@tldraw/utils/src/lib/media/avif.ts

tldraw infinite canvas SDK (private utilities).

/**
 * Determines whether an ArrayBuffer contains an animated AVIF image.
 *
 * This function performs a simple check by examining the 4th byte of the buffer.
 * AVIF animation is indicated when the byte at index 3 equals 44.
 *
 * @param buffer - The ArrayBuffer containing the AVIF image data to analyze
 * @returns True if the buffer contains an animated AVIF, false otherwise
 *
 * @example
 * ```typescript
 * // Check if an AVIF file is animated
 * const response = await fetch('image.avif')
 * const buffer = await response.arrayBuffer()
 * const isAnimated = isAvifAnimated(buffer)
 * if (isAnimated) {
 *   console.log('This AVIF contains animation!')
 * }
 * ```
 *
 * @example
 * ```typescript
 * // Use with file input
 * const fileInput = document.querySelector('input[type="file"]')
 * fileInput.addEventListener('change', async (event) => {
 *   const file = event.target.files[0]
 *   const buffer = await file.arrayBuffer()
 *   const hasAnimation = isAvifAnimated(buffer)
 *   console.log(hasAnimation ? 'Animated AVIF' : 'Static AVIF')
 * })
 * ```
 *
 * @public
 */
export const isAvifAnimated = (buffer: ArrayBuffer) => {
	const view = new Uint8Array(buffer)
	return view[3] === 44
}