/**
* Tear down the mask installed by applyDomLayerMask.
*
* Removes the mask stylesheet and restores the inline `visibility` values
* temporarily overwritten for hidden timed descendants, `extraHideIds`, and
* their render-frame/color-grading siblings.
*
* IMPORTANT: We do NOT strip inline `opacity` here. applyDomLayerMask only
* ever sets `visibility` (never `opacity`), so any inline opacity present on
* a wrapper was put there by user animation code (typically GSAP) and must
* survive across per-layer captures. GSAP's seek with suppress-events does
* not re-apply tweens when the timeline is already at the target time, so if
* we strip opacity here and then seek to the same time for the next layer,
* GSAP won't put it back and the wrapper will render fully opaque.
*/
export async function removeDomLayerMask(page: Page, _extraHideIds: string[]): Promise<void> {
await page.evaluate(
(args: {
styleId: string;
hiddenAttr: string;
prevVisibilityAttr: string;
prevPriorityAttr: string;
}) => {
const style = document.getElementById(args.styleId);
if (style) style.remove();
const masked = document.querySelectorAll(`[${args.hiddenAttr}="1"]`);
for (const node of masked) {
if (!(node instanceof HTMLElement)) continue;
const prevVisibility = node.getAttribute(args.prevVisibilityAttr);
const prevPriority = node.getAttribute(args.prevPriorityAttr);
if (prevVisibility === null) {
node.style.removeProperty("visibility");
} else {
node.style.setProperty("visibility", prevVisibility, prevPriority ?? "");
}
node.removeAttribute(args.hiddenAttr);
node.removeAttribute(args.prevVisibilityAttr);
node.removeAttribute(args.prevPriorityAttr);
}
},
{
styleId: DOM_LAYER_MASK_STYLE_ID,
hiddenAttr: DOM_LAYER_MASK_HIDDEN_ATTR,
prevVisibilityAttr: DOM_LAYER_MASK_PREV_VISIBILITY_ATTR,
prevPriorityAttr: DOM_LAYER_MASK_PREV_PRIORITY_ATTR,
},
);
}
/**
* Pre-create hidden `__render_frame__` sibling `<img>`s for every
* `video[data-start]` in the page. Idempotent — videos that already
* have a sibling are skipped.
*
* `injectVideoFramesBatch` creates the sibling on the fly the first time
* it paints a given videoId (the `isNewImage = !hasImg` branch below).
* Under chrome-headless-shell's deterministic + `HeadlessExperimental.
* BeginFrame` mode, the immediately-next BeginFrame captures before the
* freshly-inserted `<img>` layer lands in the compositor's layer tree;
* the layer arrives a frame later. That single frame paints only the
* body background + previously-composed overlays.
*
* Called from `initializeSession`: in the screenshot path at the end (that
* capture path flushes paint, so timing doesn't matter), and in the BeginFrame
* path followed by one explicit visual `HeadlessExperimental.beginFrame`
* (`noDisplayUpdates: false`) that composites the new layers before the first
* capture — the warmup ticks are `noDisplayUpdates: true` and don't paint.
* Every subsequent `injectVideoFramesBatch` then takes the `hasImg = true` path
* (just an `img.src` update). The `isNewImage` branch stays as a fallback for
* callers that don't run through `initializeSession`.
*/
export async function ensureRenderFrameSiblings(page: Page): Promise<void> {
await page.evaluate(() => {
for (const video of Array.from(
document.querySelectorAll<HTMLVideoElement>("video[data-start]"),
)) {
const next = video.nextElementSibling;
if (next !== null && next.classList.contains("__render_frame__")) continue;
const img = document.createElement("img");
img.classList.add("__render_frame__");
img.id = `__render_frame_${video.id}__`;
img.style.pointerEvents = "none";
img.style.position = "absolute";
img.style.visibility = "hidden";
video.parentNode?.insertBefore(img, video.nextSibling);
}
});
}
/**
* Returns the subset of `updates.videoId`s that were actually painted in
* this call. Videos skipped because of a hidden visual ancestor are NOT
* included — the caller relies on this to avoid recording a `lastInjected`
* cache entry for a frame that never reached the page, which would otherwise
* short-circuit the next inject at the same frameIndex and leave the host's
* first visible frame blank.
*/
export async function injectVideoFramesBatch(
page: Page,
updates: Array<{ videoId: string; dataUri: string }>,
): Promise<string[]> {
if (updates.length === 0) return [];
return await page.evaluate(
// fallow-ignore-next-line complexity
async (
items: Array<{ videoId: string; dataUri: string }>,
visualProperties: string[],
colorGradingSourceHiddenAttr: string,
) => {
const injectedIds: string[] = [];
const pendingDecodes: Array<Promise<void>> = [];
const replacementLayoutProperties = new Set([
"width",
"height",
"top",
"left",
"right",
"bottom",
"inset",
]);
// Walk ancestors looking for a host that the page has hidden. The
// runtime hides `[data-composition-src]` and `[data-start]` hosts that
// fall outside their time window; a nested `<video data-start>` inside
// such a host still appears "active" in the raw time-window check (its
// own `data-start`/`data-end` cover the whole clip), so without this
// guard we would paint a full-bleed replacement frame over a sibling
// host that *is* visible.
