source: branches/Mainform refactoring/WinFormsUI/Docking/DockPanel.cs @ 2426

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.IO;
using System.Text;
using System.Diagnostics.CodeAnalysis;
using System.Collections.Generic;

// To simplify the process of finding the toolbox bitmap resource:
// #1 Create an internal class called "resfinder" outside of the root namespace.
// #2 Use "resfinder" in the toolbox bitmap attribute instead of the control name.
// #3 use the "<default namespace>.<resourcename>" string to locate the resource.
// See: http://www.bobpowell.net/toolboxbitmap.htm
internal class resfinder
{
}

namespace WeifenLuo.WinFormsUI.Docking
{
    [SuppressMessage("Microsoft.Naming", "CA1720:AvoidTypeNamesInParameters", MessageId = "0#")]
  public delegate IDockContent DeserializeDockContent(string persistString);

    [LocalizedDescription("DockPanel_Description")]
    [Designer(typeof(System.Windows.Forms.Design.ControlDesigner))]
    [ToolboxBitmap(typeof(resfinder), "WeifenLuo.WinFormsUI.Docking.DockPanel.bmp")]
    [DefaultProperty("DocumentStyle")]
    [DefaultEvent("ActiveContentChanged")]
  public partial class DockPanel : Panel
  {
        private FocusManagerImpl m_focusManager;
        private DockPanelExtender m_extender;
        private DockPaneCollection m_panes;
        private FloatWindowCollection m_floatWindows;
        private AutoHideWindowControl m_autoHideWindow;
        private DockWindowCollection m_dockWindows;
        private DockContent m_dummyContent; 
        private Control m_dummyControl;
        
    public DockPanel()
    {
            m_focusManager = new FocusManagerImpl(this);
      m_extender = new DockPanelExtender(this);
      m_panes = new DockPaneCollection();
      m_floatWindows = new FloatWindowCollection();

            SuspendLayout();

      m_autoHideWindow = new AutoHideWindowControl(this);
      m_autoHideWindow.Visible = false;
            SetAutoHideWindowParent();

      m_dummyControl = new DummyControl();
      m_dummyControl.Bounds = new Rectangle(0, 0, 1, 1);
      Controls.Add(m_dummyControl);

      m_dockWindows = new DockWindowCollection(this);
      Controls.AddRange(new Control[] {
        DockWindows[DockState.Document],
        DockWindows[DockState.DockLeft],
        DockWindows[DockState.DockRight],
        DockWindows[DockState.DockTop],
        DockWindows[DockState.DockBottom]
        });

      m_dummyContent = new DockContent();
            ResumeLayout();
        }
        
        private Color m_BackColor;
        /// <summary>
        /// Determines the color with which the client rectangle will be drawn.
        /// If you take this property instead of the BackColor it will not have any influence on the borders to the surrounding controls (DockPane).
        /// If you use BackColor the borders to the surrounding controls (DockPane) will also change there colors.
        /// Alternatively you can use both of them (BackColor to draw the define the color of the borders and DockBackColor to define the color of the client rectangle). 
        /// For Backgroundimages: Set your prefered Image, then set the DockBackColor and the BackColor to the same Color (Control)
        /// </summary>
        public Color DockBackColor
        {
            get
            {
                return !m_BackColor.IsEmpty ? m_BackColor : base.BackColor;
            }
            set
            {
                m_BackColor = value;
            }
        }

    private AutoHideStripBase m_autoHideStripControl = null;
    internal AutoHideStripBase AutoHideStripControl
    {
      get
      { 
        if (m_autoHideStripControl == null)
        {
          m_autoHideStripControl = AutoHideStripFactory.CreateAutoHideStrip(this);
          Controls.Add(m_autoHideStripControl);
        }
        return m_autoHideStripControl;
      }
    }
        internal void ResetAutoHideStripControl()
        {
            if (m_autoHideStripControl != null)
                m_autoHideStripControl.Dispose();

            m_autoHideStripControl = null;
        }

    private void MdiClientHandleAssigned(object sender, EventArgs e)
    {
      SetMdiClient();
      PerformLayout();
    }

    private void MdiClient_Layout(object sender, LayoutEventArgs e)
    {
      if (DocumentStyle != DocumentStyle.DockingMdi)
        return;

      foreach (DockPane pane in Panes)
        if (pane.DockState == DockState.Document)
          pane.SetContentBounds();

