feature: providing a minimal launcher written in flutter for ubuntu f…

…rame (#191)

## What's new?
- Frame can now optionally support the `launcher`, which is a minimal
dock allowing the user to switch between fullscreen application

## Documentation
Ubuntu Frame's `launcher` daemon provides users with a way to navigate
between multiple applications running on a single frame instance.

### Enablement
To enable the launcher, run:

```sh
snap set ubuntu-frame launcher=true
```

### Behavior
The following specifies the behavior that you can of the launcher
daemon:

- When frame starts, the launcher will appear in the left-hand side of
the screen with a black background
- As window are opened, the launcher will display an icon that
corresponds with the application for that window
- Icons will ONLY be displayed for applications that are packaged as
snaps. The desktop files for these applications are found in the
`/var/lib/snapd/desktop` directory.
- When an icon is clicked, the corresponding window will be brought into
focus
- If a window is closed, then the icon will be removed from the launcher
- If we cannot resolve an icon for a window, then the launcher will
attempt to use the `application-x-executable` icon. If that fails, then
the icon will be missing entirely.

README.md

@@ -6,13 +6,19 @@ The foundation for many embedded graphical display implementations. `ubuntu-fram
 
 The application you choose (or provide) gets a fullscreen window (or windows) and input from touch, keyboard and mouse without needing to deal with the specific hardware.
 
+## Connections
+```sh
+snap connect ubuntu-frame:desktop-launch
+```
+
 ## Configuration
 
-There are three snap configuration options:
+There are four snap configuration options:
 
 * `daemon=[true|false]` enables the daemon (defaults to false on classic systems)
 * `config=<options for the shell>`
 * `display=<options for display layout>`
+* `launcher=[true|false]`
 
 The configuration options are described in detail in [the Ubuntu Frame reference](https://mir-server.io/docs/reference).
 

launcher/.gitignore

@@ -0,0 +1,29 @@
+# See https://www.dartlang.org/guides/libraries/private-files
+
+# Files and directories created by pub
+.dart_tool/
+.packages
+build/
+# If you're building an application, you may want to check-in your pubspec.lock
+pubspec.lock
+
+# Directory created by dartdoc
+# If you don't generate documentation locally you can remove this line.
+doc/api/
+
+# dotenv environment variables file
+.env*
+
+# Avoid committing generated Javascript files:
+*.dart.js
+*.info.json      # Produced by the --dump-info flag.
+*.js             # When generated by dart2js. Don't specify *.js if your
+                 # project includes source files written in JavaScript.
+*.js_
+*.js.deps
+*.js.map
+
+.flutter-plugins
+.flutter-plugins-dependencies
+
+linux/flutter/ephemeral

launcher/README.md

@@ -0,0 +1,21 @@
+# ubuntu-frame-launcher
+A flutter-based launcher for Ubuntu Frame.
+
+## Install
+```sh
+flutter pub get
+```
+
+## Development
+1 . Run `ubuntu-frame`:
+
+```sh
+WAYLAND_DISPLAY=wayland-98 ubuntu-frame --add-wayland-extensions zwlr_layer_shell_v1:zwlr_foreign_toplevel_manager_v1  
+```
+
+2. Run `launcher`:
+
+```sh
+cd launcher
+WAYLAND_DISPLAY=wayland-98 flutter run
+```

launcher/analysis_options.yaml

@@ -0,0 +1,29 @@
+# This file configures the analyzer, which statically analyzes Dart code to
+# check for errors, warnings, and lints.
+#
+# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
+# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
+# invoked from the command line by running `flutter analyze`.
+
+# The following line activates a set of recommended lints for Flutter apps,
+# packages, and plugins designed to encourage good coding practices.
+include: package:flutter_lints/flutter.yaml
+
+linter:
+  # The lint rules applied to this project can be customized in the
+  # section below to disable rules from the `package:flutter_lints/flutter.yaml`
+  # included above or to enable additional rules. A list of all available lints
+  # and their documentation is published at
+  # https://dart-lang.github.io/linter/lints/index.html.
+  #
+  # Instead of disabling a lint rule for the entire project in the
+  # section below, it can also be suppressed for a single line of code
+  # or a specific dart file by using the `// ignore: name_of_lint` and
+  # `// ignore_for_file: name_of_lint` syntax on the line or in the file
+  # producing the lint.
+  rules:
+    # avoid_print: false  # Uncomment to disable the `avoid_print` rule
+    # prefer_single_quotes: true  # Uncomment to enable the `prefer_single_quotes` rule
+
+# Additional information about this file can be found at
+# https://dart.dev/guides/language/analysis-options

