crop-lqip

Applies crop (+ optional hotspot) definition to an LQIP (low-quality image placeholder). Uses canvas in the browser, jimp in node.

Targets

• Node.js >= 8
• All modern browsers (Edge, Chrome, Safari, Firefox etc)

Installation

npm install --save crop-lqip

Usage

const cropLqip = require('crop-lqip')

const lqip = 'data:image/png;base64,iVBO...'
const crop = {
  top: 0.046875,
  left: 0.18164,
  bottom: 0.132812,
  right: 0.175781
}

// Optional
const hotspot =
  height: 0.6042441207142097,
  width: 0.4084778420038537,
  x: 0.5722543352601153,
  y: 0.3194544346323949
}

cropLqip(lqip, {crop, hotspot})
  .then(croppedUrl => {
    someImageEl.src = croppedUrl
  })
  .catch(err => {
    console.error(err.message)
    someImageEl.src = lqip // Fall back to uncropped LQIP
  })

Specifying width/height

Specify aspectRatio in options. For instance, if the full-size, original image is 4240x2832 pixels, and you asked to get a cropped/hotspotted image at 700x380, the LQIP equivalent crop would be:

cropLqip(lqip, {
  crop,
  hotspot,
  aspectRatio: 700 / 380
})

Scaling

Normally, you'll want to scale the LQIP by setting the width/height in CSS in a browser. Should you really want to, you can still scale it within the library - just pass a scale property:

cropLqip(lqip, {
  crop,
  scale: 3
})

Synchronous usage

** Note: ** This is only available in Node.js. Use cropLqip.hasSync to check whether or not the feature is available.

const croppedUrl = cropLqip.sync(lqip, {crop})
someImageEl.src = croppedUrl

License

MIT © Espen Hovlandsdal