source: branches/PluginInfrastructure Refactoring/WinFormsUI/Docking/DockPane.cs @ 2591

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using System.Diagnostics.CodeAnalysis;

namespace WeifenLuo.WinFormsUI.Docking
{
  [ToolboxItem(false)]
  public partial class DockPane : UserControl, IDockDragSource
  {
    public enum AppearanceStyle
    {
      ToolWindow,
      Document
    }

    private enum HitTestArea
    {
      Caption,
      TabStrip,
      Content,
      None
    }

    private struct HitTestResult
    {
      public HitTestArea HitArea;
      public int Index;

      public HitTestResult(HitTestArea hitTestArea, int index)
      {
        HitArea = hitTestArea;
        Index = index;
      }
    }

    private DockPaneCaptionBase m_captionControl;
    private DockPaneCaptionBase CaptionControl
    {
      get { return m_captionControl;  }
    }

    private DockPaneStripBase m_tabStripControl;
    internal DockPaneStripBase TabStripControl
    {
      get { return m_tabStripControl; }
    }

    internal protected DockPane(IDockContent content, DockState visibleState, bool show)
    {
      InternalConstruct(content, visibleState, false, Rectangle.Empty, null, DockAlignment.Right, 0.5, show);
    }

        [SuppressMessage("Microsoft.Naming", "CA1720:AvoidTypeNamesInParameters", MessageId = "1#")]
    internal protected DockPane(IDockContent content, FloatWindow floatWindow, bool show)
    {
            if (floatWindow == null)
                throw new ArgumentNullException("floatWindow");

      InternalConstruct(content, DockState.Float, false, Rectangle.Empty, floatWindow.NestedPanes.GetDefaultPreviousPane(this), DockAlignment.Right, 0.5, show);
    }

    internal protected DockPane(IDockContent content, DockPane previousPane, DockAlignment alignment, double proportion, bool show)
    {
      if (previousPane == null)
        throw(new ArgumentNullException("previousPane"));
      InternalConstruct(content, previousPane.DockState, false, Rectangle.Empty, previousPane, alignment, proportion, show);
    }

        [SuppressMessage("Microsoft.Naming", "CA1720:AvoidTypeNamesInParameters", MessageId = "1#")]
        internal protected DockPane(IDockContent content, Rectangle floatWindowBounds, bool show)
    {
      InternalConstruct(content, DockState.Float, true, floatWindowBounds, null, DockAlignment.Right, 0.5, show);
    }

    private void InternalConstruct(IDockContent content, DockState dockState, bool flagBounds, Rectangle floatWindowBounds, DockPane prevPane, DockAlignment alignment, double proportion, bool show)
    {
      if (dockState == DockState.Hidden || dockState == DockState.Unknown)
        throw new ArgumentException(Strings.DockPane_SetDockState_InvalidState);

      if (content == null)
        throw new ArgumentNullException(Strings.DockPane_Constructor_NullContent);

      if (content.DockHandler.DockPanel == null)
        throw new ArgumentException(Strings.DockPane_Constructor_NullDockPanel);


      SuspendLayout();
      SetStyle(ControlStyles.Selectable, false);

      m_isFloat = (dockState == DockState.Float);

      m_contents = new DockContentCollection();
      m_displayingContents = new DockContentCollection(this);
      m_dockPanel = content.DockHandler.DockPanel;
      m_dockPanel.AddPane(this);

      m_splitter = new SplitterControl(this);

      m_nestedDockingStatus = new NestedDockingStatus(this);

      m_captionControl = DockPanel.DockPaneCaptionFactory.CreateDockPaneCaption(this);
      m_tabStripControl = DockPanel.DockPaneStripFactory.CreateDockPaneStrip(this);
      Controls.AddRange(new Control[] { m_captionControl, m_tabStripControl });
      
      DockPanel.SuspendLayout(true);
      if (flagBounds)
        FloatWindow = DockPanel.FloatWindowFactory.CreateFloatWindow(DockPanel, this, floatWindowBounds);
      else if (prevPane != null)
        DockTo(prevPane.NestedPanesContainer, prevPane, alignment, proportion);

      SetDockState(dockState);
      if (show)
        content.DockHandler.Pane = this;
      else if (this.IsFloat)
        content.DockHandler.FloatPane = this;
      else
        content.DockHandler.PanelPane = this;

      ResumeLayout();
      DockPanel.ResumeLayout(true, true);
    }

    protected override void Dispose(bool disposing)
    {
      if (disposing)
      {
        m_dockState = DockState.Unknown;

        if (NestedPanesContainer != null)
          NestedPanesContainer.NestedPanes.Remove(this);

        if (DockPanel != null)
        {
          DockPanel.RemovePane(this);
          m_dockPanel = null;
        }