//
// `display: none` is always a skip signal — a `display: none` ancestor
// takes its whole subtree out of layout, and a child `<img>` cannot
// escape that. `visibility: hidden`, by contrast, is escapable: a
// descendant with `visibility: visible` overrides an ancestor's
// `visibility: hidden` per the CSS spec, and the replacement `<img>`
// intentionally sets `visibility: visible`. We therefore only treat
// `visibility: hidden` as a skip signal on sub-composition hosts
// (`[data-composition-src]` / `[data-composition-file]`), which is the
// scenario this guard exists for. Plain `[data-start]` containers may
// be hidden with `visibility: hidden` while still wanting their inner
// video's final-state frame to paint through (e.g. a GSAP timeline
// shorter than the host's authored data-duration, where the runtime
// truncates visibility but the replacement <img> must hold its last
// frame) — those must NOT be skipped here.
// fallow-ignore-next-line code-duplication
const isVisualAncestorHidden = (el: HTMLElement): boolean => {
let parent = el.parentElement;
while (parent !== null && parent !== document.documentElement) {
const computed = window.getComputedStyle(parent);
if (computed.display === "none") return true;
if (
computed.visibility === "hidden" &&
(parent.hasAttribute("data-composition-src") ||
parent.hasAttribute("data-composition-file"))
) {
return true;
}
parent = parent.parentElement;
}
return false;
};
for (const item of items) {
const video = document.getElementById(item.videoId) as HTMLVideoElement | null;
if (!video) continue;
let img = video.nextElementSibling as HTMLImageElement | null;
const hasImg = img !== null && img.classList.contains("__render_frame__");
if (isVisualAncestorHidden(video)) {
// Don't paint a frame over a hidden host — if an existing replacement
// <img> is still around from when the host was visible, hide it so it
// doesn't bleed through a sibling host that *is* visible on this seek.
//
// Use `!important` so the inline hide survives `applyDomLayerMask`'s
// stylesheet `#${showId} *{visibility:visible !important}` when the
// sub-comp host happens to land in the active layer's `show` set —
// important stylesheet beats non-important inline, but important
// inline beats important stylesheet.
if (hasImg && img) img.style.setProperty("visibility", "hidden", "important");
continue;
}
const isNewImage = !hasImg;
const computedStyle = window.getComputedStyle(video);
// Read the GSAP-controlled opacity directly from the native <video>.
// We hide the <video> below with `visibility: hidden` only (never
// `opacity: 0`), so its computed opacity is preserved across seeks
// and accurately reflects the user's intent on every frame.
const opacityParsed = parseFloat(computedStyle.opacity);
const computedOpacity = video.hasAttribute(colorGradingSourceHiddenAttr)
? 1
: Number.isNaN(opacityParsed)
? 1
: opacityParsed;
if (isNewImage) {
img = document.createElement("img");
img.classList.add("__render_frame__");
img.id = `__render_frame_${item.videoId}__`;
img.style.pointerEvents = "none";
video.parentNode?.insertBefore(img, video.nextSibling);
}
if (!img) continue;
for (const property of visualProperties) {
// Opacity is handled explicitly via `computedOpacity` below — copying
// via the generic loop would race against the opacity:0 hide applied
// to the <video> at the end of this function. GSAP may animate
// opacity either on a wrapper (the <img> inherits via the stacking
// context) or directly on the <video> (we must copy it to the <img>
// since they are siblings). Reading computedStyle.opacity before
// hiding the <video> handles both cases correctly.
if (property === "opacity") continue;
// Layout is set from the video's used box below. Copying authored
// opposing constraints such as `inset: 0` / `right: 0` onto the
// replacement <img> can overconstrain replaced-image sizing and make
// some Chrome capture paths resample the frame anisotropically.
if (replacementLayoutProperties.has(property)) {
continue;
}
const value = computedStyle.getPropertyValue(property);
if (value) {
img.style.setProperty(property, value);
}
}
// Always use absolute positioning so the <img> overlays the <video>
// instead of flowing below it. With position:relative, both elements
// stack vertically — the <img> lands below the video and gets clipped
// by any overflow:hidden ancestor (e.g., border-radius wrappers).
//
// Apply this after visual style copying so the measured used box is
// the final authority for replacement frame geometry.
