third774/ image-focus

(v1.2.0) 6 months ago

TypeScript

HTML

JavaScript

cropper

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About the developer

third774

150 Stars

8 Forks

MIT License

186 Commits

19 Opened issues

Description

A dependency free utility for cropping images based on a focus point ~2.13kB gzipped

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Kevin Kipp third774

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Readme

image-focus 📷

Name: image-focus
Brand: image-focus
SKU: //third774/image-focus
Rating: 2.125 (150 reviews)

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

Docs generated by

typedoc

Usage

Focus

Coordinates range between

-1

and

for both

and

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

import { FocusedImage } from "image-focus"

const img = document.querySelector('.focused-image') as HTMLImageElement
const focusedImage = new FocusedImage(img)

Using

focus

Option

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

and

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

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

'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

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

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.