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Updated worker-overwrites.js #110

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Updated worker-overwrites.js #110

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80 changes: 32 additions & 48 deletions engine/worker-overwrites.js
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Original file line number Diff line number Diff line change
Expand Up @@ -5,86 +5,70 @@ self.fetch = new Proxy(self.fetch, {
const [href, options] = args;

if (href.includes('.traineddata.gz')) {

const validate = r => {
if (r.ok) {
return r;
const validateResponse = response => {
if (response.ok) {
return response;
}
throw Error('[Extract Text From Image] Cannot download traineddata (' + r.status + ')');
throw new Error(`[Extract Text From Image] Failed to download traineddata: ${response.statusText} (${response.status})`);
};

const promise = new Promise(resolve => {
resolve();
}).then(async () => {
let cache = null;


const fetchTrainedData = async () => {
let cache;
try {
cache = await caches.open('traineddata');
} catch (e) {
console.warn('[Extract Text From Image] CacheStorage interface is not available which may affect performance. Might be the Brave browser or disabled cookies.');
} catch (error) {
console.warn('[Extract Text From Image] CacheStorage is unavailable. This may impact performance. Possible causes: Brave browser or disabled cookies.');
}

if (cache) {
const er = await cache.match(href);
if (er) {
// console.log('[Extract Text From Image] trained data cache hit');
return er;
const cachedResponse = await cache.match(href);
if (cachedResponse) {
return cachedResponse;
}
}

const r = await Reflect.apply(target, self, args).then(validate).catch(e => {
console.warn('[Extract Text From Image] Cannot download the traineddata', href, e);
const path = href.split('.com/')[1];

return Reflect.apply(target, self, [`https://github.com/naptha/tessdata/blob/gh-pages/${path}?raw=true`, options]).then(validate);
});

// save
if (cache) {
cache.put(href, r.clone());
try {
const response = await Reflect.apply(target, self, args).then(validateResponse);
if (cache) {
cache.put(href, response.clone());
}
return response;
} catch (error) {
console.warn('[Extract Text From Image] Error downloading traineddata:', href, error);
const fallbackUrl = `https://github.com/naptha/tessdata/blob/gh-pages/${href.split('.com/')[1]}?raw=true`;
return Reflect.apply(target, self, [fallbackUrl, options]).then(validateResponse);
}
};

// return
return Object.assign(r, {
return fetchTrainedData().then(response => {
return Object.assign(response, {
async arrayBuffer() {
const reader = r.body.getReader();
const reader = response.body.getReader();
const chunks = [];
let bytes = 0;

const length = Number(r.headers.get('Content-Length'));
let bytesRead = 0;
const totalLength = Number(response.headers.get('Content-Length'));

// eslint-disable-next-line no-constant-condition
while (true) {
const { done, value } = await reader.read();
if (done) {
break;
}
if (done) break;

bytes += value.byteLength;
bytesRead += value.byteLength;
postMessage({
status: 'progress',
data: {
status: 'loading language traineddata',
progress: bytes / length
progress: bytesRead / totalLength
}
});

chunks.push(value);
}
const ab = await new Blob(chunks).arrayBuffer();
return ab;
return new Blob(chunks).arrayBuffer();
}
});

});

return promise;
}
else {
} else {
return Reflect.apply(target, self, args);
}
}
});

self.importScripts('tesseract/worker.min.js');