        Splitter.Dispose();
                if (m_autoHidePane != null)
            m_autoHidePane.Dispose();
      }
      base.Dispose(disposing);
    }

    private IDockContent m_activeContent = null;
    public virtual IDockContent ActiveContent
    {
      get { return m_activeContent; }
      set
      {
        if (ActiveContent == value)
          return;

        if (value != null)
        {
          if (!DisplayingContents.Contains(value))
            throw(new InvalidOperationException(Strings.DockPane_ActiveContent_InvalidValue));
        }
        else
        {
          if (DisplayingContents.Count != 0)
            throw(new InvalidOperationException(Strings.DockPane_ActiveContent_InvalidValue));
        }

        IDockContent oldValue = m_activeContent;

        if (DockPanel.ActiveAutoHideContent == oldValue)
          DockPanel.ActiveAutoHideContent = null;

        m_activeContent = value;

        if (DockPanel.DocumentStyle == DocumentStyle.DockingMdi && DockState == DockState.Document)
        {
          if (m_activeContent != null)
            m_activeContent.DockHandler.Form.BringToFront();
        }
        else
        {
          if (m_activeContent != null)
            m_activeContent.DockHandler.SetVisible();
          if (oldValue != null && DisplayingContents.Contains(oldValue))
            oldValue.DockHandler.SetVisible();
                    if (IsActivated && m_activeContent != null)
                        m_activeContent.DockHandler.Activate();
        }

        if (FloatWindow != null)
          FloatWindow.SetText();

                if (DockPanel.DocumentStyle == DocumentStyle.DockingMdi &&
                    DockState == DockState.Document)
                    RefreshChanges(false);  // delayed layout to reduce screen flicker
                else
                    RefreshChanges();

        if (m_activeContent != null)
          TabStripControl.EnsureTabVisible(m_activeContent);
      }
    }
    
    private bool m_allowDockDragAndDrop = true;
    public virtual bool AllowDockDragAndDrop
    {
      get { return m_allowDockDragAndDrop;  }
      set { m_allowDockDragAndDrop = value; }
    }

        private IDisposable m_autoHidePane = null;
        internal IDisposable AutoHidePane
        {
            get { return m_autoHidePane; }
            set { m_autoHidePane = value; }
        }

        private object m_autoHideTabs = null;
        internal object AutoHideTabs
        {
            get { return m_autoHideTabs; }
            set { m_autoHideTabs = value; }
        }

        private object TabPageContextMenu
        {
            get
            {
                IDockContent content = ActiveContent;

                if (content == null)
                    return null;

                if (content.DockHandler.TabPageContextMenuStrip != null)
                    return content.DockHandler.TabPageContextMenuStrip;
                else if (content.DockHandler.TabPageContextMenu != null)
                    return content.DockHandler.TabPageContextMenu;
                else
                    return null;
            }
        }

        internal bool HasTabPageContextMenu
        {
            get { return TabPageContextMenu != null; }
        }

        internal void ShowTabPageContextMenu(Control control, Point position)
        {
            object menu = TabPageContextMenu;

            if (menu == null)
                return;

            ContextMenuStrip contextMenuStrip = menu as ContextMenuStrip;
            if (contextMenuStrip != null)
            {
                contextMenuStrip.Show(control, position);
                return;
            }

            ContextMenu contextMenu = menu as ContextMenu;
            if (contextMenu != null)
                contextMenu.Show(this, position);
        }

    private Rectangle CaptionRectangle
    {
      get
      {
        if (!HasCaption)
          return Rectangle.Empty;

        Rectangle rectWindow = DisplayingRectangle;
        int x, y, width;
        x = rectWindow.X;
        y = rectWindow.Y;
        width = rectWindow.Width;
        int height = CaptionControl.MeasureHeight();

        return new Rectangle(x, y, width, height);
      }
    }

    internal Rectangle ContentRectangle
    {
      get
      {
        Rectangle rectWindow = DisplayingRectangle;
        Rectangle rectCaption = CaptionRectangle;
        Rectangle rectTabStrip = TabStripRectangle;

        int x = rectWindow.X;

                int y = rectWindow.Y + (rectCaption.IsEmpty ? 0 : rectCaption.Height);
                if (DockState == DockState.Document && DockPanel.DocumentTabStripLocation == DocumentTabStripLocation.Top)
                    y += rectTabStrip.Height;
                
        int width = rectWindow.Width;
        int height = rectWindow.Height - rectCaption.Height - rectTabStrip.Height;

        return new Rectangle(x, y, width, height);
      }
    }

    internal Rectangle TabStripRectangle
    {
      get
      {
        if (Appearance == AppearanceStyle.ToolWindow)
          return TabStripRectangle_ToolWindow;
        else
          return TabStripRectangle_Document;
      }
    }

    private Rectangle TabStripRectangle_ToolWindow
    {
      get
      {
        if (DisplayingContents.Count <= 1 || IsAutoHide)
          return Rectangle.Empty;

