A functional library for watermarking images in the browser. Written with ES6, and made available to current browsers via Babel. Supports urls, file inputs, blobs, and on-page images.
Note: For anyone that is interested: I ported this to a ClojureScript library called Dandy Roll.
Any browser supporting File and FileReader should work. The following browsers have been tested and work:
Please feel free to update this list or submit a fix for a particular browser via a pull request.
watermark.js is available via npm and bower:
# install via npm
$ npm install watermarkjs
# install via bower
$ bower install watermarkjs
// watermark by local path
watermark(['img/photo.jpg', 'img/logo.png'])
.image(watermark.image.lowerRight(0.5))
.then(img => document.getElementById('container').appendChild(img));
// load a url and file object
const upload = document.querySelector('input[type=file]').files[0];
watermark([upload, 'img/logo.png'])
.image(watermark.image.lowerLeft(0.5))
.then(img => document.getElementById('container').appendChild(img));
// watermark from remote source
const options = {
init(img) {
img.crossOrigin = 'anonymous'
}
};
watermark(['http://host.com/photo.jpg', 'http://host.com/logo.png'], options)
.image(watermark.image.lowerRight(0.5))
.then(img => document.getElementById('container').appendChild(img));
Before building or testing, install all the deps:
npm i
There is an npm script you can run to build:
npm run build
Or to kick off the file watcher and build as you make changes, run the start task:
$ npm start
There is an npm script for that too!:
$ npm test
This library uses the Jest testing framework. Due to some current issues with Jest, Node 0.10.x is required to run the tests.
You can view examples and documentation by running the sync
task via npm:
$ npm run sync
The examples demonstrate using watermark images and text, as well as a demonstration of uploading a watermarked image to Amazon S3. It is the same content hosted at http://brianium.github.io/watermarkjs/.
Running npm run dev
will start a browser and start watching source files for changes.
Clearly watermarking on the client has some limitations when watermarking urls and on-page elements. The curious can find urls for non-watermarked images, but it is likely that most average users won't go down this path - keeping this soft barrier useful. However!...
watermark.js has the ability to accept file inputs as a source for watermarking. This makes it easy to preview, watermark, and upload without the non-watermarked image ever becoming public. Check out the uploading demo to see this in action.
This tool certainly shines in admin or CMS environments where you want to generate watermarks and upload them asynchronously where it would not be possible or preferable on the server. One less thing the server has to do can be a good thing :)
Please open issues or pull requests if you have bugs/improvements.