source: stable/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/TextAreaDefaultInputHandlers.cs @ 15377

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Input;

using ICSharpCode.AvalonEdit.Document;

namespace ICSharpCode.AvalonEdit.Editing
{
  /// <summary>
  /// Contains the predefined input handlers.
  /// </summary>
  public class TextAreaDefaultInputHandler : TextAreaInputHandler
  {
    /// <summary>
    /// Gets the caret navigation input handler.
    /// </summary>
    public TextAreaInputHandler CaretNavigation { get; private set; }
    
    /// <summary>
    /// Gets the editing input handler.
    /// </summary>
    public TextAreaInputHandler Editing { get; private set; }
    
    /// <summary>
    /// Gets the mouse selection input handler.
    /// </summary>
    public ITextAreaInputHandler MouseSelection { get; private set; }
    
    /// <summary>
    /// Creates a new TextAreaDefaultInputHandler instance.
    /// </summary>
    public TextAreaDefaultInputHandler(TextArea textArea) : base(textArea)
    {
      this.NestedInputHandlers.Add(CaretNavigation = CaretNavigationCommandHandler.Create(textArea));
      this.NestedInputHandlers.Add(Editing = EditingCommandHandler.Create(textArea));
      this.NestedInputHandlers.Add(MouseSelection = new SelectionMouseHandler(textArea));
      
      this.CommandBindings.Add(new CommandBinding(ApplicationCommands.Undo, ExecuteUndo, CanExecuteUndo));
      this.CommandBindings.Add(new CommandBinding(ApplicationCommands.Redo, ExecuteRedo, CanExecuteRedo));
    }
    
    internal static KeyBinding CreateFrozenKeyBinding(ICommand command, ModifierKeys modifiers, Key key)
    {
      KeyBinding kb = new KeyBinding(command, key, modifiers);
      // Mark KeyBindings as frozen because they're shared between multiple editor instances.
      // KeyBinding derives from Freezable only in .NET 4, so we have to use this little trick:
      Freezable f = ((object)kb) as Freezable;
      if (f != null)
        f.Freeze();
      return kb;
    }
    
    internal static void WorkaroundWPFMemoryLeak(List<InputBinding> inputBindings)
    {
      // Work around WPF memory leak:
      // KeyBinding retains a reference to whichever UIElement it is used in first.
      // Using a dummy element for this purpose ensures that we don't leak
      // a real text editor (with a potentially large document).
      UIElement dummyElement = new UIElement();
      dummyElement.InputBindings.AddRange(inputBindings);
    }
    
    #region Undo / Redo
    UndoStack GetUndoStack()
    {
      TextDocument document = this.TextArea.Document;
      if (document != null)
        return document.UndoStack;
      else
        return null;
    }
    
    void ExecuteUndo(object sender, ExecutedRoutedEventArgs e)
    {
      var undoStack = GetUndoStack();
      if (undoStack != null) {
        if (undoStack.CanUndo) {
          undoStack.Undo();
          this.TextArea.Caret.BringCaretToView();
        }
        e.Handled = true;
      }
    }
    
    void CanExecuteUndo(object sender, CanExecuteRoutedEventArgs e)
    {
      var undoStack = GetUndoStack();
      if (undoStack != null) {
        e.Handled = true;
        e.CanExecute = undoStack.CanUndo;
      }
    }
    
    void ExecuteRedo(object sender, ExecutedRoutedEventArgs e)
    {
      var undoStack = GetUndoStack();
      if (undoStack != null) {
        if (undoStack.CanRedo) {
          undoStack.Redo();
          this.TextArea.Caret.BringCaretToView();
        }
        e.Handled = true;
      }
    }
    
    void CanExecuteRedo(object sender, CanExecuteRoutedEventArgs e)
    {
      var undoStack = GetUndoStack();
      if (undoStack != null) {
        e.Handled = true;
        e.CanExecute = undoStack.CanRedo;
      }
    }
    #endregion
  }
}