fkrauthan / react-prismazoom

A pan and zoom component for React, using CSS transformations.

react-prismazoom

About

A pan and zoom component for React, using CSS transformations.

Depends only upon prop-types, react and react-dom modules.
Works on both desktop and mobile.

Online demo here!

Zoom features 🔎

• Zoom with the mouse-wheel or a two-finger pinch
• Zoom using double-click or double-tap
• Zoom on selected area and center

Pan features 👆

• Pan with the mouse pointer or with one finger when zoomed-in
• Intuitive panning depending on available space when zoomed-in
• Adjusts cursor style to indicate in which direction the element can be moved

Contribution

If you want to contribute, feel free to send a merge request or open a discussion. Currently, I just have time to maintain the package, but not enough to make big changes or add important features.

All contribution would be quite appreciated! 😉

Among changes I would like to apply:

• Migrate to TypeScript
• Transform to a functional component (that could help splitting the code)
• Make motion logic less dependant to React

Breaking changes on v2

• The package now requires React v16.3 or higher (in order to use react references)
• The zoom feature through gestures or mousewheel got some improvements to react better with all devices. You may need to adjust the scrollVelocity property passed to the component in order to keep the same effect.

Installation

Install the component

$ npm i -D react-prismazoom

Install the example project

This project includes a full-featured application example.

First clone the project.

Then, install it:

$ npm i

Run the Webpack Dev Server:

$ npm run start

Go to http://localhost:1664.

Note: sources of this example can be found in example/src.

Run unit tests

You can either run all tests at once:

$ npm test

Or run tests each time a change on source files occured:

$ npm run test:watch

Usage

Implementation

import PrismaZoom from 'react-prismazoom'

<PrismaZoom>
  <img src="my-image.png" />
  <p>A text that can be zoomed and dragged</p>
</PrismaZoom>

Props

Name	Type	Default	Description
className	string	None	Class name to apply on the zoom wrapper.
style	object	None	Style to apply on the zoom wrapper. Note that transform, transition, cursor, touch-action and will-change cannot be overridden. Example: style={{backgroundColor: 'red'}}.
minZoom	number	1	Minimum zoom ratio.
maxZoom	number	5	Maximum zoom ratio.
scrollVelocity	number	0.1	Zoom increment or decrement on each scroll wheel detection.
onZoomChange	function	null	Function called each time the zoom value changes.
onPanChange	function	null	Function called each time the posX or posY value changes (aka images was panned).
animDuration	number	0.25	Animation duration (in seconds).
doubleTouchMaxDelay	number	300	Max delay between two taps to consider a double tap (in milliseconds).
decelerationDuration	number	750	Decelerating movement duration after a mouse up or a touch end event (in milliseconds).
locked	boolean	false	Disable all user's interactions.
allowTouchEvents	boolean	false	Enables touch event propagation.

Note: all props are optional.

Public methods

These functions can be called from parent components.

zoomIn (value)
Increments the zoom with the given value.
Param {value: Number} : Zoom value

zoomOut (value)
Decrements the zoom with the given value.
Param {value: Number} : Zoom value

zoomToZone (relX, relY, relWidth, relHeight)
Zoom-in on the specified zone with the given relative coordinates and dimensions.
Param {relX: Number} : Relative X position of the zone left-top corner in pixels
Param {relY: Number} : Relative Y position of the zone left-top corner in pixels
Param {relWidth: Number} : Zone width in pixels
Param {relHeight: Number} : Zone height in pixels

reset ()
Resets the component to its initial state.

getZoom ()
Returns the current zoom value.
Return {Number} : Zone value

License

React PrismaZoom is licensed under the ISC license. See the LICENSE.md file for more details.