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93 lines
2.6 KiB
93 lines
2.6 KiB
6 years ago
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const axios = require('axios');
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const resolveURL = require('resolve-url');
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/**
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* readFromBlobOrFile
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*
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* @name readFromBlobOrFile
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* @function
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* @access private
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* @param {object} blob A blob or file objec to read
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* @param {function} res callback function after reading completes
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*/
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const readFromBlobOrFile = blob => (
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new Promise((resolve, reject) => {
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const fileReader = new FileReader();
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fileReader.onload = () => {
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resolve(fileReader.result);
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};
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fileReader.onerror = ({ target: { error: { code } } }) => {
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reject(Error(`File could not be read! Code=${code}`));
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};
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fileReader.readAsArrayBuffer(blob);
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})
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);
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/**
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* loadImage
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*
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* @name loadImage
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* @function load image from different source
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* @access private
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* @param {string, object} image - image source, supported formats:
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* string: URL string, can be relative path
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* string: base64 image
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* img HTMLElement: extract image source from src attribute
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* video HTMLElement: extract image source from poster attribute
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* canvas HTMLElement: extract image data by converting to Blob
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* File instance: data from <input type="file" />
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* @returns {array} binary image in array format
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*/
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const loadImage = async (image) => {
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let data = image;
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if (typeof image === 'undefined') {
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return 'undefined';
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}
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if (typeof image === 'string') {
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// Base64 Image
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if (/data:image\/([a-zA-Z]*);base64,([^"]*)/.test(image)) {
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data = atob(image.split(',')[1])
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.split('')
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.map(c => c.charCodeAt(0));
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} else {
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const { data: _data } = await axios.get(resolveURL(image), { responseType: 'arraybuffer' });
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data = _data;
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}
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} else if (image instanceof HTMLElement) {
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if (image.tagName === 'IMG') {
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data = loadImage(image.src);
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}
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if (image.tagName === 'VIDEO') {
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data = loadImage(image.poster);
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}
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if (image.tagName === 'CANVAS') {
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await new Promise((resolve) => {
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image.toBlob(async (blob) => {
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data = await readFromBlobOrFile(blob);
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resolve();
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});
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});
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}
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} else if (image instanceof File || image instanceof Blob) {
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data = await readFromBlobOrFile(image);
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}
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return new Uint8Array(data);
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};
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/**
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* sendPacket
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*
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* @name sendPacket
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* @function send packet to worker and create a job
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* @access public
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* @param {object} instance TesseractWorker instance
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* @param {object} iPacket data for worker
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*/
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module.exports = async (worker, _packet) => {
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const packet = { ..._packet };
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packet.payload.image = await loadImage(packet.payload.image);
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worker.postMessage(packet);
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};
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