linearunit.cs

Sharp Map 用于制作GIS系统S harp Map 用于制作GIS系统S harp Map 用于制作GIS系统

// Copyright 2005, 2006 - Morten Nielsen (www.iter.dk)
//
// This file is part of SharpMap.
// SharpMap is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// SharpMap is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with SharpMap; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.Collections.Generic;
using System.Text;

namespace SharpMap.CoordinateSystems
{
	/// <summary>
	/// Definition of linear units.
	/// </summary>
	public class LinearUnit : Info, ILinearUnit
	{
		/// <summary>
		/// Creates an instance of a linear unit
		/// </summary>
		/// <param name="metersPerUnit">Number of meters per <see cref="LinearUnit" /></param>
		/// <param name="name">Name</param>
		/// <param name="authority">Authority name</param>
		/// <param name="authorityCode">Authority-specific identification code.</param>
		/// <param name="alias">Alias</param>
		/// <param name="abbreviation">Abbreviation</param>
		/// <param name="remarks">Provider-supplied remarks</param>
		public LinearUnit(double metersPerUnit, string name, string authority, long authorityCode, string alias, string abbreviation, string remarks)
			:
			base(name, authority, authorityCode, alias, abbreviation, remarks)
		{
			_MetersPerUnit = metersPerUnit;
		}

		#region Predefined units
		/// <summary>
		/// Returns the meters linear unit.
		/// Also known as International metre. SI standard unit.
		/// </summary>
		public static ILinearUnit Metre
		{
			get { return new LinearUnit(1.0,"metre", "EPSG", 9001, "m", String.Empty, "Also known as International metre. SI standard unit."); }
		}
		/// <summary>
		/// Returns the foot linear unit (1ft = 0.3048m).
		/// </summary>
		public static ILinearUnit Foot
		{
			get { return new LinearUnit(0.3048, "foot", "EPSG", 9002, "ft", String.Empty, String.Empty); }
		}
		/// <summary>
		/// Returns the US Survey foot linear unit (1ftUS = 0.304800609601219m).
		/// </summary>
		public static ILinearUnit USSurveyFoot
		{
			get { return new LinearUnit(0.304800609601219, "US survey foot", "EPSG", 9003, "American foot", "ftUS", "Used in USA."); }
		}
		/// <summary>
		/// Returns the Nautical Mile linear unit (1NM = 1852m).
		/// </summary>
		public static ILinearUnit NauticalMile
		{
			get { return new LinearUnit(1852, "nautical mile", "EPSG", 9030, "NM", String.Empty, String.Empty); }
		}

		/// <summary>
		/// Returns Clarke's foot.
		/// </summary>
		/// <remarks>
		/// Assumes Clarke's 1865 ratio of 1 British foot = 0.3047972654 French legal metres applies to the international metre. 
		/// Used in older Australian, southern African &amp; British West Indian mapping.
		/// </remarks>
		public static ILinearUnit ClarkesFoot
		{
			get { return new LinearUnit(0.3047972654, "Clarke's foot", "EPSG", 9005, "Clarke's foot", String.Empty, "Assumes Clarke's 1865 ratio of 1 British foot = 0.3047972654 French legal metres applies to the international metre. Used in older Australian, southern African & British West Indian mapping."); }
		}
		#endregion

		#region ILinearUnit Members

		private double _MetersPerUnit;

		/// <summary>
		/// Gets or sets the number of meters per <see cref="LinearUnit"/>.
		/// </summary>
		public double MetersPerUnit
		{
			get { return _MetersPerUnit; }
			set { _MetersPerUnit = value; }
		}

		/// <summary>
		/// Returns the Well-known text for this object
		/// as defined in the simple features specification.
		/// </summary>
		public override string WKT
		{
			get
			{
				StringBuilder sb = new StringBuilder();
				sb.AppendFormat(SharpMap.Map.numberFormat_EnUS, "UNIT[\"{0}\", {1}", Name, MetersPerUnit);
				if (!String.IsNullOrEmpty(Authority) && AuthorityCode > 0)
					sb.AppendFormat(", AUTHORITY[\"{0}\", \"{1}\"]", Authority, AuthorityCode);
				sb.Append("]");
				return sb.ToString();
			}
		}

		/// <summary>
		/// Gets an XML representation of this object
		/// </summary>
		public override string XML
		{
			get
			{
				return String.Format(SharpMap.Map.numberFormat_EnUS, "<CS_LinearUnit MetersPerUnit=\"{0}\">{1}</CS_LinearUnit>", MetersPerUnit, InfoXml);
			}
		}

		#endregion

		/// <summary>
		/// Checks whether the values of this instance is equal to the values of another instance.
		/// Only parameters used for coordinate system are used for comparison.
		/// Name, abbreviation, authority, alias and remarks are ignored in the comparison.
		/// </summary>
		/// <param name="obj"></param>
		/// <returns>True if equal</returns>
		public override bool EqualParams(object obj)
		{
			if (!(obj is SharpMap.CoordinateSystems.LinearUnit))
				return false;
			return (obj as LinearUnit).MetersPerUnit == this.MetersPerUnit;
		}		
	}
}