      InvalidateWindowRegion();
    }

    private bool m_disposed = false;
    protected override void Dispose(bool disposing)
    {
      lock (this)
      {
        if (!m_disposed && disposing)
        {
                    m_focusManager.Dispose();
          if (m_mdiClientController != null)
          {
            m_mdiClientController.HandleAssigned -= new EventHandler(MdiClientHandleAssigned);
            m_mdiClientController.MdiChildActivate -= new EventHandler(ParentFormMdiChildActivate);
            m_mdiClientController.Layout -= new LayoutEventHandler(MdiClient_Layout);
            m_mdiClientController.Dispose();
          }
          FloatWindows.Dispose();
          Panes.Dispose();
          DummyContent.Dispose();

          m_disposed = true;
        }
        
        base.Dispose(disposing);
      }
    }

    [Browsable(false)]
    public IDockContent ActiveAutoHideContent
    {
      get { return AutoHideWindow.ActiveContent;  }
      set { AutoHideWindow.ActiveContent = value; }
    }

        private bool m_allowEndUserDocking = true;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_AllowEndUserDocking_Description")]
    [DefaultValue(true)]
    public bool AllowEndUserDocking
    {
      get { return m_allowEndUserDocking; }
      set { m_allowEndUserDocking = value;  }
    }

        private bool m_allowEndUserNestedDocking = true;
        [LocalizedCategory("Category_Docking")]
        [LocalizedDescription("DockPanel_AllowEndUserNestedDocking_Description")]
        [DefaultValue(true)]
        public bool AllowEndUserNestedDocking
        {
            get { return m_allowEndUserNestedDocking; }
            set { m_allowEndUserNestedDocking = value; }
        }

        private DockContentCollection m_contents = new DockContentCollection();
    [Browsable(false)]
    public DockContentCollection Contents
    {
      get { return m_contents;  }
    }

    internal DockContent DummyContent
    {
      get { return m_dummyContent;  }
    }

        private bool m_rightToLeftLayout = false;
        [DefaultValue(false)]
        [LocalizedCategory("Appearance")]
        [LocalizedDescription("DockPanel_RightToLeftLayout_Description")]
        public bool RightToLeftLayout
        {
            get { return m_rightToLeftLayout; }
            set
            {
                if (m_rightToLeftLayout == value)
                    return;

                m_rightToLeftLayout = value;
                foreach (FloatWindow floatWindow in FloatWindows)
                    floatWindow.RightToLeftLayout = value;
            }
        }

        protected override void OnRightToLeftChanged(EventArgs e)
        {
            base.OnRightToLeftChanged(e);
            foreach (FloatWindow floatWindow in FloatWindows)
            {
                if (floatWindow.RightToLeft != RightToLeft)
                    floatWindow.RightToLeft = RightToLeft;
            }
        }

    private bool m_showDocumentIcon = false;
    [DefaultValue(false)]
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_ShowDocumentIcon_Description")]
    public bool ShowDocumentIcon
    {
      get { return m_showDocumentIcon;  }
      set
      {
        if (m_showDocumentIcon == value)
          return;

        m_showDocumentIcon = value;
        Refresh();
      }
    }

        private DockPanelSkin m_dockPanelSkin = new DockPanelSkin();
        [LocalizedCategory("Category_Docking")]
        [LocalizedDescription("DockPanel_DockPanelSkin")]
        public DockPanelSkin Skin
        {
            get { return m_dockPanelSkin; }
            set { m_dockPanelSkin = value; }
        }

        private DocumentTabStripLocation m_documentTabStripLocation = DocumentTabStripLocation.Top;
        [DefaultValue(DocumentTabStripLocation.Top)]
        [LocalizedCategory("Category_Docking")]
        [LocalizedDescription("DockPanel_DocumentTabStripLocation")]
        public DocumentTabStripLocation DocumentTabStripLocation
        {
            get { return m_documentTabStripLocation; }
            set { m_documentTabStripLocation = value; }
        }

    [Browsable(false)]
    public DockPanelExtender Extender
    {
      get { return m_extender;  }
    }

    public DockPanelExtender.IDockPaneFactory DockPaneFactory
    {
      get { return Extender.DockPaneFactory;  }
    }

    public DockPanelExtender.IFloatWindowFactory FloatWindowFactory
    {
      get { return Extender.FloatWindowFactory; }
    }

    internal DockPanelExtender.IDockPaneCaptionFactory DockPaneCaptionFactory
    {
      get { return Extender.DockPaneCaptionFactory; }
    }

    internal DockPanelExtender.IDockPaneStripFactory DockPaneStripFactory
    {
      get { return Extender.DockPaneStripFactory; }
    }

    internal DockPanelExtender.IAutoHideStripFactory AutoHideStripFactory
    {
      get { return Extender.AutoHideStripFactory; }
    }

