bool isMouseDown = false;
Vector3 startPos;

public void OnPointerDown(MixedRealityPointerEventData eventData)
{
    TranslateToWebViewMouseEvent(eventData, WebViewMouseEventData.EventType.MouseDown);
    UnityEngine.Ray leftHandRay;
    bool isGetSuccess = InputRayUtils.TryGetHandRay(Microsoft.MixedReality.Toolkit.Utilities.Handedness.Right, out leftHandRay);
    if (isGetSuccess)
    {
        startPos = leftHandRay.origin;
    }
    isMouseDown = true;
}

public void OnPointerUp(MixedRealityPointerEventData eventData)
{
    TranslateToWebViewMouseEvent(eventData, WebViewMouseEventData.EventType.MouseUp);
    isMouseDown = false;
}

private void TranslateToWebViewMouseEvent(MixedRealityPointerEventData eventData, WebViewMouseEventData.EventType evenType)
{
    var hitCoord = NormalizeWorldPoint(eventData.Pointer.Result.Details.Point);

    hitCoord.x *= _webView.Width;
    hitCoord.y *= _webView.Height;

    var mouseEventsWebView = _webView as IWithMouseEvents;
    WebViewMouseEventData mouseEvent = new WebViewMouseEventData
    {
        X = (int)hitCoord.x,
        Y = (int)hitCoord.y,
        Device = WebViewMouseEventData.DeviceType.Pointer,
        Type = evenType,
        Button = WebViewMouseEventData.MouseButton.ButtonLeft,
        TertiaryAxisDeviceType = WebViewMouseEventData.TertiaryAxisDevice.PointingDevice
    };

    mouseEventsWebView.MouseEvent(mouseEvent);
}

private Vector2 NormalizeWorldPoint(Vector3 worldPoint)
{
    // Convert the world point to our control's local space.
    Vector3 localPoint = transform.InverseTransformPoint(worldPoint);

    var boundsSize = Collider.sharedMesh.bounds.size;
    var boundsExtents = Collider.sharedMesh.bounds.max;

    // Adjust the point to be based on a 0,0 origin.
    var uvTouchPoint = new Vector2((localPoint.x + boundsExtents.x), -1.0f * (localPoint.y - boundsExtents.y));

    // Normalize the point so it can be mapped to the WebView's texture.
    var normalizedPoint = new Vector2(uvTouchPoint.x / boundsSize.x, uvTouchPoint.y / boundsSize.y);

    return normalizedPoint;
}

public void OnPointerDragged(MixedRealityPointerEventData eventData) 
{
    if (isMouseDown)
    {
        UnityEngine.Ray leftHandRay;
        bool isGetSuccess = InputRayUtils.TryGetHandRay(Microsoft.MixedReality.Toolkit.Utilities.Handedness.Right, out leftHandRay);
        if (isGetSuccess)
        {
            var distance = Vector3.Distance(startPos, leftHandRay.origin);
            if (distance > 0.01)
            {
                var mouseEventsWebView = _webView as IWithMouseEvents;
                WebViewMouseEventData mouseEvent = new WebViewMouseEventData
                {
                    WheelX = 0,
                    WheelY = distance,
                    Device = WebViewMouseEventData.DeviceType.Pointer,
                    Type = WebViewMouseEventData.EventType.MouseWheel,
                    Button = WebViewMouseEventData.MouseButton.ButtonMiddle,
                    TertiaryAxisDeviceType = WebViewMouseEventData.TertiaryAxisDevice.PointingDevice
                };

                mouseEventsWebView.MouseEvent(mouseEvent);
            }
        }
    }
}