CHANGE

1. optimize the image with srcset loading, avoid being stucked.
2. add source support. <picture><source /><img /></picture>. it works like srcset

it's recommended to be used in Gatsby. (like what i am doing)

if you meet some condition worked unnormal, please submit issues.

use with Gatsby

1. install this package

yarn add @voderl/medium-zoom

2. install gatsby-plugin-images

;[
  {
    resolve: `gatsby-remark-images`,
    options: {
      linkImagesToOriginal: false, // important
    },
  },
]

3. Copy the following code into gatsby-browser.js

import mediumZoom from '@voderl/medium-zoom'

const options = {
  margin: 24,
  background: '#fff',
  scrollOffset: 40,
  container: undefined,
  template: undefined,
  zIndex: 999,
  excludedSelector: undefined,
  respectSrcsetImageSize: true,
}

export const onClientEntry = () => {
  const { zIndex } = options

  const styles = `
    .medium-zoom-overlay, .medium-zoom-image--opened {
      z-index: ${zIndex};
    }
  `

  const node = document.createElement(`style`)
  node.id = `medium-zoom-styles`
  node.innerHTML = styles
  document.head.appendChild(node)
}

export const onRouteUpdate = () => {
  mediumZoom('.gatsby-resp-image-image', options)
}

• Features
• Installation
• Usage
• API
  • Selectors
  • Options
  • Methods
  • Attributes
  • Events
• Examples
• Debugging
• Browser support
• Contributing
• License

Features

• 📱 Responsive — scale on mobile and desktop
• 🚀 Performant and lightweight — should be able to reach 60 fps
• ⚡️ High definition support — load the HD version of your image on zoom
• 🔎 Flexibility — apply the zoom to a selection of images
• 🖱 Mouse, keyboard and gesture friendly — click anywhere, press a key or scroll away to close the zoom
• 🎂 Event handling — trigger events when the zoom enters a new state
• 📦 Customization — set your own margin, background and scroll offset
• 🔧 Pluggable — add your own features to the zoom
• 💎 Custom templates — extend the default look to match the UI of your app

Installation

The module is available on the npm registry.

npm install medium-zoom
# or
yarn add medium-zoom

Download

• Normal
• Minified

CDN

• jsDelivr
• unpkg

Usage

Try it out in the browser

Import the library as a module:

import mediumZoom from 'medium-zoom'

Or import the library with a script tag:

<script src="node_modules/medium-zoom/dist/medium-zoom.min.js"></script>

That's it! You don't need to import any CSS styles.

Assuming you add the data-zoomable attribute to your images:

mediumZoom('[data-zoomable]')

API

mediumZoom(selector?: string | HTMLElement | HTMLElement[] | NodeList, options?: object): Zoom

Selectors

The selector allows attaching images to the zoom. It can be of the following types:

• CSS selectors
• HTMLElement
• NodeList
• Array

// CSS selector
mediumZoom('[data-zoomable]')

// HTMLElement
mediumZoom(document.querySelector('#cover'))

// NodeList
mediumZoom(document.querySelectorAll('[data-zoomable]'))

// Array
const images = [
  document.querySelector('#cover'),
  ...document.querySelectorAll('[data-zoomable]'),
]

mediumZoom(images)

Options

The options enable the customization of the zoom. They are defined as an object with the following properties:

| Property | Type | Default | Description | | -------------- | ------------------------------------- | -------- | --------------------------------------------------------------------------- | | margin | number | 0 | The space outside the zoomed image | | background | string | "#fff" | The background of the overlay | | scrollOffset | number | 40 | The number of pixels to scroll to close the zoom | | container | string | HTMLElement | object | null | The viewport to render the zoom in Read more → | | template | string | HTMLTemplateElement | null | The template element to display on zoom Read more → |

mediumZoom('[data-zoomable]', {
  margin: 24,
  background: '#BADA55',
  scrollOffset: 0,
  container: '#zoom-container',
  template: '#zoom-template',
})

Methods

open({ target?: HTMLElement }): Promise<Zoom>

Opens the zoom and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.open()

Emits an event open on animation start and opened when completed.

close(): Promise<Zoom>

Closes the zoom and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.close()

Emits an event close on animation start and closed when completed.

toggle({ target?: HTMLElement }): Promise<Zoom>

Opens the zoom when closed / dismisses the zoom when opened, and returns a promise resolving with the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.toggle()

attach(...selectors: string[] | HTMLElement[] | NodeList[] | Array[]): Zoom

Attaches the images to the zoom and returns the zoom.

const zoom = mediumZoom()

zoom.attach('#image-1', '#image-2')
zoom.attach(
  document.querySelector('#image-3'),
  document.querySelectorAll('[data-zoomable]')
)

detach(...selectors: string[] | HTMLElement[] | NodeList[] | Array[]): Zoom

Releases the images from the zoom and returns the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.detach('#image-1', document.querySelector('#image-2')) // detach two images
zoom.detach() // detach all images

Emits an event detach on the image.

update(options: object): Zoom

Updates the options and returns the zoom.

const zoom = mediumZoom('[data-zoomable]')

zoom.update({ background: '#BADA55' })

Emits an event update on each image of the zoom.

clone(options?: object): Zoom

Clones the zoom with provided options merged with the current ones and returns the zoom.

const zoom = mediumZoom('[data-zoomable]', { background: '#BADA55' })

const clonedZoom = zoom.clone({ margin: 48 })

clonedZoom.getOptions() // => { background: '#BADA55', margin: 48, ... }

on(type: string, listener: () => void, options?: boolean | AddEventListenerOptions): Zoom

Registers the listener on each target of the zoom.

