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Feature snap #96

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Feature snap #96

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292f8ef
added snap feature
rsm0128 Jan 14, 2023
a199498
fixed weird scrolling behavior on scroll dragging
rsm0128 Jan 14, 2023
9c028dc
updated readme, renamed option names
rsm0128 Jan 14, 2023
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40 changes: 27 additions & 13 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -103,19 +103,24 @@ const lenis = new Lenis({

## Instance settings

| Option | Type | Default | Description |
| ------------------ | ------------- | -------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `wrapper` | `NodeElement` | `window` | Default element which has overflow |
| `content` | `NodeElement` | `document.body` | `wrapper`'s direct child |
| `duration` | `number` | `1.2` | Specifies the duration of the animation |
| `easing` | `function` | `(t) => Math.min(1, 1.001 - Math.pow(2, -10 * t))` | Specifies the rate of change of a specific value, our default is custom but you can pick one from [Easings.net](https://easings.net/en) |
| `direction` | `string` | `vertical` | `vertical` or `horizontal` scrolling. |
| `gestureDirection` | `string` | `vertical` | `vertical`, `horizontal` or `both`. |
| `smooth` | `boolean` | `true` | Enable or disable 'smoothness' |
| `mouseMultiplier` | `number` | `1` | This value is passed directly to [Virtual Scroll](https://github.com/ayamflow/virtual-scroll) |
| `smoothTouch` | `boolean` | `false` | Enable or disable 'smoothness' while scrolling using touch. Note: We have disabled it by default because touch devices native smoothness is impossible to mimic |
| `touchMultiplier` | `number` | `string` | This value is passed directly to [Virtual Scroll](https://github.com/ayamflow/virtual-scroll) |
| `infinite` | `boolean` | `false` | Enable infinite scrolling! |
| Option | Type | Default | Description |
| ------------------ | ------------- | -------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `wrapper` | `NodeElement` | `window` | Default element which has overflow |
| `content` | `NodeElement` | `document.body` | `wrapper`'s direct child |
| `duration` | `number` | `1.2` | Specifies the duration of the animation |
| `easing` | `function` | `(t) => Math.min(1, 1.001 - Math.pow(2, -10 * t))` | Specifies the rate of change of a specific value, our default is custom but you can pick one from [Easings.net](https://easings.net/en) |
| `direction` | `string` | `vertical` | `vertical` or `horizontal` scrolling. |
| `gestureDirection` | `string` | `vertical` | `vertical`, `horizontal` or `both`. |
| `smooth` | `boolean` | `true` | Enable or disable 'smoothness' |
| `mouseMultiplier` | `number` | `1` | This value is passed directly to [Virtual Scroll](https://github.com/ayamflow/virtual-scroll) |
| `smoothTouch` | `boolean` | `false` | Enable or disable 'smoothness' while scrolling using touch. Note: We have disabled it by default because touch devices native smoothness is impossible to mimic |
| `touchMultiplier` | `number` | `string` | This value is passed directly to [Virtual Scroll](https://github.com/ayamflow/virtual-scroll) |
| `infinite` | `boolean` | `false` | Enable infinite scrolling! |
| `snapDuration` | `number` | `0.4` | Specifies the duration of the snap animation |
| `snapDelayOnScroll` | `number` | `0.4` | Specifies the delay of the snap animation after wheel scrolling |
| `snapDelayOnResize` | `number` | `0.1` | Specifies the delay of the snap animation after non-whell scrolling or resizing |
| `snapLength` | `number|string` | `20%` | Specifies the snap threshold value. Can be any size value `px`, `%`, `vh` or `vw` |
| `snapAlign` | `string` | `start` | Specifies the scroll-snap-align value. `start`, `end`, or `center` |

<br/>

Expand Down Expand Up @@ -166,6 +171,15 @@ body {
<div data-lenis-prevent>scroll content</div>
```

#### Use `snap` attribute on nested scroll elements for scroll snap. It will override `snapAlign` setting value for the element. `snap-length` attribute can be used to override `snapLength` setting value.

