Auto resizing floating window on startup

source/Components/AvalonDock/Controls/LayoutFloatingWindowControl.cs

@@ -233,6 +233,8 @@ internal void AttachDrag(bool onActivated = true)
 			}
 		}
 
+        internal Thickness TotalMargin { get; private set; }
+        private bool _foundMargin = false;
 		protected virtual IntPtr FilterMessage(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
 		{
 			handled = false;
@@ -248,7 +250,9 @@ protected virtual IntPtr FilterMessage(IntPtr hwnd, int msg, IntPtr wParam, IntP
 							handled = true;
 						}
 					}
-					break;
+                    UpdateWindowsSizeBasedOnMinSize();
+
+                    break;
 				case Win32Helper.WM_EXITSIZEMOVE:
 					UpdatePositionAndSizeOfPanes();
 
@@ -283,7 +287,54 @@ protected virtual IntPtr FilterMessage(IntPtr hwnd, int msg, IntPtr wParam, IntP
 			return IntPtr.Zero;
 		}
 
-		internal void InternalClose(bool closeInitiatedByUser = false)
+        private void UpdateMargins()
+        {
+            var grid = this.GetChildrenRecursive()
+                .OfType<Grid>()
+                .FirstOrDefault(g => g.RowDefinitions.Count > 0);
+            if (grid != null)
+			{
+				_foundMargin = true;
+				var margin = grid.Margin;
+                margin.Top = grid.RowDefinitions[0].MinHeight + grid.Margin.Top;
+                TotalMargin =  margin;
+            }
+        }
+
+        private void UpdateWindowsSizeBasedOnMinSize()
+        {
+            if (!_foundMargin)
+            {
+                UpdateMargins();
+                if (_foundMargin)
+                {
+                    ContentPresenter contentControl = this.GetChildrenRecursive()
+                        .OfType<ContentPresenter>()
+                        .FirstOrDefault(c => c.Content is LayoutContent);
+                    if (contentControl == null)
+                        return;
+                    var layoutContent = (LayoutContent)contentControl.Content;
+                    if (layoutContent.Content is FrameworkElement content)
+                    {
+                        var parent = VisualTreeHelper.GetParent(content) as FrameworkElement;
+                        // StackPanels among others have an ActualHeight larger than visible, hence we check the parent control as well
+                        if (content.ActualHeight < content.MinHeight ||
+							 parent != null && parent.ActualHeight < content.MinHeight)
+                        {
+                            Height = content.MinHeight + TotalMargin.Top + TotalMargin.Bottom;
+                        }
+
+                        if (content.ActualWidth < content.MinWidth ||
+                             parent != null && parent.ActualWidth < content.MinWidth)
+                        {
+                            Width = content.MinWidth + TotalMargin.Left + TotalMargin.Right;
+                        }
+                    }
+                }
+            }
+        }
+
+        internal void InternalClose(bool closeInitiatedByUser = false)
 		{
 			_internalCloseFlag = !closeInitiatedByUser;
 			if (_isClosing) return;

source/Components/AvalonDock/VisualTreeHelperExtensions.cs

@@ -0,0 +1,40 @@
+/************************************************************************
+   AvalonDock
+
+   Copyright (C) 2020 ????
+
+   This program is provided to you under the terms of the Microsoft Public
+   License (Ms-PL) as published at https://opensource.org/licenses/MS-PL
+ ************************************************************************/
+
+using System.Collections.Generic;
+using System.Windows;
+using System.Windows.Media;
+
+namespace AvalonDock
+{
+    internal static class VisualTreeHelperExtensions
+    {
+        public static IEnumerable<DependencyObject> GetChildrenRecursive(this DependencyObject dependencyObject)
+        {
+            var children = dependencyObject.GetChildren();
+            foreach (var child in children)
+            {
+                yield return child;
+                foreach (var c in GetChildrenRecursive(child))
+                {
+                    yield return c;
+                }
+            }
+        }
+
+        public static IEnumerable<DependencyObject> GetChildren(this DependencyObject dependencyObject)
+        {
+            int n = VisualTreeHelper.GetChildrenCount(dependencyObject);
+            for (int i = 0; i < n; i++)
+            {
+                yield return VisualTreeHelper.GetChild(dependencyObject, i);
+            }
+        }
+    }
+}

source/TestApp/MainWindow.xaml

@@ -54,6 +54,7 @@
 			<MenuItem Header="Tools">
 				<MenuItem Click="OnShowWinformsWindow" Header="WinForms Window" />
 				<MenuItem Click="OnShowToolWindow1" Header="Tool Window1" />
+				<MenuItem Click="OnNewFloatingWindow" Header="New floating window"/>
 			</MenuItem>
 		</Menu>
 
@@ -108,7 +109,7 @@
 								Title="Tool Window 1"
 								ContentId="toolWindow1"
 								Hiding="OnToolWindow1Hiding">
-								<StackPanel>
+								<StackPanel MinHeight="1500">
 									<local:TestUserControl />
 									<TextBox Text="{Binding TestTimer, Mode=OneWay, StringFormat='Tool Window 1 Attached to Timer ->\{0\}'}" />
 								</StackPanel>

source/TestApp/MainWindow.xaml.cs

@@ -236,5 +236,17 @@ private void OnShowHeader(object sender, RoutedEventArgs e)
 		{
 			////            LayoutDocumentPane.ShowHeader = !LayoutDocumentPane.ShowHeader;
 		}
-	}
+
+        private void OnNewFloatingWindow(object sender, RoutedEventArgs e)
+        {
+            var view = new TestUserControl();
+            var anchorable = new LayoutAnchorable()
+            {
+                Title = "New floating window",
+				Content = view
+			};
+            anchorable.AddToLayout(dockManager,AnchorableShowStrategy.Most);
+            anchorable.Float();
+        }
+    }
 }

source/TestApp/TestUserControl.xaml

@@ -13,6 +13,7 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
              mc:Ignorable="d" 
+             MinHeight="300" MinWidth="300"
              Height="300" Width="300">
     <Grid>