iiif-image-info-parser

This is a simple javascript utility the fetches and parses a iiif image API info.json file and extracts the relevant information for accessing the image.

It will calculate image tiles based on the server supplied information and can provide the optimal tiles for any given display resolution.

How to use It

Either build the library from this repository or simple use NPM npm i @iii-viewer/iiif-image-info-parser. The library can be used either in a browser or with node:

import IiifImageInfoParser from 'iiif-image-info-parser'

fetch('https://cool/iiif/resource')
.then(res => res.text())
.then(info => {
    const parser = new IiifImageInfoParser(info)
    const tileInfo = parser.calculateFullImageTiles(2000, 2000)
    /* Do something with the tiles here */
})
.catch(e => alert(e))

How it works

The IiifImageInfoParser class is instantiated with a URL for the image resource being accessed. Then you must call the async init() function, which downloads the iiif info.json and performs the initial parsing. Alternatively, you can pass an info.json file directly to the constructor, and avoid the need to call init().

The calculateImageTiles (allows image cropping) and calculateFullImageTiles functions receive a desired width and height of the image, in pixels, as parameters. They both return an array of tile objects with all the information necessary to reconstruct the image, either locally as a file, or in the browser within a canvas or SVG element, or any other desired application. The tile object provides the x and y coordinates for the starting point of the tile along with the tile width and height, finally it provides a preformatted URL to the image (or portion therof) that should be placed at those coordinates.

Get involved

I am happy to receive PRs and any improvements to the library, especially building it out to optimize for support all the variations of iiif servers that exist in the wild.

If you have a PR, please to ensure that tests have been written for any new functionality and that all current tests still pass.