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Area Selection

Simple and easy area selection library for image/video cropping.

Installation

$ npm install area-selection-js --save # or yarn add area-selection-js

Usage

  1. In your HTML document:
<img src="path/to/image.jpg" id="selection" />
  1. Create the instance in your JavaScript file:
import AreaSelection from 'area-selection-js';
import 'area-selection-js/dist/area-selection.css';

const selection = new AreaSelection('#selection', {
 // options
});

Proptip: you can also pass an HTMLElement instead of a selector

  1. To retrieve the selected value
const value = selection.getValue();
// {x: 20, y:20, width: 120, height: 120}

Options

aspectRatio

Constrain the selection region to an aspect ratio.

  • Type: Number
  • Default: null
  • Example: aspectRatio: 1 (Square)

maxSize

Constrain the selection region to a maximum size.

  • Type: [width, height, unit?]
  • Default: null
  • Example: maxSize: [50, 50, '%'] (A maximum size of 50% of the image size)

Note: unit accepts a value of 'px' or '%'. Defaults to 'px'.

minSize

Constrain the selection region to a minimum size.

  • Type: [width, height, unit?]
  • Default: null
  • Example: minSize: [20, 20, 'px'] (A minimum width and height of 20px)

Note: unit accepts a value of 'px' or '%'. Defaults to 'px'.

startSize

The starting size of the selection region when it is initialized.

  • Type: [width, height, unit?]
  • Default: [100, 100, '%'] (A starting selection region as large as possible)
  • Example: startSize: [50, 50] (A starting selection region of 50% of the image size)

Note: unit accepts a value of 'px' or '%'. Defaults to '%'.

onSelectStart

A callback function that is called when the user starts selecting.

  • Type: Function
  • Arguments: data = {x, y, width, height}
  • Example:
onSelectStart: function(data) {
  console.log(data.x, data.y, data.width, data.height);
}

onSelectMove

A callback function that is called when the selected region changes.

  • Type: Function
  • Arguments: data = {x, y, width, height}
  • Example:
onSelectMove: function(data) {
  console.log(data.x, data.y, data.width, data.height);
}

onSelectEnd

A callback function that is called when the user stops selecting.

  • Type: Function
  • Arguments: data = {x, y, width, height}
  • Example:
onSelectEnd: function(data) {
  console.log(data.x, data.y, data.width, data.height);
}

onInitialize

A callback function that is called when the AreaSelection instance is fully initialized.

  • Type: Function
  • Arguments: The AreaSelection instance
  • Example:
onInitialize: function(instance) {
  // do things here
}

returnMode

Define how the selected region should be calculated.

  • Type: String
  • Default: "real"
  • Possible values: "real", "ratio" or "raw"
    • real returns the selected region values based on the size of the image's actual sizes. This ensures that the selected region values are the same regardless if the AreaSelection element is scaled or not.
    • ratio returns the selected region values as a ratio between 0 to 1. e.g. For example, an x, y position at the center will be {x: 0.5, y: 0.5}.
    • raw returns the selected region values as is based on the size of the AreaSelection element.

Methods

getValue(returnMode?: string)

Returns the value of the selected region. returnMode inherits from options by default. Refer to returnMode for possible values.

var value = instance.getValue();
// value = {x: 21, y: 63: width: 120, height: 120}

var ratio = instance.getValue('ratio');
// value = {x: 0.1, y: 0.3: width: 0.57, height: 0.57}

destroy()

Destroys the AreaSelection instance and restores the original img element or video element.

moveTo(x: number, y: number)

Moves the selected region to the specified coordinates. Returns the AreaSelection instance.

resizeTo(width: number, height: number, origin?: Array)

Resizes the selected region to the specified size. origin is an optional argument that specifies the origin point (in ratio) to resize from in the format of [x, y]. Defaults to [0.5, 0.5] (center). Returns the AreaSelection instance.

scaleBy(factor: number, origin?: Array)

Scales the selected region by a factor. origin is an optional argument that specifies the origin point (in ratio) to resize from in the format of [x, y]. Defaults to [0.5, 0.5] (center). Returns the AreaSelection instance.

reset()

Resets the selected region to its original position and size. Returns the AreaSelection instance.

Credits

  • Babel Starter Kit - A project template for authoring and publishing JavaScript libraries using ES2015+ via Babel.
  • Croppr.js — A vanilla JavaScript image cropper that's lightweight, awesome, and has absolutely zero dependencies.
  • Cropperjs — JavaScript image cropper.