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whippy-edition/app/javascript/mastodon/components/blurhash.js
Sasha Sorokin 61c07c3731
Replace repetitive blurhash code with component (#14267)
This commit replaces all unnecessarily repeated code for decoding and
embedding blurhash canvases with separate component - <Blurhash>.

Under the hood Blurhash component will use effect dependent on its
props. This gives a few benefits: it will only be re-rendered whenever
the hash or width/height/dummy props update, and will not render if
canvas won't get to the final DOM, because then effect won't fire,
which prevents weird bugs like #14257.
2020-07-09 13:01:30 +02:00

62 lines
1.6 KiB
JavaScript

// @ts-check
import { decode } from 'blurhash';
import React, { useRef, useEffect } from 'react';
import PropTypes from 'prop-types';
/**
* @typedef BlurhashPropsBase
* @property {string} hash Hash to render
* @property {number} width
* Width of the blurred region in pixels. Defaults to 32
* @property {number} [height]
* Height of the blurred region in pixels. Defaults to width
* @property {boolean} [dummy]
* Whether dummy mode is enabled. If enabled, nothing is rendered
* and canvas left untouched
*/
/** @typedef {JSX.IntrinsicElements['canvas'] & BlurhashPropsBase} BlurhashProps */
/**
* Component that is used to render blurred of blurhash string
*
* @param {BlurhashProps} param1 Props of the component
* @returns Canvas which will render blurred region element to embed
*/
function Blurhash({
hash,
width = 32,
height = width,
dummy = false,
...canvasProps
}) {
const canvasRef = /** @type {import('react').MutableRefObject<HTMLCanvasElement>} */ (useRef());
useEffect(() => {
const { current: canvas } = canvasRef;
canvas.width = canvas.width; // resets canvas
if (dummy) return;
const pixels = decode(hash, width, height);
const ctx = canvas.getContext('2d');
const imageData = new ImageData(pixels, width, height);
ctx.putImageData(imageData, 0, 0);
}, [dummy, hash, width, height]);
return (
<canvas {...canvasProps} ref={canvasRef} width={width} height={height} />
);
}
Blurhash.propTypes = {
hash: PropTypes.string.isRequired,
width: PropTypes.number,
height: PropTypes.number,
dummy: PropTypes.bool,
};
export default React.memo(Blurhash);