source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Snippets/SnippetReplaceableTextElement.cs @ 16452

// 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
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// DEALINGS IN THE SOFTWARE.

using System;
using System.Linq;
using System.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using ICSharpCode.NRefactory.Editor;
using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Rendering;

namespace ICSharpCode.AvalonEdit.Snippets
{
  /// <summary>
  /// Text element that is supposed to be replaced by the user.
  /// Will register an <see cref="IReplaceableActiveElement"/>.
  /// </summary>
  [Serializable]
  public class SnippetReplaceableTextElement : SnippetTextElement
  {
    /// <inheritdoc/>
    public override void Insert(InsertionContext context)
    {
      int start = context.InsertionPosition;
      base.Insert(context);
      int end = context.InsertionPosition;
      context.RegisterActiveElement(this, new ReplaceableActiveElement(context, start, end));
    }
    
    /// <inheritdoc/>
    public override Inline ToTextRun()
    {
      return new Italic(base.ToTextRun());
    }
  }
  
  /// <summary>
  /// Interface for active element registered by <see cref="SnippetReplaceableTextElement"/>.
  /// </summary>
  public interface IReplaceableActiveElement : IActiveElement
  {
    /// <summary>
    /// Gets the current text inside the element.
    /// </summary>
    string Text { get; }
    
    /// <summary>
    /// Occurs when the text inside the element changes.
    /// </summary>
    event EventHandler TextChanged;
  }
  
  sealed class ReplaceableActiveElement : IReplaceableActiveElement, IWeakEventListener
  {
    readonly InsertionContext context;
    readonly int startOffset, endOffset;
    TextAnchor start, end;
    
    public ReplaceableActiveElement(InsertionContext context, int startOffset, int endOffset)
    {
      this.context = context;
      this.startOffset = startOffset;
      this.endOffset = endOffset;
    }
    
    void AnchorDeleted(object sender, EventArgs e)
    {
      context.Deactivate(new SnippetEventArgs(DeactivateReason.Deleted));
    }
    
    public void OnInsertionCompleted()
    {
      // anchors must be created in OnInsertionCompleted because they should move only
      // due to user insertions, not due to insertions of other snippet parts
      start = context.Document.CreateAnchor(startOffset);
      start.MovementType = AnchorMovementType.BeforeInsertion;
      end = context.Document.CreateAnchor(endOffset);
      end.MovementType = AnchorMovementType.AfterInsertion;
      start.Deleted += AnchorDeleted;
      end.Deleted += AnchorDeleted;
      
      // Be careful with references from the document to the editing/snippet layer - use weak events
      // to prevent memory leaks when the text area control gets dropped from the UI while the snippet is active.
      // The InsertionContext will keep us alive as long as the snippet is in interactive mode.
      TextDocumentWeakEventManager.TextChanged.AddListener(context.Document, this);
      
      background = new Renderer { Layer = KnownLayer.Background, element = this };
      foreground = new Renderer { Layer = KnownLayer.Text, element = this };
      context.TextArea.TextView.BackgroundRenderers.Add(background);
      context.TextArea.TextView.BackgroundRenderers.Add(foreground);
      context.TextArea.Caret.PositionChanged += Caret_PositionChanged;
      Caret_PositionChanged(null, null);
      
      this.Text = GetText();
    }

    public void Deactivate(SnippetEventArgs e)
    {
      TextDocumentWeakEventManager.TextChanged.RemoveListener(context.Document, this);
      context.TextArea.TextView.BackgroundRenderers.Remove(background);
      context.TextArea.TextView.BackgroundRenderers.Remove(foreground);
      context.TextArea.Caret.PositionChanged -= Caret_PositionChanged;
    }
    
    bool isCaretInside;
    
    void Caret_PositionChanged(object sender, EventArgs e)
    {
      ISegment s = this.Segment;
      if (s != null) {
        bool newIsCaretInside = s.Contains(context.TextArea.Caret.Offset, 0);
        if (newIsCaretInside != isCaretInside) {
          isCaretInside = newIsCaretInside;
          context.TextArea.TextView.InvalidateLayer(foreground.Layer);
        }
      }
    }
    
    Renderer background, foreground;
    
    public string Text { get; private set; }
    
    string GetText()
    {
      if (start.IsDeleted || end.IsDeleted)
        return string.Empty;
      else
        return context.Document.GetText(start.Offset, Math.Max(0, end.Offset - start.Offset));
    }
    
    public event EventHandler TextChanged;
    
    bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
    {
      if (managerType == typeof(TextDocumentWeakEventManager.TextChanged)) {
        string newText = GetText();
        if (this.Text != newText) {
          this.Text = newText;
          if (TextChanged != null)
            TextChanged(this, e);
        }
        return true;
      }
      return false;
    }
    
    public bool IsEditable {
      get { return true; }
    }
    
    public ISegment Segment {
      get {
        if (start.IsDeleted || end.IsDeleted)
          return null;
        else
          return new SimpleSegment(start.Offset, Math.Max(0, end.Offset - start.Offset));
      }
    }
    
    sealed class Renderer : IBackgroundRenderer
    {
      static readonly Brush backgroundBrush = CreateBackgroundBrush();
      static readonly Pen activeBorderPen = CreateBorderPen();
      
      static Brush CreateBackgroundBrush()
      {
        SolidColorBrush b = new SolidColorBrush(Colors.LimeGreen);
        b.Opacity = 0.4;
        b.Freeze();
        return b;
      }
      
      static Pen CreateBorderPen()
      {
        Pen p = new Pen(Brushes.Black, 1);
        p.DashStyle = DashStyles.Dot;
        p.Freeze();
        return p;
      }
      
      internal ReplaceableActiveElement element;
      
      public KnownLayer Layer { get; set; }
      
      public void Draw(TextView textView, System.Windows.Media.DrawingContext drawingContext)
      {
        ISegment s = element.Segment;
        if (s != null) {
          BackgroundGeometryBuilder geoBuilder = new BackgroundGeometryBuilder();
          geoBuilder.AlignToMiddleOfPixels = true;
          if (Layer == KnownLayer.Background) {
            geoBuilder.AddSegment(textView, s);
            drawingContext.DrawGeometry(backgroundBrush, null, geoBuilder.CreateGeometry());
          } else {
            // draw foreground only if active
            if (element.isCaretInside) {
              geoBuilder.AddSegment(textView, s);
              foreach (BoundActiveElement boundElement in element.context.ActiveElements.OfType<BoundActiveElement>()) {
                if (boundElement.targetElement == element) {
                  geoBuilder.AddSegment(textView, boundElement.Segment);
                  geoBuilder.CloseFigure();
                }
              }
              drawingContext.DrawGeometry(null, activeBorderPen, geoBuilder.CreateGeometry());
            }
          }
        }
      }
    }
  }
}