mirror of
https://github.com/heygen-com/hyperframes.git
synced 2026-09-01 19:42:03 +00:00
Miguel Ángel
2b65b4efce
* fix(studio): preserve composition playback continuity * feat(studio): drag compositions into the timeline * fix(studio): collapse expanded composition move aliases * fix(studio): make timeline cuts atomic * fix(studio): group inspector gesture history * test(studio): cover masked text selection * fix(studio): harden composition timeline reliability * fix(studio): satisfy CI source gates * fix(studio): harden composition mutation requests
112 lines
7.0 KiB
Plaintext
112 lines
7.0 KiB
Plaintext
---
|
||
title: Data Attributes
|
||
description: "Core attributes for controlling element timing and behavior."
|
||
---
|
||
|
||
Hyperframes uses HTML data attributes to control timing, media playback, and [composition](/concepts/compositions) structure. These are the declarative building blocks of every video.
|
||
|
||
## Timing Attributes
|
||
|
||
| Attribute | Example | Description |
|
||
|-----------|---------|-------------|
|
||
| `data-start` | `"0"` or `"intro"` | Start time in seconds, or a clip ID reference for [relative timing](#relative-timing) |
|
||
| `data-duration` | `"5"` | Duration in seconds. Required for images and sub-compositions. Optional for video/audio (defaults to source duration). On the **root** composition it sets the total render length (see [Composition Attributes](#composition-attributes)). |
|
||
| `data-track-index` | `"0"` | Timeline track number. Temporal ordering — groups clips into rows on the timeline. Clips on the same track cannot overlap. Does **not** control z-ordering (use CSS `z-index` for that). |
|
||
|
||
## Media Attributes
|
||
|
||
| Attribute | Example | Description |
|
||
|-----------|---------|-------------|
|
||
| `data-media-start` | `"2"` | Media playback offset / trim point in seconds. Default: `0` |
|
||
| `data-playback-start` | `"2"` | Source-time offset in seconds for media wrappers and nested composition hosts. Missing values default to `0`; Studio writes this attribute when a composition is trimmed or split. |
|
||
| `data-playback-rate` | `"1.5"` | Source playback multiplier, clamped to `0.1`–`5`. Source time advances by timeline elapsed time multiplied by the canonical rate; invalid values default to `1`. |
|
||
| `data-volume` | `"0.8"` | Audio/video volume, 0 to 1 |
|
||
| `data-has-audio` | `"true"` | Indicates video has an audio track |
|
||
|
||
## Composition Attributes
|
||
|
||
| Attribute | Example | Description |
|
||
|-----------|---------|-------------|
|
||
| `data-composition-id` | `"root"` | Unique ID for [composition](/concepts/compositions) wrapper (required on every composition) |
|
||
| `data-width` | `"1920"` | Composition width in pixels |
|
||
| `data-height` | `"1080"` | Composition height in pixels |
|
||
| `data-duration` (root) | `"30"` | On the **root** composition, the total render length / frame count in seconds. Read once from the source HTML at compile time, like `data-width` / `data-height`, so a script or `hyperframes render --variables` cannot change it (author it directly, one value per output). If the root omits `data-duration`, and only then, the renderer derives the total length from the live DOM / timeline after scripts run. |
|
||
| `data-composition-src` | `"./intro.html"` | Path to external [composition](/concepts/compositions) HTML file |
|
||
| `data-variable-values` | `'{"title":"Hello"}'` | JSON object of values passed to a nested composition. Inside the sub-composition, read them via `window.__hyperframes.getVariables()` — the runtime layers these over the sub-comp's own `data-composition-variables` defaults and exposes the merged result on a per-instance basis (the same source can be embedded multiple times with different values). |
|
||
| `data-composition-variables` | `'[{"id":"title","type":"string","label":"Title","default":"Hello"}]'` | JSON array of declared variables (`id`, `type`, `label`, `default`). Drives Studio editing UI and provides defaults read by `window.__hyperframes.getVariables()`. The CLI flag `hyperframes render --variables '<json>'` overrides these defaults at top-level render time; host elements override them per-instance via `data-variable-values`. |
