// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
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)
{
}
}
}
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