#region Copyright (C) Simon Bridewell
// 
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 3
// of the License, or (at your option) any later version.
// 
// This program 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 General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

// You can read the full text of the GNU General Public License at:
// http://www.gnu.org/licenses/gpl.html

// See also the Wikipedia entry on the GNU GPL at:
// http://en.wikipedia.org/wiki/GNU_General_Public_License
#endregion

using System;
using System.Collections;
using System.Collections.ObjectModel;
using System.Diagnostics.CodeAnalysis;
using System.Drawing;

namespace GifComponents
{
	/// <summary>
	/// Provides a set of static methods for working with 
	/// <see cref="System.Drawing.Image"/> instances.
	/// </summary>
	public static class ImageTools
	{
		#region GetColours method
		/// <summary>
		/// Extracts the pixels of the supplied image into a generic collection 
		/// of <see cref="System.Drawing.Color"/> instances.
		/// </summary>
		/// <param name="image">
		/// The image from which to extract the pixels.
		/// </param>
		/// <returns>
		/// A collection of the colours of all the pixels in the supplied image.
		/// </returns>
		public static Collection<Color> GetColours( Image image )
		{
			// SB comment - this comment was present when I downloaded the
			// code from thinkedge.com
			// FEATURE: improve performance: use unsafe code
			Collection<Color> pixelColours = new Collection<Color>();
			Bitmap tempBitmap = new Bitmap( image );
			for( int y = 0; y < image.Height; y++ )
			{
				for( int x = 0; x < image.Width; x++ )
				{
					Color color = tempBitmap.GetPixel( x, y );
					pixelColours.Add( color );
				}
			}
			return pixelColours;
		}
		#endregion

		#region GetDistinctColours methods
		
		#region GetDistinctColours( Collection<Color> ) method
		/// <summary>
		/// Gets a generic collection of all the distinct 
		/// <see cref="System.Drawing.Color"/>s contained in the supplied 
		/// image, i.e. each colour is included in the return value only once,
		/// regardless of how many pixels in the image are of that colour.
		/// </summary>
		/// <param name="imageColours">
		/// A collection of the colours of all the pixels in the image.
		/// </param>
		/// <returns></returns>
		public static Collection<Color> 
			GetDistinctColours( Collection<Color> imageColours )
		{
			Hashtable t = new Hashtable();
			foreach( Color c in imageColours )
			{
				if( t.Contains( c ) == false )
				{
					t.Add( c, c );
				}
			}
			Collection<Color> distinctColours = new Collection<Color>();
			foreach( Color c in t.Values )
			{
				distinctColours.Add( c );
			}
			return distinctColours;
		}
		#endregion
		
		#region GetDistinctColours( Image ) method
		/// <summary>
		/// Gets a generic collection of all the distinct 
		/// <see cref="System.Drawing.Color"/>s contained in the supplied 
		/// image, i.e. each colour is included in the return value only once,
		/// regardless of how many pixels in the image are of that colour.
		/// </summary>
		/// <param name="image">The image to examine</param>
		/// <returns>The distinct colours in the supplied image</returns>
		public static Collection<Color> GetDistinctColours( Image image )
		{
			Collection<Color> colours = GetColours( image );
			return GetDistinctColours( colours );
		}
		#endregion

		#endregion
		
		#region GetRgbArray method
		/// <summary>
		/// Gets a byte array consisting of the red, green and blue intensities 
		/// of the colours in the supplied collection.
		/// </summary>
		/// <param name="colours">
		/// The collection of colours to convert to a byte array
		/// </param>
		/// <returns>
		/// A byte array consiting of red, green and blue intensities.
		/// 3 bytes per pixel - red first, then green, then blue.
		/// </returns>
		[SuppressMessage("Microsoft.Naming", 
		                 "CA1704:IdentifiersShouldBeSpelledCorrectly", 
		                 MessageId = "Rgb")]
		public static byte[] GetRgbArray( Collection<Color> colours )
		{
			int len = colours.Count;
			byte[] rgb = new byte[len * 3];
			int rgbIndex;
			for( int colourIndex = 0; colourIndex < len; colourIndex++ )
			{
				rgbIndex = colourIndex * 3;
				rgb[rgbIndex] = (byte) colours[colourIndex].R;
				rgb[rgbIndex + 1] = (byte) colours[colourIndex].G;
				rgb[rgbIndex + 2] = (byte) colours[colourIndex].B;
			}
			return rgb;
		}
		#endregion
		
		#region GetRgbCollection method
		/// <summary>
		/// Gets a generic collection of bytes consisting of the red, green and 
		/// blue intensities of the colours in the supplied collection.
		/// </summary>
		/// <param name="colours">
		/// The collection of colours to convert to a collection of bytes
		/// </param>
		/// <returns>
		/// A collection of bytes consiting of red, green and blue intensities.
		/// 3 bytes per pixel - red first, then green, then blue.
		/// </returns>
		[Obsolete( "Use the GetRgbArray method instead - it's around 60% faster" )]
		public static Collection<byte> GetRgbCollection( Collection<Color> colours )
		{
			int len = colours.Count;
			Collection<byte> rgb = new Collection<byte>();
			for( int i = 0; i < len; i++ )
			{
				rgb.Add( (byte) colours[i].R );
				rgb.Add( (byte) colours[i].G );
				rgb.Add( (byte) colours[i].B );
			}
			return rgb;
		}
		#endregion
	}
}
