Change the way onWheel event is handled

[obadakhalili]

• Possible addressed Issue: 805, and probably more.
• Overview:

1. Removes unnecessary onScroll event in Timeline.js.
2. Handles scrolling properly in controlled mode.
3. Synchs header and timeline.

[DarioG]

This is preventing the horizontal scroll from working. I think this can be fixed with

handleWheel = e => {
    const isHorizontalScrolling = e.wheelDeltaY === 0

    // zoom in the time dimension
    if (e.ctrlKey || e.metaKey || e.altKey) {
      e.preventDefault()
      const parentPosition = getParentPosition(e.currentTarget)
      const xPosition = e.clientX - parentPosition.x

      const speed = e.ctrlKey ? 10 : e.metaKey ? 3 : 1

      // convert vertical zoom to horiziontal
      this.props.onWheelZoom(speed, xPosition, e.deltaY)
    } else if (e.shiftKey) {
      e.preventDefault()
      // shift+scroll event from a touchpad has deltaY property populated; shift+scroll event from a mouse has deltaX
      this.props.onScroll(this.scrollComponent.scrollLeft + (e.deltaY || e.deltaX))
      // no modifier pressed? we prevented the default event, so scroll or zoom as needed
    } else if (isHorizontalScrolling) {
      e.preventDefault()
      this.props.onScroll(this.scrollComponent.scrollLeft + e.deltaX) 
      }
    }

  }

Also, this will cause performance issues, so you should consider adding window.requestAnimationFrame when calling this.props.onScroll(...)

[StoikovOleh]

Hi @DarioG, please check the pr: #834

fixed this issue it was related to the another method

[DarioG]

This was just merged. Did you guys check that the vertical scrolling is still working even with these changes?

[Ilaiwi]

@DarioG working on testing this out now then I will be merging it if all is working okay. (the merge that went though was by mistake I reverted it)
I am not sure about the issue you mentioned though. If you could explain a bit more? also, did the fix @StoikovOleh suggested work for you?

[Ilaiwi]

@DarioG you are correct this PR would break horizontal scrolling. I tried @StoikovOleh and your suggested fix but both didn't work out.