问如何从Angular中将图像作为斑点发送？

EN

import { HttpClient } from "@angular/common/http";
import { Injectable } from "@angular/core";
import { Component, OnInit } from '@angular/core';



@Injectable({
    providedIn: "root"
})
export class UploadService {

    constructor(private httpClient: HttpClient) {
    }

  
    public uploadFile<T>(file: File): Observable<T> {
        let formData = new FormData();
        formData.append('file', file, file.name);

        var request = this.httpClient
            .post<T>(
                "url/to/backend/upload",
                formData
            );
        return request;

    }

}


@Component({
  selector: 'app-carga',
  templateUrl: './carga.component.html',
  template:
  `
           <input class="form-control" #fileInput type="file" [multiple]="false"/>
     <button type="button" class="btn btn-outline-success"
    (click)="uploadFile(fileInput)">Cargar</button>
  `

})
export class CargaComponent implements OnInit {

  constructor(public uploader: UploadService) {
  }

  ngOnInit(): void {
  }
  public uploadResult?: any;

  async uploadFile(fileInput: any) {
    let files: File[] = fileInput.files;
    if (files.length < 1) {
      return;
    }

    let file = files[0];
    try {

      this.uploader.uploadFile(file)
    .subscribe(result => {
      console.log(result);
      fileInput.value = null;
    },
      error => {
        console.error(error);
      })

    } catch (error) {

      console.warn("File upload failed.");
      console.error(error);

    }
  }

}

 uploadPicture(formData: FormData, code: string) {
    // /** In Angular 5, including the header Content-Type can invalidate your request */
    const headers = new HttpHeaders();
    headers.append('Content-Type', null);
    headers.append('Accept', 'application/json');
    const options =  {
        headers: headers
    };

    const url = this.xxxServiceURL + '/custom/xxx/uploadPicture/' + code;
    return this.httpClient.post(url, formData, options);
}

getBlobThumbnail(): Observable<Blob> {  
  const headers = new HttpHeaders({
    'Content-Type': 'application/json',
    'Accept': 'application/json'
  });
  return this.httpClient.post<Blob>(this.thumbnailFetchUrl,
    {
      "url": "http://acs/container/Logo.png"
    }, {headers: headers, responseType: 'blob' as 'json' });
}

imageBlobUrl: string;
getThumbnail() : void {
  this.ablobService.getBlobThumbnail()
    .subscribe(
      (val) => { 
        this.createImageFromBlob(val);
      },
      response => {
        console.log("POST in error", response);
      },
      () => {
        console.log("POST observable is now completed.");
      });
}