    [Browsable(false)]
    public DockPaneCollection Panes
    {
      get { return m_panes; }
    }

    internal Rectangle DockArea
    {
      get
      {
        return new Rectangle(DockPadding.Left, DockPadding.Top,
          ClientRectangle.Width - DockPadding.Left - DockPadding.Right,
          ClientRectangle.Height - DockPadding.Top - DockPadding.Bottom);
      }
    }

    private double m_dockBottomPortion = 0.25;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_DockBottomPortion_Description")]
    [DefaultValue(0.25)]
    public double DockBottomPortion
    {
      get { return m_dockBottomPortion; }
      set
      {
        if (value <= 0)
          throw new ArgumentOutOfRangeException("value");

        if (value == m_dockBottomPortion)
          return;

        m_dockBottomPortion = value;

                if (m_dockBottomPortion < 1 && m_dockTopPortion < 1)
                {
                    if (m_dockTopPortion + m_dockBottomPortion > 1)
                        m_dockTopPortion = 1 - m_dockBottomPortion;
                }

        PerformLayout();
      }
    }

    private double m_dockLeftPortion = 0.25;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_DockLeftPortion_Description")]
    [DefaultValue(0.25)]
    public double DockLeftPortion
    {
      get { return m_dockLeftPortion; }
      set
      {
        if (value <= 0)
          throw new ArgumentOutOfRangeException("value");

        if (value == m_dockLeftPortion)
          return;

        m_dockLeftPortion = value;

                if (m_dockLeftPortion < 1 && m_dockRightPortion < 1)
                {
                    if (m_dockLeftPortion + m_dockRightPortion > 1)
                        m_dockRightPortion = 1 - m_dockLeftPortion;
                }
        PerformLayout();
      }
    }

    private double m_dockRightPortion = 0.25;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_DockRightPortion_Description")]
    [DefaultValue(0.25)]
    public double DockRightPortion
    {
      get { return m_dockRightPortion;  }
      set
      {
        if (value <= 0)
          throw new ArgumentOutOfRangeException("value");

        if (value == m_dockRightPortion)
          return;

        m_dockRightPortion = value;

                if (m_dockLeftPortion < 1 && m_dockRightPortion < 1)
                {
                    if (m_dockLeftPortion + m_dockRightPortion > 1)
                        m_dockLeftPortion = 1 - m_dockRightPortion;
                }
        PerformLayout();
      }
    }

    private double m_dockTopPortion = 0.25;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_DockTopPortion_Description")]
    [DefaultValue(0.25)]
    public double DockTopPortion
    {
      get { return m_dockTopPortion;  }
      set
      {
        if (value <= 0)
          throw new ArgumentOutOfRangeException("value");

        if (value == m_dockTopPortion)
          return;

        m_dockTopPortion = value;

                if (m_dockTopPortion < 1 && m_dockBottomPortion < 1)
                {
                    if (m_dockTopPortion + m_dockBottomPortion > 1)
                        m_dockBottomPortion = 1 - m_dockTopPortion;
                }
        PerformLayout();
      }
    }

    [Browsable(false)]
    public DockWindowCollection DockWindows
    {
      get { return m_dockWindows; }
    }

        public void UpdateDockWindowZOrder(DockStyle dockStyle, bool fullPanelEdge)
        {
            if (dockStyle == DockStyle.Left)
            {
                if (fullPanelEdge)
                    DockWindows[DockState.DockLeft].SendToBack();
                else
                    DockWindows[DockState.DockLeft].BringToFront();
            }
            else if (dockStyle == DockStyle.Right)
            {
                if (fullPanelEdge)
                    DockWindows[DockState.DockRight].SendToBack();
                else
                    DockWindows[DockState.DockRight].BringToFront();
            }
            else if (dockStyle == DockStyle.Top)
            {
                if (fullPanelEdge)
                    DockWindows[DockState.DockTop].SendToBack();
                else
                    DockWindows[DockState.DockTop].BringToFront();
            }
            else if (dockStyle == DockStyle.Bottom)
            {
                if (fullPanelEdge)
                    DockWindows[DockState.DockBottom].SendToBack();
                else
                    DockWindows[DockState.DockBottom].BringToFront();
            }
        }

