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Text -> PNG -> ReadStream, all done on the front-end?

I'm not sure if this is even possible, but here's what I'm trying to do:

  1. Let the user enter some text
  2. Generate a PNG from that text
  3. Upload it to Pinata, which requires it to be in ReadStream format
  4. Do all of this on the front-end

I've managed to accomplish (1) and (2) using html2canvas.

The tricky part is (3). The reason it has to be in ReadStream format is because that's the format Pinata's SDK wants:

const fs = require('fs');
const readableStreamForFile = fs.createReadStream('./yourfile.png');
const options = {
    pinataMetadata: {
        name: MyCustomName,
        keyvalues: {
            customKey: 'customValue',
            customKey2: 'customValue2'
        }
    },
    pinataOptions: {
        cidVersion: 0
    }
};
pinata.pinFileToIPFS(readableStreamForFile, options).then((result) => {
    //handle results here
    console.log(result);
}).catch((err) => {
    //handle error here
    console.log(err);
});

I realize that this would be no problem to do on the backend with node, but I'd like to do it on the front-end. Is that at all possible? Or am I crazy?

I'm specifically using Vue if that matters.

about 4 years ago · Juan Pablo Isaza
1 answers
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0

For anyone interested the solution ended up being using fetch+blob:

    const generateImg = async () => {
      const canvas = await html2canvas(document.getElementById('hello'));
      const img = canvas.toDataURL('image/png');
      const res = await fetch(img);
      return res.blob();
    };

This blob can then be passed into a more manual version of their SDK:

const uploadImg = (blob: Blob) => {
    const url = `https://api.pinata.cloud/pinning/pinFileToIPFS`;

    const data = new FormData();
    data.append('file', blob);

    const metadata = JSON.stringify({
      name: 'testname',
    });
    data.append('pinataMetadata', metadata);

    const pinataOptions = JSON.stringify({
      cidVersion: 0,
    });
    data.append('pinataOptions', pinataOptions);

    return axios
      .post(url, data, {
        maxBodyLength: 'Infinity' as any, // this is needed to prevent axios from erroring out with large files
        headers: {
          // @ts-ignore
          'Content-Type': `multipart/form-data; boundary=${data._boundary}`,
          pinata_api_key: apiKey,
          pinata_secret_api_key: apiSecret,
        },
      })
      .then((response) => {
        console.log(response);
      })
      .catch((error) => {
        console.log(error);
      });
  };
about 4 years ago · Juan Pablo Isaza Report
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