Created
March 1, 2023 07:35
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React scroll based reveal
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import { motion, useInView, useScroll, useTransform } from "framer-motion"; | |
import { useElementViewportPosition } from "hooks/use-element-viewport-position"; | |
import { useRef, useEffect, useState } from "react"; | |
export const ScrollReveal = ({ offset = 0, once = true, children }) => { | |
const [initiallyVisible, setInitiallyVisible] = useState(false); | |
const [ended, setEnded] = useState(false); | |
const ref = useRef(null); | |
const isInView = useInView(ref); | |
const { position } = useElementViewportPosition(ref, offset); | |
const { scrollYProgress } = useScroll(); | |
const opacity = useTransform(scrollYProgress, position, [0, 1]); | |
const y = useTransform(scrollYProgress, position, [50, 0]); | |
opacity.on("change", (value) => { | |
if (value === 1) { | |
setEnded(true); | |
} | |
}); | |
useEffect(() => { | |
if (isInView && scrollYProgress.get() < 0.1) { | |
setInitiallyVisible(true); | |
opacity.set(1); | |
y.set(0); | |
} | |
}, [isInView, setEnded, scrollYProgress]); | |
useEffect(() => { | |
if (ended || initiallyVisible) { | |
scrollYProgress.destroy(); | |
opacity.destroy(); | |
y.destroy(); | |
} | |
}, [ended, initiallyVisible]); | |
if (initiallyVisible) | |
return ( | |
<motion.div | |
initial={{ opacity: 0, y: 50 }} | |
animate={{ opacity: 1, y: 0 }} | |
> | |
{children} | |
</motion.div> | |
); | |
return ( | |
<motion.div | |
ref={ref} | |
style={{ | |
opacity: (once && ended) || initiallyVisible ? 1 : opacity, | |
y: (once && ended) || initiallyVisible ? 0 : y, | |
}} | |
> | |
{children} | |
</motion.div> | |
); | |
}; |
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import { useState, useEffect } from "react"; | |
export function useElementViewportPosition(ref, offset = 0) { | |
const [position, setPosition] = useState([0, 0]); | |
useEffect(() => { | |
if (!ref || !ref.current) return; | |
const update = () => { | |
const pageHeight = document.body.scrollHeight; | |
const start = ref.current.offsetTop; | |
const end = start + ref.current.offsetHeight; | |
setPosition([(start + offset) / pageHeight, (end + offset) / pageHeight]); | |
}; | |
update(); | |
addEventListener("resize", update); | |
return () => { | |
removeEventListener("resize", update); | |
}; | |
}, []); | |
return { position }; | |
} |
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