https://github.com/hughsk/png-chunk-text

:scroll: Create or parse a PNG tEXt chunk for storing uncompressed text data in PNG images.
https://github.com/hughsk/png-chunk-text

Last synced: 12 days ago
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:scroll: Create or parse a PNG tEXt chunk for storing uncompressed text data in PNG images.

• Host: GitHub
• URL: https://github.com/hughsk/png-chunk-text
• Owner: hughsk
• License: mit
• Created: 2015-10-04T14:16:27.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2015-10-04T14:16:52.000Z (about 9 years ago)
• Last Synced: 2024-10-17T16:39:15.952Z (22 days ago)
• Language: JavaScript
• Homepage:
• Size: 146 KB
• Stars: 33
• Watchers: 4
• Forks: 3
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

        
# png-chunk-text

[![stable](http://badges.github.io/stability-badges/dist/stable.svg)](http://github.com/badges/stability-badges)

Create or parse a PNG tEXt chunk for storing uncompressed text data in PNG images.

Can be used in combination with [png-chunks-extract](https://github.com/hughsk/png-chunks-extract) and [png-chunks-encode](https://github.com/hughsk/png-chunks-encode) for adding and reading custom metadata in PNG images.

Works in Node, or in the browser using [browserify](http://browserify.org/).

## Usage

[![NPM](https://nodei.co/npm/png-chunk-text.png)](https://www.npmjs.com/package/png-chunk-text)

### `chunk = text.encode(key, value)`

Returns a chunk object containing the metadata for a given `key` and `value`:

``` javascript

{

  name: 'tEXt',

  data: Uint8Array([...])

}

```

``` javascript

const extract = require('png-chunks-extract')

const encode = require('png-chunks-encode')

const text = require('png-chunk-text')

const path = require('path')

const fs = require('fs')

const buffer = fs.readFileSync(path.join(__dirname, 'test.png'))

const chunks = extract(buffer)

// Add new chunks before the IEND chunk

chunks.splice(-1, 0, text.encode('hello', 'world'))

chunks.splice(-1, 0, text.encode('lorem', 'ipsum'))

fs.writeFileSync(

  path.join(__dirname, 'test-out.png'),

  new Buffer(encode(chunks))

)

```

### `data = text.decode(chunk)`

Reads a `Uint8Array` or Node.js `Buffer` instance containing a `tEXt` PNG chunk's data and returns its keyword/text:

``` javascript

{

  keyword: 'hello',

  text: 'world'

}

```

``` javascript

const extract = require('png-chunks-extract')

const text = require('png-chunk-text')

const path = require('path')

const fs = require('fs')

const buffer = fs.readFileSync(path.join(__dirname, 'test-out.png'))

const chunks = extract(buffer)

const textChunks = chunks.filter(function (chunk) {

  return chunk.name === 'tEXt'

}).map(function (chunk) {

  return text.decode(chunk.data)

})

console.log(textChunks[0].keyword) // 'hello'

console.log(textChunks[0].text)    // 'world'

console.log(textChunks[1].keyword) // 'lorem'

console.log(textChunks[1].text)    // 'ipsum'

```

## See Also

* [png-chunks-extract](https://github.com/hughsk/png-chunks-extract)

* [png-chunks-encode](https://github.com/hughsk/png-chunks-encode)

## License

MIT, see [LICENSE.md](http://github.com/hughsk/png-chunk-text/blob/master/LICENSE.md) for details.