|
||
| `data-var-src` | `"heroImage"` | Binds the element's `src` to a declared variable — the runtime substitutes the value (URL string or image `{url}`) in preview and render; the authored `src` stays as the fallback. |
|
||
| `data-var-text` | `"title"` | Binds the element's own text to a scalar variable. Element children (nested clips, animated spans) are preserved. Scalar variables are also applied as `--{id}` CSS custom properties on the composition root, so `color: var(--accent)` responds to overrides. |
|
||
|
||
## Element Visibility
|
||
|
||
Add `class="clip"` to all timed elements so the runtime can manage their visibility lifecycle:
|
||
|
||
```html index.html
|
||
<h1 id="title" class="clip"
|
||
data-start="0" data-duration="5" data-track-index="0">
|
||
Hello World
|
||
</h1>
|
||
```
|
||
|
||
## Relative Timing
|
||
|
||
Instead of calculating absolute start times, a clip can reference another clip's `id` in its `data-start` attribute. This means "start when that clip ends":
|
||
|
||
```html index.html
|
||
<video id="intro" data-start="0" data-duration="10" data-track-index="0" src="..."></video>
|
||
<video id="main" data-start="intro" data-duration="20" data-track-index="0" src="..."></video>
|
||
<video id="outro" data-start="main" data-duration="5" data-track-index="0" src="..."></video>
|
||
```
|
||
|
||
`main` resolves to second 10, `outro` resolves to second 30. If `intro`'s duration changes, downstream clips shift automatically.
|
||
|
||
### Offsets (Gaps and Overlaps)
|
||
|
||
Add `+ N` or `- N` after the ID to offset from the end of the referenced clip:
|
||
|
||
```html index.html
|
||
<!-- 2-second gap after intro -->
|
||
<video id="scene-a" data-start="intro + 2" data-duration="20"
|
||
data-track-index="0" src="..."></video>
|
||
|
||
<!-- 0.5-second overlap with intro (crossfade) -->
|
||
<video id="scene-b" data-start="intro - 0.5" data-duration="20"
|
||
data-track-index="1" src="..."></video>
|
||
```
|
||
|
||
<Note>
|
||
Overlapping clips must be on different tracks -- clips on the same track cannot overlap in time.
|
||
</Note>
|
||
|
||
<Accordion title="Relative timing rules and constraints">
|
||
**Same composition only** -- references resolve within the clip's parent [composition](/concepts/compositions). You cannot reference a clip in a sibling or parent composition.
|
||
|
||
**No circular references** -- A cannot start after B if B starts after A. The resolver detects cycles and throws an error.
|
||
|
||
**Referenced clip must have a known duration** -- either an explicit `data-duration` or a duration inferred from source media. If the referenced clip has no known duration, the reference cannot resolve.
|
||
|
||
**Parsing rules** -- if the value is a valid number, it is treated as absolute seconds. Otherwise it is parsed as one of:
|
||
- `<id>` -- start when that clip ends
|
||
- `<id> + <number>` -- start N seconds after that clip ends
|
||
- `<id> - <number>` -- start N seconds before that clip ends
|
||
|
||
**Chain length** -- references can chain (`A` -> `B` -> `C`), but deeply nested chains make the timeline harder to reason about. Keep chains under 3-4 levels for readability.
|
||
</Accordion>
|
||
|
||
## Next Steps
|
||
|
||
<CardGroup cols={2}>
|
||
<Card title="Compositions" icon="layer-group" href="/concepts/compositions">
|
||
How compositions use data attributes to define video structure
|
||
</Card>
|
||
<Card title="HTML Schema Reference" icon="book" href="/reference/html-schema">
|
||
Complete attribute reference with per-element details
|
||
</Card>
|
||
<Card title="GSAP Animation" icon="wand-magic-sparkles" href="/guides/gsap-animation">
|
||
Animate elements alongside data-attribute-driven timing
|
||
</Card>
|
||
<Card title="Common Mistakes" icon="triangle-exclamation" href="/guides/common-mistakes">
|
||
Pitfalls to avoid when setting up timing and attributes
|
||
</Card>
|
||
</CardGroup>
|