React Spring 5 useResize(), useInView(), indexed useSprings()

• Animated useSpring() with useInView() hook

• Rendering useSprings() with index-based style properties

The useResize(), a useSpring() abstraction, returns the useRef() container width/height props. Its onChange() will trigger on window resize.

//width returned in px
let quad = useRef(null)

const { width, height } = useResize({
  container: quad,
  onChange: ({value: {width} })=> {
    console.log( width )
  }
})

<div>
  <div style={{ width: "50vw", height: "30vh", background: "yellow" }} ref={quad}>
  </div>
</div>

Animated useSpring() with useInView() hook

The useInView() hook tracks an element's visibility relative to the viewpoint. It will return the useRef() for the target element and the boolean result of the Intersection Observer API

import { animated, useSpring, useInView} from '@react-spring/web'

let [ref, inview] = useInView({
  //Element's visibility percentage that will trigger the useInView() callback
  threshold: 0.5,         //independently of scroll direction
  rootMargin: '0px 0px -20% 0%',  //margins around the element (adds to threshold)
  once: true,             //will trigger the API once
})

let springs = useSpring({
  opacity: inview ? 1 : 0,
  y: inview ? 0 : 100,
  backgroundColor: inview ? "red" : "pink",
})

<div ref={ref}>
  <animated.div style={springs}>
    {inview ? "Visible" : "inVisible" }
  </animated.div>
</div>

Multi directional section with useInView()

When having multiple useInView() elements keep the threshold below 0.5, to not overlay and repeat the useSpring().

//We can add a delay to the useInView
//Instead of absolute/width animation we used margin/opacity
let [primo, visto1] = useInView({
  delay: 500,
  threshold: 0.2
})
let seePrimo = useSpring({
  opacity: visto1 ? 1 : 0,
  marginLeft: visto1 ? 0 : 500,
})

let [secon, visto2] = useInView({
  delay: 500,
  threshold: 0.2
})
let seeSeco = useSpring({
  opacity: visto2 ? 1 : 0,
  marginRight: visto2 ? 0 : 500,
})

let [tri, visto3] = useInView({
  delay: 500
})
let seeTri = useSpring({
  opacity: visto3 ? 1 : 0,
  marginTop: visto3 ? 0 : 200,
})

<div>
  <animated.div ref={primo} className="bg-warning" 
    style={{ height: "100vh", ...seePrimo }}>
  </animated.div>

  <animated.div ref={secon} className="bg-primary" 
    style={{height: "100vh" , ...seeSeco }}>
  </animated.div>

  <animated.div ref={tri} className="bg-danger" 
    style={{width: "100%", ...seeTri}}>
    <div style={{height: "100vh"}}></div>
  </animated.div>
</div>

useInView() margin/opacity animated

Rendering useSprings() with index-based style properties

The useSprings() hook renders a number of indexed springs with shared props, their indexes can set their individual properties and be used to animate specific useSpring().

//We render 3 useSprings() each with x based on their array index
//The index conditional is needed in api.start() to not animate every element
let [lista, listaapi] = useSprings(3, i => ({
  from: {x: 0},
  to: {x: i * 100}
})

listaapi.start(i =>{
  if (i !== 2) return

  return {x: 400}
})

Overlayed useDrag() swipe effect and function from/to useSpring() props

We use the useSprings() index as arguments for the from/to functions.

The starting animation is a translateY(-1000), we distance (4px) and rotate each card, and the delay adds the stack effect.

import { animated, useSprings, to as interpolate} from '@react-spring/web'
import { useDrag } from '@use-gesture/react'

const cards = [
  'https://RWS_Tarot_08_Strength.jpg',
  'https://RWS_Tarot_16_Tower.jpg',
  'https://RWS_Tarot_07_Chariot.jpg',
  'https://RWS_Tarot_06_Lovers.jpg',
  'https://RWS_Tarot_02_High_Priestess.jpg',
  'https://RWS_Tarot_01_Magician.jpg',
]

const from = (_i) => ({ x: 0, rot: 0, scale: 1.5, y: -1000 })

const to = (i) => ({
  x: 0,
  y: i * -4,
  scale: 1,
  rot: -10 + Math.random() * 20,
})

const [props, api] = useSprings(cards.length, i => ({
  from: from(i),
  to: to(i),
  config: { duration: 2000 },
  delay: i * 100,
})) 

