Designer: Scroll Bar and error panel

src/Windows/Perspex.Designer/AppHost/HostedAppModel.cs

@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using JetBrains.Annotations;
+
+namespace Perspex.Designer.AppHost
+{
+    public class HostedAppModel : INotifyPropertyChanged
+    {
+        private IntPtr _nativeWindowHandle;
+        private string _error;
+        private string _errorDetails;
+
+        public IntPtr NativeWindowHandle
+        {
+            get { return _nativeWindowHandle; }
+            set
+            {
+                if (value.Equals(_nativeWindowHandle)) return;
+                _nativeWindowHandle = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public string Error
+        {
+            get { return _error; }
+            private set
+            {
+                if (value == _error) return;
+                _error = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public string ErrorDetails
+        {
+            get { return _errorDetails; }
+            private set
+            {
+                if (value == _errorDetails) return;
+                _errorDetails = value;
+                OnPropertyChanged();
+            }
+        }
+
+        public void SetError(string error, string details = null)
+        {
+            Error = error;
+            ErrorDetails = details;
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        [NotifyPropertyChangedInvocator]
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}

src/Windows/Perspex.Designer/AppHost/PerspexAppHost.cs

@@ -5,10 +5,11 @@ using System.Linq;
 using System.Reflection;
 using System.Text;
 using System.Threading;
-using System.Threading.Tasks;
-using System.Windows.Data;
 using System.Windows.Forms;
+using System.Windows.Forms.Integration;
+using System.Xml;
 using Perspex.Designer.Comm;
+using Perspex.Designer.InProcDesigner;
 using Perspex.Designer.Metadata;
 using Timer = System.Windows.Forms.Timer;
 
@@ -21,8 +22,9 @@ namespace Perspex.Designer.AppHost
         private string _lastXaml;
         private string _currentXaml;
         private Func<Stream, object> _xamlReader;
-        private WindowHost _host;
         private bool _initSuccess;
+        private HostedAppModel _appModel = new HostedAppModel();
+        private Control _window;
 
         public PerspexAppHost(CommChannel channel)
         {
@@ -222,17 +224,47 @@ namespace Perspex.Designer.AppHost
                 LookupType("OmniXaml.XamlLoader").GetConstructors().First().Invoke(new object[] {xamlFactory});
 
             _xamlReader = (stream) => xamlLoader.Load(stream);
-            _host = new WindowHost();
+
+            _window = new Control
+            {
+                Controls =
+                {
+                    new ElementHost()
+                    {
+                        Child = new InProcDesignerView(_appModel),
+                        Dock = DockStyle.Fill
+                    }
+                }
+            };
+            _window.CreateControl();
+            
             new Timer {Interval = 10, Enabled = true}.Tick += delegate
             {
                 dispatcher.RunJobs();
             };
             new Timer {Interval = 200, Enabled = true}.Tick += delegate { XamlUpdater(); };
-            _comm.SendMessage(new WindowCreatedMessage(_host.Handle));
+            _comm.SendMessage(new WindowCreatedMessage(_window.Handle));
             _initSuccess = true;
         }
 
 
+        bool ValidateXml(string xml)
+        {
+            try
+            {
+                var rdr = new XmlTextReader(new StringReader(xml));
+                while (rdr.Read())
+                {
+                    
+                }
+            }
+            catch
+            {
+                return false;
+            }
+            return true;
+        }
+
         void XamlUpdater()
         {
             if (!_initSuccess)
@@ -240,6 +272,14 @@ namespace Perspex.Designer.AppHost
             if(_lastXaml == _currentXaml)
                 return;
             _lastXaml = _currentXaml;
+
+            if (!ValidateXml(_currentXaml))
+            {
+                _appModel.SetError("Invalid markup");
+                return;
+            }
+
+
             try
             {
                 const string windowType = "Perspex.Controls.Window";
@@ -254,13 +294,13 @@ namespace Perspex.Designer.AppHost
 
 
                 var hWnd = (IntPtr)window.PlatformImpl.Handle;
-                _host.SetWindow(hWnd);
+                _appModel.NativeWindowHandle = hWnd;
                 window.Show();
+                _appModel.SetError(null);
             }
             catch (Exception e)
             {
-                _host.SetWindow(IntPtr.Zero);
-                _host.PlaceholderText = e.ToString();
+                _appModel.SetError("XAML load error", e.ToString());
             }
         }
 