```html
<div snap>scroll content</div>
<div snap="start">scroll content</div>
<div snap="center" snap-length="20vh">scroll content</div>
<div snap="end" snap-lenght="20">scroll content</div>
```

#### Manually use `lenis.scrollTo('#anchor')` on anchor link click ([see this issue](https://github.com/studio-freight/lenis/issues/19))

```html
Expand Down
115 changes: 105 additions & 10 deletions src/lenis.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ import { TinyEmitter as EventEmitter } from 'tiny-emitter'
import VirtualScroll from 'virtual-scroll'
import { version } from '../package.json'
import { clamp, clampedModulo } from './maths'
import { getSnapLength } from './util'

class Animate {
to(target, { duration = 1, easing = (t) => t, ...keys } = {}) {
Expand All @@ -28,34 +29,30 @@ class Animate {
raf(deltaTime) {
if (!this.isRunning) return

this.currentTime = Math.min(this.currentTime + deltaTime, this.duration)
this.currentTime += deltaTime

const progress = this.progress >= 1 ? 1 : this.easing(this.progress)
const progress = this.currentTime >= this.duration ? 1 : this.easing(this.currentTime / this.duration)

this.keys.forEach((key) => {
const from = this.fromKeys[key]
const to = this.toKeys[key]

const value = from + (to - from) * progress

this.target[key] = value
this.target[key] = from + (to - from) * progress
})

if (progress === 1) {
this.stop()
}
}

get progress() {
return this.currentTime / this.duration
}
}

export default class Lenis extends EventEmitter {
/**
* @typedef {(t: number) => number} EasingFunction
* @typedef {'vertical' | 'horizontal'} Direction
* @typedef {'vertical' | 'horizontal' | 'both'} GestureDirection
* @typedef {'start' | 'end' | 'center'} SnapAlign
*
* @typedef LenisOptions
* @property {number} [duration]
Expand All @@ -69,6 +66,11 @@ export default class Lenis extends EventEmitter {
* @property {boolean} [infinite]
* @property {Window | HTMLElement} [wrapper]
* @property {HTMLElement} [content]
* @property {number} [snapDuration]
* @property {number} [snapDelayOnWheel]
* @property {number} [snapDelayOnResize]
* @property {string|number} [snapLength]
* @property {SnapAlign} [snapAlign]
*
* @param {LenisOptions}
*/
Expand All @@ -84,6 +86,11 @@ export default class Lenis extends EventEmitter {
infinite = false,
wrapper = window,
content = document.body,
snapDuration = 0.4,
snapDelayOnWheel = 0.4,
snapDelayOnResize = 0.1,
snapLength = '20%',
snapAlign = 'start', // start, end, center
} = {}) {
super()

Expand Down Expand Up @@ -115,7 +122,16 @@ export default class Lenis extends EventEmitter {
this.wrapperNode = wrapper
this.contentNode = content

this.snapAlign = snapAlign || 'start';
this.snapLength = snapLength || 'start';
this.snapDuration = snapDuration;
this.snapDelayOnWheelMS = snapDelayOnWheel * 1000; // MS => MilliSeconds
this.snapDelayOnResizeMS = snapDelayOnResize < 0.05 ? 100 : snapDelayOnResize * 1000 // Snap delay should be bigger than 50ms to avoid weird behavior
this.isHorizontal = this.direction === 'horizontal'

this.wrapperNode.addEventListener('scroll', this.onScroll)
this.wrapperNode.addEventListener('mousedown', this.onMouseDown)
this.wrapperNode.addEventListener('mouseup', this.onMouseUp)

//observe wrapper node size
if (this.wrapperNode === window) {
Expand Down Expand Up @@ -162,6 +178,8 @@ export default class Lenis extends EventEmitter {
})

this.virtualScroll.on(this.onVirtualScroll)

this.initSnapElements()
}

get scrollProperty() {
Expand Down Expand Up @@ -205,13 +223,15 @@ export default class Lenis extends EventEmitter {
onWindowResize = () => {
this.wrapperWidth = window.innerWidth
this.wrapperHeight = window.innerHeight
this.scheduleSnap(this.snapDelayOnResizeMS)
}

onWrapperResize = ([entry]) => {
if (entry) {
const rect = entry.contentRect
this.wrapperWidth = rect.width
this.wrapperHeight = rect.height
this.scheduleSnap(this.snapDelayOnResizeMS)
}
}

Expand All @@ -220,6 +240,7 @@ export default class Lenis extends EventEmitter {
const rect = entry.contentRect
this.contentWidth = rect.width
this.contentHeight = rect.height
this.scheduleSnap(this.snapDelayOnResizeMS)
}
}

Expand Down Expand Up @@ -276,6 +297,8 @@ export default class Lenis extends EventEmitter {
// this.targetScroll = clamp(0, this.targetScroll, this.limit)

this.scrollTo(this.targetScroll)
this.scheduleSnap(this.snapDelayOnWheelMS)

