?#region Copyright & License
/*----------------------------------------------------------------
// Copyright (C) 2008 jillzhang 版權所有。 
//  
// 文件名：GraphicEx.cs
// 文件功能描述：
// 
// 創建標識：jillzhang 
// 修改標識：
// 修改描述：
//
// 修改標識：
// 修改描述：
//----------------------------------------------------------------*/
/*-------------------------New BSD License ------------------
 Copyright (c) 2008, jillzhang
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

* Neither the name of jillzhang nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */
#endregion

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

namespace Jillzhang.GifUtility
{
    #region 類GraphicEx
    /// <summary>
    /// 圖形控制擴展(Graphic Control Extension)這一部分是可選的（需要89a版本），
    /// 可以放在一個圖象塊(包括圖象標識符、局部顏色列表和圖象數據)或文本擴展塊的前面，
    /// 用來控制跟在它后面的第一個圖象（或文本）的渲染(Render)形式
    /// </summary>
    internal class GraphicEx:ExData
    {
        #region private fields
        byte _packed;
        short _delay;
        byte _tranIndex;
        bool _transFlag;
        int _disposalMethod;
        #endregion

        /// <summary>
        /// Block Size - 不包括塊終結器，固定值4
        /// </summary>
        internal static readonly byte BlockSize = 4;    

        /// <summary>
        /// i - 用戶輸入標志
        /// </summary>
        internal bool TransparencyFlag
        {
            get { return _transFlag; }
            set { _transFlag = value; }
        }
      
        /// <summary>
        /// 處置方法(Disposal Method)：指出處置圖形的方法，當值為：
        /// 0 - 不使用處置方法
        /// 1 - 不處置圖形，把圖形從當前位置移去
        /// 2 - 回復到背景色
        /// 3 - 回復到先前狀態
        /// 4-7 - 自定義
        /// </summary>
        internal int DisposalMethod
        {
            get { return _disposalMethod; }
            set { _disposalMethod = value; }
        }	
        /// <summary>
        /// Packed
        /// </summary>
        internal byte Packed
        {
            get
            {
                return _packed;
            }
            set
            {
                _packed = value;
            }
        }
        /// <summary>
        /// Delay Time - 單位1/100秒，如果值不為1，表示暫停規定的時間后再繼續往下處理數據流
        /// </summary>
        internal short Delay
        {
            get
            {
                return _delay;
            }
            set
            {
                _delay = value;
            }
        }
        /// <summary>
        /// Transparent Color Index - 透明色索引值
        /// </summary>
        internal byte TranIndex
        {
            get
            {
                return _tranIndex;
            }
            set
            {
                _tranIndex = value;
            }
        }
        internal GraphicEx()
        {
        }
        
        internal byte[] GetBuffer()
        {
            List<byte> list = new List<byte>();
            list.Add(GifExtensions.ExtensionIntroducer);
            list.Add(GifExtensions.GraphicControlLabel);
            list.Add(BlockSize);
            int t = 0;
            if (_transFlag)
            {
                t = 1;
            }
            _packed = (byte)((_disposalMethod << 2) | t);
            list.Add(_packed);
            list.AddRange(BitConverter.GetBytes(_delay));
            list.Add(_tranIndex);
            list.Add(GifExtensions.Terminator);
            return list.ToArray();
        }
    }
    #endregion
}