        public int DocumentsCount
        {
            get
            {
                int count = 0;
                foreach (IDockContent content in Documents)
                    count++;

                return count;
            }
        }

        public IDockContent[] DocumentsToArray()
        {
            int count = DocumentsCount;
            IDockContent[] documents = new IDockContent[count];
            int i = 0;
            foreach (IDockContent content in Documents)
            {
                documents[i] = content;
                i++;
            }

            return documents;
        }

    public IEnumerable<IDockContent> Documents
    {
            get
            {
                foreach (IDockContent content in Contents)
                {
                    if (content.DockHandler.DockState == DockState.Document)
                        yield return content;
                }
            }
    }

    private Rectangle DocumentRectangle
    {
      get
      {
        Rectangle rect = DockArea;
        if (DockWindows[DockState.DockLeft].VisibleNestedPanes.Count != 0)
        {
          rect.X += (int)(DockArea.Width * DockLeftPortion);
          rect.Width -= (int)(DockArea.Width * DockLeftPortion);
        }
        if (DockWindows[DockState.DockRight].VisibleNestedPanes.Count != 0)
          rect.Width -= (int)(DockArea.Width * DockRightPortion);
        if (DockWindows[DockState.DockTop].VisibleNestedPanes.Count != 0)
        {
          rect.Y += (int)(DockArea.Height * DockTopPortion);
          rect.Height -= (int)(DockArea.Height * DockTopPortion);
        }
        if (DockWindows[DockState.DockBottom].VisibleNestedPanes.Count != 0)
          rect.Height -= (int)(DockArea.Height * DockBottomPortion);

        return rect;
      }
    }

    private Control DummyControl
    {
      get { return m_dummyControl;  }
    }

    [Browsable(false)]
    public FloatWindowCollection FloatWindows
    {
      get { return m_floatWindows;  }
    }

        private Size m_defaultFloatWindowSize = new Size(300, 300);
        [Category("Layout")]
        [LocalizedDescription("DockPanel_DefaultFloatWindowSize_Description")]
        public Size DefaultFloatWindowSize
        {
            get { return m_defaultFloatWindowSize; }
            set { m_defaultFloatWindowSize = value; }
        }
        private bool ShouldSerializeDefaultFloatWindowSize()
        {
            return DefaultFloatWindowSize != new Size(300, 300);
        }

    private DocumentStyle m_documentStyle = DocumentStyle.DockingMdi;
    [LocalizedCategory("Category_Docking")]
    [LocalizedDescription("DockPanel_DocumentStyle_Description")]
    [DefaultValue(DocumentStyle.DockingMdi)]
    public DocumentStyle DocumentStyle
    {
      get { return m_documentStyle; }
      set
      {
        if (value == m_documentStyle)
          return;

        if (!Enum.IsDefined(typeof(DocumentStyle), value))
          throw new InvalidEnumArgumentException();

        if (value == DocumentStyle.SystemMdi && DockWindows[DockState.Document].VisibleNestedPanes.Count > 0)
          throw new InvalidEnumArgumentException();

        m_documentStyle = value;

        SuspendLayout(true);

                SetAutoHideWindowParent();
        SetMdiClient();
        InvalidateWindowRegion();

        foreach (IDockContent content in Contents)
        {
          if (content.DockHandler.DockState == DockState.Document)
            content.DockHandler.SetPaneAndVisible(content.DockHandler.Pane);
        }

                PerformMdiClientLayout();

        ResumeLayout(true, true);
      }
    }

        private int GetDockWindowSize(DockState dockState)
        {
            if (dockState == DockState.DockLeft || dockState == DockState.DockRight)
            {
                int width = ClientRectangle.Width - DockPadding.Left - DockPadding.Right;
                int dockLeftSize = m_dockLeftPortion >= 1 ? (int)m_dockLeftPortion : (int)(width * m_dockLeftPortion);
                int dockRightSize = m_dockRightPortion >= 1 ? (int)m_dockRightPortion : (int)(width * m_dockRightPortion);

                if (dockLeftSize < MeasurePane.MinSize)
                    dockLeftSize = MeasurePane.MinSize;
                if (dockRightSize < MeasurePane.MinSize)
                    dockRightSize = MeasurePane.MinSize;

