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Src/Xceed.Wpf.Toolkit/Core/Input/KeyModifierCollection.cs

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+/*************************************************************************************
+
+   Extended WPF Toolkit
+
+   Copyright (C) 2007-2013 Xceed Software Inc.
+
+   This program is provided to you under the terms of the Microsoft Public
+   License (Ms-PL) as published at http://wpftoolkit.codeplex.com/license 
+
+   For more features, controls, and fast professional support,
+   pick up the Plus Edition at http://xceed.com/wpf_toolkit
+
+   Stay informed: follow @datagrid on Twitter or Like http://facebook.com/datagrids
+
+  ***********************************************************************************/
+
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Windows.Input;
+
+namespace Xceed.Wpf.Toolkit.Core.Input
+{
+  [TypeConverter( typeof( KeyModifierCollectionConverter ) )]
+  public class KeyModifierCollection : Collection<KeyModifier>
+  {
+    #region AreActive Property
+
+    public bool AreActive
+    {
+      get
+      {
+        if( this.Count == 0 )
+          return true;
+
+        // if the Blocked modifier is present, then the action is not allowed
+        // so simply return false
+        if( this.Contains( KeyModifier.Blocked ) )
+          return false;
+
+        if( this.Contains( KeyModifier.Exact ) )
+          return this.IsExactMatch();
+
+        return this.MatchAny();
+      }
+    }
+
+    #endregion
+
+    private static bool IsKeyPressed( KeyModifier modifier, ICollection<Key> keys )
+    {
+      switch( modifier )
+      {
+        case KeyModifier.Alt:
+          return keys.Contains( Key.LeftAlt )
+              || keys.Contains( Key.RightAlt );
+
+        case KeyModifier.LeftAlt:
+          return keys.Contains( Key.LeftAlt );
+
+        case KeyModifier.RightAlt:
+          return keys.Contains( Key.RightAlt );
+
+        case KeyModifier.Ctrl:
+          return keys.Contains( Key.LeftCtrl )
+              || keys.Contains( Key.RightCtrl );
+
+        case KeyModifier.LeftCtrl:
+          return keys.Contains( Key.LeftCtrl );
+
+        case KeyModifier.RightCtrl:
+          return keys.Contains( Key.RightCtrl );
+
+        case KeyModifier.Shift:
+          return keys.Contains( Key.LeftShift )
+              || keys.Contains( Key.RightShift );
+
+        case KeyModifier.LeftShift:
+          return keys.Contains( Key.LeftShift );
+
+        case KeyModifier.RightShift:
+          return keys.Contains( Key.RightShift );
+
+        case KeyModifier.None:
+          return true;
+
+        default:
+          throw new NotSupportedException( "Unknown modifier" );
+      }
+    }
+
+    private static bool HasModifier( Key key, ICollection<KeyModifier> modifiers )
+    {
+      switch( key )
+      {
+        case Key.LeftAlt:
+          return modifiers.Contains( KeyModifier.Alt )
+              || modifiers.Contains( KeyModifier.LeftAlt );
+
+        case Key.RightAlt:
+          return modifiers.Contains( KeyModifier.Alt )
+              || modifiers.Contains( KeyModifier.RightAlt );
+
+        case Key.LeftCtrl:
+          return modifiers.Contains( KeyModifier.Ctrl )
+              || modifiers.Contains( KeyModifier.LeftCtrl );
+
+        case Key.RightCtrl:
+          return modifiers.Contains( KeyModifier.Ctrl )
+              || modifiers.Contains( KeyModifier.RightCtrl );
+
+        case Key.LeftShift:
+          return modifiers.Contains( KeyModifier.Shift )
+              || modifiers.Contains( KeyModifier.LeftShift );
+
+        case Key.RightShift:
+          return modifiers.Contains( KeyModifier.Shift )
+              || modifiers.Contains( KeyModifier.RightShift );
+
+        default:
+          throw new NotSupportedException( "Unknown key" );
+      }
+    }
+
+    private bool IsExactMatch()
+    {
+      HashSet<KeyModifier> modifiers = this.GetKeyModifiers();
+      HashSet<Key> keys = this.GetKeysPressed();
+
+      // No key must be pressed for the modifier None.
+      if( this.Contains( KeyModifier.None ) )
+        return ( modifiers.Count == 0 )
+            && ( keys.Count == 0 );
+
+      // Make sure every modifier has a matching key pressed.
+      foreach( KeyModifier modifier in modifiers )
+      {
+        if( !KeyModifierCollection.IsKeyPressed( modifier, keys ) )
+          return false;
+      }
+
+      // Make sure every key pressed has a matching modifier.
+      foreach( Key key in keys )
+      {
+        if( !KeyModifierCollection.HasModifier( key, modifiers ) )
+          return false;
+      }
+
+      return true;
+    }
+
+    private bool MatchAny()
+    {
+      if( this.Contains( KeyModifier.None ) )
+        return true;
+
+      HashSet<KeyModifier> modifiers = this.GetKeyModifiers();
+      HashSet<Key> keys = this.GetKeysPressed();
+
+      foreach( KeyModifier modifier in modifiers )
+      {
+        if( KeyModifierCollection.IsKeyPressed( modifier, keys ) )
+          return true;
+      }
+
+      return false;
+    }
+
+    private HashSet<KeyModifier> GetKeyModifiers()
+    {
+      HashSet<KeyModifier> modifiers = new HashSet<KeyModifier>();
+
+      foreach( KeyModifier modifier in this )
+      {
+        switch( modifier )
+        {
+          case KeyModifier.Alt:
+          case KeyModifier.LeftAlt:
+          case KeyModifier.RightAlt:
+          case KeyModifier.Ctrl:
+          case KeyModifier.LeftCtrl:
+          case KeyModifier.RightCtrl:
+          case KeyModifier.Shift:
+          case KeyModifier.LeftShift:
+          case KeyModifier.RightShift:
+            {
+              if( !modifiers.Contains( modifier ) )
+              {
+                modifiers.Add( modifier );
+              }
+            }
+            break;
+
+          default:
+            break;
+        }
+      }
+
+      return modifiers;
+    }
+
+    private HashSet<Key> GetKeysPressed()
+    {
+      HashSet<Key> keys = new HashSet<Key>();
+
+      if( Keyboard.IsKeyDown( Key.LeftAlt ) )
+        keys.Add( Key.LeftAlt );
+      if( Keyboard.IsKeyDown( Key.RightAlt ) )
+        keys.Add( Key.RightAlt );
+      if( Keyboard.IsKeyDown( Key.LeftCtrl ) )
+        keys.Add( Key.LeftCtrl );
+      if( Keyboard.IsKeyDown( Key.RightCtrl ) )
+        keys.Add( Key.RightCtrl );
+      if( Keyboard.IsKeyDown( Key.LeftShift ) )
+        keys.Add( Key.LeftShift );
+      if( Keyboard.IsKeyDown( Key.RightShift ) )
+        keys.Add( Key.RightShift );
+
+      return keys;
+    }
+  }
+}