Select first tab when switching out of mobile display

src-ui/src/app/components/document-detail/document-detail.component.ts

@@ -1,8 +1,8 @@
-import { Component, OnInit } from '@angular/core';
+import { Component, OnInit, ViewChild, ElementRef } from '@angular/core';
 import { FormControl, FormGroup } from '@angular/forms';
 import { Title } from '@angular/platform-browser';
 import { ActivatedRoute, Router } from '@angular/router';
-import { NgbModal } from '@ng-bootstrap/ng-bootstrap';
+import { NgbModal, NgbNav } from '@ng-bootstrap/ng-bootstrap';
 import { PaperlessCorrespondent } from 'src/app/data/paperless-correspondent';
 import { PaperlessDocument } from 'src/app/data/paperless-document';
 import { PaperlessDocumentMetadata } from 'src/app/data/paperless-document-metadata';
@@ -48,6 +48,15 @@ export class DocumentDetailComponent implements OnInit {
     tags: new FormControl([])
   })
 
+  @ViewChild('nav') nav: NgbNav
+  @ViewChild('pdfPreview') set pdfPreview(element): void {
+    // this gets called when compontent added or removed from DOM
+    if (element && element.nativeElement.offsetParent !== null) { // its visible
+
+      setTimeout(()=> this.nav?.select(1));
+    }
+  }
+
   constructor(
     private documentsService: DocumentService,
     private route: ActivatedRoute,
@@ -170,4 +179,14 @@ export class DocumentDetailComponent implements OnInit {
   hasNext() {
     return this.documentListViewService.hasNext(this.documentId)
   }
+
+  previewCreated() {
+    console.log('Preview Created');
+
+  }
+
+  mobilePreviewCreated() {
+    console.log('Mobile Preview Created');
+
+  }
 }