                if (dockLeftSize + dockRightSize > width - MeasurePane.MinSize)
                {
                    int adjust = (dockLeftSize + dockRightSize) - (width - MeasurePane.MinSize);
                    dockLeftSize -= adjust / 2;
                    dockRightSize -= adjust / 2;
                }

                return dockState == DockState.DockLeft ? dockLeftSize : dockRightSize;
            }
            else if (dockState == DockState.DockTop || dockState == DockState.DockBottom)
            {
                int height = ClientRectangle.Height - DockPadding.Top - DockPadding.Bottom;
                int dockTopSize = m_dockTopPortion >= 1 ? (int)m_dockTopPortion : (int)(height * m_dockTopPortion);
                int dockBottomSize = m_dockBottomPortion >= 1 ? (int)m_dockBottomPortion : (int)(height * m_dockBottomPortion);

                if (dockTopSize < MeasurePane.MinSize)
                    dockTopSize = MeasurePane.MinSize;
                if (dockBottomSize < MeasurePane.MinSize)
                    dockBottomSize = MeasurePane.MinSize;

                if (dockTopSize + dockBottomSize > height - MeasurePane.MinSize)
                {
                    int adjust = (dockTopSize + dockBottomSize) - (height - MeasurePane.MinSize);
                    dockTopSize -= adjust / 2;
                    dockBottomSize -= adjust / 2;
                }

                return dockState == DockState.DockTop ? dockTopSize : dockBottomSize;
            }
            else
                return 0;
        }

        protected override void OnLayout(LayoutEventArgs levent)
    {
      SuspendLayout(true);

      AutoHideStripControl.Bounds = ClientRectangle;

      CalculateDockPadding();

            DockWindows[DockState.DockLeft].Width = GetDockWindowSize(DockState.DockLeft);
      DockWindows[DockState.DockRight].Width = GetDockWindowSize(DockState.DockRight);
      DockWindows[DockState.DockTop].Height = GetDockWindowSize(DockState.DockTop);
      DockWindows[DockState.DockBottom].Height = GetDockWindowSize(DockState.DockBottom);

      AutoHideWindow.Bounds = GetAutoHideWindowBounds(AutoHideWindowRectangle);

      DockWindows[DockState.Document].BringToFront();
      AutoHideWindow.BringToFront();

      base.OnLayout(levent);

            if (DocumentStyle == DocumentStyle.SystemMdi && MdiClientExists)
            {
                SetMdiClientBounds(SystemMdiClientBounds);
                InvalidateWindowRegion();
            }
            else if (DocumentStyle == DocumentStyle.DockingMdi)
                InvalidateWindowRegion();

      ResumeLayout(true, true);
    }

    internal Rectangle GetTabStripRectangle(DockState dockState)
    {
      return AutoHideStripControl.GetTabStripRectangle(dockState);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
      base.OnPaint(e);

        if (DockBackColor == BackColor) return;

        Graphics g = e.Graphics;
        SolidBrush bgBrush = new SolidBrush(DockBackColor);
        g.FillRectangle(bgBrush, ClientRectangle);
    }

    internal void AddContent(IDockContent content)
    {
      if (content == null)
        throw(new ArgumentNullException());

      if (!Contents.Contains(content))
      {
        Contents.Add(content);
        OnContentAdded(new DockContentEventArgs(content));
      }
    }

    internal void AddPane(DockPane pane)
    {
      if (Panes.Contains(pane))
        return;

      Panes.Add(pane);
    }

    internal void AddFloatWindow(FloatWindow floatWindow)
    {
      if (FloatWindows.Contains(floatWindow))
        return;

      FloatWindows.Add(floatWindow);
    }

    private void CalculateDockPadding()
    {
      DockPadding.All = 0;

      int height = AutoHideStripControl.MeasureHeight();

      if (AutoHideStripControl.GetNumberOfPanes(DockState.DockLeftAutoHide) > 0)
        DockPadding.Left = height;
      if (AutoHideStripControl.GetNumberOfPanes(DockState.DockRightAutoHide) > 0)
        DockPadding.Right = height;
      if (AutoHideStripControl.GetNumberOfPanes(DockState.DockTopAutoHide) > 0)
        DockPadding.Top = height;
      if (AutoHideStripControl.GetNumberOfPanes(DockState.DockBottomAutoHide) > 0)
        DockPadding.Bottom = height;
    }

    internal void RemoveContent(IDockContent content)
    {
      if (content == null)
        throw(new ArgumentNullException());
      
      if (Contents.Contains(content))
      {
        Contents.Remove(content);
        OnContentRemoved(new DockContentEventArgs(content));
      }
    }

    internal void RemovePane(DockPane pane)
    {
      if (!Panes.Contains(pane))
        return;

