How to access canvas context in React

In accordance to React16 You can use React.createRef()

class ColorPicker extends React.Component {
constructor(props) {
   super(props);

   this.colorPickerRef = React.createRef();
}

componentDidMount() {
   this.context = this.colorPickerRef.current.getContext('2d');
}

render() {
   return (
      <canvas ref={this.colorPickerRef} />
   )
}
}

Here is the answer with react hooks:

import { useEffect, useRef } from 'react'

export default function Canvas() {
  const ref = useRef()

  useEffect(() => {
    if (ref.current) {
      const canvas = ref.current.getContext('2d')
      // do something here with the canvas
    }
  }, [])

  return <canvas ref={ref} />
}

It should just be accessing the target of the click

colorStripClick: function(e) {
  var ctx = e.target.getContext('2d')
}

You can add a ref function attribute on the canvas element:

<canvas id="color-strip" ref={(c) => this.context = c.getContext('2d')} height="...

Then you’ll have access to the context through this.context:

colorStripClick: function() {
    var imageData = this.context.getImageData(x, y, 1, 1).data
}

You can also use the event object to access to DOM node as already pointed out, but this way you’ll have access from anywhere, not just event handlers.

How to access canvas context in React

Tags:

Javascript

Html

Canvas

Reactjs

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