`blur`

Blurs away, or wipes the new theme in out of focus.

The full recording — the example app on an Android emulator and an iOS simulator at once, with blur played several times over. Scrub or pause with the controls.

Two quite different animations behind one kind, chosen with blurStyle. uniform blurs the whole screen at once and lets it recede. sweep is a wipe that brings the new theme in out of focus and pulls it sharp as it arrives — the outgoing copy is never blurred at all, it is simply taken away by the mask.

Options it takes

Option	Type	Default	What it does here
`blurStyle`	`'uniform' \| 'sweep'`	`'uniform'`	How the blur applies itself. `'uniform'` the whole screen blurs and recedes at once (default) `'sweep'` a wipe brings the NEW theme in out of focus and pulls it sharp
`direction`	`'top' \| 'bottom' \| 'left' \| 'right'`	`'bottom'`	The edge the sweep travels through. Only read when `blurStyle` is `sweep`; ignored under `uniform`. `'top'` sweeps upward — horizontal edge `'bottom'` sweeps downward — horizontal edge (default) `'left'` sweeps left — vertical edge `'right'` sweeps right — vertical edge
`angleDeg`	`number`	`0`	Tilt of the sweep’s boundary line, exactly as `slide` takes it. Only read when `blurStyle` is `sweep`.
`durationMs`	`number`	`650`	Animation length. Clamped up to this kind’s floor; `0` means no animation and is never clamped.
`settleFrames`	`number`	`2`	Display frames to hold the snapshot before revealing, so the theme swap has painted underneath.

Ignored by this kind: origin, shape, bands. Passing them is harmless.

Minimum duration

A request below 300ms is clamped up to it, natively, so both platforms agree. Below that floor a full-screen copy coming apart has too few frames to read as motion — the eye gets the start and the end and nothing in between, which looks like a flicker rather than a fast transition. durationMs: 0 still means “no animation” and is never clamped.

Usage

withThemeTransition(applyTheme, {
  kind: 'blur',
  durationMs: 650,
  blurStyle: 'sweep',
  direction: 'bottom',
  angleDeg: 0,
});

How it is done

iOS	`UIVisualEffectView` + property animator
Android	`RenderEffect.createBlurEffect`