Magic Device

Device signals for Flutter apps: whether the device is on mains power, whether the viewer is away, and the macOS window fullscreen state.

Alpha: magic_device is under active development. APIs may change between minor versions until 1.0.0.

Install

flutter pub add magic_device

DevicePower needs no setup. WindowFullscreen registers its own macOS plugin, so a macOS host needs no edit to its Runner either.

DevicePower

Two hardware signals a background job can gate on: whether the device draws from the mains, and whether the viewer has been away long enough that the work would not disturb them.

import 'package:magic_device/magic_device.dart';

final DevicePower power = DevicePower(television: () => isTelevision);
power.start();

if (await power.charging && power.idle) {
  // Safe to run the heavy job.
}

power.stop();

Signal	Meaning
charging	On mains power. full, charging and connectedNotCharging count; discharging and unknown do not. A platform with no battery implementation answers false.
idle	Away for at least DevicePower.idleThreshold (2 minutes). macOS and Windows read the system-wide last-input clock every pollInterval (30 seconds); every other platform reports idle whenever the app is not in front, read from the current lifecycle state at start() and followed from there.

Nothing is collected until start(), and stop() forgets both answers.

Televisions

A batteryless Android TV reports unknown, which would read as not charging forever. Pass a television predicate and charging answers true without asking the platform. The default is () => false.

Testing

Every platform read is a constructor parameter: batteryState, idleDuration, platform and television.

WindowFullscreen

Whether the macOS window is fullscreen, and the one call that flips it. The package's macOS plugin registers the magic_device/window channel itself, so the host's MainFlutterWindow.swift stays Flutter's stock one.

import 'package:magic_device/magic_device.dart';

final WindowFullscreen fullscreen = WindowFullscreen.instance;
fullscreen.addListener(() => setState(() {}));

if (fullscreen.available) {
  await fullscreen.toggle();
}

Reading	Meaning
available	True on macOS only. Everywhere else toggle() sends nothing, so gate the control on it.
active	Fullscreen, as the window last confirmed (AppKit's did-notification).
target	Fullscreen or on its way there: moves on the will-notification, so a layout can animate with the window.
transitioning	Between the two: the window's size changes on every frame.

The state follows the window, not the calls: the green button, Esc and the Window menu notify listeners just as toggle() does, and a window that opens already fullscreen is read once on first use.

toggle() is ignored while a press or an animation is under way, so a double press cannot undo itself. It throws a PlatformException (no_window) when the Flutter view is not in a window, and that refusal releases the press. AppKit silently ignores the call for an app that is not frontmost; when the window posts nothing within WindowFullscreen.pressTimeout (1 second), the press ends and the window's state is read again.

Use the one instance: the channel takes one handler. A view adds and removes a listener and never disposes it. A test calls WindowFullscreen.resetInstance() in tearDown.

The example/ app toggles the window from a button and logs each notification in order.

Dependencies

battery_plus for the battery state (one Battery() per process, held by DevicePower) and flutter_inactive_timer for the desktop idle clock, loaded through a conditional export so dart:ffi never reaches the web compiler. The web has no system-wide input clock. WindowFullscreen uses the Flutter SDK only.