        Rectangle rectWindow = DisplayingRectangle;

        int width = rectWindow.Width;
        int height = TabStripControl.MeasureHeight();
        int x = rectWindow.X;
        int y = rectWindow.Bottom - height;
        Rectangle rectCaption = CaptionRectangle;
        if (rectCaption.Contains(x, y))
          y = rectCaption.Y + rectCaption.Height;

        return new Rectangle(x, y, width, height);
      }
    }

    private Rectangle TabStripRectangle_Document
    {
      get
      {
        if (DisplayingContents.Count == 0)
          return Rectangle.Empty;

        if (DisplayingContents.Count == 1 && DockPanel.DocumentStyle == DocumentStyle.DockingSdi)
          return Rectangle.Empty;

        Rectangle rectWindow = DisplayingRectangle;
        int x = rectWindow.X;
        int width = rectWindow.Width;
        int height = TabStripControl.MeasureHeight();

                int y = 0;
                if (DockPanel.DocumentTabStripLocation == DocumentTabStripLocation.Bottom)
                    y = rectWindow.Height - height;
                else
                    y = rectWindow.Y;

        return new Rectangle(x, y, width, height);
      }
    }

    public virtual string CaptionText
    {
      get { return ActiveContent == null ? string.Empty : ActiveContent.DockHandler.TabText;  }
    }

    private DockContentCollection m_contents;
    public DockContentCollection Contents
    {
      get { return m_contents;  }
    }

    private DockContentCollection m_displayingContents;
    public DockContentCollection DisplayingContents
    {
      get { return m_displayingContents;  }
    }

    private DockPanel m_dockPanel;
    public DockPanel DockPanel
    {
      get { return m_dockPanel; }
    }

    private bool HasCaption
    {
      get
      { 
        if (DockState == DockState.Document ||
          DockState == DockState.Hidden ||
          DockState == DockState.Unknown ||
          (DockState == DockState.Float && FloatWindow.VisibleNestedPanes.Count <= 1))
          return false;
        else
          return true;
      }
    }

    private bool m_isActivated = false;
    public bool IsActivated
    {
      get { return m_isActivated; }
    }
    internal void SetIsActivated(bool value)
    {
      if (m_isActivated == value)
        return;

      m_isActivated = value;
      if (DockState != DockState.Document)
        RefreshChanges(false);
      OnIsActivatedChanged(EventArgs.Empty);
    }

    private bool m_isActiveDocumentPane = false;
    public bool IsActiveDocumentPane
    {
      get { return m_isActiveDocumentPane;  }
    }
    internal void SetIsActiveDocumentPane(bool value)
    {
      if (m_isActiveDocumentPane == value)
        return;

      m_isActiveDocumentPane = value;
      if (DockState == DockState.Document)
        RefreshChanges();
      OnIsActiveDocumentPaneChanged(EventArgs.Empty);
    }

    public bool IsDockStateValid(DockState dockState)
    {
      foreach (IDockContent content in Contents)
        if (!content.DockHandler.IsDockStateValid(dockState))
          return false;

      return true;
    }

    public bool IsAutoHide
    {
      get { return DockHelper.IsDockStateAutoHide(DockState); }
    }

    public AppearanceStyle Appearance
    {
      get { return (DockState == DockState.Document) ? AppearanceStyle.Document : AppearanceStyle.ToolWindow; }
    }

    internal Rectangle DisplayingRectangle
    {
      get { return ClientRectangle; }
    }

    public void Activate()
    {
      if (DockHelper.IsDockStateAutoHide(DockState) && DockPanel.ActiveAutoHideContent != ActiveContent)
        DockPanel.ActiveAutoHideContent = ActiveContent;
      else if (!IsActivated && ActiveContent != null)
        ActiveContent.DockHandler.Activate();
    }

    internal void AddContent(IDockContent content)
    {
      if (Contents.Contains(content))
        return;

      Contents.Add(content);
    }

    internal void Close()
    {
      Dispose();
    }

    public void CloseActiveContent()
    {
      CloseContent(ActiveContent);
    }

    internal void CloseContent(IDockContent content)
    {
            DockPanel dockPanel = DockPanel;
            dockPanel.SuspendLayout(true);

      if (content == null)
        return;

      if (!content.DockHandler.CloseButton)
        return;

      if (content.DockHandler.HideOnClose)
        content.DockHandler.Hide();
      else
        content.DockHandler.Close();

            dockPanel.ResumeLayout(true, true);
        }

    private HitTestResult GetHitTest(Point ptMouse)
    {
      Point ptMouseClient = PointToClient(ptMouse);

