[BUG]: cannot use touch scroll on UI

[gawinwong]

Package version

3.1.0-exp.3

Environment

* OS: Ubuntu 18.04
* Unity version: 2020.3.3
* Graphics API: Vulkan
* Browser: chrome 102.0.5005.61

Steps To Reproduce

1. use broadcast sample
2. add scroll view on canvas
3. use webapp to receive render stream

Current Behavior

I can use mouse or wheel to scroll the the viewport, but cannot do that with touch slide on screen. I have found that this action will dispatch the event "touchmove", but cannot scroll the viewport. Whether it's the problem that Unity Input System doesn't support touch scroll or it's a bug of webapp?

Expected Behavior

No response

Anything else?

No response

[gawinwong]

Alright, it's because input system cannot process touch event. We can convert touch events to mouse events to scroll on UI. Hers is my solution, apply these changes to client/public/js/sender.js. And this can only use with one finger touch on screen.

_onTouchEvent(event) {
      // this.touchscreen.queueEvent(event, this.timeSinceStartup);
      // for (let touch of this.touchscreen.currentState.touchData) {
      //   this._queueStateEvent(touch, this.touchscreen);
      // }
    var touch = event.changedTouches[0];
    var simulatedEvent = new MouseEvent({
      touchstart: "mousedown",
      touchmove: "mousemove",
      touchend: "mouseup",
    }[event.type], {
      bubbles: true, cancelable: true, view: window, detail: 1, composed: true,
      screenX: touch.screenX, screenY: touch.screenY, clientX: touch.clientX, clientY: touch.clientY,
      ctrlKey: false, altKey: false, shiftKey: false, metaKey: false, button: 0, buttons: 1, relatedTarget: null
    });
    touch.target.dispatchEvent(simulatedEvent);
    if(event.type === "touchend") {
      // add this action to prevent jump back to previous position
      touch.target.dispatchEvent(new MouseEvent("mousedown", {}));
    }
  }

[karasusan]

memo: URS-454

[kannan-xiao4]

@gawinwong Thanks reporting issue and suggestion for improvement. We will reproduce this issue and check InputSystem bug or WebApp implementation bug. If webapp implementation bug, we refer to your solution.