index.js

import { NativeModules, Platform } from 'react-native';

const { RNReactNativeImageData } = NativeModules;

const ReactNativeImageData = {

    getSimpleGrayscalePixels : (imagePath, {scaledWidth, scaledHeight}) => {
        
        if (Platform.OS == "ios") {
            return RNReactNativeImageData.getSimpleGrayscalePixels(imagePath, {scaledWidth, scaledHeight});
        } else {
            return RNReactNativeImageData.getSimpleGrayscalePixels(imagePath, scaledWidth, scaledHeight);
        }
    },

    getSimpleGrayscalePixelsAsXYMatrix : (imagePath, {scaledWidth, scaledHeight}) => {
        
        return new Promise((resolve, reject) => {

            ReactNativeImageData.getSimpleGrayscalePixels(imagePath, {scaledWidth, scaledHeight})
                    .then((imagePixelsArray) => {

                        let imageXYMatrix = [];
    
                        for (let i = 0; i < scaledWidth; i++) {
                            imageXYMatrix[i] = [];
                        }
                
                        let index = 0;
                
                        for (let i = 0; i < scaledWidth; i++) {
                            for (let j = 0; j < scaledHeight; j++) {
                                imageXYMatrix[j][i] = imagePixelsArray[index++];
                            }
                        }
                
                        resolve(imageXYMatrix);
                    })
                    .catch(() => {reject()});
        })

    }
}

export default ReactNativeImageData;