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node_modules/better-scroll/src/scroll/mouse-wheel.js 3.55 KB
aaac7fed   liuqimichale   add
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  import { addEvent, removeEvent } from '../util/dom'
  import { ease } from '../util/ease'
  
  export function mouseWheelMixin(BScroll) {
    BScroll.prototype._initMouseWheel = function () {
      this._handleMouseWheelEvent(addEvent)
  
      this.on('destroy', () => {
        clearTimeout(this.mouseWheelTimer)
        clearTimeout(this.mouseWheelEndTimer)
        this._handleMouseWheelEvent(removeEvent)
      })
  
      this.firstWheelOpreation = true
    }
  
    BScroll.prototype._handleMouseWheelEvent = function (eventOperation) {
      eventOperation(this.wrapper, 'wheel', this)
      eventOperation(this.wrapper, 'mousewheel', this)
      eventOperation(this.wrapper, 'DOMMouseScroll', this)
    }
  
    BScroll.prototype._onMouseWheel = function (e) {
      if (!this.enabled) {
        return
      }
      e.preventDefault()
  
      if (this.options.stopPropagation) {
        e.stopPropagation()
      }
  
      if (this.firstWheelOpreation) {
        this.trigger('scrollStart')
      }
      this.firstWheelOpreation = false
  
      const {speed = 20, invert = false, easeTime = 300} = this.options.mouseWheel
  
      clearTimeout(this.mouseWheelTimer)
      this.mouseWheelTimer = setTimeout(() => {
        if (!this.options.snap && !easeTime) {
          this.trigger('scrollEnd', {
            x: this.x,
            y: this.y
          })
        }
        this.firstWheelOpreation = true
      }, 400)
  
      let wheelDeltaX
      let wheelDeltaY
  
      switch (true) {
        case 'deltaX' in e:
          if (e.deltaMode === 1) {
            wheelDeltaX = -e.deltaX * speed
            wheelDeltaY = -e.deltaY * speed
          } else {
            wheelDeltaX = -e.deltaX
            wheelDeltaY = -e.deltaY
          }
          break
        case 'wheelDeltaX' in e:
          wheelDeltaX = e.wheelDeltaX / 120 * speed
          wheelDeltaY = e.wheelDeltaY / 120 * speed
          break
        case 'wheelDelta' in e:
          wheelDeltaX = wheelDeltaY = e.wheelDelta / 120 * speed
          break
        case 'detail' in e:
          wheelDeltaX = wheelDeltaY = -e.detail / 3 * speed
          break
        default:
          return
      }
  
      let direction = invert ? -1 : 1
      wheelDeltaX *= direction
      wheelDeltaY *= direction
  
      if (!this.hasVerticalScroll) {
        wheelDeltaX = wheelDeltaY
        wheelDeltaY = 0
      }
  
      let newX
      let newY
      if (this.options.snap) {
        newX = this.currentPage.pageX
        newY = this.currentPage.pageY
  
        if (wheelDeltaX > 0) {
          newX--
        } else if (wheelDeltaX < 0) {
          newX++
        }
  
        if (wheelDeltaY > 0) {
          newY--
        } else if (wheelDeltaY < 0) {
          newY++
        }
  
        this._goToPage(newX, newY)
        return
      }
  
      newX = this.x + Math.round(this.hasHorizontalScroll ? wheelDeltaX : 0)
      newY = this.y + Math.round(this.hasVerticalScroll ? wheelDeltaY : 0)
  
      this.movingDirectionX = this.directionX = wheelDeltaX > 0 ? -1 : wheelDeltaX < 0 ? 1 : 0
      this.movingDirectionY = this.directionY = wheelDeltaY > 0 ? -1 : wheelDeltaY < 0 ? 1 : 0
  
      if (newX > this.minScrollX) {
        newX = this.minScrollX
      } else if (newX < this.maxScrollX) {
        newX = this.maxScrollX
      }
  
      if (newY > this.minScrollY) {
        newY = this.minScrollY
      } else if (newY < this.maxScrollY) {
        newY = this.maxScrollY
      }
  
      const needTriggerEnd = this.y === newY
      this.scrollTo(newX, newY, easeTime, ease.swipe)
      this.trigger('scroll', {
        x: this.x,
        y: this.y
      })
      clearTimeout(this.mouseWheelEndTimer)
      if (needTriggerEnd) {
        this.mouseWheelEndTimer = setTimeout(() => {
          this.trigger('scrollEnd', {
            x: this.x,
            y: this.y
          })
        }, easeTime)
      }
    }
  }