mcs/class/System/System.ComponentModel/Component.cs

   1 //
   2 // System.ComponentModel.Component.cs
   3 //
   4 // Author:
   5 //  Miguel de Icaza (miguel@ximian.com)
   6 //  Andreas Nahr (ClassDevelopment@A-SoftTech.com)
   7 //
   8 // (C) Ximian, Inc.  http://www.ximian.com
   9 // (C) 2003 Andreas Nahr
  10 //
  11
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System;
  34 using System.ComponentModel;
  35 using System.Runtime.InteropServices;
  36
  37 namespace System.ComponentModel {
  38
  39         [DesignerCategory ("Component")]
  40         [ComVisible (true)]
  41         [ClassInterface (ClassInterfaceType.AutoDispatch)]
  42         public class Component : MarshalByRefObject, IComponent, IDisposable
  43         {
  44
  45                 private EventHandlerList event_handlers;
  46                 private ISite mySite;
  47                 static readonly object disposedEvent = new object ();
  48
  49                 public Component ()
  50                 {
  51                         event_handlers = null;
  52                 }
  53
  54                 protected virtual bool CanRaiseEvents {
  55                         get { return false; }
  56                 }
  57
  58                 [Browsable (false), DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  59                 public virtual ISite Site
  60                 {
  61                         get { return mySite; }
  62                         set { mySite = value; }
  63                 }
  64
  65                 [Browsable (false), DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  66                 public IContainer Container {
  67                         get {
  68                                 if (mySite == null)
  69                                         return null;
  70                                 return mySite.Container;
  71                         }
  72                 }
  73
  74                 [Browsable (false), DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  75                 protected bool DesignMode {
  76                         get {
  77                                 if (mySite == null)
  78                                         return false;
  79                                 return mySite.DesignMode;
  80                         }
  81                 }
  82
  83                 protected EventHandlerList Events {
  84                         get {
  85                                 // Note: space vs. time tradeoff
  86                                 // We create the object here if it's never be accessed before.  This potentially
  87                                 // saves space. However, we must check each time the propery is accessed to
  88                                 // determine whether we need to create the object, which increases overhead.
  89                                 // We could put the creation in the contructor, but that would waste space
  90                                 // if it were never used.  However, accessing this property would be faster.
  91                                 if (null == event_handlers)
  92                                         event_handlers = new EventHandlerList();
  93
  94                                 return event_handlers;
  95                         }
  96                 }
  97
  98                 ~Component()
  99                 {
 100                         Dispose (false);
 101                 }
 102
 103                 public void Dispose ()
 104                 {
 105                         Dispose (true);
 106                         GC.SuppressFinalize (this);
 107                 }
 108
 109                 // <summary>
 110                 //   Controls disposal of resources used by this.
 111                 // </summary>
 112                 //
 113                 // <param name="release_all"> Controls which resources are released</param>
 114                 //
 115                 // <remarks>
 116                 //   if release_all is set to true, both managed and unmanaged
 117                 //   resources should be released.  If release_all is set to false,
 118                 //   only unmanaged resources should be disposed
 119                 // </remarks>
 120                 protected virtual void Dispose (bool release_all)
 121                 {
 122                         if (release_all) {
 123                                 if (mySite != null && mySite.Container != null)
 124                                         mySite.Container.Remove (this);
 125                                 EventHandler eh = (EventHandler) Events [disposedEvent];
 126                                 if (eh != null)
 127                                         eh (this, EventArgs.Empty);
 128                         }
 129                 }
 130
 131                 protected virtual object GetService (Type service)
 132                 {
 133                         if (mySite != null) {
 134                                 return mySite.GetService(service);
 135                         }
 136                         return null;
 137                 }
 138
 139                 public override string ToString ()
 140                 {
 141                         if (mySite == null)
 142                                 return GetType ().ToString ();
 143                         return String.Format ("{0} [{1}]", mySite.Name, GetType ().ToString ());
 144                 }
 145
 146                 [Browsable (false), EditorBrowsable (EditorBrowsableState.Advanced)]
 147                 public event EventHandler Disposed {
 148                         add { Events.AddHandler (disposedEvent, value); }
 149                         remove { Events.RemoveHandler (disposedEvent, value); }
 150                 }
 151         }
 152
 153 }