source: trunk/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Rendering/SingleCharacterElementGenerator.cs @ 17507

// 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.Windows;
using System.Windows.Documents;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;

using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Rendering
{
  // This class is internal because it does not need to be accessed by the user - it can be configured using TextEditorOptions.
  
  /// <summary>
  /// Element generator that displays · for spaces and » for tabs and a box for control characters.
  /// </summary>
  /// <remarks>
  /// This element generator is present in every TextView by default; the enabled features can be configured using the
  /// <see cref="TextEditorOptions"/>.
  /// </remarks>
  [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1702:CompoundWordsShouldBeCasedCorrectly", MessageId = "Whitespace")]
  sealed class SingleCharacterElementGenerator : VisualLineElementGenerator, IBuiltinElementGenerator
  {
    /// <summary>
    /// Gets/Sets whether to show · for spaces.
    /// </summary>
    public bool ShowSpaces { get; set; }
    
    /// <summary>
    /// Gets/Sets whether to show » for tabs.
    /// </summary>
    public bool ShowTabs { get; set; }
    
    /// <summary>
    /// Gets/Sets whether to show a box with the hex code for control characters.
    /// </summary>
    public bool ShowBoxForControlCharacters { get; set; }
    
    /// <summary>
    /// Creates a new SingleCharacterElementGenerator instance.
    /// </summary>
    public SingleCharacterElementGenerator()
    {
      this.ShowSpaces = true;
      this.ShowTabs = true;
      this.ShowBoxForControlCharacters = true;
    }
    
    void IBuiltinElementGenerator.FetchOptions(TextEditorOptions options)
    {
      this.ShowSpaces = options.ShowSpaces;
      this.ShowTabs = options.ShowTabs;
      this.ShowBoxForControlCharacters = options.ShowBoxForControlCharacters;
    }
    
    public override int GetFirstInterestedOffset(int startOffset)
    {
      DocumentLine endLine = CurrentContext.VisualLine.LastDocumentLine;
      StringSegment relevantText = CurrentContext.GetText(startOffset, endLine.EndOffset - startOffset);
      
      for (int i = 0; i < relevantText.Count; i++) {
        char c = relevantText.Text[relevantText.Offset + i];
        switch (c) {
          case ' ':
            if (ShowSpaces)
              return startOffset + i;
            break;
          case '\t':
            if (ShowTabs)
              return startOffset + i;
            break;
          default:
            if (ShowBoxForControlCharacters && char.IsControl(c)) {
              return startOffset + i;
            }
            break;
        }
      }
      return -1;
    }
    
    public override VisualLineElement ConstructElement(int offset)
    {
      char c = CurrentContext.Document.GetCharAt(offset);
      if (ShowSpaces && c == ' ') {
        return new SpaceTextElement(CurrentContext.TextView.cachedElements.GetTextForNonPrintableCharacter("\u00B7", CurrentContext));
      } else if (ShowTabs && c == '\t') {
        return new TabTextElement(CurrentContext.TextView.cachedElements.GetTextForNonPrintableCharacter("\u00BB", CurrentContext));
      } else if (ShowBoxForControlCharacters && char.IsControl(c)) {
        var p = new VisualLineElementTextRunProperties(CurrentContext.GlobalTextRunProperties);
        p.SetForegroundBrush(Brushes.White);
        var textFormatter = TextFormatterFactory.Create(CurrentContext.TextView);
        var text = FormattedTextElement.PrepareText(textFormatter,
                                                    TextUtilities.GetControlCharacterName(c), p);
        return new SpecialCharacterBoxElement(text);
      } else {
        return null;
      }
    }
    
    sealed class SpaceTextElement : FormattedTextElement
    {
      public SpaceTextElement(TextLine textLine) : base(textLine, 1)
      {
        BreakBefore = LineBreakCondition.BreakPossible;
        BreakAfter = LineBreakCondition.BreakDesired;
      }
      
      public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
      {
        if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
          return base.GetNextCaretPosition(visualColumn, direction, mode);
        else
          return -1;
      }
      
      public override bool IsWhitespace(int visualColumn)
      {
        return true;
      }
    }
    
    sealed class TabTextElement : VisualLineElement
    {
      internal readonly TextLine text;
      
      public TabTextElement(TextLine text) : base(2, 1)
      {
        this.text = text;
      }
      
