add FileUtilsService to provide utility methods for file operations in Angular

docs/en/UI/Angular/File-Utils-Service.md

@@ -0,0 +1,37 @@
+# File Utils Service
+FileUtilsService is an Angular service designed to provide utility methods related to file operations. The service has a `downloadBlob` function, which is used for downloading blobs as files within the context of a web application.
+
+## Usage
+
+To make use of the FileUtilsService in your Angular application, follow the steps below:
+
+Injection:
+Firstly, ensure that the service is injected into the component or any other Angular entity where you wish to use it.
+
+```js
+import { FileUtilsService } from '@abp/ng.core';
+
+constructor(private fileUtils: FileUtilsService) { }
+// or
+// private fileUtils   = inject(FileUtilsService)
+```
+
+Downloading a Blob:
+
+Once you have the service injected, you can use the downloadBlob method to initiate the download of blob data as a file. For instance:
+
+```js
+someMethod() {
+  const myBlob = new Blob(["Hello, World!"], { type: "text/plain" });
+  this.fileUtils.downloadBlob(myBlob, "hello.txt");
+}
+```
+
+Permissions & Considerations:
+
+Ensure that you have appropriate permissions and user interactions before triggering a download. Since downloadBlob initiates a download programmatically, it's best to tie this action to direct user interactions, such as button clicks, to prevent unexpected behaviors or browser restrictions.
+
+
+### DOCUMENT Token in Service
+
+Angular, being a platform-agnostic framework, is designed to support not only browser-based applications but also other environments like server-side rendering (SSR) through Angular Universal. This design philosophy introduces challenges when accessing global browser-specific objects like window or document directly. To address this, Angular provides a DOCUMENT token that can be used to inject the document object into Angular entities like components and services.

docs/en/docs-nav.json

@@ -1153,6 +1153,10 @@
                 {
                   "text": "Content Security Strategy",
                   "path": "UI/Angular/Content-Security-Strategy.md"
+                },
+                {
+                  "text":"File Utils Service",
+                  "path":"UI/Angular/File-Utils-Service.md"
                 }
               ]
             },

npm/ng-packs/packages/core/src/lib/services/file-utils.service.ts

@@ -0,0 +1,29 @@
+import { Injectable, inject } from '@angular/core';
+import { DOCUMENT } from '@angular/common';
+
+@Injectable({
+  providedIn: 'root',
+})
+export class FileUtilsService {
+  protected readonly document = inject(DOCUMENT);
+  get window() {
+    return this.document.defaultView;
+  }
+  downloadBlob(blob: Blob, fileName: string) {
+    const blobUrl = this.window.URL.createObjectURL(blob);
+    const a = this.document.createElement('a');
+    a.style.display = 'none';
+    a.href = blobUrl;
+    a.download = fileName;
+    this.document.body.appendChild(a);
+    a.dispatchEvent(
+      new MouseEvent('click', {
+        bubbles: true,
+        cancelable: true,
+        view: this.window,
+      }),
+    );
+    this.window.URL.revokeObjectURL(blobUrl);
+    this.document.body.removeChild(a);
+  }
+}

npm/ng-packs/packages/core/src/lib/services/index.ts

@@ -21,3 +21,4 @@ export * from './track-by.service';
 export * from './local-storage.service';
 export * from './window.service';
 export * from './internet-connection-service'
+export * from './file-utils.service'