Add Battery service support to Flet

Introduces Battery service integration in Flet, including Dart and Python implementations, documentation, and example usage. Updates plugin registrants for macOS and Windows, adds battery_plus dependency, and exposes Battery-related types and events in the Python SDK.

Author: FeodorFitsner

client/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -6,6 +6,7 @@ import FlutterMacOS
 import Foundation
 
 import audioplayers_darwin
+import battery_plus
 import device_info_plus
 import file_picker
 import geolocator_apple
@@ -27,6 +28,7 @@ import window_to_front
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   AudioplayersDarwinPlugin.register(with: registry.registrar(forPlugin: "AudioplayersDarwinPlugin"))
+  BatteryPlusMacosPlugin.register(with: registry.registrar(forPlugin: "BatteryPlusMacosPlugin"))
   DeviceInfoPlusMacosPlugin.register(with: registry.registrar(forPlugin: "DeviceInfoPlusMacosPlugin"))
   FilePickerPlugin.register(with: registry.registrar(forPlugin: "FilePickerPlugin"))
   GeolocatorPlugin.register(with: registry.registrar(forPlugin: "GeolocatorPlugin"))

client/pubspec.lock

@@ -81,6 +81,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.2.1"
+  battery_plus:
+    dependency: transitive
+    description:
+      name: battery_plus
+      sha256: "03d5a6bb36db9d2b977c548f6b0262d5a84c4d5a4cfee2edac4a91d57011b365"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.2.3"
+  battery_plus_platform_interface:
+    dependency: transitive
+    description:
+      name: battery_plus_platform_interface
+      sha256: e8342c0f32de4b1dfd0223114b6785e48e579bfc398da9471c9179b907fa4910
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.1"
   boolean_selector:
     dependency: transitive
     description:
@@ -1339,6 +1355,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  upower:
+    dependency: transitive
+    description:
+      name: upower
+      sha256: cf042403154751180affa1d15614db7fa50234bc2373cd21c3db666c38543ebf
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.0"
   uri_parser:
     dependency: transitive
     description:

client/windows/flutter/generated_plugin_registrant.cc

@@ -7,6 +7,7 @@
 #include "generated_plugin_registrant.h"
 
 #include <audioplayers_windows/audioplayers_windows_plugin.h>
+#include <battery_plus/battery_plus_windows_plugin.h>
 #include <geolocator_windows/geolocator_windows.h>
 #include <media_kit_libs_windows_video/media_kit_libs_windows_video_plugin_c_api.h>
 #include <media_kit_video/media_kit_video_plugin_c_api.h>
@@ -23,6 +24,8 @@
 void RegisterPlugins(flutter::PluginRegistry* registry) {
   AudioplayersWindowsPluginRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("AudioplayersWindowsPlugin"));
+  BatteryPlusWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("BatteryPlusWindowsPlugin"));
   GeolocatorWindowsRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("GeolocatorWindows"));
   MediaKitLibsWindowsVideoPluginCApiRegisterWithRegistrar(

client/windows/flutter/generated_plugins.cmake

@@ -4,6 +4,7 @@
 
 list(APPEND FLUTTER_PLUGIN_LIST
   audioplayers_windows
+  battery_plus
   geolocator_windows
   media_kit_libs_windows_video
   media_kit_video

packages/flet/lib/src/flet_core_extension.dart

@@ -107,6 +107,7 @@ import 'flet_extension.dart';
 import 'flet_service.dart';
 import 'models/control.dart';
 import 'services/browser_context_menu.dart';
+import 'services/battery.dart';
 import 'services/clipboard.dart';
 import 'services/file_picker.dart';
 import 'services/haptic_feedback.dart';
@@ -377,6 +378,8 @@ class FletCoreExtension extends FletExtension {
         return AccelerometerService(control: control);
       case "Barometer":
         return BarometerService(control: control);
+      case "Battery":
+        return BatteryService(control: control);
       case "Clipboard":
         return ClipboardService(control: control);
       case "FilePicker":