      Rectangle rectCaption = CaptionRectangle;
      if (rectCaption.Contains(ptMouseClient))
        return new HitTestResult(HitTestArea.Caption, -1);

      Rectangle rectContent = ContentRectangle;
      if (rectContent.Contains(ptMouseClient))
        return new HitTestResult(HitTestArea.Content, -1);

      Rectangle rectTabStrip = TabStripRectangle;
      if (rectTabStrip.Contains(ptMouseClient))
        return new HitTestResult(HitTestArea.TabStrip, TabStripControl.HitTest(TabStripControl.PointToClient(ptMouse)));

      return new HitTestResult(HitTestArea.None, -1);
    }

    private bool m_isHidden = true;
    public bool IsHidden
    {
      get { return m_isHidden;  }
    }
    private void SetIsHidden(bool value)
    {
      if (m_isHidden == value)
        return;

      m_isHidden = value;
      if (DockHelper.IsDockStateAutoHide(DockState))
      {
        DockPanel.RefreshAutoHideStrip();
        DockPanel.PerformLayout();
      }
      else if (NestedPanesContainer != null)
        ((Control)NestedPanesContainer).PerformLayout();
    }

    protected override void OnLayout(LayoutEventArgs levent)
    {
      SetIsHidden(DisplayingContents.Count == 0);
      if (!IsHidden)
      {
        CaptionControl.Bounds = CaptionRectangle;
        TabStripControl.Bounds = TabStripRectangle;

        SetContentBounds();

        foreach (IDockContent content in Contents)
        {
          if (DisplayingContents.Contains(content))
            if (content.DockHandler.FlagClipWindow && content.DockHandler.Form.Visible)
              content.DockHandler.FlagClipWindow = false;
        }
      }

      base.OnLayout(levent);
    }

    internal void SetContentBounds()
    {
      Rectangle rectContent = ContentRectangle;
            if (DockState == DockState.Document && DockPanel.DocumentStyle == DocumentStyle.DockingMdi)
                rectContent = DockPanel.RectangleToMdiClient(RectangleToScreen(rectContent));

            Rectangle rectInactive = new Rectangle(-rectContent.Width, rectContent.Y, rectContent.Width, rectContent.Height);
      foreach (IDockContent content in Contents)
                if (content.DockHandler.Pane == this)
                {
                    if (content == ActiveContent)
                        content.DockHandler.Form.Bounds = rectContent;
                    else
                        content.DockHandler.Form.Bounds = rectInactive;
                }
    }

    internal void RefreshChanges()
    {
            RefreshChanges(true);
    }

        private void RefreshChanges(bool performLayout)
        {
            if (IsDisposed)
                return;

            CaptionControl.RefreshChanges();
            TabStripControl.RefreshChanges();
            if (DockState == DockState.Float)
                FloatWindow.RefreshChanges();
            if (DockHelper.IsDockStateAutoHide(DockState) && DockPanel != null)
            {
                DockPanel.RefreshAutoHideStrip();
                DockPanel.PerformLayout();
            }

            if (performLayout)
                PerformLayout();
        }

    internal void RemoveContent(IDockContent content)
    {
      if (!Contents.Contains(content))
        return;
      
      Contents.Remove(content);
    }

    public void SetContentIndex(IDockContent content, int index)
    {
      int oldIndex = Contents.IndexOf(content);
      if (oldIndex == -1)
        throw(new ArgumentException(Strings.DockPane_SetContentIndex_InvalidContent));

      if (index < 0 || index > Contents.Count - 1)
        if (index != -1)
          throw(new ArgumentOutOfRangeException(Strings.DockPane_SetContentIndex_InvalidIndex));
        
      if (oldIndex == index)
        return;
      if (oldIndex == Contents.Count - 1 && index == -1)
        return;

      Contents.Remove(content);
      if (index == -1)
        Contents.Add(content);
      else if (oldIndex < index)
        Contents.AddAt(content, index - 1);
      else
        Contents.AddAt(content, index);

      RefreshChanges();
    }

    private void SetParent()
    {
      if (DockState == DockState.Unknown || DockState == DockState.Hidden)
      {
        SetParent(null);
        Splitter.Parent = null;
      }
      else if (DockState == DockState.Float)
      {
        SetParent(FloatWindow);
        Splitter.Parent = FloatWindow;
      }
      else if (DockHelper.IsDockStateAutoHide(DockState))
      {
        SetParent(DockPanel.AutoHideControl);
        Splitter.Parent = null;
      }
      else
      {
        SetParent(DockPanel.DockWindows[DockState]);
        Splitter.Parent = Parent;
      }
    }

    private void SetParent(Control value)
    {
      if (Parent == value)
        return;

