背景图像未显示在 Angular 中

Question

Yes, I did search and found many examples, but none worked for me. I am not sure what am I doing wrong. Need help!

I can see the image if I put in <img> tag, but not when I put as background-image . But I can see the binary image when I do inspect element.

Tried doing an example in stackblitz https://stackblitz.com/edit/display-image-from-rest-api-qpnspq?embed=1&file=src/app/app.component.ts

HTML:

 <!-- This works -->
 <div class="row" style="max-width: 100%; margin-left: 1px;" >
     <img id="dashboardImage" [src]='imageBlobDataUrl' height='500' width='500' />
 </div>

 <!-- This does NOT works -->
<div class="row" style="max-width: 100%; margin-left: 1px;" [style.background-image]="image"> </div>

TS:

    @Input() imageBlobDataUrl: any;
    selectedImage: QiImage = new QiImage();

    public header:SafeHtml;
    public content:SafeHtml[];
    public image:SafeStyle;

  constructor(
          private qiImageService: QiImageService,
          private sanitizer: DomSanitizer,
          private imageService: ImageService
  ) {}
  populateImageDetails(lineId, bitmapFileName) {
      this.imageService
          .populateImageDetails(lineId, bitmapFileName)
              .subscribe( (selectedImage : any) => {
                  this.selectedImage = selectedImage;
                  //let TYPED_ARRAY = new Uint8Array(selectedImage.imageData);
                  //const STRING_CHAR = String.fromCharCode.apply(null, TYPED_ARRAY);
                  //let base64String = btoa(STRING_CHAR);
                  let objectURL = 'data:image/png;base64,' + selectedImage.imageData;
                  this.imageBlobDataUrl = this.sanitizer.bypassSecurityTrustUrl(objectURL);
                  this.image = this.sanitizer.bypassSecurityTrustStyle(`url(${objectURL})`);
              });
  }

Answer 1

You can just put the URL image on src even if it's on base64

 <img id="dashboardImage" [src]='objectURL' height='500' width='500' />

Answer 2

if you try to set the background image using CSS? like this:

.bg {
  background-image: url("../../yourimage");
  height: 100%;
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
  display: flex;
  justify-content: center;
  align-items: center;

}

In the template you can use the binding to set the css class as you like

Answer 3

It works fine when i tried your stackblitz . You need to Fix CSS to get the image displayed on view.

Do not use bypassSecurityTrustUrl for Style Url. So the below for thumbnail is not valid:

this.thumbnail = this.sanitizer.bypassSecurityTrustUrl(objectURL); // Do NOT Use

this.image = this.sanitizer.bypassSecurityTrustStyle(`url(${objectURL})`); // This works fine and is Valid

Try to adjust the CSS position for your image and it will show up:

<div class="row" 
  style="width: 100%; height: 100%; position:absolute; 
  margin-left: 1px;  background-repeat: no-repeat;" 
  [style.background-image]="image"> </div>