image-focus
v1.2.1
Published
A dependency free utility for cropping images based on a focal point ~2.13kB gzipped
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image-focus 📷
A dependency free utility for cropping images based on a focus point ~2.13kB gzipped
Demo
Check out the demo and then play with editing it
Docs
Usage
Focus
Coordinates range between -1
and 1
for both x
and y
axes. The FocusPicker
class will help enable users to select the focus point to be used with an image.
FocusedImage
There are two ways to supply the coordinates when initializing the FocusedImage
class
Data Tags
<div class="focused-image-container">
<img class="focused-image" src="https://picsum.photos/2400/1400" data-focus-x="0.34" data-focus-y="-0.21">
</div>
import { FocusedImage } from "image-focus"
const img = document.querySelector('.focused-image') as HTMLImageElement
const focusedImage = new FocusedImage(img)
Using focus
Option
<div class="focused-image-container">
<img class="focused-image" src="https://picsum.photos/2400/1400">
</div>
import { FocusedImage } from "image-focus"
const img = document.querySelector('.focused-image') as HTMLImageElement
const focusedImage = new FocusedImage(img, {
focus: {
x: 0.34,
y: -0.21
}
})
FocusPicker
Provide an onChange
callback that will receive a Focus
object that has x
and y
properties for the newly selected coordinates. Optionally supply a focus
to initialize with, or a retina
src to use instead of the default white ring SVG.
import {FocusedImage, FocusPicker} from "image-focus"
const imgEl = document.getElementById("focused-image") as HTMLImageElement
const focusedImage = new FocusedImage(imgEl)
const focusPickerEl = document.getElementById("focus-picker-img") as HTMLImageElement
const focusPicker = new FocusPicker(focusPickerEl, {
onChange: focus => focusedImage.setFocus(focus),
focus: startingFocus,
})
What's going on?
The <img/>
element is being set to position: absolute;
and having its top
and left
properties adjusted based on some calculations using the image and parent containers' aspect ratios and dimensions. The <img/>
's parent container gets set to position: relative;
and overflow: hidden;
to create the effect. There are a few other inline styles that get applied, so if anything appears to be behaving unexpectedly, be sure to check that the inline styles on both the <img/>
and its parent aren't being overridden by CSS on your page (especially from rules using !important
).
Additionally, because the FocusedImage
is positioned absolutely so it can shift as needed, its container needs to manage its own height and width. If you aren't seeing an image appear at all, it is likely that the parent div's height
is fully collapsed.
What if I'm not using npm and a build process?
That's okay! unpkg has you covered. Just add this script tag to your page and the image-focus
module is exposed in the global namespace under window.imageFocus
.
<script src="https://unpkg.com/[email protected]"></script>
Then in some script that loads after the above script tag:
var imgEl = document.querySelector('img.focused-image');
var focusedImage = new imageFocus.FocusedImage(imgEl, {x: 0.25, y: -0.3});
Attributions
This project was largely inspired by and adapted from jquery-focuspoint by jonom and used typescript-library-starter to scaffold the build process.