d3 v5 tree is not draggable on initialization with angular 7

问题

I have encountered a weird problem i have created a D3 tree which allows me to drag only after zoom otherwise it does not.I have tried @hostListerner and event binding but those things are outside D3 event hence these events are not working properly. here is code please correct me id i am doing something wrong. Initialization of D3 tree

  displayTree() {
    d3.json("./assets/flare.json").then(data => {
      data = this.d3Object;
      this.root = d3.hierarchy(data);
      this.root.x0 = height;
      this.root.y0 = 0;
      let collapse = function(d) {
        if (d.children) {
          d._children = d.children;
          d._children.forEach(collapse);
          d.children = null;
        }
      };
      this.update(this.root);
    });
    const w = 2000;
   const treeAdjustMent=-(this.heightNew/1.3);
   let d={x:0,y:0};
   //console.log("treeAdjustMent:::"+treeAdjustMent);
    this.svg = d3
      .select("svg")
      .attr("width", width + margin.right + margin.left)
      .attr("height", this.heightNew + margin.top + margin.bottom)
      .attr("viewBox", "0 1 "  + w/0.7 + " " + this.heightNew*1.7)
      .attr("overflow", "hidden")
      .attr("padding", "50px")
      .attr("id", "zoomableOf")
      .call(this.dragHelper)
      .on("click", function(d) {
        d3.select("body")
          .selectAll("div.tooltip1")
          .remove();
      })
      .append("g")
       .attr("id", "zoomable_id")
      .attr("transform", "translate(900,"+treeAdjustMent+") scale(1.3,1.3)");
    this.treeLayout = d3.tree().size([this.widthNew, this.heightNew]);
  }

And zoom service

import { Injectable, EventEmitter } from '@angular/core';
import * as d3 from 'd3';
import {event, BaseEvent} from "d3-selection";
@Injectable({
  providedIn: 'root'
})
export class D3ZoomService {

  constructor() { }
  applyZoomableBehaviour(svgElement, containerElement) {
    let svg,g, container, zoomed, zoom;
    svg = d3.select("svg");
    svg = d3.select(svgElement);
    g=d3.select("#zoomable_id");
    //svgElement=eve.target;
    container = d3.select(containerElement);
    let duration = -1000;
    let translateX,translateY,scaleX,scaleY,scale;
    let transform;
    zoomed = () => {
   if(d3.event){
    transform = d3.event.transform;
   }else{
       try {
        transform = svgElement.attr("transform");
       } catch (error) {
           return;
       }
   }
   // var offset = svgElement.getBoundingClientRect();
    //var matrix = svgElement.getScreenCTM();
    //coord= { x: (matrix.a * offset.x) + (matrix.c * offset.y) + matrix.e - offset.left,y: (matrix.b * offset.x) + (matrix.d * offset.y) + matrix.f - offset.top};
      scaleX =  transform.x;
      scaleY =  transform.y;
       //relCoords = d3.mouse(d3.select('svg')[0]);
      //scaleY=Math.min(coord.y,ZOOM_MAX.y);
      //scaleY = coord.y; 
      g.transition().duration(duration).attr("transform", "translate(" + scaleX + "," + scaleY + ")scale(" + transform.k + ")")
      .on("end", function(){
           zoomed.call(zoom.transform, d3.zoomIdentity.translate(scaleX,scaleY).scale(transform.k))
        });
    }
    zoom = d3.zoom().on('zoom', zoomed);
    svg.call(zoom);
//return;
  }

}

来源：https://stackoverflow.com/questions/58954149/d3-v5-tree-is-not-draggable-on-initialization-with-angular-7