fast-image-zoom

v7.0.1

Published

2 years ago

🏞 Fast image zoom on click as seen on popular publishing platform

Downloads

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mvoloskov

plugin medium image-zoom

🏞 Fast Image Zoom

Image zoom on click as seen on the popular publishing platform.

What does it do?

You click on an image and it smoothly zooms in or out to fit the screen. You click again — it smoothly goes back to normal. You scroll — it also goes back.

Why is it better than alternatives?

🛠 Framework-agnostic — works with everything from Knockout.js to Web Components
👌 Zero-dependency
🧬 Perfect for dynamic content, mutation-agnostic — you can do whatever you want with images, it'll work
⚡️ Blazing fast — no matter if it's 10 images or 10000, it uses only two event listeners. Not per image, just two listeners. Complexity is always O(1)
🤓 Powered by quirky math to precisely calculate everything and do the trick with only one transformation
🦋 Looks good on both dark and light modes
🍦 Zero-configuration by default but extensible when you need it
🗿 Works flawlessly even on iOS Safari, in every orientation, with every image no matter the size and dimensions

Basic usage

npm install fast-image-zoom --save

yarn add fast-image-zoom

import imageZoom from 'fast-image-zoom'
imageZoom()

Alternative — use CDN

<script src="https://unpkg.com/[email protected]/dist/fast-image-zoom.js"></script>
<script>
  imageZoom()
</script>

That's it!

How it works

Plugin targets meaningful, content images:

<!-- yes -->
<img src="foo.jpg" alt="Cute kitten" />

<!-- no -->
<img src="bar.jpg" />
<img src="bar.jpg" alt="" />

Configuration

Here are the defaults:

imageZoom({
    selector: `img[alt]:not([alt=""]):not([data-image-zoom-disabled])`,
    containerSelector: null,
    cb: () => {},
    exceed: false,
    padding: 20,
})

selector (string) is used to target images. By default it only targets meaningful images (e.g. ones with alt), so your icons won't be magnified on click.
containerSelector limits plugin's scope to a certain element. It's useful for modals. Only the images inside that element will be clickable, and the scroll handler that un-zooms images will work on that element only.
cb (function) is called after the plugin is initialized.
exceed (boolean) defines whether images should exceed their natural size when zoomed. For example, if you zoom 100x100 image on a 1080p screen with exceed: false, its final size will be 100px, meanwhile, with exceed: true it will be 1080px.
padding (integer) defines a gap in pixels between a zoomed image and the closest edge of the viewport.

Note that if exceed is false and smaller images appear to have a larger gap between their edges and the edge of the viewport, padding won't be added. For example, if you zoom a 100x100 image on a 1080p screen and your padding is set to 20, a natural gap between an image and the viewport edge would be (1080 - 100) / 2 = 490, thus there is no need to add that 20px gap.

Only pixels are supported by now.

Setting `exceed` per image

You can explicitly define exceed for a specific picture via a data attribute:

<img src="..." alt="..." data-image-zoom-exceed="true">

Disabling the plugin for the specific image

You can disable zooming for any image you like, even if it has alt:

<img src="..." alt="..." data-image-zoom-disabled>

Note that if you redefine the selector in a way that doesn't account data-image-zoom-disabled attribute, this feature will stop working.

Restyling

You can always hack the plugin redefining straightforward CSS:

Changing a timing function

.image-zoom,
.image-zoom-wrapper::after {
    transition-timing-function: ease-in-out;
}

Changing the background color

.image-zoom-wrapper::after {
    background-color: hotpink;
}

For now, !important might be needed, as styles are injected into <head>. This will probably be changed in the future.

Anatomy

.image-zoom-wrapper — element that wraps every image. Mimicks its display property. We use it to add page background and slightly separate the zoomed image from what is behind.
.image-zoom-wrapper-zoomed — the same wrapper but when the image is zoomed.
.image-zoom — the image itself that was processed and is interactive, ready to zoom.
.image-zoom-zoomed — zoomed image.

Disabling the plugin

Being called, the plugin returns the destroy function that you may call to remove event listeners. It will also remove related styles from <head> and from the images themselves.

const destroy = imageZoom()

// don't need it anymore
destroy()

Limitations

img inline styles will be destroyed. Use CSS selectors to stylize images.
img shouldn't have transforms. If needed, wrap it with a container and apply transforms there instead.
Container's overflow-x will be hidden. If containerSelector is null, then overflow-x will be hidden for the root element.

Enjoy!

Note

The old URL (https://cdn.jsdelivr.net/gh/mvoloskov/fast-image-zoom/dist/fast-image-zoom.min.js) is deprecated. Please use the new, versioned one: https://unpkg.com/[email protected]/dist/fast-image-zoom.js.

To migrate, just replace this

<script src="https://cdn.jsdelivr.net/gh/mvoloskov/fast-image-zoom/dist/fast-image-zoom.min.js"></script>

...with this:

<script src="https://unpkg.com/[email protected]/dist/fast-image-zoom.js"></script>

The old URL was a historic mistake. I sincerely apologize for the inconvenience.