shaunstanislauslau / react-with-gesture Goto Github PK

npm install react-with-gesture

import { useGesture, withGesture, Gesture } from 'react-with-gesture'

Ever thought about doing that sidebar pull-out, or a view pager, some slider, any gesture on the web basically, and dropped the idea because it's way too hard? In that case, this is your lib. The attempt was to gather the right amount of data needed to make even complex interaction possible without ending up either in complex math-, or implicit magic-hell.

React-with-gesture is a small utility that lets you bind richer, captured mouse and touch events to any component or view. It calculates initial position, deltas, velocity, direction, distance, etc. With this data it becomes trivial to set up gesture controls, 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 a animation library, preferrably react-spring (nothing complements gestures better than physics-based springs).

Demos

Viewpager/carousel: https://codesandbox.io/embed/n9vo1my91p

Draggable list: https://codesandbox.io/embed/r5qmj8m6lq

Slider: https://codesandbox.io/embed/zrj66y8714

Api

The api is straight forward. You can use React hooks, render-props or higher-order-components. You bind handlers to your view (done automatically for you if you use render-props or hoc's), and you will receive events when the user is clicking/dragging/pulling/releasing them.

// Full config with event handler
const bind = useGesture({ onAction: event => eventHandler, ...config })
return <div {...bind(optionalArgs)} />

// Short cut with event handler (becomes onAction + default config)
const bind = useGesture(event => eventHandler)
return <div {...bind(optionalArgs)} />

// No event handler (will re-render the component on event changes with fresh props)
const [bind, props] = useGesture()
return <div {...bind(optionalArgs)} />

// Render props
<Gesture {...config}>
  {event => <div />}
</Gesture>

// HOC with decorator
@withGesture(config)
class extends React.Component {
  render() {
    const event = this.props.event
    return <div />
  }
}

// Plain standard HOC
withGesture(config)(Component)

Config

{ 
  touch: true,                  // accept mouse input
  mouse: true,                  // accept touch input
  passive: { passive: true },   // event handler 3rd argument input, passive by default
  onAction: undefined           // event => eventHandler, respond to events outside Reacts render cycle
}

Event data

{
  event,                        // source event
  target,                       // dom node
  time,                         // time tag
  initial,                      // click coordinates (vec2)
  xy,                           // page coordinates (vec2)
  previous,                     // previous page coordinates (vec2)
  delta,                        // delta offset (xy - initial) (vec2)
  direction,                    // direction normal (vec2)
  local,                        // delta with book-keeping (vec2)
  velocity,                     // drag momentuum / speed
  distance,                     // delta distance
  down,                         // mouse / touch down
  first,                        // marks first event (mouse / touch down)
  args,                         // arguments optionally passed to bind(a,b,c,d,..)
  temp,                         // arguments optionally returned by onActions eventHandler
}

Examples

React hooks (basic drag/n/drop)

Demo: https://codesandbox.io/embed/l2wy87l28l

In this example we use useGesture's default syntax, where each change ends up re-rendering the component so that we get fresh props that we simply stick into the view. In this case we fetch local off the gesture event, which keeps track of delta positions after release. Deltas are especially important in this lib, becuase they make it possible to use transitions for positioning, instead of doing complex getBoundingClientRect() calculations to figure out where a node went on the screen.

const [bind, { local: [x, y] }] = useGesture()
return <div {...bind()} style={{ transform: `translate3d(${x}px,${y}px,0)` }} />

React hooks with onAction (and react-spring) (basic pull & release)

Demo: https://codesandbox.io/embed/r24mzvo3q

Re-rendering on every event can be taxing, but it can be avoided. If you are using an animation lib that can update the view outside of React (for instance react-spring or animated), then you can use the onAction syntax, which gives you a callback in which you receive events.

const [{ xy }, set] = useSpring(() => ({ xy: [0, 0] }))
const bind = useGesture(({ down, delta }) => set({ xy: down ? delta : [0, 0] }))
return (
  <animated.div
    {...bind()}
    style={{ transform: xy.interpolate((x, y) => `translate3d(${x}px,${y}px,0)`) }}
  />
)

React hooks with onAction (and react-spring) (decay)

Demo: https://codesandbox.io/embed/zq19y1xr9m

This demo reads out further data like velocity and direction to calculate decay. temp 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 xy value somewhere else and conditionally update it when the gesture begins.

const [{ xy }, set] = useSpring(() => ({ xy: [0, 0] }))
const bind = useGesture(({ down, delta, velocity, direction, temp = xy.getValue() }) => {
  set({ 
    xy: add(delta, temp),
    immediate: down,
    config: { velocity: scale(direction, velocity), decay: true }
  })
  return temp
})
return (
  <animated.div
    {...bind()}
    style={{ transform: xy.interpolate((x, y) => `translate3d(${x}px,${y}px,0)`) }}
  />
)