source: stable/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Editing/AbstractMargin.cs @ 17932

// 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.Diagnostics;
using System.Windows;

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Rendering;

namespace ICSharpCode.AvalonEdit.Editing
{
  /// <summary>
  /// Base class for margins.
  /// Margins don't have to derive from this class, it just helps maintaining a reference to the TextView
  /// and the TextDocument.
  /// AbstractMargin derives from FrameworkElement, so if you don't want to handle visual children and rendering
  /// on your own, choose another base class for your margin!
  /// </summary>
  public abstract class AbstractMargin : FrameworkElement, ITextViewConnect
  {
    /// <summary>
    /// TextView property.
    /// </summary>
    public static readonly DependencyProperty TextViewProperty =
      DependencyProperty.Register("TextView", typeof(TextView), typeof(AbstractMargin),
                                  new FrameworkPropertyMetadata(OnTextViewChanged));
    
    /// <summary>
    /// Gets/sets the text view for which line numbers are displayed.
    /// </summary>
    /// <remarks>Adding a margin to <see cref="TextArea.LeftMargins"/> will automatically set this property to the text area's TextView.</remarks>
    public TextView TextView {
      get { return (TextView)GetValue(TextViewProperty); }
      set { SetValue(TextViewProperty, value); }
    }
    
    static void OnTextViewChanged(DependencyObject dp, DependencyPropertyChangedEventArgs e)
    {
      AbstractMargin margin = (AbstractMargin)dp;
      margin.wasAutoAddedToTextView = false;
      margin.OnTextViewChanged((TextView)e.OldValue, (TextView)e.NewValue);
    }
    
    // automatically set/unset TextView property using ITextViewConnect
    bool wasAutoAddedToTextView;
    
    void ITextViewConnect.AddToTextView(TextView textView)
    {
      if (this.TextView == null) {
        this.TextView = textView;
        wasAutoAddedToTextView = true;
      } else if (this.TextView != textView) {
        throw new InvalidOperationException("This margin belongs to a different TextView.");
      }
    }
    
    void ITextViewConnect.RemoveFromTextView(TextView textView)
    {
      if (wasAutoAddedToTextView && this.TextView == textView) {
        this.TextView = null;
        Debug.Assert(!wasAutoAddedToTextView); // setting this.TextView should have unset this flag
      }
    }
    
    TextDocument document;
    
    /// <summary>
    /// Gets the document associated with the margin.
    /// </summary>
    public TextDocument Document {
      get { return document; }
    }
    
    /// <summary>
    /// Called when the <see cref="TextView"/> is changing.
    /// </summary>
    protected virtual void OnTextViewChanged(TextView oldTextView, TextView newTextView)
    {
      if (oldTextView != null) {
        oldTextView.DocumentChanged -= TextViewDocumentChanged;
      }
      if (newTextView != null) {
        newTextView.DocumentChanged += TextViewDocumentChanged;
      }
      TextViewDocumentChanged(null, null);
    }
    
    void TextViewDocumentChanged(object sender, EventArgs e)
    {
      OnDocumentChanged(document, TextView != null ? TextView.Document : null);
    }
    
    /// <summary>
    /// Called when the <see cref="Document"/> is changing.
    /// </summary>
    protected virtual void OnDocumentChanged(TextDocument oldDocument, TextDocument newDocument)
    {
      document = newDocument;
    }
  }
}