/**
 * @file
 *
 * Pure helpers for screenshot capture: building the CDP device-metrics override
 * payload, decoding a base64-encoded PNG, and reading a PNG's pixel dimensions
 * out of its IHDR header.
 *
 * Kept separate from the transports (which are integration-only and excluded
 * from unit tests) so the payload shape and the PNG parsing stay unit-testable —
 * the transports themselves only talk to CDP / Appium.
 */
import type { Except } from 'type-fest';
/**
 * Parameters for capturing a screenshot of a running Obsidian instance.
 */
export interface CaptureScreenshotParams {
    /**
     * The working directory (vault path) identifying which Obsidian window to
     * capture.
     *
     * Mirrors the `cwd` of an evaluation: a desktop instance can hold several
     * vault windows, and the capture has to be routed to the right one.
     */
    readonly cwd: string;
    /**
     * The exact height in pixels the captured image should have.
     *
     * Desktop only, and only meaningful together with {@link widthInPixels}: the
     * viewport is pinned to these metrics for the duration of the capture, so the
     * resulting PNG is exactly this size whatever size the window happens to be.
     * Omit both to capture the window at its natural size.
     *
     * Ignored by the Appium transport, which can only return the device's native
     * framebuffer — size a mobile capture by choosing an AVD with the wanted
     * screen geometry instead.
     */
    readonly heightInPixels?: number;
    /**
     * The exact width in pixels the captured image should have.
     *
     * See {@link heightInPixels} — the two are set together or not at all.
     */
    readonly widthInPixels?: number;
}
/**
 * The pixel dimensions read out of a PNG's IHDR header.
 */
export interface PngDimensions {
    /**
     * The image height in pixels.
     */
    readonly heightInPixels: number;
    /**
     * The image width in pixels.
     */
    readonly widthInPixels: number;
}
/**
 * Builds the `Emulation.setDeviceMetricsOverride` payload that pins a desktop
 * capture to an exact pixel size.
 *
 * Takes only the size half of {@link CaptureScreenshotParams} — routing the
 * capture to a window is the transport's job, not the payload's.
 *
 * @param params - The requested capture size.
 * @returns The CDP payload, or `undefined` when no size was requested (capture the window as it is).
 * @throws Error if exactly one of the two dimensions is given — a half-specified size cannot be honoured.
 */
export declare function buildDeviceMetricsOverride(params: Except<CaptureScreenshotParams, 'cwd'>): Record<string, unknown> | undefined;
/**
 * Decodes the base64 payload both CDP (`Page.captureScreenshot`) and Appium
 * (`takeScreenshot`) return into raw PNG bytes.
 *
 * @param base64 - The base64-encoded image data.
 * @returns The decoded bytes.
 */
export declare function decodeBase64Png(base64: string): Uint8Array;
/**
 * Decides whether the given bytes are a PNG carrying an IHDR chunk.
 *
 * Used to fail a capture loudly when a transport hands back something that is
 * not an image, rather than writing a corrupt file to disk.
 *
 * @param bytes - The bytes to check.
 * @returns `true` when the bytes are a PNG.
 */
export declare function isPng(bytes: Uint8Array): boolean;
/**
 * Reads a PNG's pixel dimensions from its IHDR header.
 *
 * The whole point is verification: a capture that silently comes back at the
 * wrong size is the failure mode that produces an off-spec screenshot set, so
 * the size is read back from the bytes rather than assumed from the request.
 *
 * @param bytes - The PNG bytes.
 * @returns The image's width and height in pixels.
 * @throws Error if the bytes are not a PNG, or are too short to carry an IHDR header.
 */
export declare function readPngDimensions(bytes: Uint8Array): PngDimensions;