            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
            // Workaround of .Net Framework bug:
            // Change the parent of a control with focus may result in the first
            // MDI child form get activated. 
            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
            IDockContent contentFocused = GetFocusedContent();
            if (contentFocused != null)
                DockPanel.SaveFocus();

            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

            Parent = value;

            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
            // Workaround of .Net Framework bug:
            // Change the parent of a control with focus may result in the first
            // MDI child form get activated. 
            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
            if (contentFocused != null)
                contentFocused.DockHandler.Activate();
            //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
        }

    public new void Show()
    {
      Activate();
    }

        internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline)
        {
            if (!dragSource.CanDockTo(this))
                return;

            Point ptMouse = Control.MousePosition;

            HitTestResult hitTestResult = GetHitTest(ptMouse);
            if (hitTestResult.HitArea == HitTestArea.Caption)
                dockOutline.Show(this, -1);
            else if (hitTestResult.HitArea == HitTestArea.TabStrip && hitTestResult.Index != -1)
                dockOutline.Show(this, hitTestResult.Index);
        }

    internal void ValidateActiveContent()
    {
      if (ActiveContent == null)
      {
        if (DisplayingContents.Count != 0)
          ActiveContent = DisplayingContents[0];
        return;
      }

      if (DisplayingContents.IndexOf(ActiveContent) >= 0)
        return;

      IDockContent prevVisible = null;
      for (int i=Contents.IndexOf(ActiveContent)-1; i>=0; i--)
        if (Contents[i].DockHandler.DockState == DockState)
        {
          prevVisible = Contents[i];
          break;
        }

      IDockContent nextVisible = null;
      for (int i=Contents.IndexOf(ActiveContent)+1; i<Contents.Count; i++)
        if (Contents[i].DockHandler.DockState == DockState)
        {
          nextVisible = Contents[i];
          break;
        }

      if (prevVisible != null)
        ActiveContent = prevVisible;
      else if (nextVisible != null)
        ActiveContent = nextVisible;
      else
        ActiveContent = null;
    }

    private static readonly object DockStateChangedEvent = new object();
    public event EventHandler DockStateChanged
    {
      add { Events.AddHandler(DockStateChangedEvent, value);  }
      remove  { Events.RemoveHandler(DockStateChangedEvent, value); }
    }
    protected virtual void OnDockStateChanged(EventArgs e)
    {
      EventHandler handler = (EventHandler)Events[DockStateChangedEvent];
      if (handler != null)
        handler(this, e);
    }

    private static readonly object IsActivatedChangedEvent = new object();
    public event EventHandler IsActivatedChanged
    {
      add { Events.AddHandler(IsActivatedChangedEvent, value);  }
      remove  { Events.RemoveHandler(IsActivatedChangedEvent, value); }
    }
    protected virtual void OnIsActivatedChanged(EventArgs e)
    {
      EventHandler handler = (EventHandler)Events[IsActivatedChangedEvent];
      if (handler != null)
        handler(this, e);
    }

    private static readonly object IsActiveDocumentPaneChangedEvent = new object();
    public event EventHandler IsActiveDocumentPaneChanged
    {
      add { Events.AddHandler(IsActiveDocumentPaneChangedEvent, value); }
      remove  { Events.RemoveHandler(IsActiveDocumentPaneChangedEvent, value);  }
    }
    protected virtual void OnIsActiveDocumentPaneChanged(EventArgs e)
    {
      EventHandler handler = (EventHandler)Events[IsActiveDocumentPaneChangedEvent];
      if (handler != null)
        handler(this, e);
    }

    public DockWindow DockWindow
    {
      get { return (m_nestedDockingStatus.NestedPanes == null) ? null : m_nestedDockingStatus.NestedPanes.Container as DockWindow;  }
      set
      {
        DockWindow oldValue = DockWindow;
        if (oldValue == value)
          return;

        DockTo(value);
      }
    }

    public FloatWindow FloatWindow
    {
      get { return (m_nestedDockingStatus.NestedPanes == null) ? null : m_nestedDockingStatus.NestedPanes.Container as FloatWindow; }
      set
      {
        FloatWindow oldValue = FloatWindow;
        if (oldValue == value)
          return;

        DockTo(value);
      }
    }

    private NestedDockingStatus m_nestedDockingStatus;
    public NestedDockingStatus NestedDockingStatus
    {
      get { return m_nestedDockingStatus; }
    }
  
    private bool m_isFloat;
    public bool IsFloat
    {
      get { return m_isFloat; }
    }

    public INestedPanesContainer NestedPanesContainer
    {
      get
      {
        if (NestedDockingStatus.NestedPanes == null)
          return null;
        else
          return NestedDockingStatus.NestedPanes.Container;
      }
    }

    private DockState m_dockState = DockState.Unknown;
    public DockState DockState
    {
      get { return m_dockState; }
      set
      {
        SetDockState(value);
      }
    }

    public DockPane SetDockState(DockState value)
    {
      if (value == DockState.Unknown || value == DockState.Hidden)
        throw new InvalidOperationException(Strings.DockPane_SetDockState_InvalidState);

      if ((value == DockState.Float) == this.IsFloat)
      {
        InternalSetDockState(value);
        return this;
      }

      if (DisplayingContents.Count == 0)
        return null;