      Panes.Remove(pane);
    }

    internal void RemoveFloatWindow(FloatWindow floatWindow)
    {
      if (!FloatWindows.Contains(floatWindow))
        return;

      FloatWindows.Remove(floatWindow);
    }

    public void SetPaneIndex(DockPane pane, int index)
    {
      int oldIndex = Panes.IndexOf(pane);
      if (oldIndex == -1)
        throw(new ArgumentException(Strings.DockPanel_SetPaneIndex_InvalidPane));

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

      Panes.Remove(pane);
      if (index == -1)
        Panes.Add(pane);
      else if (oldIndex < index)
        Panes.AddAt(pane, index - 1);
      else
        Panes.AddAt(pane, index);
    }

    public void SuspendLayout(bool allWindows)
    {
            FocusManager.SuspendFocusTracking();
      SuspendLayout();
      if (allWindows)
        SuspendMdiClientLayout();
    }

    public void ResumeLayout(bool performLayout, bool allWindows)
    {
            FocusManager.ResumeFocusTracking();
            ResumeLayout(performLayout);
            if (allWindows)
                ResumeMdiClientLayout(performLayout);
    }

      internal Form ParentForm
    {
      get
      { 
        if (!IsParentFormValid())
          throw new InvalidOperationException(Strings.DockPanel_ParentForm_Invalid);

        return GetMdiClientController().ParentForm;
      }
    }

    private bool IsParentFormValid()
    {
      if (DocumentStyle == DocumentStyle.DockingSdi || DocumentStyle == DocumentStyle.DockingWindow)
        return true;

            if (!MdiClientExists)
                GetMdiClientController().RenewMdiClient();

            return (MdiClientExists);
    }

    protected override void OnParentChanged(EventArgs e)
    {
            SetAutoHideWindowParent();
            GetMdiClientController().ParentForm = (this.Parent as Form);
      base.OnParentChanged (e);
    }

        private void SetAutoHideWindowParent()
        {
            Control parent;
            if (DocumentStyle == DocumentStyle.DockingMdi ||
                DocumentStyle == DocumentStyle.SystemMdi)
                parent = this.Parent;
            else
                parent = this;
            if (AutoHideWindow.Parent != parent)
            {
                AutoHideWindow.Parent = parent;
                AutoHideWindow.BringToFront();
            }
        }

    protected override void OnVisibleChanged(EventArgs e)
    {
      base.OnVisibleChanged (e);

      if (Visible)
        SetMdiClient();
    }

    private Rectangle SystemMdiClientBounds
    {
      get
      {
        if (!IsParentFormValid() || !Visible)
          return Rectangle.Empty;

        Rectangle rect = ParentForm.RectangleToClient(RectangleToScreen(DocumentWindowBounds));
        return rect;
      }
    }

    internal Rectangle DocumentWindowBounds
    {
      get
      {
        Rectangle rectDocumentBounds = DisplayRectangle;
        if (DockWindows[DockState.DockLeft].Visible)
        {
          rectDocumentBounds.X += DockWindows[DockState.DockLeft].Width;
          rectDocumentBounds.Width -= DockWindows[DockState.DockLeft].Width;
        }
        if (DockWindows[DockState.DockRight].Visible)
          rectDocumentBounds.Width -= DockWindows[DockState.DockRight].Width;
        if (DockWindows[DockState.DockTop].Visible)
        {
          rectDocumentBounds.Y += DockWindows[DockState.DockTop].Height;
          rectDocumentBounds.Height -= DockWindows[DockState.DockTop].Height;
        }
        if (DockWindows[DockState.DockBottom].Visible)
          rectDocumentBounds.Height -= DockWindows[DockState.DockBottom].Height;

        return rectDocumentBounds;

      }
    }

        private PaintEventHandler m_dummyControlPaintEventHandler = null;
        private void InvalidateWindowRegion()
        {
            if (DesignMode)
                return;

            if (m_dummyControlPaintEventHandler == null)
                m_dummyControlPaintEventHandler = new PaintEventHandler(DummyControl_Paint);