//We can add perspective(1500px) rotateX(30deg) for 3D effect
const trans = (r, s) =>
  `rotateY(${r / 10}deg) rotateZ(${r}deg) scale(${s})`

We create a useState() set to store the swiped cards (like an array but with no repeated elements and has() method)

We useDrag() the current passed argument index element, on mx only movement, we add() it to the set if it exceeds the minimal velocity after it stops being dragged.

We api.start() only the useDrag() index useSpring(), onDrag() its scale gets bigger, its position and rotation depend on the mx drag distance if it's in the set() then we swipe it out of viewpoint.

When drag is finished and all cards are set() we clean() it and api.start() the last card keyframe (to)

//on '@use-gesture/react' velocity is an array, sow e take [1]
//The config tension gets changed onDrag()
const [gone] = useState(() => new Set())

const bind = useDrag(({ args: [index], down, movement: [mx], velocity }) => {

  const trigger = velocity[1] > 0.15 
  const dir = mx < 0 ? -1 : 1 

  if (!down && trigger) gone.add(index) 

  api.start(i => {
    if (index !== i) return

    const isGone = gone.has(index)

    const x = isGone ? (200 + window.innerWidth) * dir : down ? mx : 0 
    const rot = mx / 100 + (isGone ? dir * 10 * velocity[1] : 0) 
    const scale = down ? 1.1 : 1 

    return {
      x, rot, scale,
      config: { friction: 150, tension: down ? 800 : isGone ? 200 : 500 },
    }
  })

  if (!down && gone.size === cards.length)
    setTimeout(() => {
      gone.clear()
      api.start(i => to(i))
    }, 600)
})

We loop useSprings() into 2 components, with its index in the useDrag() as argument. A relative container for the overlayed absolute cards, with overflow to not expand the width on swipe.

//We use interpolate to set the useSpring() props in the trans function
//We need touchAction and axis for the useDrag()
import {to as interpolate} from '@react-spring/web'

<div className="d-block position-relative" 
     style={{width: "100%", height: "60vh", overflow: "hidden"}}>
     
  {props.map(({ x, y, rot, scale }, i) => (
    <animated.div className="deck1" key={i} style={{ x, y }}>

    <animated.div
      {...bind(i)}
      style={{
        transform: interpolate([rot, scale], trans),
        backgroundImage: `url(${cards[i]})`,
        touchAction: 'pan-x',
        axis: 'x'
      }}
    />
    </animated.div>
  ))}

</div>

We add a custom circle cursor to the absolute cards, and set the background properties.

.deck1{
  position: absolute;
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  touch-action: none;
}

.deck1 > div{
  cursor: url('
    https://uploads.codesandbox.io/uploads/user/b3e56831-8b98-4fee-b941-0e27f39883ab/Ad1_-cursor.png') 
    39 39, auto;

  background-color: white;
  background-size: auto 85%;
  background-repeat: no-repeat;
  background-position: center center;
  width: 45vh;
  height: 85vh;
  box-shadow: 0 12.5px 100px -10px rgba(50, 50, 73, 0.4);
}

We can mimic a useChain() sequential animation with useSprings(), we distance the delay of each element by their index, the effect depends on the duration-delay ratio.

//Each letter (and empty space) needs to be centered and have its own area
//We use the map() index for the useSprings() index
//3 letters will share their animation time 
let star = "Kai Ashen"
let [nome, setNome] = useState(star.split("")) 

let [mosso, mossoApi] = useSprings(nome.length, (i)=>({
  from: { top: 0 },
  to: [ {top: 15}, {top: -15}, {top: 0} ],
  delay: (i * 200),
  config: { duration: 600 }
}) )

<div className="bg-success" style={{ height: "30vh", width: "55vw" }}>
  {nome.map((cont, index)=>(
  <animated.h1 className=" position-relative" 
    key={index} style={{width: "0.7em", height: "1em", top: mosso[index].top }}>
    {cont}
  </animated.h1>)
  )}
</div>

useSpring() index sequential animation.

from/to functions on useSprings() indexed elements

We use the from/to functions to render useSprings() props, the starting point (deck) from is shared between the springs while the endpoint to depends on the index position.