      IDockContent firstContent = null;
      for (int i=0; i<DisplayingContents.Count; i++)
      {
        IDockContent content = DisplayingContents[i];
        if (content.DockHandler.IsDockStateValid(value))
        {
          firstContent = content;
          break;
        }
      }
      if (firstContent == null)
        return null;

      firstContent.DockHandler.DockState = value;
      DockPane pane = firstContent.DockHandler.Pane;
      DockPanel.SuspendLayout(true);
      for (int i=0; i<DisplayingContents.Count; i++)
      {
        IDockContent content = DisplayingContents[i];
        if (content.DockHandler.IsDockStateValid(value))
          content.DockHandler.Pane = pane;
      }
      DockPanel.ResumeLayout(true, true);
      return pane;
    }

    private void InternalSetDockState(DockState value)
    {
      if (m_dockState == value)
        return;

      DockState oldDockState = m_dockState;
      INestedPanesContainer oldContainer = NestedPanesContainer;

      m_dockState = value;

      SuspendRefreshStateChange();

            IDockContent contentFocused = GetFocusedContent();
            if (contentFocused != null)
                DockPanel.SaveFocus();

            if (!IsFloat)
                DockWindow = DockPanel.DockWindows[DockState];
            else if (FloatWindow == null)
                FloatWindow = DockPanel.FloatWindowFactory.CreateFloatWindow(DockPanel, this);

            if (contentFocused != null)
                DockPanel.ContentFocusManager.Activate(contentFocused);

      ResumeRefreshStateChange(oldContainer, oldDockState);
        }

    private int m_countRefreshStateChange = 0;
    private void SuspendRefreshStateChange()
    {
      m_countRefreshStateChange ++;
      DockPanel.SuspendLayout(true);
    }

    private void ResumeRefreshStateChange()
    {
      m_countRefreshStateChange --;
      System.Diagnostics.Debug.Assert(m_countRefreshStateChange >= 0);
      DockPanel.ResumeLayout(true, true);
    }

    private bool IsRefreshStateChangeSuspended
    {
      get { return m_countRefreshStateChange != 0;  }
    }

    private void ResumeRefreshStateChange(INestedPanesContainer oldContainer, DockState oldDockState)
    {
      ResumeRefreshStateChange();
      RefreshStateChange(oldContainer, oldDockState);
    }

    private void RefreshStateChange(INestedPanesContainer oldContainer, DockState oldDockState)
    {
      lock (this)
      {
        if (IsRefreshStateChangeSuspended)
          return;

        SuspendRefreshStateChange();
      }

            DockPanel.SuspendLayout(true);

            IDockContent contentFocused = GetFocusedContent();
            if (contentFocused != null)
                DockPanel.SaveFocus();
      SetParent();

      if (ActiveContent != null)
        ActiveContent.DockHandler.SetDockState(ActiveContent.DockHandler.IsHidden, DockState, ActiveContent.DockHandler.Pane);
      foreach (IDockContent content in Contents)
      {
        if (content.DockHandler.Pane == this)
          content.DockHandler.SetDockState(content.DockHandler.IsHidden, DockState, content.DockHandler.Pane);
      }

      if (oldContainer != null)
      {
                Control oldContainerControl = (Control)oldContainer;
        if (oldContainer.DockState == oldDockState && !oldContainerControl.IsDisposed)
          oldContainerControl.PerformLayout();
      }
      if (DockHelper.IsDockStateAutoHide(oldDockState))
        DockPanel.RefreshActiveAutoHideContent();

      if (NestedPanesContainer.DockState == DockState)
        ((Control)NestedPanesContainer).PerformLayout();
      if (DockHelper.IsDockStateAutoHide(DockState))
        DockPanel.RefreshActiveAutoHideContent();

      if (DockHelper.IsDockStateAutoHide(oldDockState) ||
        DockHelper.IsDockStateAutoHide(DockState))
      {
        DockPanel.RefreshAutoHideStrip();
        DockPanel.PerformLayout();
      }

      ResumeRefreshStateChange();

            if (contentFocused != null)
                contentFocused.DockHandler.Activate();