packages/flet/lib/src/services/battery.dart

@@ -0,0 +1,64 @@
+import 'dart:async';
+
+import 'package:battery_plus/battery_plus.dart';
+import 'package:flutter/foundation.dart';
+
+import '../flet_service.dart';
+import '../utils/numbers.dart';
+
+class BatteryService extends FletService {
+  final Battery _battery = Battery();
+  StreamSubscription<BatteryState>? _stateSub;
+
+  BatteryService({required super.control});
+
+  @override
+  void init() {
+    super.init();
+    debugPrint("BatteryService(${control.id}).init");
+    control.addInvokeMethodListener(_invokeMethod);
+    _updateListeners();
+  }
+
+  @override
+  void update() {
+    _updateListeners();
+  }
+
+  Future<dynamic> _invokeMethod(String name, dynamic args) async {
+    switch (name) {
+      case "get_battery_level":
+        return _battery.batteryLevel;
+      case "get_battery_state":
+        final state = await _battery.batteryState;
+        return state.name;
+      case "is_in_battery_save_mode":
+        return _battery.isInBatterySaveMode;
+      default:
+        throw Exception("Unknown Battery method: $name");
+    }
+  }
+
+  void _updateListeners() {
+    final listenState = control.getBool("on_state_change") == true;
+    if (listenState && _stateSub == null) {
+      _stateSub = _battery.onBatteryStateChanged.listen((state) {
+        control.triggerEvent("state_change", {"state": state.name});
+      }, onError: (error) {
+        debugPrint("BatteryService: error listening to state changes: $error");
+      });
+    } else if (!listenState && _stateSub != null) {
+      _stateSub?.cancel();
+      _stateSub = null;
+    }
+  }
+
+  @override
+  void dispose() {
+    debugPrint("BatteryService(${control.id}).dispose()");
+    control.removeInvokeMethodListener(_invokeMethod);
+    _stateSub?.cancel();
+    _stateSub = null;
+    super.dispose();
+  }
+}

packages/flet/pubspec.yaml

@@ -21,6 +21,7 @@ dependencies:
     sdk: flutter
   flutter_localizations:
     sdk: flutter
+  battery_plus: ^6.2.2
   collection: ^1.19.0
   device_info_plus: ^12.1.0
   equatable: ^2.0.3

sdk/python/examples/controls/battery/basic.py

@@ -0,0 +1,43 @@
+import flet as ft
+
+
+async def main(page: ft.Page):
+    battery = ft.Battery()
+    page.services.append(battery)  # need to keep a reference to the service
+
+    info = ft.Text()
+    state_text = ft.Text()
+
+    async def refresh_info(_=None):
+        level = await battery.get_battery_level()
+        state = await battery.get_battery_state()
+        save_mode = await battery.is_in_battery_save_mode()
+        info.value = (
+            f"Level: {level}% | State: {state} | "
+            f"Battery saver: {'on' if save_mode else 'off'}"
+        )
+
+    async def on_state_change(e: ft.BatteryStateChangeEvent):
+        state_text.value = f"State changed: {e.state}"
+        await refresh_info()
+
+    battery.on_state_change = on_state_change
+
+    await refresh_info()
+
+    page.add(
+        ft.Column(
+            [
+                info,
+                ft.Row(
+                    [
+                        ft.Button("Refresh battery info", on_click=refresh_info),
+                    ]
+                ),
+                state_text,
+            ],
+        )
+    )
+
+
+ft.run(main)

sdk/python/packages/flet/docs/controls/battery.md

@@ -0,0 +1,14 @@
+---
+class_name: flet.Battery
+examples: ../../examples/controls/battery
+---
+
+{{ class_summary(class_name) }}
+
+## Examples
+
+```python
+--8<-- "{{ examples }}/basic.py"
+```
+
+{{ class_members(class_name) }}

sdk/python/packages/flet/docs/types/batterystate.md

@@ -0,0 +1 @@
+{{ class_all_options("flet.BatteryState", separate_signature=False) }}