{
const videoRect = video.getBoundingClientRect();
const offsetLeft = Number.isFinite(video.offsetLeft) ? video.offsetLeft : 0;
const offsetTop = Number.isFinite(video.offsetTop) ? video.offsetTop : 0;
const offsetWidth = video.offsetWidth > 0 ? video.offsetWidth : videoRect.width;
const offsetHeight = video.offsetHeight > 0 ? video.offsetHeight : videoRect.height;
img.style.position = "absolute";
img.style.inset = "auto";
img.style.left = `${offsetLeft}px`;
img.style.top = `${offsetTop}px`;
img.style.right = "auto";
img.style.bottom = "auto";
img.style.width = `${offsetWidth}px`;
img.style.height = `${offsetHeight}px`;
}
img.style.objectFit = computedStyle.objectFit;
img.style.objectPosition = computedStyle.objectPosition;
img.style.zIndex = computedStyle.zIndex;
img.decoding = "sync";
if (img.getAttribute("src") !== item.dataUri) {
img.src = item.dataUri;
pendingDecodes.push(
img
.decode()
.catch(() => undefined)
.then(() => undefined),
);
}
img.style.opacity = String(computedOpacity);
img.style.visibility = "visible";
// Hide the native <video> with visibility only — never clobber inline
// opacity, so subsequent reads (and queryElementStacking) see the real
// GSAP-controlled value.
video.style.setProperty("visibility", "hidden", "important");
video.style.setProperty("pointer-events", "none", "important");
injectedIds.push(item.videoId);
}
if (pendingDecodes.length > 0) {
await Promise.all(pendingDecodes);
}
if (injectedIds.length > 0) {
const redraw = (window as Window & { __hf?: { colorGrading?: { redraw?: () => void } } })
.__hf?.colorGrading?.redraw;
redraw?.();
}
return injectedIds;
},
updates,
[...MEDIA_VISUAL_STYLE_PROPERTIES],
COLOR_GRADING_SOURCE_HIDDEN_ATTR,
);
}
export async function syncVideoFrameVisibility(
page: Page,
activeVideoIds: string[],
): Promise<void> {
await page.evaluate(
// fallow-ignore-next-line complexity
(ids: string[], colorGradingSourceHiddenAttr: string) => {
// Mirror the ancestor-visibility guard from `injectVideoFramesBatch`.
// See that copy for the full rationale on why `visibility: hidden` is
// narrowed to sub-composition hosts only — keep these two functions in
// sync so the inactive-arm decision matches the inject-time decision.
const isVisualAncestorHidden = (el: HTMLElement): boolean => {
let parent = el.parentElement;
while (parent !== null && parent !== document.documentElement) {
const computed = window.getComputedStyle(parent);
if (computed.display === "none") return true;
if (
computed.visibility === "hidden" &&
(parent.hasAttribute("data-composition-src") ||
parent.hasAttribute("data-composition-file"))
) {
return true;
}
parent = parent.parentElement;
}
return false;
};
const active = new Set(ids);
const setColorGradingVisibility = (
window as Window & {
__hf?: {
colorGrading?: { setSourceVisibility?: (target: Element, visible: boolean) => boolean };
};
}
).__hf?.colorGrading?.setSourceVisibility;
const videos = Array.from(
document.querySelectorAll("video[data-start]"),
) as HTMLVideoElement[];
for (const video of videos) {
const img = video.nextElementSibling as HTMLElement | null;
const hasImg = img && img.classList.contains("__render_frame__");
const ancestorHidden = isVisualAncestorHidden(video);
const visible = active.has(video.id) && !ancestorHidden;
if (visible) {
// Active video: show injected <img>, hide native <video>.
// Do NOT clobber inline opacity here — GSAP-controlled opacity must
// survive until injectVideoFramesBatch reads it via getComputedStyle.
// visibility:hidden alone hides the native element without affecting
// its computed opacity.
video.style.setProperty("visibility", "hidden", "important");
video.style.setProperty("pointer-events", "none", "important");
if (hasImg) {
if (video.hasAttribute(colorGradingSourceHiddenAttr)) img.style.opacity = "1";
img.style.visibility = "visible";
}
} else {
// Inactive (or ancestor-hidden) video: hide both. Use visibility only
// (never opacity) so we never clobber GSAP-controlled inline opacity.
// Use `!important` on the <img> hide so `applyDomLayerMask`'s
// important stylesheet rule (`#${showId} *{visibility:visible !important}`)
// cannot revive a stale frame when the sub-comp host lands in the
// active layer's `show` set — same mask-defense reasoning as the
// `isVisualAncestorHidden` branch in `injectVideoFramesBatch`.
video.style.removeProperty("display");
video.style.setProperty("visibility", "hidden", "important");
video.style.setProperty("pointer-events", "none", "important");
if (hasImg) {
img.style.setProperty("visibility", "hidden", "important");
}
}
setColorGradingVisibility?.(video, visible);
}
},
activeVideoIds,
COLOR_GRADING_SOURCE_HIDDEN_ATTR,
);
}