mdiclientcontroller.cs

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#region Using Directives

using System;
using System.Drawing;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Windows.Forms;
using System.Runtime.InteropServices;

#endregion // Using Directives


namespace Custom.Windows.Forms
{
	/// <summary>
	/// Listens for messages sent to a <see cref="System.Windows.Forms.MdiClient"/>
	/// class and controls its properties.
	/// </summary>
	[ToolboxBitmap(typeof(MdiClientController))]
	public class MdiClientController : NativeWindow, IComponent, IDisposable
	{
		#region Private Fields

		private Form parentForm;
		private MdiClient mdiClient;
		private BorderStyle borderStyle;
		private Color backColor;
		private bool autoScroll;
		private Image image;
		private ContentAlignment imageAlign;
		private bool stretchImage;
		private ISite site;

		#endregion // Private Fields


		#region Public Constructors

		/// <summary>
		/// Initializes a new instance of the <see cref="Slusser.Components.MdiClientController"/> class.
		/// </summary>
		public MdiClientController() : this(null)
		{
		}


		/// <summary>
		/// Initializes a new instance of the <see cref="Slusser.Components.MdiClientController"/> class
		/// for the given MDI form.
		/// </summary>
		/// <param name="parentForm">The MDI form.</param>
		public MdiClientController(Form parentForm)
		{
			// Initialize the variables.
			this.site = null;
			this.parentForm = null;
			this.mdiClient = null;
			this.backColor = SystemColors.AppWorkspace;
			this.borderStyle = BorderStyle.Fixed3D;
			this.autoScroll = true;
			this.image = null;
			this.imageAlign = ContentAlignment.MiddleCenter;
			this.stretchImage = false;
			
			// Set the ParentForm property.
			this.ParentForm = parentForm;
		}

		#endregion // Public Constructors


		#region Public Events

		/// <summary>
		/// Occurs when the control is redrawn.
		/// </summary>
		[Category("Appearance"), Description("Occurs when a control needs repainting.")]
		public event PaintEventHandler Paint;


		/// <summary>
		/// Occurs when the control is disposed.
		/// </summary>
		[Browsable(false)]
		public event EventHandler Disposed;


		/// <summary>
		/// Occurs when the <see cref="System.Windows.Forms.NativeWindow"/> handle
		/// is assigned.
		/// </summary>
		[Browsable(false)]
		public event EventHandler HandleAssigned;

		#endregion // Public Events


		#region Public Properties

		/// <summary>
		/// Gets or sets the <see cref="System.ComponentModel.ISite"/> of
		/// the <see cref="System.ComponentModel.Component"/>.
		/// </summary>
		[Browsable(false)]
		[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
		public ISite Site
		{
			get { return site; }
			set
			{
				site = value;

				if(site == null)
					return;

				// If the component is dropped onto a form during design-time,
				// set the ParentForm property.
				IDesignerHost host = (value.GetService(typeof(IDesignerHost)) as IDesignerHost);
				if(host != null)
				{
					Form parent = host.RootComponent as Form;
					if(parent != null)
						ParentForm = parent;
				}
			}
		}


		/// <summary>
		/// Gets or sets the form that the <see cref="System.Windows.Forms.MdiClient"/>
		/// control is assigned to.
		/// </summary>
		[Browsable(false)]
		public Form ParentForm
		{
			get { return parentForm; }
			set
			{
				// If the ParentForm has previously been set,
				// unwire events connected to the old parent.
				if(parentForm != null)
					parentForm.HandleCreated -= new EventHandler(ParentFormHandleCreated);

				parentForm = value;

				if(parentForm == null)
					return;

				// If the parent form has not been created yet,
				// wait to initialize the MDI client until it is.
				if(parentForm.IsHandleCreated)
				{
					InitializeMdiClient();
					RefreshProperties();
				}
				else
					parentForm.HandleCreated += new EventHandler(ParentFormHandleCreated);
			}
		}


		/// <summary>
		/// Gets the <see cref="System.Windows.Forms.MdiClient"/> being controlled.
		/// </summary>
		[Browsable(false)]
		public MdiClient MdiClient
		{
			get { return mdiClient; }
		}


		/// <summary>
		/// Gets or sets the background color for the control.
		/// </summary>
		[Category("Appearance"), DefaultValue(typeof(Color), "AppWorkspace")]
		[Description("The backcolor used to display text and graphics in the control.")]
		public Color BackColor
		{
			// Use the BackColor property of the MdiClient control. This is one of
			// the few properties in the MdiClient class that actually works.

			get
			{
				if(mdiClient != null)
                    return mdiClient.BackColor;

				return backColor;
			}
			set
			{
				backColor = value;
				if(mdiClient != null)
                    mdiClient.BackColor = value;
			}
		}


		/// <summary>
		/// Indicates the border style for the control.
		/// </summary>
		/// <exception cref="System.ComponentModel.InvalidEnumArgumentException">The value
		/// assigned to the property is not a member of
		/// the <see cref="System.Windows.Forms.BorderStyle"/> enumeration.</exception>
		[DefaultValue(BorderStyle.Fixed3D), Category("Appearance")]
		[Description("Indicates whether the MDI area should have a border.")]
		public BorderStyle BorderStyle
		{
			get { return borderStyle; }
			set
			{
				// Error-check the enum.
				if(!Enum.IsDefined(typeof(BorderStyle), value))
					throw new InvalidEnumArgumentException("value", (int)value, typeof(BorderStyle));

				borderStyle = value;

				if(mdiClient == null)
					return;

				// This property can actually be visible in design-mode,
				// but to keep it consistent with the others,
				// prevent this from being show at design-time.
				if(site != null && site.DesignMode)
					return;

				// There is no BorderStyle property exposed by the MdiClient class,
				// but this can be controlled by Win32 functions. A Win32 ExStyle
				// of WS_EX_CLIENTEDGE is equivalent to a Fixed3D border and a
				// Style of WS_BORDER is equivalent to a FixedSingle border.
				