            DockPanel.ResumeLayout(true, true);

            if (oldDockState != DockState)
                OnDockStateChanged(EventArgs.Empty);
    }

        private IDockContent GetFocusedContent()
        {
            IDockContent contentFocused = null;
            foreach (IDockContent content in Contents)
            {
                if (content.DockHandler.Form.ContainsFocus)
                {
                    contentFocused = content;
                    break;
                }
            }

            return contentFocused;
        }

    public DockPane DockTo(INestedPanesContainer container)
    {
      if (container == null)
        throw new InvalidOperationException(Strings.DockPane_DockTo_NullContainer);

      DockAlignment alignment;
      if (container.DockState == DockState.DockLeft || container.DockState == DockState.DockRight)
        alignment = DockAlignment.Bottom;
      else
        alignment = DockAlignment.Right;

      return DockTo(container, container.NestedPanes.GetDefaultPreviousPane(this), alignment, 0.5);
    }

    public DockPane DockTo(INestedPanesContainer container, DockPane previousPane, DockAlignment alignment, double proportion)
    {
      if (container == null)
        throw new InvalidOperationException(Strings.DockPane_DockTo_NullContainer);

      if (container.IsFloat == this.IsFloat)
      {
        InternalAddToDockList(container, previousPane, alignment, proportion);
        return this;
      }

      IDockContent firstContent = GetFirstContent(container.DockState);
      if (firstContent == null)
        return null;

      DockPane pane;
      DockPanel.DummyContent.DockPanel = DockPanel;
      if (container.IsFloat)
        pane = DockPanel.DockPaneFactory.CreateDockPane(DockPanel.DummyContent, (FloatWindow)container, true);
      else
        pane = DockPanel.DockPaneFactory.CreateDockPane(DockPanel.DummyContent, container.DockState, true);

      pane.DockTo(container, previousPane, alignment, proportion);
      SetVisibleContentsToPane(pane);
      DockPanel.DummyContent.DockPanel = null;

      return pane;
    }

    private void SetVisibleContentsToPane(DockPane pane)
    {
      SetVisibleContentsToPane(pane, ActiveContent);
    }

    private void SetVisibleContentsToPane(DockPane pane, IDockContent activeContent)
    {
      for (int i=0; i<DisplayingContents.Count; i++)
      {
        IDockContent content = DisplayingContents[i];
        if (content.DockHandler.IsDockStateValid(pane.DockState))
        {
          content.DockHandler.Pane = pane;
          i--;
        }
      }

            if (activeContent.DockHandler.Pane == pane)
          pane.ActiveContent = activeContent;
    }

    private void InternalAddToDockList(INestedPanesContainer container, DockPane prevPane, DockAlignment alignment, double proportion)
    {
      if ((container.DockState == DockState.Float) != IsFloat)
        throw new InvalidOperationException(Strings.DockPane_DockTo_InvalidContainer);

      int count = container.NestedPanes.Count;
      if (container.NestedPanes.Contains(this))
        count --;
      if (prevPane == null && count > 0)
        throw new InvalidOperationException(Strings.DockPane_DockTo_NullPrevPane);

      if (prevPane != null && !container.NestedPanes.Contains(prevPane))
        throw new InvalidOperationException(Strings.DockPane_DockTo_NoPrevPane);

      if (prevPane == this)
        throw new InvalidOperationException(Strings.DockPane_DockTo_SelfPrevPane);

      INestedPanesContainer oldContainer = NestedPanesContainer;
      DockState oldDockState = DockState;
      container.NestedPanes.Add(this);
      NestedDockingStatus.SetStatus(container.NestedPanes, prevPane, alignment, proportion);

      if (DockHelper.IsDockWindowState(DockState))
        m_dockState = container.DockState;

      RefreshStateChange(oldContainer, oldDockState);
    }

    public void SetNestedDockingProportion(double proportion)
    {
      NestedDockingStatus.SetStatus(NestedDockingStatus.NestedPanes, NestedDockingStatus.PreviousPane, NestedDockingStatus.Alignment, proportion);
      if (NestedPanesContainer != null)
        ((Control)NestedPanesContainer).PerformLayout();
    }

    public DockPane Float()
    {
            DockPanel.SuspendLayout(true);

      IDockContent activeContent = ActiveContent;

      DockPane floatPane = GetFloatPaneFromContents();
      if (floatPane == null)
      {
        IDockContent firstContent = GetFirstContent(DockState.Float);
                if (firstContent == null)
                {
                    DockPanel.ResumeLayout(true, true);
                    return null;
                }
        floatPane = DockPanel.DockPaneFactory.CreateDockPane(firstContent,DockState.Float, true);
      }
      SetVisibleContentsToPane(floatPane, activeContent);

