React-use-gesture is a hook that lets you bind richer mouse and touch events to any component or view. With the data you receive, it becomes trivial to set up gestures, and often takes no more than a few lines of code.
You can use it stand-alone, but to make the most of it you should combine it with an animation library like react-spring, though you can most certainly use any other.
The demos are real click them!
import { useSpring, animated } from 'react-spring'
import { useDrag } from 'react-use-gesture'
function PullRelease() {
const [{ xy }, set] = useSpring(() => ({ xy: [0, 0] }))
// 1. Define the gesture
const bind = useDrag(({ down, movement }) => set({ xy: down ? movement : [0, 0] }))
return (
<animated.div
// 2. Bind it to a component
{...bind()}
style={{ transform: xy.to((x, y) => `translate3D(${x}px, ${y}px, 0)`) }} />The example above makes a div draggable so that it follows your mouse on drag, and returns to its initial position on release.
➡️ Why using react-spring instead of React.useState?
React-use-gesture exports several hooks that can handle different gestures.
| Hook | Description |
|---|---|
useDrag |
Handles the drag gesture |
useMove |
Handles mouse move events (touch devices not supported) |
useHover |
Handles mouse over events (touch devices not supported) |
useScroll |
Handles scroll events |
useWheel |
Handles wheel events |
usePinch |
Handles pinch events |
useGesture |
Handles multiple gestures in one hook (read more here) |
Every time a handler is called, it will get passed a gesture state that includes the source event and adds multiple attributes such as speed, previous value, and much mroe.
const bind = useDrag(({
event, // * the source event
// * event.gesture indicates which gesture originated the event
xy, // [x,y] position of the pointer or scroll value for useScroll or useWheel
previous, // * previous xy
initial, // * xy value when the gesture has started
delta, // * delta between current and previous values (xy - previous)
movement, // * last gesture offset (xy - initial)
offset, // * offset since the first gesture (movement with book-keeping)
vxvy, // [vx, vy] momentum / speed of the gesture
velocity, // combined moment / speed of the gesture
distance, // offset distance
direction, // * [dirx, diry] direction per axis
time, // * timestamp of the current gesture
first, // * true when it's the first event
last, // * true when it's the last event
active, // * true when the gesture is active
memo, // * stores the value returned by your handler during its previous run
cancel, // * function you can call to interrupt relevant gestures (drag and pinch only)
canceled, // * whether the gesture has been canceled (drag and pinch only)
down, // * true when a mouse button or touch is down
buttons, // * buttons pressed (see https://developer.mozilla.org/fr/docs/Web/API/MouseEvent/button)
touches // * numbers of touches pressing the screen
shiftKey, altKey, ctrlKey, metaKey, // * true when modifier keys are pressed
args // * arguments you passed to bind
}) => {
/* gesture logic */
}
)Pinch is about scaling and rotating, therefore the keys xy and vxvy are renamed da (for distance and angle) and vdva respectively.
const bind = usePinch(({
da, // [d,a] absolute distance and angle of the two pointers
vdva, // momentum / speed of the distance and rotation
origin // coordinates of the center between the two touch event
}) => {
/* gesture logic */
}
)You can pass a an object as an optional second argument to use[Gesture] hooks to customize their behavior.
const bind = useScroll(handler, {
// lets you specify a dom node or ref you want to attach the gesture to
domTarget: undefined,
// the event config attribute lets you configure `passive` and `capture` options passed to event listeners
event: { passive: true, capture: false },
// uses PointerEvent handlers for compatible gestures (disabled by default)
dragDelay: false // you can set a delay in ms that will prevent drag from triggering if you just "click" on your element
pointerEvents: false,
// lets you specify which window element the gesture should use.
window: window,
// enables or disables gestures
enabled: true,
// enables or disables gestures individually (relevant for the useGesture hook)
drag: true,
pinch: true,
scroll: true,
wheel: true,
move: true
})➡️ See this thread for a relevant use case of window.
If you want your component to support multiple gestures at once, it is preferred that you use the useGesture hook as below.
const bind = useGesture({
onDrag: state => {...}, // fires on drag
onPinch: state => {...}, // fires on pinch
onScroll: state => {...}, // fires on scroll
onHover: state => {...}, // fires on mouse enter, mouse leave
onMove: state => {...}, // fires on mouse move over the element
onWheel: state => {...} // fires on mouse wheel over the element
})Drag, pinch, move, scroll and wheel gestures also have two additional handlers that let you perform actions when they start or end. For example, onScrollEnd fires when the user finished scrolling.
Note #1:
on[Gesture]Startandon[Gesture]Endmethods are provided as a commodity.on[Gesture]handlers also receivefirstandlastproperties that indicate if the event fired is the first (i.e. gesture has started) or the last one (i.e. gesture has ended).
