[cross_file] [web] Separate "Save As" implementation details from XFile web class

packages/cross_file/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.3.6
+
+* Separate "Save As" implementation details from XFile web class.
+
 ## 0.3.5
 
 * Fixes a bug where the bytes of an XFile, that is created using the `XFile.fromData` constructor, are ignored on web.

packages/cross_file/lib/src/types/html.dart

@@ -7,7 +7,6 @@ import 'dart:convert';
 import 'dart:js_interop';
 import 'dart:typed_data';
 
-import 'package:meta/meta.dart';
 import 'package:web/web.dart';
 
 import '../web_helpers/web_helpers.dart';
@@ -35,11 +34,9 @@ class XFile extends XFileBase {
     int? length,
     Uint8List? bytes,
     DateTime? lastModified,
-    @visibleForTesting CrossFileTestOverrides? overrides,
   }) : _mimeType = mimeType,
        _path = path,
        _length = length,
-       _overrides = overrides,
        _lastModified = lastModified ?? DateTime.fromMillisecondsSinceEpoch(0),
        _name = name ?? '',
        super(path) {
@@ -57,10 +54,8 @@ class XFile extends XFileBase {
     int? length,
     DateTime? lastModified,
     String? path,
-    @visibleForTesting CrossFileTestOverrides? overrides,
   }) : _mimeType = mimeType,
        _length = length,
-       _overrides = overrides,
        _lastModified = lastModified ?? DateTime.fromMillisecondsSinceEpoch(0),
        _name = name ?? '',
        super(path) {
@@ -82,12 +77,16 @@ class XFile extends XFileBase {
 
   // MimeType of the file (eg: "image/gif").
   final String? _mimeType;
+
   // Name (with extension) of the file (eg: "anim.gif")
   final String _name;
+
   // Path of the file (must be a valid Blob URL, when set manually!)
   late String _path;
+
   // The size of the file (in bytes).
   final int? _length;
+
   // The time the file was last modified.
   final DateTime _lastModified;
 
@@ -97,17 +96,6 @@ class XFile extends XFileBase {
   // (Similar to a (read-only) dart:io File.)
   Blob? _browserBlob;
 
-  // An html Element that will be used to trigger a "save as" dialog later.
-  // TODO(dit): https://github.com/flutter/flutter/issues/91400 Remove this _target.
-  late Element _target;
-
-  // Overrides for testing
-  // TODO(dit): https://github.com/flutter/flutter/issues/91400 Remove these _overrides,
-  // they're only used to Save As...
-  final CrossFileTestOverrides? _overrides;
-
-  bool get _hasTestOverrides => _overrides != null;
-
   @override
   String? get mimeType => _mimeType;
 
@@ -203,37 +191,8 @@ class XFile extends XFileBase {
 
   /// Saves the data of this CrossFile at the location indicated by path.
   /// For the web implementation, the path variable is ignored.
-  // TODO(dit): https://github.com/flutter/flutter/issues/91400
-  // Move implementation to web_helpers.dart
   @override
   Future<void> saveTo(String path) async {
-    // Create a DOM container where the anchor can be injected.
-    _target = ensureInitialized('__x_file_dom_element');
-
-    // Create an <a> tag with the appropriate download attributes and click it
-    // May be overridden with CrossFileTestOverrides
-    final HTMLAnchorElement element =
-        _hasTestOverrides
-            ? _overrides!.createAnchorElement(this.path, name)
-                as HTMLAnchorElement
-            : createAnchorElement(this.path, name);
-
-    // Clear the children in _target and add an element to click
-    while (_target.children.length > 0) {
-      _target.removeChild(_target.children.item(0)!);
-    }
-    addElementToContainerAndClick(_target, element);
+    await saveFileAs(this, path);
   }
 }
-
-/// Overrides some functions to allow testing
-// TODO(dit): https://github.com/flutter/flutter/issues/91400
-// Move this to web_helpers_test.dart
-@visibleForTesting
-class CrossFileTestOverrides {
-  /// Default constructor for overrides
-  CrossFileTestOverrides({required this.createAnchorElement});
-
-  /// For overriding the creation of the file input element.
-  Element Function(String href, String suggestedName) createAnchorElement;
-}

packages/cross_file/lib/src/web_helpers/web_helpers.dart

@@ -3,6 +3,14 @@
 // found in the LICENSE file.
 
 import 'package:web/web.dart';
+import '../types/html.dart';
+
+/// Type definition for function that creates anchor elements
+typedef CreateAnchorElement =
+    HTMLAnchorElement Function(String href, String? suggestedName);
+
+/// Override for creating anchor elements for testing purposes
+CreateAnchorElement? anchorElementOverride;
 
 /// Create anchor element with download attribute
 HTMLAnchorElement createAnchorElement(String href, String? suggestedName) =>
@@ -35,3 +43,23 @@ Element ensureInitialized(String id) {
 bool isSafari() {
   return window.navigator.vendor == 'Apple Computer, Inc.';
 }
+
+/// Saves the given [XFile] to user's device ("Save As" dialog).
+Future<void> saveFileAs(XFile file, String path) async {
+  // Create container element.
+  final Element target = ensureInitialized('__x_file_dom_element');
+
+  // Create <a> element.
+  final HTMLAnchorElement element =
+      anchorElementOverride != null
+          ? anchorElementOverride!(file.path, file.name)
+          : createAnchorElement(file.path, file.name);
+
+  // Clear existing children before appending new one.
+  while (target.children.length > 0) {
+    target.removeChild(target.children.item(0)!);
+  }
+
+  // Add and click.
+  addElementToContainerAndClick(target, element);
+}

packages/cross_file/pubspec.yaml

@@ -2,7 +2,7 @@ name: cross_file
 description: An abstraction to allow working with files across multiple platforms.
 repository: https://github.com/flutter/packages/tree/main/packages/cross_file
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+cross_file%22
-version: 0.3.5
+version: 0.3.6
 
 environment:
   sdk: ^3.7.0

packages/cross_file/test/x_file_html_test.dart

@@ -10,6 +10,7 @@ import 'dart:js_interop';
 import 'dart:typed_data';
 
 import 'package:cross_file/cross_file.dart';
+import 'package:cross_file/src/web_helpers/web_helpers.dart' as helpers;
 import 'package:test/test.dart';
 import 'package:web/web.dart' as html;
 
@@ -147,15 +148,9 @@ void main() {
         final html.HTMLAnchorElement mockAnchor =
             html.document.createElement('a') as html.HTMLAnchorElement;
 
-        final CrossFileTestOverrides overrides = CrossFileTestOverrides(
-          createAnchorElement: (_, __) => mockAnchor,
-        );
+        helpers.anchorElementOverride = (_, __) => mockAnchor;
 
-        final XFile file = XFile.fromData(
-          bytes,
-          name: textFile.name,
-          overrides: overrides,
-        );
+        final XFile file = XFile.fromData(bytes, name: textFile.name);
 
         bool clicked = false;
         mockAnchor.onClick.listen((html.MouseEvent event) => clicked = true);