javascript - 如何以角度显示拖放图像的预览？

Question

我正在尝试显示以角度拖放的图像的预览。

医院.component.html

<tab heading="Gallery">

          <div id="drop_zone" (drop)="dropHandler($event)" (dragover)="onDragover($event)">
            <p>drag one or more files to this dropzone</p>
            <img src="" id="imgPreview">
          </div>
</tab>

医院组件.ts

 dropHandler(ev){
    console.log("file dropped");
    ev.preventDefault();
    let dataTransfer = ev.dataTransfer.getData('data');
   this.imagepreview= <HTMLImageElement>document.getElementById('imgPreview');
    this.imagepreview.src=ev.target.result;

  }
  onDrop(event){
    event.preventDefault();
     console.log("drag and dropped file");
  }
  onDragover(event){
    event.stopPropagation();
    event.preventDefault();
  }

当我将 Image 拖放到放置区时，Image src 属性更改为http://localhost:4200/undefined。如何以角度获取选定的图像网址？