message: opimize picker click and select
diff: @@ -5,7 +5,8 @@ import {
  tap,
  click,
  style,
  - offset
  + offset,
  + offsetToBody
  } from '../util/dom'
  import { ease } from '../util/ease'
  import { momentum } from '../util/momentum'
  @@ -341,7 +342,7 @@ export function coreMixin(BScroll) {
  if (this.options.wheel) {
  if (this.target && this.target.className === this.options.wheel.wheelWrapperClass) {
  let index = Math.abs(Math.round(this.y / this.itemHeight))
  - let _offset = Math.round((this.pointY + offset(this.target).top - this.itemHeight / 2) / this.itemHeight)
  + let _offset = Math.round((this.pointY + offsetToBody(this.wrapper).top - this.wrapperHeight / 2) / this.itemHeight)
  this.target = this.items[index + _offset]
  }
  this.scrollToElement(this.target, this.options.wheel.adjustTime || 400, true, true, ease.swipe)
  