}

raf(now) {
Expand All @@ -287,19 +310,22 @@ export default class Lenis extends EventEmitter {
this.lastScroll = this.scroll

// where this.scroll is updated
this.animate.raf(deltaTime * 0.001)
if (!this.pause) {
this.animate.raf(deltaTime * 0.001)
}

if (this.scroll === this.targetScroll) {
// if target reached velocity should be 0
this.lastScroll = this.scroll
this.animate.stop()
}

if (this.isScrolling) {
this.setScroll(this.scroll)
this.notify()
}

this.isScrolling = this.scroll !== this.targetScroll
this.isScrolling = this.scroll !== this.lastScroll
}

get velocity() {
Expand All @@ -323,6 +349,8 @@ export default class Lenis extends EventEmitter {
this.lastScroll =
this.wrapperNode[this.scrollProperty]

this.scheduleSnap(this.snapDelayOnResizeMS)

this.notify()
}
}
Expand Down Expand Up @@ -410,4 +438,71 @@ export default class Lenis extends EventEmitter {
})
}
}

initSnapElements() {
let allSnapElements = this.contentNode.querySelectorAll('[snap]');
allSnapElements.forEach(snapElement => {
snapElement.snapAlign = snapElement.getAttribute('snap') || this.snapAlign; // start, end, center
snapElement.snapLength = getSnapLength(snapElement, snapElement.getAttribute('snap-length') || this.snapLength);
})

this.snapElements = allSnapElements;
}

snap() {
if (!this.snapElements?.length) {
return
}

let wrapperRect;
if (this.wrapperNode === window) {
wrapperRect = {
left: 0,
top: 0,
right: this.wrapperWidth,
bottom: this.wrapperHeight,
}
} else {
wrapperRect = this.wrapperNode.getBoundingClientRect();
}

this.snapElements.forEach(snapElement => {
const snapAlign = snapElement.snapAlign; // start, end, center
const snapLength = snapElement.snapLength;
const elRect = snapElement.getBoundingClientRect();

let delta;
if ('end' === snapAlign) {
delta = this.isHorizontal ? elRect.right - wrapperRect.right : elRect.bottom - wrapperRect.bottom
} else if ('center' === snapAlign) {
delta = this.isHorizontal ? (elRect.left - wrapperRect.left + (elRect.width - this.wrapperWidth) / 2) : (elRect.top - wrapperRect.top + (elRect.height - this.wrapperHeight) / 2)
} else {
// default type 'start'
delta = this.isHorizontal ? elRect.left - wrapperRect.left : elRect.top - wrapperRect.top;
}

if (Math.abs(delta) <= snapLength) {
this.scrollTo(this.scroll + delta, { duration: this.snapDuration });
return;
}
})
}

scheduleSnap(delay) {
if (this.snapTimer) {
clearTimeout(this.snapTimer)
}

this.snapTimer = setTimeout(() => {
this.snap();
}, delay);
}

onMouseUp = () => {
this.pause = false;
}

onMouseDown = () => {
this.pause = true;
}
}
45 changes: 45 additions & 0 deletions src/util.js
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@@ -0,0 +1,45 @@
export function getSnapLength(obj, snapVal, axis='horizontal') {
const clientSize = axis === 'horizontal' ? 'clientWidth' : 'clientHeight';

const declaration = parseUnitValue(snapVal)
// get y snap length based on declaration unit
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if (declaration.unit === 'vh') {
return (
(Math.max(document.documentElement.clientHeight, window.innerHeight || 1) / 100) *
declaration.value
)
} else if (declaration.unit === 'vw') {
return (
(Math.max(document.documentElement.clientWidth, window.innerWidth || 1) / 100) *
declaration.value
)
} else if (declaration.unit === '%') {
return (obj[clientSize] / 100) * declaration.value
} else {
return declaration.value
}
}

function parseUnitValue(unitValue) {
// regex to parse lengths
const regex = /([+-]?(?=\.\d|\d)(?:\d+)?(?:\.?\d*)(?:[eE][+-]?\d+)?)(px|%|vw|vh)/
// defaults
let parsed = {
value: 0,
unit: 'px',
}

if (typeof unitValue === 'number') {
parsed.value = unitValue
} else {
const match = regex.exec(unitValue)
if (match !== null) {
parsed = {
value: Number(match[1]),
unit: match[2],
}
}
}

return parsed
}