source: branches/CodeEditor/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Rendering/ColorizingTransformer.cs @ 11700

// 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;

namespace ICSharpCode.AvalonEdit.Rendering
{
  /// <summary>
  /// Base class for <see cref="IVisualLineTransformer"/> that helps
  /// splitting visual elements so that colors (and other text properties) can be easily assigned
  /// to individual words/characters.
  /// </summary>
  public abstract class ColorizingTransformer : IVisualLineTransformer, ITextViewConnect
  {
    /// <summary>
    /// Gets the list of elements currently being transformed.
    /// </summary>
    protected IList<VisualLineElement> CurrentElements { get; private set; }
    
    /// <summary>
    /// <see cref="IVisualLineTransformer.Transform"/> implementation.
    /// Sets <see cref="CurrentElements"/> and calls <see cref="Colorize"/>.
    /// </summary>
    public void Transform(ITextRunConstructionContext context, IList<VisualLineElement> elements)
    {
      if (elements == null)
        throw new ArgumentNullException("elements");
      if (this.CurrentElements != null)
        throw new InvalidOperationException("Recursive Transform() call");
      this.CurrentElements = elements;
      try {
        Colorize(context);
      } finally {
        this.CurrentElements = null;
      }
    }
    
    /// <summary>
    /// Performs the colorization.
    /// </summary>
    protected abstract void Colorize(ITextRunConstructionContext context);
    
    /// <summary>
    /// Changes visual element properties.
    /// This method accesses <see cref="CurrentElements"/>, so it must be called only during
    /// a <see cref="Transform"/> call.
    /// This method splits <see cref="VisualLineElement"/>s as necessary to ensure that the region
    /// can be colored by setting the <see cref="VisualLineElement.TextRunProperties"/> of whole elements,
    /// and then calls the <paramref name="action"/> on all elements in the region.
    /// </summary>
    /// <param name="visualStartColumn">Start visual column of the region to change</param>
    /// <param name="visualEndColumn">End visual column of the region to change</param>
    /// <param name="action">Action that changes an individual <see cref="VisualLineElement"/>.</param>
    protected void ChangeVisualElements(int visualStartColumn, int visualEndColumn, Action<VisualLineElement> action)
    {
      if (action == null)
        throw new ArgumentNullException("action");
      for (int i = 0; i < CurrentElements.Count; i++) {
        VisualLineElement e = CurrentElements[i];
        if (e.VisualColumn > visualEndColumn)
          break;
        if (e.VisualColumn < visualStartColumn &&
            e.VisualColumn + e.VisualLength > visualStartColumn)
        {
          if (e.CanSplit) {
            e.Split(visualStartColumn, CurrentElements, i--);
            continue;
          }
        }
        if (e.VisualColumn >= visualStartColumn && e.VisualColumn < visualEndColumn) {
          if (e.VisualColumn + e.VisualLength > visualEndColumn) {
            if (e.CanSplit) {
              e.Split(visualEndColumn, CurrentElements, i--);
              continue;
            }
          } else {
            action(e);
          }
        }
      }
    }
    
    /// <summary>
    /// Called when added to a text view.
    /// </summary>
    protected virtual void OnAddToTextView(TextView textView)
    {
    }
    
    /// <summary>
    /// Called when removed from a text view.
    /// </summary>
    protected virtual void OnRemoveFromTextView(TextView textView)
    {
    }
    
    void ITextViewConnect.AddToTextView(TextView textView)
    {
      OnAddToTextView(textView);
    }
    
    void ITextViewConnect.RemoveFromTextView(TextView textView)
    {
      OnRemoveFromTextView(textView);
    }
  }
}