Drag and drop image with image preview in angular2+

Question

Here, is stackblitz link:- https://stackblitz.com/edit/angular6-ledera?file=app%2Fapp.component.ts

I am trying to drag an image from desktop etc directly and drop on the dropzone div.

1) get preview of the image 2) get the file object.

.html

<div *ngIf="!imageDrop" class="col-12 rmpm dropzone" appDrag>
    <div class="text-wrapper">
        <div class="centered">Drop your file here!</div>
    </div>
</div>
<!--droped image preview-->
<img  *ngIf="imageDrop" [src]="imageDrop" width="100px" height="100px">

dragDrop.directive.ts

@HostBinding("style.background") private background = "#eee";

  constructor() {}

  @HostListener("dragover", ["$event"]) public onDragOver(evt) {
    evt.preventDefault();
    evt.stopPropagation();
    this.background = "#999";
    console.log( '4444:::' + JSON.stringify(evt.target.files));
  }
  @HostListener("dragleave", ["$event"]) public onDragLeave(evt) {
    evt.preventDefault();
    evt.stopPropagation();
    this.background = "#eee";
    console.log( '222:::' + JSON.stringify(evt.target.files));
  }
  @HostListener("drop", ["$event"]) public onDrop(evt) {
    evt.preventDefault();
    evt.stopPropagation();
    let files = evt.dataTransfer.files;
    if (files.length > 0) {
      this.background = "#eee";
      console.log( '1111:::' + JSON.stringify(files));
      console.log( '33333:::' + JSON.stringify(evt.target.files));
    }
  }

Answer 1

Here is a Stackblitz demo for the file drop.

The directive handles one or multiple files being drop at once.

It triggers a files event with the file list as parameter, each file is wrapped in a FileHandle interface containing the file and a SafeUrl for the blob created with window.URL.createObjectURL(file).

export interface FileHandle {
  file: File,
  url: SafeUrl
}

@HostListener('drop', ['$event']) public onDrop(evt: DragEvent) {
  evt.preventDefault();
  evt.stopPropagation();
  this.background = '#eee';

  let files: FileHandle[] = [];
  for (let i = 0; i < evt.dataTransfer.files.length; i++) {
    const file = evt.dataTransfer.files[i];
    const url = this.sanitizer.bypassSecurityTrustUrl(window.URL.createObjectURL(file));
    files.push({ file, url });
  }
  if (files.length > 0) {
    this.files.emit(files);
  }
}

The consuming component can then display the list of images using the Url created for each file.

<div *ngFor="let file of files">
  <img *ngIf="file" [src]="file.url" width="100px" height="100px">
</div>

Hope that helps.