source: branches/3107_LearningALPS/HeuristicLab.ExtLibs/HeuristicLab.AvalonEdit/5.0.1/AvalonEdit-5.0.1/Rendering/VisualLineElement.cs @ 17852

// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
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// 
// 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 System;
using System.Collections.Generic;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.TextFormatting;

using ICSharpCode.AvalonEdit.Document;

namespace ICSharpCode.AvalonEdit.Rendering
{
  /// <summary>
  /// Represents a visual element in the document.
  /// </summary>
  public abstract class VisualLineElement
  {
    /// <summary>
    /// Creates a new VisualLineElement.
    /// </summary>
    /// <param name="visualLength">The length of the element in VisualLine coordinates. Must be positive.</param>
    /// <param name="documentLength">The length of the element in the document. Must be non-negative.</param>
    protected VisualLineElement(int visualLength, int documentLength)
    {
      if (visualLength < 1)
        throw new ArgumentOutOfRangeException("visualLength", visualLength, "Value must be at least 1");
      if (documentLength < 0)
        throw new ArgumentOutOfRangeException("documentLength", documentLength, "Value must be at least 0");
      this.VisualLength = visualLength;
      this.DocumentLength = documentLength;
    }
    
    /// <summary>
    /// Gets the length of this element in visual columns.
    /// </summary>
    public int VisualLength { get; private set; }
    
    /// <summary>
    /// Gets the length of this element in the text document.
    /// </summary>
    public int DocumentLength { get; private set; }
    
    /// <summary>
    /// Gets the visual column where this element starts.
    /// </summary>
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1721:PropertyNamesShouldNotMatchGetMethods",
                                                     Justification = "This property holds the start visual column, use GetVisualColumn to get inner visual columns.")]
    public int VisualColumn { get; internal set; }
    
    /// <summary>
    /// Gets the text offset where this element starts, relative to the start text offset of the visual line.
    /// </summary>
    public int RelativeTextOffset { get; internal set; }
    
    /// <summary>
    /// Gets the text run properties.
    /// A unique <see cref="VisualLineElementTextRunProperties"/> instance is used for each
    /// <see cref="VisualLineElement"/>; colorizing code may assume that modifying the
    /// <see cref="VisualLineElementTextRunProperties"/> will affect only this
    /// <see cref="VisualLineElement"/>.
    /// </summary>
    public VisualLineElementTextRunProperties TextRunProperties { get; private set; }
    
    /// <summary>
    /// Gets/sets the brush used for the background of this <see cref="VisualLineElement" />.
    /// </summary>
    public Brush BackgroundBrush { get; set; }
    
    internal void SetTextRunProperties(VisualLineElementTextRunProperties p)
    {
      this.TextRunProperties = p;
    }
    
    /// <summary>
    /// Creates the TextRun for this line element.
    /// </summary>
    /// <param name="startVisualColumn">
    /// The visual column from which the run should be constructed.
    /// Normally the same value as the <see cref="VisualColumn"/> property is used to construct the full run;
    /// but when word-wrapping is active, partial runs might be created.
    /// </param>
    /// <param name="context">
    /// Context object that contains information relevant for text run creation.
    /// </param>
    public abstract TextRun CreateTextRun(int startVisualColumn, ITextRunConstructionContext context);
    
    /// <summary>
    /// Retrieves the text span immediately before the visual column.
    /// </summary>
    /// <remarks>This method is used for word-wrapping in bidirectional text.</remarks>
    public virtual TextSpan<CultureSpecificCharacterBufferRange> GetPrecedingText(int visualColumnLimit, ITextRunConstructionContext context)
    {
      return null;
    }
    
    /// <summary>
    /// Gets if this VisualLineElement can be split.
    /// </summary>
    public virtual bool CanSplit {
      get { return false; }
    }
    
    /// <summary>
    /// Splits the element.
    /// </summary>
    /// <param name="splitVisualColumn">Position inside this element at which it should be broken</param>
    /// <param name="elements">The collection of line elements</param>
    /// <param name="elementIndex">The index at which this element is in the elements list.</param>
    public virtual void Split(int splitVisualColumn, IList<VisualLineElement> elements, int elementIndex)
    {
      throw new NotSupportedException();
    }
    
    /// <summary>
    /// Helper method for splitting this line element into two, correctly updating the
    /// <see cref="VisualLength"/>, <see cref="DocumentLength"/>, <see cref="VisualColumn"/>
    /// and <see cref="RelativeTextOffset"/> properties.
    /// </summary>
    /// <param name="firstPart">The element before the split position.</param>
    /// <param name="secondPart">The element after the split position.</param>
    /// <param name="splitVisualColumn">The split position as visual column.</param>
    /// <param name="splitRelativeTextOffset">The split position as text offset.</param>
    protected void SplitHelper(VisualLineElement firstPart, VisualLineElement secondPart, int splitVisualColumn, int splitRelativeTextOffset)
    {
      if (firstPart == null)
        throw new ArgumentNullException("firstPart");
      if (secondPart == null)
        throw new ArgumentNullException("secondPart");
      int relativeSplitVisualColumn = splitVisualColumn - VisualColumn;
      int relativeSplitRelativeTextOffset = splitRelativeTextOffset - RelativeTextOffset;
      
