Shimmer

The sweep is clipped to the glyphs, so the letters catch the light rather than a box over them.

A highlight that sweeps through text and content, for loading, thinking and streaming states.

The content is used as a mask and a gradient band is swept behind it on the UI thread, so the highlight is clipped to the glyph shapes — the letters catch the light rather than sitting under a passing overlay.

For a placeholder where there is no content yet, use Skeleton.

Installation

Shimmer ships with the library — no separate install.

import { Shimmer, Skeleton } from 'panelui-native';

Or copy the source into your project, to own and edit it:

npx panelui-cli@latest add shimmer

Usage

<Shimmer>Thinking…</Shimmer>

<Shimmer duration={1400} textClassName="text-lg font-medium">
  Generating response…
</Shimmer>

// Mask arbitrary content instead of a string.
<Shimmer as="view" className="w-full gap-2">
  <Skeleton className="h-4 w-3/4" />
  <Skeleton className="h-4 w-full" />
</Shimmer>

Examples

A thinking indicator

The default. The sweep is clipped to the glyphs, so the letters catch the light instead of sitting under a passing band.

<Shimmer>Thinking…</Shimmer>

<Shimmer duration={1400} textClassName="text-lg font-medium">
  Generating response…
</Shimmer>

Masking a subtree

as="view" masks the sweep to whatever you pass instead of to a string.

<Shimmer as="view" className="w-full gap-2">
  <Skeleton className="h-4 w-3/4" />
  <Skeleton className="h-4 w-full" />
  <Skeleton className="h-4 w-1/2" />
</Shimmer>

Tuning the sweep

{/* Reverses on each pass instead of restarting from the left. */}
<Shimmer mode="ping-pong" duration={1600}>Ping-pong</Shimmer>

{/* Right to left. */}
<Shimmer reverse>Reversed</Shimmer>

{/* A wider, slower band. */}
<Shimmer spread={4} duration={2600}>Slow and broad</Shimmer>

{/* One pass, then stop. */}
<Shimmer once>Sweeps once</Shimmer>

Custom colours

Both default to theme tokens, so you only need these on a surface the tokens do not suit.

<Shimmer baseColor="#3f3f46" shimmerColor="#fafafa">
  Neutral on dark
</Shimmer>

Turning it off

Renders the content statically in baseColor. Useful for stopping the sweep the moment a stream finishes, without swapping components.

<Shimmer enabled={isStreaming}>{status}</Shimmer>

API Reference

Prop	Type	Default	Description
`className`	`string`	—
`as`	`'text' \| 'view'`	`'text'`	`text` renders `children` as a single styled string and masks the sweep to the glyphs. `view` masks the sweep to whatever subtree you pass.
`duration`	`number`	`2000`	Milliseconds for one sweep.
`spread`	`number`	`2`	Width of the highlight band, as a multiple of the content width.
`baseColor`	`string`	—	Colour of the content at rest. Defaults to the theme's muted foreground.
`shimmerColor`	`string`	—	Colour at the centre of the sweep. Defaults to the theme's foreground.
`mode`	`'loop' \| 'ping-pong'`	`'loop'`	`loop` restarts from the left; `ping-pong` reverses on each pass.
`once`	`boolean`	`false`	Sweep once instead of repeating.
`reverse`	`boolean`	`false`	Sweep right-to-left.
`enabled`	`boolean`	`true`	Set false to render the content statically without animating.
`textClassName`	`string`	—	Extra classes for the text when `as="text"`.
`textStyle`	`StyleProp<TextStyle>`	—	Extra styles for the text when `as="text"`.
`color`	`string`	—	Deprecated. Use `shimmerColor`.
`intensity`	`number`	—	Peak opacity of the highlight. Deprecated. Set `shimmerColor` to a colour with the alpha you want.

Every part also accepts the underlying React Native props (ViewProps or TextProps) and a className for Tailwind utilities.

Notes

The sweep runs entirely on the UI thread and never re-renders React while animating.

It stops when the OS reduce-motion setting is on, and when enabled is false — in both cases the content renders statically in baseColor.

baseColor and shimmerColor default to the theme's muted-foreground and foreground tokens, so the effect reads correctly on any surface without configuration. color and intensity still work but are deprecated in favour of the two colour props.

Public exports

Values: Shimmer

Types: ShimmerProps

Shimmer

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