react-native-executorch/lib/module/hooks/computer_vision/useOCR.js

An easy way to run AI models in React Native with ExecuTorch

"use strict";

import { useCallback, useEffect, useState } from 'react';
import { OCRController } from '../../controllers/OCRController';
/**
 * React hook for managing an OCR instance.
 * @category Hooks
 * @param OCRProps - Configuration object containing `model` sources and optional `preventLoad` flag.
 * @returns Ready to use OCR model.
 */
export const useOCR = ({
  model,
  preventLoad = false
}) => {
  const [isReady, setIsReady] = useState(false);
  const [isGenerating, setIsGenerating] = useState(false);
  const [downloadProgress, setDownloadProgress] = useState(0);
  const [error, setError] = useState(null);
  const [runOnFrame, setRunOnFrame] = useState(null);
  const [controller] = useState(() => new OCRController({
    isReadyCallback: setIsReady,
    isGeneratingCallback: setIsGenerating,
    errorCallback: setError
  }));
  useEffect(() => {
    setDownloadProgress(0);
    setError(null);
    if (preventLoad) return;
    controller.load(model.detectorSource, model.recognizerSource, model.language, setDownloadProgress).then(() => {
      const worklet = controller.runOnFrame;
      if (worklet) setRunOnFrame(() => worklet);
    });
    return () => {
      setRunOnFrame(null);
      if (controller.isReady) {
        controller.delete();
      }
    };
  }, [controller, model.modelName, model.detectorSource, model.recognizerSource, model.language, preventLoad]);
  const forward = useCallback(imageSource => controller.forward(imageSource), [controller]);
  return {
    error,
    isReady,
    isGenerating,
    forward,
    downloadProgress,
    runOnFrame
  };
};
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