      public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
      {
        // the TabTextElement consists of two TextRuns:
        // first a TabGlyphRun, then TextCharacters '\t' to let WPF handle the tab indentation
        if (startVisualColumn == this.VisualColumn)
          return new TabGlyphRun(this, this.TextRunProperties);
        else if (startVisualColumn == this.VisualColumn + 1)
          return new TextCharacters("\t", 0, 1, this.TextRunProperties);
        else
          throw new ArgumentOutOfRangeException("startVisualColumn");
      }
      
      public override int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
      {
        if (mode == CaretPositioningMode.Normal || mode == CaretPositioningMode.EveryCodepoint)
          return base.GetNextCaretPosition(visualColumn, direction, mode);
        else
          return -1;
      }
      
      public override bool IsWhitespace(int visualColumn)
      {
        return true;
      }
    }
    
    sealed class TabGlyphRun : TextEmbeddedObject
    {
      readonly TabTextElement element;
      TextRunProperties properties;
      
      public TabGlyphRun(TabTextElement element, TextRunProperties properties)
      {
        if (properties == null)
          throw new ArgumentNullException("properties");
        this.properties = properties;
        this.element = element;
      }
      
      public override LineBreakCondition BreakBefore {
        get { return LineBreakCondition.BreakPossible; }
      }
      
      public override LineBreakCondition BreakAfter {
        get { return LineBreakCondition.BreakRestrained; }
      }
      
      public override bool HasFixedSize {
        get { return true; }
      }
      
      public override CharacterBufferReference CharacterBufferReference {
        get { return new CharacterBufferReference(); }
      }
      
      public override int Length {
        get { return 1; }
      }
      
      public override TextRunProperties Properties {
        get { return properties; }
      }
      
      public override TextEmbeddedObjectMetrics Format(double remainingParagraphWidth)
      {
        double width = Math.Min(0, element.text.WidthIncludingTrailingWhitespace - 1);
        return new TextEmbeddedObjectMetrics(width, element.text.Height, element.text.Baseline);
      }
      
      public override Rect ComputeBoundingBox(bool rightToLeft, bool sideways)
      {
        double width = Math.Min(0, element.text.WidthIncludingTrailingWhitespace - 1);
        return new Rect(0, 0, width, element.text.Height);
      }
      
      public override void Draw(DrawingContext drawingContext, Point origin, bool rightToLeft, bool sideways)
      {
        origin.Y -= element.text.Baseline;
        element.text.Draw(drawingContext, origin, InvertAxes.None);
      }
    }
    
    sealed class SpecialCharacterBoxElement : FormattedTextElement
    {
      public SpecialCharacterBoxElement(TextLine text) : base(text, 1)
      {
      }
      
      public override TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context)
      {
        return new SpecialCharacterTextRun(this, this.TextRunProperties);
      }
    }
    
    sealed class SpecialCharacterTextRun : FormattedTextRun
    {
      static readonly SolidColorBrush darkGrayBrush;
      
      static SpecialCharacterTextRun()
      {
        darkGrayBrush = new SolidColorBrush(Color.FromArgb(200, 128, 128, 128));
        darkGrayBrush.Freeze();
      }
      
      public SpecialCharacterTextRun(FormattedTextElement element, TextRunProperties properties)
        : base(element, properties)
      {
      }
      
      public override void Draw(DrawingContext drawingContext, Point origin, bool rightToLeft, bool sideways)
      {
        Point newOrigin = new Point(origin.X + 1.5, origin.Y);
        var metrics = base.Format(double.PositiveInfinity);
        Rect r = new Rect(newOrigin.X - 0.5, newOrigin.Y - metrics.Baseline, metrics.Width + 2, metrics.Height);
        drawingContext.DrawRoundedRectangle(darkGrayBrush, null, r, 2.5, 2.5);
        base.Draw(drawingContext, newOrigin, rightToLeft, sideways);
      }
      
      public override TextEmbeddedObjectMetrics Format(double remainingParagraphWidth)
      {
        TextEmbeddedObjectMetrics metrics = base.Format(remainingParagraphWidth);
        return new TextEmbeddedObjectMetrics(metrics.Width + 3,
                                             metrics.Height, metrics.Baseline);
      }
      
      public override Rect ComputeBoundingBox(bool rightToLeft, bool sideways)
      {
        Rect r = base.ComputeBoundingBox(rightToLeft, sideways);
        r.Width += 3;
        return r;
      }
    }
  }
}