launcher/lib/controllers/application_controller.dart

@@ -0,0 +1,84 @@
+/*
+ * Copyright © Canonical Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import 'dart:async';
+
+import 'package:logging/logging.dart';
+import 'package:ubuntu_frame_launcher/models/desktop_file.dart';
+import 'package:ubuntu_frame_launcher/models/window_event.dart';
+import 'package:ubuntu_frame_launcher/services/window_service.dart';
+
+import '../services/desktop_file_manager.dart';
+
+class ApplicationController {
+  final WindowService windowService;
+  final DesktopFileManager desktopFileManager;
+
+  final _controller = StreamController<List<DesktopFile>>.broadcast();
+  late Future<List<DesktopFile>> _installedAppFuture;
+  final _logger = Logger("ApplicationController");
+
+  ApplicationController(this.windowService, this.desktopFileManager) {
+    _installedAppFuture = _loadInstalledApplications();
+
+    windowService.watcher.listen((event) async {
+      if (event.eventType == WindowEventType.created ||
+          event.eventType == WindowEventType.removed) {
+        _controller.add(await getOpenApplications());
+      }
+    });
+  }
+
+  Future<List<DesktopFile>> _loadInstalledApplications() async {
+    final applications = await desktopFileManager.getAllDesktopFiles();
+    applications.sort((a, b) {
+      final aName = a.name?.toLowerCase() ?? '';
+      final bName = b.name?.toLowerCase() ?? '';
+      return aName.compareTo(bName);
+    });
+    return applications;
+  }
+
+  /// Returns a list of applications installed on the system. This list
+  /// is guaranteed to be sorted alphabetically by name.
+  Future<List<DesktopFile>> getInstalledApplications() async {
+    // TODO: Watch directories and dynamically reload if they change
+    return await _installedAppFuture;
+  }
+
+  void focus(DesktopFile file) {
+    final handle = windowService.getWindowById(file.id);
+    if (handle != null) {
+      handle.activate();
+      return;
+    }
+
+    _logger.shout("Unable to focus desktop file with id = ${file.id}}");
+  }
+
+  Stream<List<DesktopFile>> getOpenedAppsStream() {
+    return _controller.stream;
+  }
+
+  Future<List<DesktopFile>> getOpenApplications() async {
+    final List<DesktopFile> result = [];
+    for (final handle in windowService.getWindowList()) {
+      result.add(await desktopFileManager.resolveId(handle.getAppId()));
+    }
+
+    return result;
+  }
+}

launcher/lib/controllers/window_controller.dart

@@ -0,0 +1,38 @@
+/*
+ * Copyright © Canonical Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import 'package:ubuntu_frame_launcher/models/desktop_file.dart';
+import 'package:ubuntu_frame_launcher/services/window_handle.dart';
+
+import '../services/window_service.dart';
+
+class WindowController {
+  WindowService service;
+
+  WindowController(this.service);
+
+  WindowHandle? getWindowById(String appId) {
+    return service.getWindowById(appId);
+  }
+
+  List<WindowHandle> getWindowList() {
+    return service.getWindowList();
+  }
+
+  bool isOpen(DesktopFile file) {
+    return service.getWindowById(file.id) != null;
+  }
+}

launcher/lib/main.dart

@@ -0,0 +1,87 @@
+/*
+ * Copyright © Canonical Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import 'package:flutter/material.dart';
+import 'package:ubuntu_frame_launcher/services/wayland_window_watcher.dart';
+import 'package:ubuntu_frame_launcher/controllers/window_controller.dart';
+import 'package:ubuntu_frame_launcher/services/window_service.dart';
+import 'services/desktop_file_manager.dart';
+import 'package:get_it/get_it.dart';
+import 'views/dock.dart';
+import 'controllers/application_controller.dart';
+import 'package:logging/logging.dart';
+
+void main() async {
+  Logger.root.level = Level.ALL; // defaults to Level.INFO
+  Logger.root.onRecord.listen((record) {
+    print('${record.level.name}: ${record.time}: ${record.message}');
+  });
+
+  final logger = Logger("main");
+  logger.info("Ubuntu Frame launcher is starting");
+
+  final getIt = GetIt.instance;
+
+  // Services
+  getIt.registerLazySingleton<WindowService>(
+      () => WindowService(WaylandWindowWatcherService()));
+  getIt.registerLazySingleton<DesktopFileManager>(() => DesktopFileManager());
+
+  // Controllers
+  getIt.registerLazySingleton<ApplicationController>(() =>
+      ApplicationController(
+          getIt.get<WindowService>(), getIt.get<DesktopFileManager>()));
+  getIt.registerLazySingleton<WindowController>(
+      () => WindowController(getIt.get<WindowService>()));
+
+  runApp(const LauncherApp());
+}
+
+class LauncherApp extends StatelessWidget {
+  const LauncherApp({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      theme: ThemeData(
+          colorScheme: ColorScheme.fromSeed(seedColor: Colors.black),
+          primaryColor: Colors.black,
+          useMaterial3: true,
+          fontFamily: 'Ubuntu',
+          iconTheme: const IconThemeData(color: Colors.white, size: 20),
+          textTheme: const TextTheme(
+            bodyMedium: TextStyle(
+              color: Colors.white,
+            ),
+          )),
+      home: const Launcher(),
+    );
+  }
+}
+
+class Launcher extends StatelessWidget {
+  const Launcher({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+        body: Column(
+      mainAxisSize: MainAxisSize.min,
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: <Widget>[Dock()],
+    ));
+  }
+}