The same options as addEventListener are used.

const zoom = mediumZoom('[data-zoomable]')

zoom.on('closed', event => {
  // the image has been closed
})

zoom.on(
  'open',
  event => {
    // the image has been opened (tracked only once)
  },
  { once: true }
)

The zoom object is accessible in event.detail.zoom.

off(type: string, listener: () => void, options?: boolean | AddEventListenerOptions): Zoom

Removes the previously registered listener on each target of the zoom.

The same options as removeEventListener are used.

const zoom = mediumZoom('[data-zoomable]')

function listener(event) {
  // ...
}

zoom.on('open', listener)
// ...
zoom.off('open', listener)

The zoom object is accessible in event.detail.zoom.

getOptions(): object

Returns the zoom options as an object.

const zoom = mediumZoom({ background: '#BADA55' })

zoom.getOptions() // => { background: '#BADA55', ... }

getImages(): HTMLElement[]

Returns the images attached to the zoom as an array of HTMLElements.

const zoom = mediumZoom('[data-zoomable]')

zoom.getImages() // => [HTMLElement, HTMLElement]

getZoomedImage(): HTMLElement

Returns the current zoomed image as an HTMLElement or null if none.

const zoom = mediumZoom('[data-zoomable]')

zoom.getZoomedImage() // => null
zoom.open().then(() => {
  zoom.getZoomedImage() // => HTMLElement
})

Attributes

data-zoom-src

Specifies the high definition image to open on zoom. This image loads when the user clicks on the source image.

<img src="image-thumbnail.jpg" data-zoom-src="image-hd.jpg" alt="My image" />

Events

| Event | Description | | ------ | --------------------------------------------------- | | open | Fired immediately when the open method is called | | opened | Fired when the zoom has finished being animated | | close | Fired immediately when the close method is called | | closed | Fired when the zoom out has finished being animated | | detach | Fired when the detach method is called | | update | Fired when the update method is called |

const zoom = mediumZoom('[data-zoomable]')

zoom.on('open', event => {
  // track when the image is zoomed
})

The zoom object is accessible in event.detail.zoom.

Examples

const button = document.querySelector('[data-action="zoom"]')
const zoom = mediumZoom('#image')

button.addEventListener('click', () => zoom.open())

You can use the open event to keep track of how many times a user interacts with your image. This can be useful if you want to gather some analytics on user engagement.

let counter = 0
const zoom = mediumZoom('#image-tracked')

zoom.on('open', event => {
  console.log(`"${event.target.alt}" has been zoomed ${++counter} times`)
})

const zoom = mediumZoom('[data-zoomable]')

zoom.on('closed', () => zoom.detach(), { once: true })

jQuery elements are compatible with medium-zoom once converted to an array.

mediumZoom($('[data-zoomable]').toArray())

Using React hooks

import React from 'react'
import mediumZoom from 'medium-zoom'

function ImageZoom({ zoom, src, alt, background }) {
  const zoomRef = React.useRef(zoom.clone({ background }))

  function attachZoom(image) {
    zoomRef.current.attach(image)
  }

  return <img src={src} alt={alt} ref={attachZoom} />
}

function App() {
  const zoom = React.useRef(mediumZoom({ background: '#000', margin: 48 }))

  render() {
    return (
      <ImageZoom src="image.jpg" alt="Image" zoom={zoom.current} color="#BADA55" />
    )
  }
}

Using React classes

import React, { Component } from 'react'
import mediumZoom from 'medium-zoom'

class ImageZoom extends Component {
  zoom = this.props.zoom.clone({
    background: this.props.color,
  })

  attachZoom = image => {
    this.zoom.attach(image)
  }

  render() {
    return (
      <img src={this.props.src} alt={this.props.alt} ref={this.attachZoom} />
    )
  }
}

class App extends Component {
  zoom = mediumZoom({ background: '#000', margin: 48 })

  render() {
    return (
      <ImageZoom src="image.jpg" alt="Image" zoom={this.zoom} color="#BADA55" />
    )
  }
}

You can see more examples including React and Vue, or check out the storybook.

Debugging

The library doesn't provide a z-index value on the zoomed image to avoid conflicts with other frameworks. Some frameworks might specify a z-index for their elements, which makes the zoomed image not visible.

If that's the case, you can provide a z-index value in your CSS:

.medium-zoom-overlay,
.medium-zoom-image--opened {
  z-index: 999;
}

Browser support

| IE | Edge | Chrome | Firefox | Safari | | --------------- | --------------- | ------ | ------- | ------ | | 10* | 12* | 36 | 34 | 9 |

* These browsers require a template polyfill when using custom templates.

Contributing

• Run yarn to install Node dev dependencies
• Run yarn start to build the library in watch mode
• Run yarn run storybook to see your changes at http://localhost:9001

Please read the contributing guidelines for more detailed explanations.

You can also use npm.

License

MIT © François Chalifour