Add save and restore form size

Source/LibationWinForms/AvaloniaUI/FormSaveExtension2.cs

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+using System.Linq;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
+using LibationFileManager;
+
+namespace LibationWinForms.AvaloniaUI
+{
+	public static class FormSaveExtension2
+	{
+		static readonly WindowIcon WindowIcon;
+		static FormSaveExtension2()
+		{
+			if (Application.Current.ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+				WindowIcon = desktop.MainWindow.Icon;
+			else
+				WindowIcon = null;
+		}
+
+		public static void SetLibationIcon(this Window form)
+		{
+			form.Icon = WindowIcon;
+		}
+
+		public static void RestoreSizeAndLocation(this Window form, Configuration config)
+		{
+			FormSizeAndPosition savedState = config.GetNonString<FormSizeAndPosition>(form.Name);
+
+			if (savedState is null)
+				return;
+
+			// too small -- something must have gone wrong. use defaults
+			if (savedState.Width < form.MinWidth || savedState.Height < form.MinHeight)
+			{
+				savedState.Width = (int)form.Width;
+				savedState.Height = (int)form.Height;
+			}
+
+			// Fit to the current screen size in case the screen resolution changed since the size was last persisted
+			if (savedState.Width > form.Screens.Primary.WorkingArea.Width)
+				savedState.Width = form.Screens.Primary.WorkingArea.Width;
+			if (savedState.Height > form.Screens.Primary.WorkingArea.Height)
+				savedState.Height = form.Screens.Primary.WorkingArea.Height;
+
+			var rect = new PixelRect(savedState.X, savedState.Y, savedState.Width, savedState.Height);
+
+			form.Width = savedState.Width;
+			form.Height = savedState.Height;
+
+			// is proposed rect on a screen?
+			if (form.Screens.All.Any(screen => screen.WorkingArea.Contains(rect)))
+			{
+				form.WindowStartupLocation = WindowStartupLocation.Manual;
+				form.Position = new PixelPoint(savedState.X, savedState.Y);
+			}
+			else
+			{
+				form.WindowStartupLocation = WindowStartupLocation.CenterScreen;
+			}
+
+			// FINAL: for Maximized: start normal state, set size and location, THEN set max state
+			form.WindowState = savedState.IsMaximized ? WindowState.Maximized : WindowState.Normal;
+		}
+		public static void SaveSizeAndLocation(this Window form, Configuration config)
+		{
+			var saveState = new FormSizeAndPosition();
+
+			saveState.IsMaximized = form.WindowState == WindowState.Maximized;
+
+			// restore normal state to get real window size.
+			if (form.WindowState != WindowState.Normal)
+			{
+				form.WindowState = WindowState.Normal;
+			}
+
+			saveState.X = form.Position.X;
+			saveState.Y = form.Position.Y;
+
+			saveState.Width = (int)form.Bounds.Size.Width;
+			saveState.Height = (int)form.Bounds.Size.Height;
+
+			config.SetObject(form.Name, saveState);
+		}
+
+		class FormSizeAndPosition
+		{
+			public int X;
+			public int Y;
+			public int Height;
+			public int Width;
+			public bool IsMaximized;
+		}
+	}
+}