      if (relativeSplitVisualColumn <= 0 || relativeSplitVisualColumn >= VisualLength)
        throw new ArgumentOutOfRangeException("splitVisualColumn", splitVisualColumn, "Value must be between " + (VisualColumn + 1) + " and " + (VisualColumn + VisualLength - 1));
      if (relativeSplitRelativeTextOffset < 0 || relativeSplitRelativeTextOffset > DocumentLength)
        throw new ArgumentOutOfRangeException("splitRelativeTextOffset", splitRelativeTextOffset, "Value must be between " + (RelativeTextOffset) + " and " + (RelativeTextOffset + DocumentLength));
      int oldVisualLength = VisualLength;
      int oldDocumentLength = DocumentLength;
      int oldVisualColumn = VisualColumn;
      int oldRelativeTextOffset = RelativeTextOffset;
      firstPart.VisualColumn = oldVisualColumn;
      secondPart.VisualColumn = oldVisualColumn + relativeSplitVisualColumn;
      firstPart.RelativeTextOffset = oldRelativeTextOffset;
      secondPart.RelativeTextOffset = oldRelativeTextOffset + relativeSplitRelativeTextOffset;
      firstPart.VisualLength = relativeSplitVisualColumn;
      secondPart.VisualLength = oldVisualLength - relativeSplitVisualColumn;
      firstPart.DocumentLength = relativeSplitRelativeTextOffset;
      secondPart.DocumentLength = oldDocumentLength - relativeSplitRelativeTextOffset;
      if (firstPart.TextRunProperties == null)
        firstPart.TextRunProperties = TextRunProperties.Clone();
      if (secondPart.TextRunProperties == null)
        secondPart.TextRunProperties = TextRunProperties.Clone();
    }
    
    /// <summary>
    /// Gets the visual column of a text location inside this element.
    /// The text offset is given relative to the visual line start.
    /// </summary>
    public virtual int GetVisualColumn(int relativeTextOffset)
    {
      if (relativeTextOffset >= this.RelativeTextOffset + DocumentLength)
        return VisualColumn + VisualLength;
      else
        return VisualColumn;
    }
    
    /// <summary>
    /// Gets the text offset of a visual column inside this element.
    /// </summary>
    /// <returns>A text offset relative to the visual line start.</returns>
    public virtual int GetRelativeOffset(int visualColumn)
    {
      if (visualColumn >= this.VisualColumn + VisualLength)
        return RelativeTextOffset + DocumentLength;
      else
        return RelativeTextOffset;
    }
    
    /// <summary>
    /// Gets the next caret position inside this element.
    /// </summary>
    /// <param name="visualColumn">The visual column from which the search should be started.</param>
    /// <param name="direction">The search direction (forwards or backwards).</param>
    /// <param name="mode">Whether to stop only at word borders.</param>
    /// <returns>The visual column of the next caret position, or -1 if there is no next caret position.</returns>
    /// <remarks>
    /// In the space between two line elements, it is sufficient that one of them contains a caret position;
    /// though in many cases, both of them contain one.
    /// </remarks>
    public virtual int GetNextCaretPosition(int visualColumn, LogicalDirection direction, CaretPositioningMode mode)
    {
      int stop1 = this.VisualColumn;
      int stop2 = this.VisualColumn + this.VisualLength;
      if (direction == LogicalDirection.Backward) {
        if (visualColumn > stop2 && mode != CaretPositioningMode.WordStart && mode != CaretPositioningMode.WordStartOrSymbol)
          return stop2;
        else if (visualColumn > stop1)
          return stop1;
      } else {
        if (visualColumn < stop1)
          return stop1;
        else if (visualColumn < stop2 && mode != CaretPositioningMode.WordStart && mode != CaretPositioningMode.WordStartOrSymbol)
          return stop2;
      }
      return -1;
    }
    
    /// <summary>
    /// Gets whether the specified offset in this element is considered whitespace.
    /// </summary>
    public virtual bool IsWhitespace(int visualColumn)
    {
      return false;
    }
    
    /// <summary>
    /// Gets whether the <see cref="GetNextCaretPosition"/> implementation handles line borders.
    /// If this property returns false, the caller of GetNextCaretPosition should handle the line
    /// borders (i.e. place caret stops at the start and end of the line).
    /// This property has an effect only for VisualLineElements that are at the start or end of a
    /// <see cref="VisualLine"/>.
    /// </summary>
    public virtual bool HandlesLineBorders {
      get { return false; }
    }
    
    /// <summary>
    /// Queries the cursor over the visual line element.
    /// </summary>
    protected internal virtual void OnQueryCursor(QueryCursorEventArgs e)
    {
    }
    
    /// <summary>
    /// Allows the visual line element to handle a mouse event.
    /// </summary>
    protected internal virtual void OnMouseDown(MouseButtonEventArgs e)
    {
    }
    
    /// <summary>
    /// Allows the visual line element to handle a mouse event.
    /// </summary>
    protected internal virtual void OnMouseUp(MouseButtonEventArgs e)
    {
    }
  }
}