[Share] OCR math to latex from image annotations

[windingwind]

Description

OCR the math to latex from image annotations. Inherited from implementation of Better Notes plugin

Support bing, mathpix(need setup), simpletex(need setup), and xunfei(need setup).

For services that need setup, please modify the corresponding lines in the script.

Event

None

Operation

Script

Data

/**
 * OCR math to latex from image annotations
 * @author windingwind
 * @usage in annotation menu
 * @link https://github.com/windingwind/zotero-actions-tags/discussions/220
 * @see https://github.com/windingwind/zotero-actions-tags/discussions/220
 */
/** { 👍 "mathpix" | 👍 "simpletex" | "xunfei" | "bing" } service provider */
const SERVICE = "simpletex";

// https://mathpix.com/
const MATHPIX = {
  APP_ID: "NOT SET",
  APP_KEY: "NOT SET",
};

// https://www.xfyun.cn/service/formula-discern
const XUNFEI = {
  APP_ID: "NOT SET",
  API_KEY: "NOT SET",
  API_SECRET: "NOT SET",
};

// https://simpletex.cn/
const SIMPLETEX = {
  APP_ID: "NOT SET",
  APP_SECRET: "NOT SET",
};

if (!item) {
  return;
}

const FormData = Zotero.getMainWindow().FormData;

return await OCRImageAnnotation(item);

async function OCRImageAnnotation(annotationItem) {
  if (
    !annotationItem.isAnnotation() ||
    annotationItem.annotationType !== "image"
  ) {
    return "Not an image annotation item";
  }
  const src = await Zotero.File.generateDataURI(
    Zotero.Annotations.getCacheImagePath(annotationItem),
    "image/png"
  );
  let result;
  let success;
  switch (SERVICE) {
    case "mathpix":
      ({ result, success } = await mathpix(src));
      break;
    case "xunfei":
      ({ result, success } = await xunfei(src));
      break;
    case "bing":
      ({ result, success } = await bing(src));
      break;
    case "simpletex":
      ({ result, success } = await simpletex(src));
      break;
    default:
      result = "OCR Engine Not Found";
      success = false;
  }

  if (success) {
    annotationItem.annotationComment = `${
      annotationItem.annotationComment
        ? `${annotationItem.annotationComment}\n`
        : ""
    }${result}`;

    return `OCR Result: ${result}`;
  } else {
    return `OCR Error: ${result}`;
  }
}

async function mathpix(src) {
  const xhr = await Zotero.HTTP.request(
    "POST",
    "https://api.mathpix.com/v3/text",
    {
      headers: {
        "Content-Type": "application/json; charset=utf-8",
        app_id: MATHPIX.APP_ID,
        app_key: MATHPIX.APP_KEY,
      },
      body: JSON.stringify({
        src,
        math_inline_delimiters: ["$", "$"],
        math_display_delimiters: ["$$", "$$"],
        rm_spaces: true,
      }),
      responseType: "json",
    }
  );
  if (xhr && xhr.status && xhr.status === 200 && xhr.response.text) {
    return {
      success: true,
      result: xhr.response.text,
    };
  } else {
    return {
      result: xhr.status === 200 ? xhr.response.error : `${xhr.status} Error`,
      success: false,
    };
  }
}

async function xunfei(src) {
  /**
   * 1.Doc：https://www.xfyun.cn/doc/words/formula-discern/API.html
   * 2.Error code：https://www.xfyun.cn/document/error-code
   * @author iflytek
   */

  const config = {
    hostUrl: "https://rest-api.xfyun.cn/v2/itr",
    host: "rest-api.xfyun.cn",
    appid: XUNFEI.APP_ID,
    apiSecret: XUNFEI.API_SECRET,
    apiKey: XUNFEI.API_KEY,
    uri: "/v2/itr",
  };

  const date = new Date().toUTCString();
  const postBody = {
    common: {
      app_id: config.appid,
    },
    business: {
      ent: "teach-photo-print",
      aue: "raw",
    },
    data: {
      image: src.split(",").pop(),
    },
  };
  const digest = "SHA-256=" + arrayBufferToBase64(await sha256(postBody));

  const signatureOrigin = `host: ${config.host}\ndate: ${date}\nPOST ${config.uri} HTTP/1.1\ndigest: ${digest}`;
  const signature = arrayBufferToBase64(
    await hmacSha256Digest(signatureOrigin, config.apiSecret)
  );
  const authorizationOrigin = `api_key="${config.apiKey}", algorithm="hmac-sha256", headers="host date request-line digest", signature="${signature}"`;

  const xhr = await Zotero.HTTP.request("POST", config.hostUrl, {
    headers: {
      "Content-Type": "application/json",
      Accept: "application/json,version=1.0",
      Host: config.host,
      Date: date,
      Digest: digest,
      Authorization: authorizationOrigin,
    },
    body: JSON.stringify(postBody),
    responseType: "json",
  });

  if (xhr?.response?.code === 0) {
    result = success = true;
    return {
      success: true,
      result: xhr.response.data.region
        .filter((r) => r.type === "text")
        .map((r) => r.recog.content)
        .join(" ")
        .replace(/ifly-latex-(begin)?(end)?/g, "$"),
    };
  } else {
    return {
      result:
        xhr.status === 200
          ? `${xhr.response.code} ${xhr.response.message}`
          : `${xhr.status} Error`,
      success: false,
    };
  }
}

