import type { BoxItem, Orientation, Rectangle, TextItem, TextUnit } from './ocr-engine';
export declare type OcrWorkerInit = {
    workerUrl?: string;
    wasmUrl?: string;
    wasmFallbackUrl?: string;
};
export interface IOcrWorker {
    loadModel(model: string | ArrayBuffer): Promise<void>;
    loadImage(image: ImageBitmap | ImageData, rectangle?: Rectangle | undefined): Promise<void>;
    clearImage(): Promise<void>;
    getBoundingBoxes(unit: TextUnit): Promise<BoxItem[]>;
    getTextBoxes(unit: TextUnit): Promise<TextItem[]>;
    getText(): Promise<string>;
    getVariable(name: string): Promise<string>;
    setVariable(name: string, value: string): Promise<void>;
    getOrientation(): Promise<Orientation>;
}
/**
 * High-level async API for performing document image layout analysis and
 * OCR.
 */
export declare class OcrWorker implements IOcrWorker {
    private _id;
    private _worker;
    private _ocrEngine;
    /**
     * Initialize an OCR engine.
     *
     * This will start a Worker in which the OCR operations will actually be
     * performed.
     *
     */
    constructor({ workerUrl, wasmUrl, wasmFallbackUrl, }?: OcrWorkerInit);
    get id(): string;
    destroy(): Promise<void>;
    /**
     * Load a trained model for a specific language. This can be specified either
     * as a URL to fetch or a buffer containing an already-loaded model.
     */
    loadModel(model: string | ArrayBuffer): Promise<void>;
    /**
     * Load an image into the OCR engine for processing.
     */
    loadImage(image: ImageBitmap | ImageData, rectangle?: Rectangle): Promise<void>;
    /**
     * Clear the current image and text recognition results.
     *
     * This will clear the loaded image data internally, but keep the text
     * recognition model loaded.
     *
     * At present there is no way to shrink WebAssembly memory, so this will not
     * return the memory used by the image to the OS/browser. To release memory,
     * the web worker needs to be shut down via {@link destroy}.
     */
    clearImage(): Promise<void>;
    /**
     * Perform layout analysis on the current image, if not already done, and
     * return bounding boxes for a given unit of text.
     *
     * This operation is relatively cheap compared to text recognition, so can
     * provide much faster results if only the location of lines/words etc. on
     * the page is required, not the text content.
     */
    getBoundingBoxes(unit: TextUnit): Promise<BoxItem[]>;
    /**
     * Perform layout analysis and text recognition on the current image, if
     * not already done, and return bounding boxes and text content for a given
     * unit of text.
     */
    getTextBoxes(unit: TextUnit): Promise<TextItem[]>;
    /**
     * Perform layout analysis and text recognition on the current image, if
     * not already done, and return the image's text as a string.
     */
    getText(): Promise<string>;
    /**
     * Get the value, represented as a string, of a Tesseract configuration variable.
     *
     * See {@link setVariable} for available variables.
     */
    getVariable(name: string): Promise<string>;
    /**
     * Set the value of a Tesseract configuration variable.
     *
     * For a list of configuration variables, see
     * https://github.com/tesseract-ocr/tesseract/blob/677f5822f247ccb12b4e026265e88b959059fb59/src/ccmain/tesseractclass.cpp#L53
     *
     * If you have Tesseract installed locally, executing `tesseract --print-parameters`
     * will also display a list of configuration variables.
     */
    setVariable(name: string, value: string): Promise<void>;
    /**
     * Attempt to determine the orientation of the image.
     *
     * This currently uses a simplistic algorithm [1] which is designed for
     * non-uppercase Latin text. It will likely perform badly for other scripts or
     * if the text is all uppercase.
     *
     * [1] See http://www.leptonica.org/papers/skew-measurement.pdf
     */
    getOrientation(): Promise<Orientation>;
}