// this:
useGesture({ onDragStart: doStuffOnStart, onDragEnd:doStuffOnEnd })
// is equivalent to this:
useDrag(({first, last}) {
if (first) { /* do stuff on drag start */ }
if (last) { /* do stuff on drag end */ }
})React-use-gesture also supports adding handlers to dom nodes directly (or the window or document objects). In that case, you shouldn't spread the bind() object returned by use[Gesture] hooks as a prop, but use the React.useEffect hook as below.
// this will add a scroll listener to the window
const bind = useScroll(state => doStuff, { domTarget: window })
React.useEffect(bind, [bind])You can also directly pass a ref to domTarget:
const myRef = React.useRef(null)
// this will add a scroll listener the div
const bind = useScroll(state => doStuff, { domTarget: myRef })
React.useEffect(bind, [bind])
/*...*/
return <div ref={myRef} />Note that using
useEffectwill also take care of removing event listeners when the component is unmounted.
This demo reads out further data like velocity and direction to calculate decay. memo in this case is a simple storage that picks up whatever value you (optionally) return inside the event handler. It's valid as long as the gesture is active. Without this you would need to store the initial pos value somewhere else and conditionally update it when the gesture begins.
const [{ pos }, set] = useSpring(() => ({ pos: [0, 0] }))
const bind = useDrag(({ active, movement, velocity, direction, memo = pos.getValue() }) => {
set({
pos: addV(movement, memo),
immediate: active,
config: { velocity: scale(direction, velocity), decay: true },
})
return memo
})
return <animated.div {...bind()} style={{ transform: pos.to((x, y) => `translate3d(${x}px,${y}px,0)`) }} />You can set gestures to use PointerEvent instead of traditional mouse or touch events. It might be useful if you use React-three-fiber. Note that only drag, move and hover gestures currently support this option.
const bind = useDrag(fn, { pointerEvents: true })React-use-gesture also exports two methods that add or substract vectors formed as arrays. They might be handy in the case you need to manipulate positions.
import { addV, subV } from 'react-use-gesture'
const sum = addV([10, 10], [5, 5]) // => [15, 15]
const sub = subV([10, 10], [5, 5]) // => [5, 5]Simply because setting state in the gesture handler would re-render the component on each gesture frame, which isn't always good for performance. react-spring lets us animate components without triggering renders. You could still use useState if you'd like though!
Not a lot! Essentially these use[Gesture] hooks simplify the implementation of the drag and pinch gestures, calculate kinematics values you wouldn't get out of the box from the listeners, and debounce move, scroll and wheel events to let you know when they end.
onDrag only fires while you touch or press the element. You just need to hover your mouse above the element to trigger onMove.
Scrolling and wheeling are structurally different events although they produce similar results (i.e. scrolling a page). First of all, wheel is a mouse-only event. Then, for onScroll to be fired, the element you're scrolling needs to actually scroll, therefore have content overflowing, while you just need to wheel over an element to trigger onWheel. If you use react-three-fiber, onWheel might prove useful to simulate scroll on canvas elements.
You're probably trying to access an event in onScroll, onMove or onWheel handlers. The last event is debounced, and therefore not accessible asynchronously because of how React pools events. A possible solution would be to make sure the event is not part of the last state update:
useScroll(({ event, last }) => {
!last && event.preventDefault() // <-- event will not be accessed in the last event
})As you've seen in some examples, whenever memo is used, it is imperatively returned in the handler function. Essentially memo is a gesture state attribute that is undefined when the gesture starts, but then takes the return value of the handler function.
In many use cases, we want memo to hold the original value of our element position when the gesture starts so that it becomes our point of reference when adding the gesture movement. So we set memo to the value of our position when memo is undefined, which is in fact when the gesture starts. Usually it looks like so:
const [{ x }, set] = useSpring(() => ({ x: 0 }))
const bind = useDrag(({ movement: [mx], memo = x.getValue() }) => {
set({ x: ox + memo })
return memo
})If we don’t return memo, then memo will remain undefined and in the next drag frame memo will take again the value of x, which will have updated in the meantime (therefore not being the point of reference when the gesture starts anymore).
It may sound silly but returning memo makes sure that we continue holding a reference to the initial value of memo, ie the original value of x when the gesture started.
This is typically a-feature-not-a-bug situation 🙃 Drag is triggered as soon as you mouse down on your component, which means it will be triggered when you "just" briefly click on it. However, there is an option to not trigger the drag before a certain delay, using the config option dragDelay.
// using the default delay
const bind = useDrag(() => {
console.log(`Won't show if you hold your mouse less than 180ms`)
}, { dragDelay: true })
// using a custom delay
const bind = useDrag(() => {
console.log(`Won't show if you hold your mouse less than 1000ms`)
}, { dragDelay: 1000 })The basic use of <Component {...bind()) /> passes the task of attaching listeners to React. React does not (yet) support binding passive listeners via props. To have useGesture attach the listeners, you must also use a domTarget. This is only required if you plan to preventDefault or cancel the event.