stillFrame

function stillFrame(source: HTMLCanvasElement, overlay?: FrameOverlay, drawFrame?: (ctx: CanvasRenderingContext2D, width: number, height: number) => void): HTMLCanvasElement | null

import { stillFrame } from '@driftengine/core';

Parameters

In depth

A free function rather than a static on FrameRecorder, and it was that static until 2026-08-07. The reason for the move is the same reason it was static in the first place, taken one step further: a still needs no MediaRecorder, so a browser that cannot record video must still be able to save a screenshot. As a static it could be called without a recorder but not reached without one — a bundler sees the class, and the class drags the recorder, the export target and the frame pacer in behind it. A consumer taking a screenshot was paying for the whole clip pipeline to do it. Here it costs the overlay compositor and nothing else.

Composited at the source's own size, because a still is a picture of what is on screen rather than a clip that needs a platform's shape.

Call this inside the render pass, before the page composites: a WebGL drawing buffer is not guaranteed readable afterwards, and this copies black when it is not. The same rule governs Renderer.copyRegionTo, and it has now cost a session twice — once as a black still with a watermark on it, once as an empty preview box.