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//---------------------------------------------------------------------------
//
// <copyright file=?HighlightLayer.cs? company=?Microsoft?>
// Copyright (C) Microsoft Corporation. All rights reserved.
// </copyright>
//
//
// Description: A group of non-overlapping text highlights with a single owner.
//
// History:
// 07/01/2004 : benwest - Created
//
//---------------------------------------------------------------------------
using System.Collections;
namespace System.Windows.Documents
{
/// <summary>
/// A group of non-overlapping text highlights with a single owner.
///
/// Conceptually, this object is a collection of ranges and a list
/// of property/values pairs highlighting content under each range.
/// </summary>
internal abstract class HighlightLayer
{
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
#region Internal Methods
/// <summary>
/// Returns the value of a property stored on scoping highlight, if any.
/// </summary>
/// <param name="textPosition">
/// Position to query.
/// </param>
/// <param name="direction">
/// Direction of content to query.
/// </param>
/// <returns>
/// The property value if set on any scoping highlight. If no property
/// value is set, returns DependencyProperty.UnsetValue.
/// </returns>
internal abstract object GetHighlightValue(StaticTextPointer textPosition, LogicalDirection direction);
/// <summary>
/// Returns true iff the indicated content has scoping highlights.
/// </summary>
/// <param name="textPosition">
/// Position to query.
/// </param>
/// <param name="direction">
/// Direction of content to query.
/// </param>
internal abstract bool IsContentHighlighted(StaticTextPointer textPosition, LogicalDirection direction);
/// <summary>
/// Returns the position of the next highlight start or end in an
/// indicated direction, or null if there is no such position.
/// </summary>
/// <param name="textPosition">
/// Position to query.
/// </param>
/// <param name="direction">
/// Direction of content to query.
/// </param>
internal abstract StaticTextPointer GetNextChangePosition(StaticTextPointer textPosition, LogicalDirection direction);
#endregion Internal Methods
//------------------------------------------------------
//
// Internal Properties
//
//------------------------------------------------------
#region Internal Properties
/// <summary>
/// Type identifying the owner of this layer for Highlights.GetHighlightValue calls.
/// </summary>
internal abstract Type OwnerType { get; }
#endregion Internal Properties
//------------------------------------------------------
//
// Internal Events
//
//------------------------------------------------------
#region Internal Events
/// <summary>
/// Event raised when a highlight is inserted, removed, moved, or
/// has a local property value change.
/// </summary>
internal abstract event HighlightChangedEventHandler Changed;
#endregion Internal Events
}
}
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