Added in-app fileviewer for images and pdf files

lib/widget/fileViewer.dart

@@ -0,0 +1,66 @@
+import 'dart:io';
+
+import 'package:better_open_file/better_open_file.dart';
+import 'package:flutter/material.dart';
+import 'package:photo_view/photo_view.dart';
+import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';
+
+import 'confirmDialog.dart';
+import 'placeholderView.dart';
+
+class FileViewer extends StatelessWidget {
+  final String path;
+  final bool openExternal;
+  const FileViewer({super.key, required this.path, this.openExternal = false});
+
+
+  @override
+  Widget build(BuildContext context) {
+    AppBar appbar = AppBar(
+      title: Text(path.split("/").last),
+      actions: [
+        IconButton(onPressed: () => ConfirmDialog(
+          title: "Extern öffnen",
+          content: "Möchtest du die Datei mit dem Systemdialog öffnen?",
+          onConfirm: () => Navigator.of(context).push(MaterialPageRoute(builder: (context) => FileViewer(path: path, openExternal: true))),
+          confirmButton: "Öffnen",
+        ).asDialog(context), icon: const Icon(Icons.open_in_new))
+      ],
+    );
+    switch(openExternal ? "x" : path.split(".").last) {
+      case "png":
+      case "jpg":
+      case "jpeg":
+        return Scaffold(
+            appBar: appbar,
+            backgroundColor: Colors.white,
+            body: PhotoView(
+              imageProvider: Image.file(File(path)).image,
+              backgroundDecoration: const BoxDecoration(color: Colors.white60),
+            )
+        );
+
+
+      case "pdf":
+        return Scaffold(
+          appBar: appbar,
+          body: SfPdfViewer.file(
+            File(path),
+          ),
+        );
+
+      default:
+        OpenFile.open(path).then((result) {
+          Navigator.of(context).pop();
+          if(result.type != ResultType.done) {
+            showDialog(context: context, builder: (context) {
+              return AlertDialog(
+                content: Text(result.message),
+              );
+            });
+          }
+        });
+        return const PlaceholderView(text: "Datei wird extern geöffnet...", icon: Icons.open_in_new);
+    }
+  }
+}