The useState() reverse resets the cards to their starting point.

//We reset x each 4th card to for the rows, on y we increase Y each 4
//we also randomize the ending rotation for each card
let carta = "https://i.pinimg.com/1dc1f9add0ea9e1580c8cee22b6ef39f.jpg";

let carte1 = [
  "https://static.tcgcollector.com/...jpg",
  "https://static.tcgcollector.com/...jpg",
  "https://static.tcgcollector.com/...jpg",
  "https://static.tcgcollector.com/...jpg",
  "https://static.tcgcollector.com/...jpg",
  "https://static.tcgcollector.com/...jpg",
]

let from = (i) => ({
  x: 30 + "vw",
  y: -50 + "vh",
  rot: 0,
  scale: 1.2,
  back: `url(${carta})`,
})

let to = (i) => ({
  x: (i % 4) * 20 + "vw",
  y: Math.floor(i / 4) * 30 + "vh",
  scale: 1,
  rot: -20 + Math.random() * 40,
  back: `url(${carta})`,
})

const trans = (r, s) => `rotateZ(${r}deg) scale(${s})`

let [reve, setReve] = useState(false)

const [mazzo, mazzoapi] = useSprings(carte1.length, i => ({
  from: from(i),
  to: to(i),
  config: {duration: 2000},
  delay: i * 1100,
  reverse: reve
}), [reve])

function cambio(){ setReve( (x)=> !x ) }

<button className="btn btn-primary p-2" onClick={cambio}>
  Re-Draw PKM cards
</button>

On click, we reverse animate the card's rotate prop and set() its new index background (set() quickly loads the new image instead of waiting for the duration)

We create the draw-from-top effect by interpolating the z-index prop at the very start of their animation.

//We pass the useSprings() index to only animate the clicked card
//We can only use the ternary operator conditional inside the set() start()
//We also set() because its not possible to animate between 2 url() images.
function gira(i){
  mazzoapi.set(n => (
    n == i ?
      {
        back: (mazzo[i].back.animation.to == `url(${carta})`) ? 
        `url(${carte1[i]})` : `url(${carta})`
      }
    :
    null
  ))

  mazzoapi.start(n => (
    n == i ?
      {
        rot: mazzo[i].rot.animation.to * -1,
        config: {duration: 500}
      }
    : 
    null
  ))
}

<div className="d-flex justify-content-center align-items-center ">
  <div style={{marginTop: "60vh",width: "80%", height: "70vh" }}>

    {mazzo.map(({ x, y, rot, scale, back }, i) => (
      <>
      <animated.div
        onClick= {()=> gira(i)}
        className="deck2"
        style={{
          x, y,
          transform: interpolate([rot, scale], trans),
          backgroundImage: back,
          touchAction: 'pan-x',
          axis: 'x',
          zIndex: scale.to(val => val < 1.2 ? 1 : 0 )
        }}
      >
      </animated.div>
      </>
    ))}

  </div>
</div>

We translate(vw, vh) the cards but their width/height is fixed.

//We set their background-image props
.deck2{
  position: absolute;
  width: 170px;
  height: 240px;
  display: flex;

  background-color: white;
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center center;
}

useSprings() reverse set() and start()

We can set transition on the style object and the transition style property on the looped map() elements, without using springs().

const itemStyle = {
  ...
  transition: "top 2s, left 2s"
};

const [items, set] = useState(
  [1, 2, 3, 4, 5, 6, 7].map((item, i) => ({ position: i, value: item }))
);

<>
{items.map(({ position, value }) => (
  <div style={{ ...itemStyle, 
    top: `${Math.floor(position/5) * 100}px`, 
    left: `${(position%5) * 100}px`}}>
    {value}
  </div>
))}
</>

Transition CSS properties

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