				// This code is inspired Jason Dori's article:
				// "Adding designable borders to user controls".
				// http://www.codeproject.com/cs/miscctrl/CsAddingBorders.asp

				// Get styles using Win32 calls
				int style = GetWindowLong(mdiClient.Handle, GWL_STYLE);
				int exStyle = GetWindowLong(mdiClient.Handle, GWL_EXSTYLE);

				// Add or remove style flags as necessary.
				switch(borderStyle)
				{
					case BorderStyle.Fixed3D:
						exStyle |= WS_EX_CLIENTEDGE;
						style &= ~WS_BORDER;
						break;

					case BorderStyle.FixedSingle:
						exStyle &= ~WS_EX_CLIENTEDGE;
						style |= WS_BORDER;
						break;

					case BorderStyle.None:
						style &= ~WS_BORDER;
						exStyle &= ~WS_EX_CLIENTEDGE;
						break;
				}
					
				// Set the styles using Win32 calls
				SetWindowLong(mdiClient.Handle, GWL_STYLE, style);
				SetWindowLong(mdiClient.Handle, GWL_EXSTYLE, exStyle);

				// Cause an update of the non-client area.
				UpdateStyles();
			}
		}


		/// <summary>
		/// Gets or sets a value indicating whether the container will allow the user to
		/// scroll to any controls placed outside of its visible boundaries.
		/// </summary>
		[DefaultValue(true), Category("Layout")]
		[Description("Determines whether scrollbars will automatically appear if controls are placed outside the MDI client area.")]
		public bool AutoScroll
		{
			get { return autoScroll; }
			set
			{
				// By default the MdiClient control scrolls. It can appear though that
				// there are no scrollbars by turning them off when the non-client
				// area is calculated. I decided to expose this method following
				// the .NET vernacular of an AutoScroll property.

				autoScroll = value;
				if(mdiClient != null)
                    UpdateStyles();
			}
		}


		/// <summary>
		/// Gets or sets the image that the
		/// <see cref="Slusser.Components.MdiClientController"/> displays.
		/// </summary>
		[DefaultValue(null), Category("Appearance")]
		[Description("The image displayed in the MDI client area.")]
		public Image Image
		{
			get { return image; }
			set
			{
				image = value;
				if(mdiClient != null)
                    mdiClient.Invalidate();
			}
		}


		/// <summary>
		/// Gets or sets the alignment of the background image.
		/// </summary>
		/// <exception cref="System.ComponentModel.InvalidEnumArgumentException">The
		/// value assigned to the property is not a member of
		/// the <see cref="System.Drawing.ContentAlignment"/> enumeration.</exception>
		[Category("Appearance"), DefaultValue(ContentAlignment.MiddleCenter)]
		[Description("Determines the position of the image within the MDI client area.")]
		public ContentAlignment ImageAlign
		{
			get { return imageAlign; }
			set
			{
				// Error-check the enum.
				if(!Enum.IsDefined(typeof(ContentAlignment), value))
					throw new InvalidEnumArgumentException("value", (int)value, typeof(ContentAlignment));

				imageAlign = value;
				if(mdiClient != null)
					mdiClient.Invalidate();
			}
		}


		/// <summary>
		/// Gets or sets a value indicating whether the
		/// <see cref="Slusser.Components.MdiClientController.Image"/> should
		/// be stretched to fill the entire client area.
		/// </summary>
		[Category("Appearance"), DefaultValue(false)]
		[Description("Determines whether the image should be scaled to fill the entire client area.")]
		public bool StretchImage
		{
			get { return stretchImage; }
			set
			{
				stretchImage = value;
				if(mdiClient != null)
					mdiClient.Invalidate();
			}
		}


		/// <summary>
		/// Gets the handle for this window.
		/// </summary>
		[Browsable(false)]
		public new IntPtr Handle
		{
			// Hide this from the property grid during design-time.
			get { return base.Handle; }
		}

		#endregion // Public Properties


		#region Public Methods

		/// <summary>
		/// Releases all resources used by the
		/// <see cref="System.ComponentModel.Component"/>.
		/// </summary>
		public void Dispose()
		{
			Dispose(true);
			GC.SuppressFinalize(this);
		}


		/// <summary>
		/// Reestablishes a connection to the <see cref="System.Windows.Forms.MdiClient"/>
		/// control if the <see cref="Slusser.Components.MdiClientController.ParentForm"/>
		/// hasn't changed but its <see cref="System.Windows.Forms.Form.IsMdiContainer"/>
		/// property has.
		/// </summary>
		public void RenewMdiClient()
		{