/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2012  Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
 * 
 * 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 1 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, see <http://www.gnu.org/licenses/>.
 */
using System;
using System.Runtime.InteropServices;

namespace GreenshotPlugin.Core {
	/// <summary>
	/// A helper class which does the mashalling for structs
	/// </summary>
	public static class BinaryStructHelper {
		/// <summary>
		/// Get a struct from a byte array
		/// </summary>
		/// <typeparam name="T">typeof struct</typeparam>
		/// <param name="bytes">byte[]</param>
		/// <returns>struct</returns>
		public static T FromByteArray<T>(byte[] bytes) where T : struct {
			IntPtr ptr = IntPtr.Zero;
			try {
				int size = Marshal.SizeOf(typeof(T));
				ptr = Marshal.AllocHGlobal(size);
				Marshal.Copy(bytes, 0, ptr, size);
				return FromIntPtr<T>(ptr);
			} finally {
				if (ptr != IntPtr.Zero) {
					Marshal.FreeHGlobal(ptr);
				}
			}
		}

		/// <summary>
		/// Get a struct from a byte array
		/// </summary>
		/// <typeparam name="T">typeof struct</typeparam>
		/// <param name="bytes">byte[]</param>
		/// <returns>struct</returns>
		public static T FromIntPtr<T>(IntPtr intPtr) where T : struct {
			object obj = Marshal.PtrToStructure(intPtr, typeof(T));
			return (T)obj;
		}

		/// <summary>
		/// copy a struct to a byte array
		/// </summary>
		/// <typeparam name="T">typeof struct</typeparam>
		/// <param name="obj">struct</param>
		/// <returns>byte[]</returns>
		public static byte[] ToByteArray<T>(T obj) where T : struct {
			IntPtr ptr = IntPtr.Zero;
			try {
				int size = Marshal.SizeOf(typeof(T));
				ptr = Marshal.AllocHGlobal(size);
				Marshal.StructureToPtr(obj, ptr, true);
				return FromPtrToByteArray<T>(ptr);
			} finally {
				if (ptr != IntPtr.Zero) {
					Marshal.FreeHGlobal(ptr);
				}
			}
		}

		/// <summary>
		/// copy a struct from a pointer to a byte array
		/// </summary>
		/// <typeparam name="T">typeof struct</typeparam>
		/// <param name="ptr">IntPtr to struct</param>
		/// <returns>byte[]</returns>
		public static byte[] FromPtrToByteArray<T>(IntPtr ptr) where T : struct {
			int size = Marshal.SizeOf(typeof(T));
			byte[] bytes = new byte[size];
			Marshal.Copy(ptr, bytes, 0, size);
			return bytes;
		}
	}
}