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How to zoom-in and zoom-out image using ReactJS?

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  • Last Updated : 03 Dec, 2021

React is a JavaScript library for building user interfaces. React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes.

In ReactJS whatever we write that looks like HTML is not pure HTML actually. All the HTML looking stuff are JSX, Behind the scene, they are converted to vanilla JavaScript using babel. These all work in this way to make the developer’s life easier. Since JSX are not HTML that’s why we do have any direct reference to the HTML elements and that’s why we can’t direct fetch properties of any HTML element. To fetch the elements’ property, React gives something called as ‘ref’. Using ref we can create a direct reference to any HTML elements and get controlled over HTML elements properties. Here we use the ‘ref’ system to fetch image height and width. After getting image height and width we set a click handler and increase the dimension of the image which gets faded into the DOM property.

Example: This example illustrates how to zoom an image using react

  • index.js:

Javascript




import React from 'react'
import ReactDOM from 'react-dom'
import App from './App'
 
ReactDOM.render(<App />, document.querySelector('#root'))


  • App.js:

Javascript




import React, { Component } from 'react'
class App extends Component{
  constructor(props){
    super(props)
     
    // Initializing states
    this.state = {height:null, width:null}
     
    // Bind context of 'this'
    this.handleZoomIn = this.handleZoomIn.bind(this)
    this.handleZoomOut = this.handleZoomOut.bind(this)
     
    // Create reference of DOM object
    this.imgRef = React.createRef()
  }
 
  componentDidMount(){
    // Saving initial dimension of image as class properties
    this.initialHeight = this.imgRef.current.clientHeight
    this.initialWidth = this.imgRef.current.clientWidth
  }
 
  // Event handler callback for zoom in
  handleZoomIn(){
   
    // Fetching current height and width
    const height = this.imgRef.current.clientHeight
    const width = this.imgRef.current.clientWidth
     
    // Increase dimension(Zooming)
    this.setState({
      height : height + 10,
      width : width + 10,
    }) 
  }
 
  // Event handler callback zoom out
  handleZoomOut(){
   
    // Assigning original height and width
    this.setState({
      height : this.initialHeight,
      width : this.initialWidth,
    })
  }
 
  render(){
    // Assign current height and width to the image
    const imgStyle = { height : this.state.height, width: this.state.width}
    return(
      <div>
        <h2>GeeksforGeeks</h2>
        {/* Assign reference to DOM element     */}
        <img style={imgStyle} ref={this.imgRef} src=
        <div>
          <button onClick={this.handleZoomIn}>Zoom In</button>
          <button onClick={this.handleZoomOut}>Zoom Out</button>
        </div>
      </div>   
    
  }
}
export default App


Output :


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