            DockPanel.ResumeLayout(true, true);
      return floatPane;
    }

    private DockPane GetFloatPaneFromContents()
    {
      DockPane floatPane = null;
      for (int i=0; i<DisplayingContents.Count; i++)
      {
        IDockContent content = DisplayingContents[i];
        if (!content.DockHandler.IsDockStateValid(DockState.Float))
          continue;

        if (floatPane != null && content.DockHandler.FloatPane != floatPane)
          return null;
        else
          floatPane = content.DockHandler.FloatPane;
      }

      return floatPane;
    }

    private IDockContent GetFirstContent(DockState dockState)
    {
      for (int i=0; i<DisplayingContents.Count; i++)
      {
        IDockContent content = DisplayingContents[i];
        if (content.DockHandler.IsDockStateValid(dockState))
          return content;
      }
      return null;
    }

    public void RestoreToPanel()
    {
            DockPanel.SuspendLayout(true);

      IDockContent activeContent = DockPanel.ActiveContent;

      for (int i=DisplayingContents.Count-1; i>=0; i--)
      {
        IDockContent content = DisplayingContents[i];
                if (content.DockHandler.CheckDockState(false) != DockState.Unknown)
            content.DockHandler.IsFloat = false;
      }

            DockPanel.ResumeLayout(true, true);
    }

        [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
        protected override void WndProc(ref Message m)
        {
            if (m.Msg == (int)Win32.Msgs.WM_MOUSEACTIVATE)
                Activate();

            base.WndProc(ref m);
        }

        #region IDockDragSource Members

        #region IDragSource Members

        Control IDragSource.DragControl
        {
            get { return this; }
        }

        #endregion

        bool IDockDragSource.IsDockStateValid(DockState dockState)
        {
            return IsDockStateValid(dockState);
        }

        bool IDockDragSource.CanDockTo(DockPane pane)
        {
            if (!IsDockStateValid(pane.DockState))
                return false;

            if (pane == this)
                return false;

            return true;
        }

        Rectangle IDockDragSource.BeginDrag(Point ptMouse)
        {
            Point location = PointToScreen(new Point(0, 0));
            Size size;

            DockPane floatPane = ActiveContent.DockHandler.FloatPane;
            if (DockState == DockState.Float || floatPane == null || floatPane.FloatWindow.NestedPanes.Count != 1)
                size = DockPanel.DefaultFloatWindowSize;
            else
                size = floatPane.FloatWindow.Size;

            if (ptMouse.X > location.X + size.Width)
                location.X += ptMouse.X - (location.X + size.Width) + Measures.SplitterSize;

            return new Rectangle(location, size);
        }

        public void FloatAt(Rectangle floatWindowBounds)
        {
            if (FloatWindow == null || FloatWindow.NestedPanes.Count != 1)
                FloatWindow = DockPanel.FloatWindowFactory.CreateFloatWindow(DockPanel, this, floatWindowBounds);
            else
                FloatWindow.Bounds = floatWindowBounds;

            DockState = DockState.Float;
        }

        public void DockTo(DockPane pane, DockStyle dockStyle, int contentIndex)
        {
            if (dockStyle == DockStyle.Fill)
            {
                IDockContent activeContent = ActiveContent;
                for (int i = Contents.Count - 1; i >= 0; i--)
                {
                    IDockContent c = Contents[i];
                    if (c.DockHandler.DockState == DockState)
                    {
                        c.DockHandler.Pane = pane;
                        if (contentIndex != -1)
                            pane.SetContentIndex(c, contentIndex);
                    }
                }
                pane.ActiveContent = activeContent;
            }
            else
            {
                if (dockStyle == DockStyle.Left)
                    DockTo(pane.NestedPanesContainer, pane, DockAlignment.Left, 0.5);
                else if (dockStyle == DockStyle.Right)
                    DockTo(pane.NestedPanesContainer, pane, DockAlignment.Right, 0.5);
                else if (dockStyle == DockStyle.Top)
                    DockTo(pane.NestedPanesContainer, pane, DockAlignment.Top, 0.5);
                else if (dockStyle == DockStyle.Bottom)
                    DockTo(pane.NestedPanesContainer, pane, DockAlignment.Bottom, 0.5);

                DockState = pane.DockState;
            }
        }

        public void DockTo(DockPanel panel, DockStyle dockStyle)
        {
            if (panel != DockPanel)
                throw new ArgumentException(Strings.IDockDragSource_DockTo_InvalidPanel, "panel");

            if (dockStyle == DockStyle.Top)
                DockState = DockState.DockTop;
            else if (dockStyle == DockStyle.Bottom)
                DockState = DockState.DockBottom;
            else if (dockStyle == DockStyle.Left)
                DockState = DockState.DockLeft;
            else if (dockStyle == DockStyle.Right)
                DockState = DockState.DockRight;
            else if (dockStyle == DockStyle.Fill)
                DockState = DockState.Document;
        }

        #endregion
    }
}