react-dnd-scrollzone

Cross browser compatible scrolling containers for drag and drop interactions.

Basic Example

import React from 'react';
import Scrollzone from 'react-dnd-scrollzone';

import DraggableItem from './path/to/DraggableItem';

const scrollStyle = {
  overflowX: 'scroll',
  overflowY: 'scroll',
}

export default App(props) {
  return (
    <main>
      <header />
      <Scrollzone style={scrollStyle} >
        <DraggableItem />
        <DraggableItem />
        <DraggableItem />
      </Scrollzone>
    </main>
  );
}

Easing Example

import React from 'react';
import Scrollzone, { createHorizontalStrength, createVerticalStrength } from 'react-dnd-scrollzone';

import DraggableItem from './path/to/DraggableItem';

const linearHorizontalStrength = createHorizontalStrength(150);

const linearVerticalStrength = createVerticalStrength(150);

// this easing function is from https://gist.github.com/gre/1650294 and
// expects/returns a number between [0, 1], however strength functions
// expects/returns a value between [-1, 1]
function ease(val) {
  const t = val / 2 + 1; // [-1, 1] -> [0, 1]
  const easedT = t<.5 ? 2*t*t : -1+(4-2*t)*t;
  return easedT * 2 - 1; // [0, 1] -> [-1, 1]
}

function hStrength(box, point) {
  return ease(linearHorizontalStrength(box, point));
}

function vStrength(box, point) {
  return ease(linearVerticalStrength(box, point));
}

export default App(props) {
  return (
    <main>
      <header />
      <Scrollzone verticalStrength={vStrength} horizontalStrength={hStrength} >
        <DraggableItem />
        <DraggableItem />
        <DraggableItem />
      </Scrollzone>
    </main>
  );
}

API

`Scrollzone`

A React component with the following properties:

<Scrollzone
  verticalStrength={Function}
  horizontalStrength={Function}
  speed={Number}
  tag={String|Component} >

  {children}

</Scrollzone>

verticalStrength - a function that returns the strength of the vertical scroll direction
horizontalStrength a function that returns the strength of the horizontal scroll direction
speed - strength multiplier, play around with this (default 30)
tag - tag to render as (default "div")

The strength functions are both called with two arguments. An object representing the rectangle occupied by the Scrollzone, and an object representing the coordinates of mouse.

They should return a value between -1 and 1.

Negative values scroll up or left.
Positive values scroll down or right.
0 stops all scrolling.

`createVerticalStrength(buffer)` and `createHorizontalStrength(buffer)`

These allow you to create linearly scaling strength functions with a sensitivity different than the default value of 150px. This replaces the old buffer prop.

Example

import Scrollzone, { createVerticalStrength, createHorizontalStrength } from 'react-dnd-scrollzone';

const vStrength = createVerticalStrength(500);
const hStrength = createHorizontalStrength(300);

// zone will scroll when the cursor drags within
// 500px of the top/bottom and 300px of the left/right
const zone = (
  <Scrollzone verticalStrength={vStrength} horizontalStrength={hStrength}>

  </Scrollzone>
);

pipefy/react-dnd-scrollzone