            DummyControl.Paint += m_dummyControlPaintEventHandler;
            DummyControl.Invalidate();
        }

        void DummyControl_Paint(object sender, PaintEventArgs e)
        {
            DummyControl.Paint -= m_dummyControlPaintEventHandler;
            UpdateWindowRegion();
        }

    private void UpdateWindowRegion()
    {
      if (this.DocumentStyle == DocumentStyle.DockingMdi)
        UpdateWindowRegion_ClipContent();
      else if (this.DocumentStyle == DocumentStyle.DockingSdi ||
        this.DocumentStyle == DocumentStyle.DockingWindow)
        UpdateWindowRegion_FullDocumentArea();
      else if (this.DocumentStyle == DocumentStyle.SystemMdi)
        UpdateWindowRegion_EmptyDocumentArea();
    }

    private void UpdateWindowRegion_FullDocumentArea()
    {
      SetRegion(null);
    }

    private void UpdateWindowRegion_EmptyDocumentArea()
    {
      Rectangle rect = DocumentWindowBounds;
      SetRegion(new Rectangle[] { rect });
    }

    private void UpdateWindowRegion_ClipContent()
    {
      int count = 0;
      foreach (DockPane pane in this.Panes)
      {
        if (!pane.Visible || pane.DockState != DockState.Document)
          continue;

        count ++;
      }

            if (count == 0)
            {
                SetRegion(null);
                return;
            }

      Rectangle[] rects = new Rectangle[count];
      int i = 0;
      foreach (DockPane pane in this.Panes)
      {
        if (!pane.Visible || pane.DockState != DockState.Document)
          continue;

                rects[i] = RectangleToClient(pane.RectangleToScreen(pane.ContentRectangle));
        i++;
      }

      SetRegion(rects);
    }

    private Rectangle[] m_clipRects = null;
    private void SetRegion(Rectangle[] clipRects)
    {
      if (!IsClipRectsChanged(clipRects))
        return;

      m_clipRects = clipRects;

      if (m_clipRects == null || m_clipRects.GetLength(0) == 0)
        Region = null;
      else
      {
        Region region = new Region(new Rectangle(0, 0, this.Width, this.Height));
        foreach (Rectangle rect in m_clipRects)
          region.Exclude(rect);
        Region = region;
      }
    }

    private bool IsClipRectsChanged(Rectangle[] clipRects)
    {
      if (clipRects == null && m_clipRects == null)
        return false;
      else if ((clipRects == null) != (m_clipRects == null))
        return true;

      foreach (Rectangle rect in clipRects)
      {
        bool matched = false;
        foreach (Rectangle rect2 in m_clipRects)
        {
          if (rect == rect2)
          {
            matched = true;
            break;
          }
        }
        if (!matched)
          return true;
      }

      foreach (Rectangle rect2 in m_clipRects)
      {
        bool matched = false;
        foreach (Rectangle rect in clipRects)
        {
          if (rect == rect2)
          {
            matched = true;
            break;
          }
        }
        if (!matched)
          return true;
      }
      return false;
    }

    private static readonly object ContentAddedEvent = new object();
    [LocalizedCategory("Category_DockingNotification")]
    [LocalizedDescription("DockPanel_ContentAdded_Description")]
    public event EventHandler<DockContentEventArgs> ContentAdded
    {
      add { Events.AddHandler(ContentAddedEvent, value);  }
      remove  { Events.RemoveHandler(ContentAddedEvent, value); }
    }
    protected virtual void OnContentAdded(DockContentEventArgs e)
    {
      EventHandler<DockContentEventArgs> handler = (EventHandler<DockContentEventArgs>)Events[ContentAddedEvent];
      if (handler != null)
        handler(this, e);
    }

    private static readonly object ContentRemovedEvent = new object();
    [LocalizedCategory("Category_DockingNotification")]
    [LocalizedDescription("DockPanel_ContentRemoved_Description")]
    public event EventHandler<DockContentEventArgs> ContentRemoved
    {
      add { Events.AddHandler(ContentRemovedEvent, value);  }
      remove  { Events.RemoveHandler(ContentRemovedEvent, value); }
    }
    protected virtual void OnContentRemoved(DockContentEventArgs e)
    {
      EventHandler<DockContentEventArgs> handler = (EventHandler<DockContentEventArgs>)Events[ContentRemovedEvent];
      if (handler != null)
        handler(this, e);
    }
    }
}