async function bing(src) {
  const xhr = await Zotero.HTTP.request(
    "POST",
    "https://www.bing.com/cameraexp/api/v1/getlatex",
    {
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({
        data: src.split(",").pop(),
        inputForm: "Image",
        clientInfo: { platform: "edge" },
      }),
      responseType: "json",
    }
  );
  if (xhr && xhr.status && xhr.status === 200 && !xhr.response.isError) {
    return {
      success: true,
      result: xhr.response.latex || xhr.response.ocrText,
    };
  } else {
    return {
      result:
        xhr.status === 200 ? xhr.response.errorMessage : `${xhr.status} Error`,
      success: false,
    };
  }
}

async function simpletex(src) {
  const image = base64ToArrayBuffer(src.split(",").pop());
  // send image to server
  const formData = new FormData();
  // generate random string length = 16, including 0-9, a-z, A-Z
  const randomString = generateRandomString(16);
  //  timestamp in seconds
  const timestamp = Math.floor(Date.now() / 1000);
  let signature = `app-id=${SIMPLETEX.APP_ID}&random-str=${randomString}&timestamp=${timestamp}&secret=${SIMPLETEX.APP_SECRET}`;
  // md5
  signature = Zotero.Utilities.Internal.md5(signature);
  const headers = {
    timestamp: timestamp,
    "random-str": randomString,
    "app-id": SIMPLETEX.APP_ID,
    sign: signature,
  };
  const configs = {
    headers: headers,
  };

  formData.append("file", new Blob([image]), "annotation.png");

  const response = await fetch("https://server.simpletex.cn/api/latex_ocr", {
    method: "POST",
    body: formData,
    ...configs,
  });

  const result = await response.json();

  if (result.status) {
    return {
      result: `$${result.res.latex}$`,
      success: true,
    };
  }
  return {
    result: "OCR failed",
    success: false,
  };
}

function base64ToArrayBuffer(base64) {
  const binaryString = atob(base64);
  const bytes = new Uint8Array(binaryString.length);
  for (let i = 0; i < binaryString.length; i++) {
    bytes[i] = binaryString.charCodeAt(i);
  }
  return bytes.buffer;
}

function generateRandomString(length) {
  const characters =
    "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
  let result = "";
  for (let i = 0; i < length; i++) {
    result += characters.charAt(Math.floor(Math.random() * characters.length));
  }
  return result;
}

function arrayBufferToBase64(buffer) {
  const bytes = new Uint8Array(buffer);
  let binary = "";
  for (let i = 0; i < bytes.length; i++) {
    binary += String.fromCharCode(bytes[i]);
  }
  return btoa(binary);
}

async function sha256(str) {
  const enc = new TextEncoder();
  const hashBuffer = await crypto.subtle.digest("SHA-256", enc.encode(str));
  return hashBuffer;
}

async function hmacSha256Digest(stringToSign, secretKey) {
  const enc = new TextEncoder();
  const key = await crypto.subtle.importKey(
    "raw",
    enc.encode(secretKey),
    {
      name: "HMAC",
      hash: "SHA-256",
    },
    false,
    ["sign"]
  );
  return crypto.subtle.sign("HMAC", key, enc.encode(stringToSign));
}

Anything else

[QianC95]

请问讯飞的设置是把脚本中的XUNFEI对应的ID、SECRET和KEY替换成自己的就可以了吗？我替换之后每次操作都显示ORC failed，我要怎么才能知道为什么不成功呢？我在讯飞网页端试了一下是可以识别的，那么或许不是讯飞的问题？

[windingwind]

const SERVICE = 也需要改

[QianC95]

感谢！搞定！

[mjthoraval]

I do not understand how to use this.
I have tried to use Bing, but I get the following error:

I understand that the other options need some kind of setup:

For services that need setup, please modify the corresponding lines in the script.

But I do not understand how I should generate the APP_ID, API_KEY, API_SECRET or APP_SECRET.
Can these be generated for free, or are they related to paying accounts?
Can someone help me on this?

[windingwind]

The bing code uses the Bing math API and is inherited from the old Better Notes plugin and I haven't tested it for a long time, it works at least when I create this post; so if it does not work, then it does not.

mathpix could be a choice. To use EN in simpletext:

[windingwind]

Can these be generated for free, or are they related to paying accounts?

I think there's free quota, but after that you need to pay (same as mathpix)

[mjthoraval]

Thank you. I have managed to get it working.
I have created an account on the SimpleTeX website.
Then following the instructions here: https://simpletex.cn/api_doc
I went to https://simpletex.cn/user/center
Then created a New App from:

I just chose "OCR" as the name of the app. It does not seem to change anything.
Then I got the needed information from there.

It is working nicely now.

[Purewhiter]

It works nice on my macOS, but when I use it under windows, there is no reaction when I click on the 'OCR math'. Maybe there is any way to solve this?

[wakewon]

I suspect this is an issue caused by the Zotero update. It doesn't respond on my macOS.

[rpj-07]

how can i insert the script in the better notes add on at zotero, as a template and which parts in the Code do i have to change for simpletext ocr?

[rpj-07]

Thank you!
I updated to Zotero 7, with Zotero 6 that not work.
That better bibtex or zotfile does not work on zotero 7, I have now also realized :-(., but I like Zotero 7 now so much so I still use Zotero 7.

[wakewon]

Better Bibtex have a Zotero 7 compatible version. There is another plugin named Attanger have almost all functions of Zotfile. You can find them here (in Chinese):
https://zotero-chinese.com/plugins

[rpj-07]

That's right, it works with BBT. Thank you very much for your help!

[rpj-07]

One last think:
Do you know how I can set up the script that the OCR begin automatically when I Highlight the math objects?

[wakewon]

This is not possible with current scripts. Perhaps you can consider customizing a script of your own to trigger when you create a new annotation (Event: Create Annotation). Since Zotero cannot tell if you are marking a picture of a math formula, you may also need to use a specific annotation color specifically for marking formulas, and try to see if you can use the annotation color in your script to determine whether or not to do OCR recognition.