Restore window placement on startup

lib/utils/loop.dart

@@ -0,0 +1,21 @@
+import 'dart:async';
+
+class Loop {
+  static final List<void Function()> _callbacks = [];
+
+  static void start() {
+    Timer.periodic(const Duration(milliseconds: 100), (timer) {
+      for(var func in _callbacks) {
+        func.call();
+      }
+    });
+  }
+
+  static void register(void Function() func) {
+    _callbacks.add(func);
+  }
+
+  static void remove(void Function() func) {
+    _callbacks.remove(func);
+  }
+}

lib/utils/window.dart

@@ -0,0 +1,64 @@
+import 'dart:convert';
+import 'dart:ui';
+import 'dart:io';
+
+import 'package:pixes/foundation/app.dart';
+import 'package:window_manager/window_manager.dart';
+
+class WindowPlacement {
+  final Rect rect;
+
+  final bool isMaximized;
+
+  const WindowPlacement(this.rect, this.isMaximized);
+
+  Future<void> applyToWindow() async {
+    await windowManager.setBounds(rect);
+
+    if (isMaximized) {
+      await windowManager.maximize();
+    }
+  }
+
+  Future<void> writeToFile() async {
+    var file = File("${App.dataPath}/window_placement");
+    await file.writeAsString(jsonEncode({
+      'width': rect.width,
+      'height': rect.height,
+      'x': rect.topLeft.dx,
+      'y': rect.topLeft.dy,
+      'isMaximized': isMaximized
+    }));
+  }
+
+  static Future<WindowPlacement> loadFromFile() async {
+    var file = File("${App.dataPath}/window_placement");
+    if (!file.existsSync()) {
+      return defaultPlacement;
+    }
+    var json = jsonDecode(await file.readAsString());
+    var rect =
+        Rect.fromLTWH(json['x'], json['y'], json['width'], json['height']);
+    return WindowPlacement(rect, json['isMaximized']);
+  }
+
+  static Future<WindowPlacement> get current async {
+    var rect = await windowManager.getBounds();
+    var isMaximized = await windowManager.isMaximized();
+    return WindowPlacement(rect, isMaximized);
+  }
+
+  static const defaultPlacement =
+      WindowPlacement(Rect.fromLTWH(10, 10, 900, 600), false);
+
+  static WindowPlacement cache = defaultPlacement;
+
+  static void loop() async {
+    var placement = await WindowPlacement.current;
+    if (placement.rect != cache.rect ||
+        placement.isMaximized != cache.isMaximized) {
+      cache = placement;
+      await placement.writeToFile();
+    }
+  }
+}