@expofp/floorplan/dist/esm/utils/blob-image-size.d.ts

Interactive floor plan library for expos and events

/**
 * Measures an image's intrinsic size without keeping its pixels.
 *
 * Floorplan needs one number from a logo's pixels: the aspect ratio, to fit the logo inside a
 * booth. `createImageBitmap` gives that number at low cost. The browser decodes the image on its
 * own thread. Then it resolves a promise. The main thread pays only for the call and for the
 * promise resolution, not for the decode itself. This is the difference between
 * `createImageBitmap` and an `<img>` element, which decodes on the same thread as the page.
 *
 * The function closes the bitmap right after it reads the size. A caller can start as many calls
 * as it wants. At any instant, only a few bitmaps exist in memory: the ones the browser's decoder
 * already finished but did not yet hand back. The whole batch of logos never sits in memory
 * together. One cost remains, and this cost is accepted: each logo gets decoded twice, once here
 * and once in the atlas worker. This happens because a Blob cannot report its own size, and the
 * renderer does not report one back either.
 *
 * This function has no `<img>` fallback. `createImageBitmap` works on every build target that
 * this SDK supports. The only targets that lack `createImageBitmap` are targets where the whole
 * SDK already fails to run.
 * @param blob - The image bytes.
 * @returns The size, or `null` if the bytes cannot be decoded.
 */
export declare function blobImageSize(blob: Blob): Promise<{
    width: number;
    height: number;
} | null>;
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