@handtracking.io/yoha/dist/core/engine/base.js

Yoha is currently available for the web via JavaScript. More languages will be added in the future. If you want to port Yoha to another language and need help feel free reach out.

import { MirrorCoordinatesHorizontally, ApplyPaddingToCoordinates, ConvertLandmarkCoordinatesToGlobalCoordinates, MakeCoordinateOrderUserFriendly, AssembleTrackResultFromCoordinatesAndClasses, } from '../post_model/post_model';
import { ComputePreprocInfoFromBoxCoords, ComputePreprocInfoFromLanCoords, } from '../pre_model/preproc_comp';
import { RequestAnimationFrame } from '../../util/animation_frame';
import { ApplyConfigDefaults } from '../../util/config_helper';
/**
 * The default configuration that is used to fill in any gaps in the user supplied
 * configuration.
 */
export const DEFAULT_CONFIG = {
    mirrorX: true,
    padding: 0.00,
    minHandPresenceProbabilityThreshold: 0.5,
    __userFriendlyCoordinateOrder: true,
    __boxSlack: 0.75,
};
const BOX_PREPROC_INFO = {
    topLeft: [0.0, 0.0],
    bottomRight: [1.0, 1.0],
    flip: false,
    rotationCenter: [0.5, 0.5],
    rotationInRadians: 0.0,
};
/**
 * @public
 *
 * @param config - Engine configuration.
 * @param trackSource - The element to be analyzed.
 * @param preprocCb - Calllback that transforms track source (rotation/crop/resize).
 * @param boxCb - Callback that runs bounding box model.
 * @param lanCb - Callback that runs landmark model.
 * @param resCb - Callback that is called with hand tracking results. The
 * callback may be called with high frequency.
 *
 * @returns Promise that resolves with a callback that can be used to stop the
 * analysis.
 */
export async function StartEngine(config, trackSource, preprocCb, boxCb, lanCb, resCb) {
    config = ApplyConfigDefaults(DEFAULT_CONFIG, config);
    const aspectRatio = [trackSource.width, trackSource.height];
    let stopped = false;
    let preprocInfo = null;
    while (!stopped) {
        if (!preprocInfo) {
            await RequestAnimationFrame();
            const boxModelInput = await preprocCb(trackSource, BOX_PREPROC_INFO);
            const boxRes = await boxCb(boxModelInput);
            preprocInfo = ComputePreprocInfoFromBoxCoords(boxRes.coordinates, aspectRatio, config.__boxSlack);
        }
        await RequestAnimationFrame();
        const lanModelInput = await preprocCb(trackSource, preprocInfo);
        const lanRes = await lanCb(lanModelInput);
        const classes = lanRes.classes;
        let coords = ConvertLandmarkCoordinatesToGlobalCoordinates(preprocInfo, aspectRatio, lanRes.coordinates);
        preprocInfo =
            ComputePreprocInfoFromLanCoords(coords, aspectRatio, config.__boxSlack);
        coords = ApplyPostProcessingToCoordinates(config, coords);
        const result = AssembleTrackResultFromCoordinatesAndClasses(coords, classes);
        resCb(result);
        if (result.isHandPresentProb < config.minHandPresenceProbabilityThreshold) {
            // Make the box model look for hand again.
            preprocInfo = null;
        }
    }
    return () => { stopped = true; };
}
/**
 * Applies any post processing to the result coordinates.
 * @param config - Engine configuration.
 * @param coords - The coordinates to transform.
 */
export function ApplyPostProcessingToCoordinates(config, coords) {
    if (config.padding) {
        coords = ApplyPaddingToCoordinates(config.padding, coords);
    }
    if (config.mirrorX) {
        coords = MirrorCoordinatesHorizontally(coords);
    }
    if (config.__userFriendlyCoordinateOrder) {
        coords = MakeCoordinateOrderUserFriendly(coords);
    }
    return coords;
}
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