src/Windows/Perspex.Designer/AppHost/WindowHost.cs

@@ -9,29 +9,58 @@ using System.Windows.Forms;
 
 namespace Perspex.Designer.AppHost
 {
-    class WindowHost : Control
+    class WindowHost : UserControl
     {
         public WindowHost()
         {
-            BackColor = Color.AliceBlue;
-            _textBox = new TextBox {Dock = DockStyle.Fill, ReadOnly = true, Multiline = true, Visible = false};
-            Controls.Add(_textBox);
+            AutoScroll = true;
+            VerticalScroll.Enabled = true;
+            HorizontalScroll.Enabled = true;
+            SetStyle(ControlStyles.AllPaintingInWmPaint, true);
+            Text = "ScrollableArea";
+            Controls.Add(_windowHost);
+            _windowHost.Anchor = AnchorStyles.None;
+            _timer.Tick += delegate { FixWindow(); };
         }
-        
+
+        private Control _windowHost = new Control() {Text = "WindowWrapper"};
+        private Timer _timer = new Timer {Enabled = true, Interval = 50};
         private IntPtr _hWnd;
-        private TextBox _textBox;
+        private int _desiredWidth;
+        private int _desiredHeight;
+
+        private const int WM_HSCROLL = 0x114;
+        private const int WM_VSCROLL = 0x115;
 
-        public string PlaceholderText
+        protected override void WndProc(ref Message m)
         {
-            get { return _textBox.Text; }
-            set
+            if ((m.Msg == WM_HSCROLL || m.Msg == WM_VSCROLL)
+                && (((int) m.WParam & 0xFFFF) == 5))
             {
-                _textBox.Text = value;
-                FixWindow();
+                // Change SB_THUMBTRACK to SB_THUMBPOSITION
+                m.WParam = (IntPtr) (((int) m.WParam & ~0xFFFF) | 4);
             }
+            base.WndProc(ref m);
         }
 
-        
+        void FixPosition()
+        {
+            AutoScrollMinSize = new Size(_desiredWidth, _desiredHeight);
+            var width = Width - AutoScrollMargin.Width;
+            var height = Height - AutoScrollMargin.Height;
+            var x = Math.Max(0, (width - _windowHost.Width)/2);
+            var y = Math.Max(0, (height - _windowHost.Height)/2);
+            _windowHost.Location = new Point(x, y);
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                _timer.Dispose();
+            }
+            base.Dispose(disposing);
+        }
 
         public void SetWindow(IntPtr hWnd)
         {
@@ -40,21 +69,34 @@ namespace Perspex.Designer.AppHost
             _hWnd = hWnd;
             if (_hWnd != IntPtr.Zero)
             {
-                WinApi.SetParent(hWnd, Handle);
+                WinApi.SetParent(hWnd, _windowHost.Handle);
                 FixWindow();
             }
         }
-
+        
         void FixWindow()
         {
             if (_hWnd != IntPtr.Zero)
-                WinApi.MoveWindow(_hWnd, 0, 0, Width, Height, true);
-            _textBox.Visible = _hWnd == IntPtr.Zero && !string.IsNullOrWhiteSpace(_textBox.Text);
+            {
+                WinApi.RECT rc;
+                WinApi.GetWindowRect(_hWnd, out rc);
+                _desiredWidth = rc.Right - rc.Left;
+                _desiredHeight = rc.Bottom - rc.Top;
+                var pt = _windowHost.PointToClient(new Point(rc.Left, rc.Top));
+                
+                if (pt.Y == 0 && pt.X == 0 && _desiredWidth == _windowHost.Width && _desiredHeight == _windowHost.Height)
+                    return;
+                _windowHost.Width = _desiredWidth;
+                _windowHost.Height = _desiredHeight;
+                WinApi.MoveWindow(_hWnd, 0, 0, _desiredWidth, _desiredHeight, true);
+                FixPosition();
+
+            }
         }
 
         protected override void OnResize(EventArgs e)
         {
-            FixWindow();
+            FixPosition();
             base.OnResize(e);
         }
     }

