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// 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;
namespace ICSharpCode.AvalonEdit.Rendering
{
/// <summary>
/// Abstract base class for generators that produce new visual line elements.
/// </summary>
public abstract class VisualLineElementGenerator
{
/// <summary>
/// Gets the text run construction context.
/// </summary>
protected ITextRunConstructionContext CurrentContext { get; private set; }
/// <summary>
/// Initializes the generator for the <see cref="ITextRunConstructionContext"/>
/// </summary>
public virtual void StartGeneration(ITextRunConstructionContext context)
{
if (context == null)
throw new ArgumentNullException("context");
this.CurrentContext = context;
}
/// <summary>
/// De-initializes the generator.
/// </summary>
public virtual void FinishGeneration()
{
this.CurrentContext = null;
}
/// <summary>
/// Should only be used by VisualLine.ConstructVisualElements.
/// </summary>
internal int cachedInterest;
/// <summary>
/// Gets the first offset >= startOffset where the generator wants to construct an element.
/// Return -1 to signal no interest.
/// </summary>
public abstract int GetFirstInterestedOffset(int startOffset);
/// <summary>
/// Constructs an element at the specified offset.
/// May return null if no element should be constructed.
/// </summary>
/// <remarks>
/// Avoid signalling interest and then building no element by returning null - doing so
/// causes the generated <see cref="VisualLineText"/> elements to be unnecessarily split
/// at the position where you signalled interest.
/// </remarks>
public abstract VisualLineElement ConstructElement(int offset);
}
internal interface IBuiltinElementGenerator
{
void FetchOptions(TextEditorOptions options);
}
}
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