[url_launcher] Add an inAppBrowserView mode (#5205)

Platform interface portion of https://github.com/flutter/packages/pull/5155. Adds the `inAppBrowserView` launch mode, as well as the `supportsMode` and `supportsCloseForMode` support query APIs.

packages/url_launcher/url_launcher_platform_interface/CHANGELOG.md

@@ -1,3 +1,11 @@
+## 2.2.0
+
+* Adds a new `inAppBrowserView` launch mode, to distinguish in-app browser
+  views (such as Android Custom Tabs or SFSafariViewController) from simple
+  web views.
+* Adds `supportsMode` and `supportsCloseForMode` to query platform support for
+  launching and closing with various modes.
+
 ## 2.1.5
 
 * Updates documentation to mention support for Android Custom Tabs.

packages/url_launcher/url_launcher_platform_interface/lib/src/types.dart

@@ -13,9 +13,13 @@ enum PreferredLaunchMode {
   /// implementation.
   platformDefault,
 
-  /// Loads the URL in an in-app web view (e.g., Android Custom Tabs, Safari View Controller).
+  /// Loads the URL in an in-app web view (e.g., Android WebView).
   inAppWebView,
 
+  /// Loads the URL in an in-app browser view (e.g., Android Custom Tabs,
+  /// SFSafariViewController).
+  inAppBrowserView,
+
   /// Passes the URL to the OS to be handled by another application.
   externalApplication,
 

packages/url_launcher/url_launcher_platform_interface/lib/src/url_launcher_platform.dart

@@ -9,6 +9,7 @@ import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import '../link.dart';
 import '../method_channel_url_launcher.dart';
 import '../url_launcher_platform_interface.dart';
+import 'types.dart';
 
 /// The interface that implementations of url_launcher must implement.
 ///
@@ -72,6 +73,7 @@ abstract class UrlLauncherPlatform extends PlatformInterface {
   Future<bool> launchUrl(String url, LaunchOptions options) {
     final bool isWebURL = url.startsWith('http:') || url.startsWith('https:');
     final bool useWebView = options.mode == PreferredLaunchMode.inAppWebView ||
+        options.mode == PreferredLaunchMode.inAppBrowserView ||
         (isWebURL && options.mode == PreferredLaunchMode.platformDefault);
 
     return launch(
@@ -87,8 +89,31 @@ abstract class UrlLauncherPlatform extends PlatformInterface {
     );
   }
 
-  /// Closes the WebView, if one was opened earlier by [launch].
+  /// Closes the web view, if one was opened earlier by [launchUrl].
+  ///
+  /// This will only work if the launch mode (the actual launch mode used,
+  /// not the requested launch mode, which may not match if [supportsMode] is
+  /// false for the requested mode) was one for which [supportsCloseForMode]
+  /// returns true.
   Future<void> closeWebView() {
     throw UnimplementedError('closeWebView() has not been implemented.');
   }
+
+  /// Returns true if the given launch mode is supported by the current
+  /// implementation.
+  ///
+  /// Clients are not required to query this, as implementations are strongly
+  /// encouraged to automatically fall back to other modes if a launch is
+  /// requested using an unsupported mode (matching historical behavior of the
+  /// plugin, and thus maximizing compatibility with existing code).
+  Future<bool> supportsMode(PreferredLaunchMode mode) {
+    return Future<bool>.value(mode == PreferredLaunchMode.platformDefault);
+  }
+
+  /// Returns true if the given launch mode can be closed with [closeWebView].
+  Future<bool> supportsCloseForMode(PreferredLaunchMode mode) {
+    // This is the historical documented behavior, so default to that for
+    // compatibility.
+    return Future<bool>.value(mode == PreferredLaunchMode.inAppWebView);
+  }
 }

packages/url_launcher/url_launcher_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/packages/tree/main/packages/url_launcher/
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+url_launcher%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 2.1.5
+version: 2.2.0
 
 environment:
   sdk: ">=2.19.0 <4.0.0"

packages/url_launcher/url_launcher_platform_interface/test/url_launcher_platform_test.dart

@@ -118,4 +118,55 @@ void main() {
     expect(launcher.headers['foo'], 'bar');
     expect(launcher.webOnlyWindowName, 'a_name');
   });
+
+  test('supportsMode defaults to true for platform default', () async {
+    final UrlLauncherPlatform launcher = CapturingUrlLauncher();
+
+    expect(
+        await launcher.supportsMode(PreferredLaunchMode.platformDefault), true);
+  });
+
+  test('supportsMode defaults to false for all specific values', () async {
+    final UrlLauncherPlatform launcher = CapturingUrlLauncher();
+
+    expect(await launcher.supportsMode(PreferredLaunchMode.externalApplication),
+        false);
+    expect(
+        await launcher
+            .supportsMode(PreferredLaunchMode.externalNonBrowserApplication),
+        false);
+    expect(await launcher.supportsMode(PreferredLaunchMode.inAppBrowserView),
+        false);
+    expect(
+        await launcher.supportsMode(PreferredLaunchMode.inAppWebView), false);
+  });
+
+  test('supportsCloseForMode defaults to true for in-app web views', () async {
+    final UrlLauncherPlatform launcher = CapturingUrlLauncher();
+
+    expect(
+        await launcher.supportsCloseForMode(PreferredLaunchMode.inAppWebView),
+        true);
+  });
+
+  test('supportsCloseForMode defaults to false for all other values', () async {
+    final UrlLauncherPlatform launcher = CapturingUrlLauncher();
+
+    expect(
+        await launcher
+            .supportsCloseForMode(PreferredLaunchMode.externalApplication),
+        false);
+    expect(
+        await launcher.supportsCloseForMode(
+            PreferredLaunchMode.externalNonBrowserApplication),
+        false);
+    expect(
+        await launcher
+            .supportsCloseForMode(PreferredLaunchMode.inAppBrowserView),
+        false);
+    expect(
+        await launcher
+            .supportsCloseForMode(PreferredLaunchMode.platformDefault),
+        false);
+  });
 }