src/Windows/Perspex.Designer/Comm/ProcessHost.cs

@@ -152,7 +152,7 @@ namespace Perspex.Designer.Comm
         {
             try
             {
-                _proc.Kill();
+                _proc?.Kill();
                 _proc = null;
             }
             catch

src/Windows/Perspex.Designer/DesignerAppHost.cs

@@ -1,13 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-
-namespace Perspex.Designer
-{
-    class DesignerAppHost
-    {
-        
-    }
-}

src/Windows/Perspex.Designer/InProcDesigner/InProcDesignerView.xaml

@@ -0,0 +1,20 @@
+<UserControl x:Class="Perspex.Designer.InProcDesigner.InProcDesignerView"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:appHost="clr-namespace:Perspex.Designer.AppHost"
+             mc:Ignorable="d" 
+             d:DesignHeight="300" d:DesignWidth="300" d:DataContext="{d:DesignInstance appHost:HostedAppModel}">
+    <DockPanel>
+        <Border x:Name="ErrorPanel" DockPanel.Dock="Bottom" BorderBrush="Red" BorderThickness="3" Padding="3">
+            <StackPanel   Orientation="Horizontal">
+                <TextBlock Text="{Binding Error}" FontSize="16"/>
+                <TextBlock x:Name="DetailsBlock" FontSize="16">
+                <Run> (</Run><Hyperlink Click="Hyperlink_OnClick">View details</Hyperlink><Run>)</Run>
+                </TextBlock>
+            </StackPanel>
+        </Border>
+        <WindowsFormsHost x:Name="WindowHostControl"/>
+    </DockPanel>
+</UserControl>

src/Windows/Perspex.Designer/InProcDesigner/InProcDesignerView.xaml.cs

@@ -0,0 +1,84 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using System.Windows.Documents;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Navigation;
+using System.Windows.Shapes;
+using Perspex.Designer.AppHost;
+
+namespace Perspex.Designer.InProcDesigner
+{
+    /// <summary>
+    /// Interaction logic for InProcDesignerView.xaml
+    /// </summary>
+    public partial class InProcDesignerView : UserControl
+    {
+        private readonly HostedAppModel _appModel;
+        private readonly WindowHost _host;
+
+        public InProcDesignerView(HostedAppModel appModel)
+        {
+            _appModel = appModel;
+            InitializeComponent();
+            DataContext = _appModel;
+            _appModel.PropertyChanged += ModelPropertyChanged;
+            WindowHostControl.Child = _host = new WindowHost();
+            HandleVisibility();
+            HandleWindow();
+
+        }
+
+        private void ModelPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
+        {
+            if (e.PropertyName == nameof(HostedAppModel.Error) || e.PropertyName == nameof(HostedAppModel.ErrorDetails))
+                HandleVisibility();
+            if (e.PropertyName == nameof(HostedAppModel.NativeWindowHandle))
+                HandleWindow();
+        }
+
+        private void HandleWindow()
+        {
+            _host.SetWindow(_appModel.NativeWindowHandle);
+        }
+
+        private void HandleVisibility()
+        {
+            ErrorPanel.Visibility = string.IsNullOrEmpty(_appModel.Error)
+                       ? Visibility.Collapsed
+                       : Visibility.Visible;
+            DetailsBlock.Visibility = string.IsNullOrWhiteSpace(_appModel.ErrorDetails)
+                ? Visibility.Collapsed
+                : Visibility.Visible;
+        }
+
+
+
+        public InProcDesignerView()
+        {
+            
+        }
+
+        private void Hyperlink_OnClick(object sender, RoutedEventArgs e)
+        {
+            var wnd = new Window()
+            {
+                Content = new TextBox()
+                {
+                    IsReadOnly = true,
+                    AcceptsReturn = true,
+                    TextWrapping = TextWrapping.Wrap,
+                    Text = _appModel.ErrorDetails
+                }
+            };
+            wnd.ShowDialog();
+        }
+    }
+}

