source: stable/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/TextAreaInputHandler.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
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// 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
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using ICSharpCode.AvalonEdit.Utils;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Windows.Input;

namespace ICSharpCode.AvalonEdit.Editing
{
  /// <summary>
  /// A set of input bindings and event handlers for the text area.
  /// </summary>
  /// <remarks>
  /// <para>
  /// There is one active input handler per text area (<see cref="Editing.TextArea.ActiveInputHandler"/>), plus
  /// a number of active stacked input handlers.
  /// </para>
  /// <para>
  /// The text area also stores a reference to a default input handler, but that is not necessarily active.
  /// </para>
  /// <para>
  /// Stacked input handlers work in addition to the set of currently active handlers (without detaching them).
  /// They are detached in the reverse order of being attached.
  /// </para>
  /// </remarks>
  public interface ITextAreaInputHandler
  {
    /// <summary>
    /// Gets the text area that the input handler belongs to.
    /// </summary>
    TextArea TextArea {
      get;
    }
    
    /// <summary>
    /// Attaches an input handler to the text area.
    /// </summary>
    void Attach();
    
    /// <summary>
    /// Detaches the input handler from the text area.
    /// </summary>
    void Detach();
  }
  
  /// <summary>
  /// Stacked input handler.
  /// Uses OnEvent-methods instead of registering event handlers to ensure that the events are handled in the correct order.
  /// </summary>
  public abstract class TextAreaStackedInputHandler : ITextAreaInputHandler
  {
    readonly TextArea textArea;
    
    /// <inheritdoc/>
    public TextArea TextArea {
      get { return textArea; }
    }
    
    /// <summary>
    /// Creates a new TextAreaInputHandler.
    /// </summary>
    protected TextAreaStackedInputHandler(TextArea textArea)
    {
      if (textArea == null)
        throw new ArgumentNullException("textArea");
      this.textArea = textArea;
    }
    
    /// <inheritdoc/>
    public virtual void Attach()
    {
    }
    
    /// <inheritdoc/>
    public virtual void Detach()
    {
    }
    
    /// <summary>
    /// Called for the PreviewKeyDown event.
    /// </summary>
    public virtual void OnPreviewKeyDown(KeyEventArgs e)
    {
    }
    
    /// <summary>
    /// Called for the PreviewKeyUp event.
    /// </summary>
    public virtual void OnPreviewKeyUp(KeyEventArgs e)
    {
    }
  }
  
  /// <summary>
  /// Default-implementation of <see cref="ITextAreaInputHandler"/>.
  /// </summary>
  /// <remarks><inheritdoc cref="ITextAreaInputHandler"/></remarks>
  public class TextAreaInputHandler : ITextAreaInputHandler
  {
    readonly ObserveAddRemoveCollection<CommandBinding> commandBindings;
    readonly ObserveAddRemoveCollection<InputBinding> inputBindings;
    readonly ObserveAddRemoveCollection<ITextAreaInputHandler> nestedInputHandlers;
    readonly TextArea textArea;
    bool isAttached;
    
    /// <summary>
    /// Creates a new TextAreaInputHandler.
    /// </summary>
    public TextAreaInputHandler(TextArea textArea)
    {
      if (textArea == null)
        throw new ArgumentNullException("textArea");
      this.textArea = textArea;
      commandBindings = new ObserveAddRemoveCollection<CommandBinding>(CommandBinding_Added, CommandBinding_Removed);
      inputBindings = new ObserveAddRemoveCollection<InputBinding>(InputBinding_Added, InputBinding_Removed);
      nestedInputHandlers = new ObserveAddRemoveCollection<ITextAreaInputHandler>(NestedInputHandler_Added, NestedInputHandler_Removed);
    }
    
    /// <inheritdoc/>
    public TextArea TextArea {
      get { return textArea; }
    }
    
    /// <summary>
    /// Gets whether the input handler is currently attached to the text area.
    /// </summary>
    public bool IsAttached {
      get { return isAttached; }
    }
    
    #region CommandBindings / InputBindings
    /// <summary>
    /// Gets the command bindings of this input handler.
    /// </summary>
    public ICollection<CommandBinding> CommandBindings {
      get { return commandBindings; }
    }
    
    void CommandBinding_Added(CommandBinding commandBinding)
    {
      if (isAttached)
        textArea.CommandBindings.Add(commandBinding);
    }
    
    void CommandBinding_Removed(CommandBinding commandBinding)
    {
      if (isAttached)
        textArea.CommandBindings.Remove(commandBinding);
    }
    
    /// <summary>
    /// Gets the input bindings of this input handler.
    /// </summary>
    public ICollection<InputBinding> InputBindings {
      get { return inputBindings; }
    }
    
    void InputBinding_Added(InputBinding inputBinding)
    {
      if (isAttached)
        textArea.InputBindings.Add(inputBinding);
    }
    
    void InputBinding_Removed(InputBinding inputBinding)
    {
      if (isAttached)
        textArea.InputBindings.Remove(inputBinding);
    }
    
    /// <summary>
    /// Adds a command and input binding.
    /// </summary>
    /// <param name="command">The command ID.</param>
    /// <param name="modifiers">The modifiers of the keyboard shortcut.</param>
    /// <param name="key">The key of the keyboard shortcut.</param>
    /// <param name="handler">The event handler to run when the command is executed.</param>
    public void AddBinding(ICommand command, ModifierKeys modifiers, Key key, ExecutedRoutedEventHandler handler)
    {
      this.CommandBindings.Add(new CommandBinding(command, handler));
      this.InputBindings.Add(new KeyBinding(command, key, modifiers));
    }
    #endregion
    
    #region NestedInputHandlers
    /// <summary>
    /// Gets the collection of nested input handlers. NestedInputHandlers are activated and deactivated
    /// together with this input handler.
    /// </summary>
    public ICollection<ITextAreaInputHandler> NestedInputHandlers {
      get { return nestedInputHandlers; }
    }
    
    void NestedInputHandler_Added(ITextAreaInputHandler handler)
    {
      if (handler == null)
        throw new ArgumentNullException("handler");
      if (handler.TextArea != textArea)
        throw new ArgumentException("The nested handler must be working for the same text area!");
      if (isAttached)
        handler.Attach();
    }
    
    void NestedInputHandler_Removed(ITextAreaInputHandler handler)
    {
      if (isAttached)
        handler.Detach();
    }
    #endregion
    
    #region Attach/Detach
    /// <inheritdoc/>
    public virtual void Attach()
    {
      if (isAttached)
        throw new InvalidOperationException("Input handler is already attached");
      isAttached = true;
      
      textArea.CommandBindings.AddRange(commandBindings);
      textArea.InputBindings.AddRange(inputBindings);
      foreach (ITextAreaInputHandler handler in nestedInputHandlers)
        handler.Attach();
    }
    
    /// <inheritdoc/>
    public virtual void Detach()
    {
      if (!isAttached)
        throw new InvalidOperationException("Input handler is not attached");
      isAttached = false;
      
      foreach (CommandBinding b in commandBindings)
        textArea.CommandBindings.Remove(b);
      foreach (InputBinding b in inputBindings)
        textArea.InputBindings.Remove(b);
      foreach (ITextAreaInputHandler handler in nestedInputHandlers)
        handler.Detach();
    }
    #endregion
  }
}