src/HScroller

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

import React, { useContext, useCallback } from 'react' import { ScrollerStateType } from './prop-types' import { ScrollerDispatch, HSCROLL } from './reducers/scrollerReducer' import { LEVELS, log } from './utils' import './HScroller.css' const margin = 6 const HScroller = props => { log('HScroller', LEVELS.INFO, props) const { state: { scrolling, scrollLeft, scrollableBody } } = props const scrollerDispatch = useContext(ScrollerDispatch) let section = null let sectionWidth = 0 let bodyWidth = 0 let tableWidth = 0 if (scrollableBody && scrollableBody.isConnected) {

scrollableBody may be temporarily detached if one hides all previously fixed columns

section = scrollableBody.closest('.rrt-section') sectionWidth = section.getBoundingClientRect().width bodyWidth = scrollableBody.getBoundingClientRect().width tableWidth = section.closest('.rrt-table').getBoundingClientRect().width } const visible = bodyWidth > sectionWidth const scrollerWidth = tableWidth - 2 * margin const thumbWidth = bodyWidth ? (scrollerWidth * sectionWidth) / bodyWidth : 0 const scrollLeftMax = scrollerWidth - thumbWidth const marginLeft = margin + scrollLeft const scrollSection = useCallback( left => { const newLeft = (left * bodyWidth) / scrollerWidth section.scrollLeft = newLeft scrollerDispatch({ type: HSCROLL, scrolling: true, scrollLeft: left }) }, [section, bodyWidth, scrollerWidth, scrollerDispatch] ) const handleMouseDown = useCallback( event => { event.stopPropagation() event.preventDefault() const x0 = event.clientX const inThumb = event.target.closest('.rrt-hscroller-thumb') !== null let left0 = scrollLeft if (!inThumb) { const { left } = event.target .closest('.rrt-hscroller') .getBoundingClientRect() left0 = Math.min(x0 - left, scrollLeftMax) scrollSection(left0) } const handlers = {}

Position mouse handlers to create a modal drag loop

handlers.handleMouseMove = event => { event.preventDefault() event.stopPropagation() const dx = event.clientX - x0 const left1 = Math.min(Math.max(0, left0 + dx), scrollLeftMax) scrollSection(left1) } handlers.handleMouseUp = event => { event.preventDefault() event.stopPropagation() window.removeEventListener('mousemove', handlers.handleMouseMove, true) window.removeEventListener('mouseup', handlers.handleMouseUp, true) scrollerDispatch({ type: HSCROLL, scrolling: false }) } window.addEventListener('mousemove', handlers.handleMouseMove, true) window.addEventListener('mouseup', handlers.handleMouseUp, true) }, [scrollerDispatch, scrollLeft, scrollLeftMax, scrollSection] ) const handleWheel = useCallback( event => { event.stopPropagation()

Cannot prevent default due to react not supporting passive events yet event.preventDefault()

const { deltaY } = event const left = Math.min( Math.max(0, scrollLeft + Math.sign(deltaY) * 30), scrollLeftMax ) scrollSection(left) }, [scrollSection, scrollLeft, scrollLeftMax] ) return visible ? ( <div className='rrt-hscroller' onMouseDown={handleMouseDown} onWheel={handleWheel} > <div className={`rrt-hscroller-thumb${ scrolling ? ' rrt-hscroller-thumb-active' : '' }`} style={{ width: `${thumbWidth}px`, left: `${marginLeft}px` }} /> </div> ) : null } HScroller.propTypes = { state: ScrollerStateType } HScroller.displayName = 'HScroller' export default HScroller