LayerPosition.cs

// 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
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// 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
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// DEALINGS IN THE SOFTWARE.

using System;
using System.Diagnostics.CodeAnalysis;

namespace Unity.CodeEditor.Rendering
{
	/// <summary>
	/// An enumeration of well-known layers.
	/// </summary>
	internal enum KnownLayer
	{
		/// <summary>
		/// This layer is in the background.
		/// There is no UIElement to represent this layer, it is directly drawn in the TextView.
		/// It is not possible to replace the background layer or insert new layers below it.
		/// </summary>
		/// <remarks>This layer is below the Selection layer.</remarks>
		Background,
		/// <summary>
		/// This layer contains the selection rectangle.
		/// </summary>
		/// <remarks>This layer is between the Background and the Text layers.</remarks>
		Selection,
		/// <summary>
		/// This layer contains the text and inline UI elements.
		/// </summary>
		/// <remarks>This layer is between the Selection and the Caret layers.</remarks>
		Text,
		/// <summary>
		/// This layer contains the blinking caret.
		/// </summary>
		/// <remarks>This layer is above the Text layer.</remarks>
		Caret
	}
	
	/// <summary>
	/// Specifies where a new layer is inserted, in relation to an old layer.
	/// </summary>
	internal enum LayerInsertionPosition
	{
		/// <summary>
		/// The new layer is inserted below the specified layer.
		/// </summary>
		Below,
		/// <summary>
		/// The new layer replaces the specified layer. The old layer is removed
		/// from the <see cref="TextView.Layers"/> collection.
		/// </summary>
		Replace,
		/// <summary>
		/// The new layer is inserted above the specified layer.
		/// </summary>
		Above
	}
	
	internal sealed class LayerPosition : IComparable<LayerPosition>
	{
		internal readonly KnownLayer KnownLayer;
		internal readonly LayerInsertionPosition Position;
		
		internal LayerPosition(KnownLayer knownLayer, LayerInsertionPosition position)
		{
			KnownLayer = knownLayer;
			Position = position;
		}
		
		[SuppressMessage("ReSharper", "ImpureMethodCallOnReadonlyValueField")]
		public int CompareTo(LayerPosition other)
		{
			var r = KnownLayer.CompareTo(other.KnownLayer);
			return r != 0 ? r : Position.CompareTo(other.Position);
		}
	}
}