src/Windows/Perspex.Designer/Perspex.Designer.csproj

@@ -46,6 +46,10 @@
     <StartupObject />
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="JetBrains.Annotations, Version=9.2.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325, processorArchitecture=MSIL">
+      <HintPath>..\..\..\packages\JetBrains.Annotations.9.2.0\lib\net20\JetBrains.Annotations.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
     <Reference Include="PresentationCore" />
     <Reference Include="PresentationFramework" />
     <Reference Include="System" />
@@ -66,9 +70,10 @@
     <Compile Include="App.xaml.cs">
       <DependentUpon>App.xaml</DependentUpon>
     </Compile>
+    <Compile Include="AppHost\HostedAppModel.cs" />
     <Compile Include="AppHost\PerspexAppHost.cs" />
     <Compile Include="AppHost\WindowHost.cs">
-      <SubType>Component</SubType>
+      <SubType>UserControl</SubType>
     </Compile>
     <Compile Include="Comm\CommChannel.cs" />
     <Compile Include="Comm\InitMessage.cs" />
@@ -80,7 +85,9 @@
     <Compile Include="DemoWindow.xaml.cs">
       <DependentUpon>DemoWindow.xaml</DependentUpon>
     </Compile>
-    <Compile Include="DesignerAppHost.cs" />
+    <Compile Include="InProcDesigner\InProcDesignerView.xaml.cs">
+      <DependentUpon>InProcDesignerView.xaml</DependentUpon>
+    </Compile>
     <Compile Include="Metadata\PerspexDesignerMetadata.cs" />
     <Compile Include="PerspexDesigner.xaml.cs">
       <DependentUpon>PerspexDesigner.xaml</DependentUpon>
@@ -91,6 +98,7 @@
   </ItemGroup>
   <ItemGroup>
     <None Include="App.config" />
+    <None Include="packages.config" />
     <None Include="perspex.designer.snk" />
   </ItemGroup>
   <ItemGroup>
@@ -102,6 +110,10 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="InProcDesigner\InProcDesignerView.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="PerspexDesigner.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>

src/Windows/Perspex.Designer/PerspexDesigner.xaml

@@ -10,5 +10,8 @@
         <ScrollViewer VerticalScrollBarVisibility="Auto" Panel.ZIndex="0">
             <TextBox IsReadOnly="True" TextWrapping="WrapWithOverflow" x:Name="State"/>
         </ScrollViewer>
+        <StackPanel x:Name="ErrorContainer">
+            <TextBlock ></TextBlock>
+        </StackPanel>
     </Grid>
 </UserControl>

src/Windows/Perspex.Designer/PerspexDesigner.xaml.cs

@@ -80,13 +80,33 @@ namespace Perspex.Designer
                 }
                 if (_host.WindowHandle != IntPtr.Zero)
                 {
-                    var host = new WindowHost();
-                    host.SetWindow(_host.WindowHandle);
-                    NativeContainer.Content = new WindowsFormsHost() {Child = host};
+                    var host = new NativeWindowHost(_host.WindowHandle);
+                    NativeContainer.Content = host;
                 }
             }
         }
 
+        class NativeWindowHost  :HwndHost
+        {
+            private readonly IntPtr _hWnd;
+
+            public NativeWindowHost(IntPtr hWnd)
+            {
+                _hWnd = hWnd;
+            }
+
+            protected override HandleRef BuildWindowCore(HandleRef hwndParent)
+            {
+                WinApi.SetParent(_hWnd, hwndParent.Handle);
+                return new HandleRef(this, _hWnd);
+            }
+
+            protected override void DestroyWindowCore(HandleRef hwnd)
+            {
+                WinApi.SendMessage(hwnd.Handle, WinApi.WM_CLOSE, IntPtr.Zero, IntPtr.Zero);
+            }
+        }
+
         public void KillProcess()
         {
             _host.Kill();

src/Windows/Perspex.Designer/WinApi.cs

@@ -18,5 +18,16 @@ namespace Perspex.Designer
 
         public const uint WM_CLOSE = 0x0010;
 
+        [DllImport("user32.dll", SetLastError = true)]
+        public static extern bool GetWindowRect(IntPtr hwnd, out RECT lpRect);
+
+        [StructLayout(LayoutKind.Sequential)]
+        public struct RECT
+        {
+            public int Left;        // x position of upper-left corner
+            public int Top;         // y position of upper-left corner
+            public int Right;       // x position of lower-right corner
+            public int Bottom;      // y position of lower-right corner
+        }
     }
 }

src/Windows/Perspex.Designer/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="JetBrains.Annotations" version="9.2.0" targetFramework="net45" />
+</packages>