Created
November 27, 2022 02:55
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import { useEffect, useRef, useState } from 'react'; | |
type RotatedImage = { | |
src: string; | |
width: number; | |
height: number; | |
} | null; | |
let canvas: HTMLCanvasElement | null = null; | |
let canvasCtx2D: CanvasRenderingContext2D | null = null; | |
const getRotatedImage = ( | |
image: HTMLImageElement | null, | |
rotation: number, | |
): RotatedImage => { | |
if (!canvas) { | |
canvas = document.createElement('canvas'); | |
canvasCtx2D = canvas.getContext('2d'); | |
} | |
if (!image || !canvasCtx2D) return null; | |
const { width: imageWidth, height: imageHeight, currentSrc } = image; | |
const degree = rotation % 360; | |
if (!degree) { | |
return { | |
src: currentSrc, | |
width: imageWidth, | |
height: imageHeight, | |
}; | |
} | |
const { PI, sin, cos, abs } = Math; | |
const angle = (degree * PI) / 180; | |
const sinAngle = sin(angle); | |
const cosAngle = cos(angle); | |
canvas.width = abs(imageWidth * cosAngle) + abs(imageHeight * sinAngle); | |
canvas.height = abs(imageWidth * sinAngle) + abs(imageHeight * cosAngle); | |
// The width and height of the canvas will be automatically rounded. | |
const { width: canvasWidth, height: canvasHeight } = canvas; | |
canvasCtx2D.clearRect(0, 0, canvasWidth, canvasHeight); | |
canvasCtx2D.translate(canvasWidth / 2, canvasHeight / 2); | |
canvasCtx2D.rotate(angle); | |
canvasCtx2D.drawImage( | |
image, | |
-imageWidth / 2, | |
-imageHeight / 2, | |
imageWidth, | |
imageHeight, | |
); | |
const src = canvas.toDataURL('image/png'); | |
canvas.width = 0; | |
canvas.height = 0; | |
return { | |
src, | |
width: canvasWidth, | |
height: canvasHeight, | |
}; | |
}; | |
const useRotateImage = (imageSrc: string, rotation?: number): RotatedImage => { | |
const imageEle = useRef<HTMLImageElement | null>(null); | |
const [rotatedImage, setRotatedImage] = useState<RotatedImage>(null); | |
useEffect(() => { | |
if (typeof rotation === 'number') { | |
let currImage = imageEle.current; | |
if (currImage?.currentSrc !== imageSrc) { | |
currImage = new Image(); | |
imageEle.current = currImage; | |
currImage.src = imageSrc; | |
} | |
currImage.decode().then( | |
() => setRotatedImage(getRotatedImage(currImage, rotation)), | |
() => setRotatedImage(null), | |
); | |
} | |
}, [imageSrc, rotation]); | |
return rotatedImage; | |
}; | |
export default useRotateImage; |
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