C#制作透明色GIF动画的类

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C#制作透明色GIF动画的类
前几天,关注了下GIF的文件结构

发现一个GIF文件大小错很多.发现主要是3个地方的问题.

一是色彩表的问题.GIF有全局色彩表和图形色彩表.

二是GIF图形的大小并不一定是一样的桢1可能是100*100的桢2可能是10*10 比如天空是黑色100*100 星星在是10*10

三是描述区,没什么作用就是描述

图形一样大小不一样的就这两个地方区别大.

用C#来实现下

并没用LZW是通过.NET来实现LZW的.这里只是进行了文件头的更改和合并.

如果你用这个类打开一个GIF 你通过SAVE方法再保存一次描述类会放到图形类的后面.

有兴趣到这里逛逛：http://baidv.taobao.com

使用方式
       Zgke.MyImage.ImageGif _Gif = new Zgke.MyImage.ImageGif(20, 32);

            int _Temp =(int)'A';
            for (int i = 0; i != 26; i++)
            {
                Bitmap _BitMap = new Bitmap(20, 32);
                Graphics _G = Graphics.FromImage(_BitMap);
                char T = (char)_Temp;
                _G.DrawString(T.ToString(), new Font("宋体", 20), Brushes.Black, 0, 0);
                _Gif.AddImage(_BitMap, 1, true, Zgke.MyImage.ImageGif.DisposalMethod.NoDisposalImage);
                _G.Dispose();
                _Temp++;
                _BitMap.Dispose();
            }

            pictureBox1.Image = _Gif.Image;
            _Gif.SaveFile(@"C:\1.gif");
下面是全部的类
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
using System.Runtime.InteropServices;

namespace Zgke.MyImage
{
    /// <summary>
    /// GIF操作类
    /// zgke@sina.com
    /// QQ:116149
    /// </summary>
    public class ImageGif
    {
        private Header m_Header;
        private LogicalScreen m_LogicalScreen;
        private ColorTable m_GlobalColorTable;
        private IList<ExtensionIntroducer> m_ExtensionIntroducer = new List<ExtensionIntroducer>();
        private ApplicationExtension m_ApplicationExtension;
        private IList<GraphicControlExtension> m_GraphicControlExtension = new List<GraphicControlExtension>();

        /// <summary>
        /// 当前位置
        /// </summary>
        private int m_Index = 0;

        private bool m_Open = false;
        /// <summary>
        /// 是否正常打开
        /// </summary>
        public bool OpenOK { get { return m_Open; } }
        /// <summary>
        /// 图形数量
        /// </summary>
        public int ImageCount { get { return m_GraphicControlExtension.Count; } }
        /// <summary>
        /// 获取GIF图形
        /// </summary>
        public Image Image
        {
            get
            {
                if (m_GraphicControlExtension.Count == 0) return null;
                MemoryStream _MemoryImage = new MemoryStream();
                _MemoryImage.Position = 0;
                byte[] _Temp = m_Header.GetByte();
                _MemoryImage.Write(_Temp, 0, _Temp.Length);

                _Temp = m_LogicalScreen.GetByte();
                _MemoryImage.Write(_Temp, 0, _Temp.Length);

                _Temp = m_GlobalColorTable.GetByte();
                _MemoryImage.Write(_Temp, 0, _Temp.Length);

                _Temp = m_ApplicationExtension.GetByte();
                _MemoryImage.Write(_Temp, 0, _Temp.Length);

                for (int i = 0; i != m_GraphicControlExtension.Count; i++)  //保存图形
                {
                    _Temp = m_GraphicControlExtension[i].GetByte();
                    _MemoryImage.Write(_Temp, 0, _Temp.Length);
                }
                for (int i = 0; i != m_ExtensionIntroducer.Count; i++)  //保存描述
                {
                    _Temp = m_ExtensionIntroducer[i].GetByte();
                    _MemoryImage.Write(_Temp, 0, _Temp.Length);
                }
                _MemoryImage.WriteByte(0x3B);

                return Image.FromStream(_MemoryImage);
            }
        }

        /// <summary>
        /// 由文件打开
        /// </summary>
        /// <param name="p_GifFileName"></param>
        public ImageGif(string p_GifFileName)
        {
            System.IO.FileStream _FileStream = new FileStream(p_GifFileName, FileMode.Open);
            byte[] _GifByte = new byte[_FileStream.Length];
            _FileStream.Read(_GifByte, 0, _GifByte.Length);
            _FileStream.Close();

            m_Header = new Header(_GifByte, ref m_Index, ref m_Open);
            if (m_Open == false) return;
            m_LogicalScreen = new LogicalScreen(_GifByte, ref m_Index, ref m_Open);
            if (m_Open == false) return;
            m_GlobalColorTable = new ColorTable(m_LogicalScreen.GlobalPal, m_LogicalScreen.GlobalColorSize, _GifByte, ref m_Index, ref m_Open);
            if (m_Open == false) return;
            //固定位置信息读取完成

            m_Open = false;
            while (true)   //不知道有多少个模块一直循环吧
            {
                #region 判断位置
                switch (_GifByte[m_Index])
                {

                    case 0x21:
                        m_Index += 2;   //坐标移动到类别后面  取类类别用-1方式少一行代码
                        switch (_GifByte[m_Index - 1])
                        {
                            case 0xFE:
                                m_ExtensionIntroducer.Add(new ExtensionIntroducer(_GifByte, ref m_Index, ref m_Open));
                                if (m_Open == false) return;   //获取失败每必要继续了直接返回
                                break;
                            case 0xFF:
                                m_ApplicationExtension = new ApplicationExtension(_GifByte, ref m_Index, ref m_Open);
                                if (m_Open == false) return;
                                break;
                            case 0xF9:         //图形在这个区 LZW数据
                                m_GraphicControlExtension.Add(new GraphicControlExtension(_GifByte, ref m_Index, ref m_Open));
                                if (m_Open == false) return;
                                break;
                            default:         //找不到类别直接结束
                                System.Windows.Forms.MessageBox.Show(_GifByte[m_Index - 1].ToString("X02"));
                                return;
                        }
                        break;
                    case 0x3B:
                        m_Open = true;
                        return;
                    default:
                        m_Open = false;
                        System.Windows.Forms.MessageBox.Show(_GifByte[m_Index].ToString("X02"), m_Index.ToString());
                        return;
                }
                #endregion
            }
        }
        /// <summary>
        /// 建立新的图形
        /// </summary>
        /// <param name="p_Width"></param>
        /// <param name="p_Height"></param>
        public ImageGif(ushort p_Width, ushort p_Height)
        {
            m_Header = new Header();
            m_LogicalScreen = new LogicalScreen(p_Width, p_Height);
            m_ApplicationExtension = new ApplicationExtension();
            m_ExtensionIntroducer.Add(new ExtensionIntroducer("http://blog.csdn.net/zgke"));  //这东西可以很多个描述就是描述没发现什么作用


        }

        #region 添加图形删除插入
        /// <summary>
        /// 添加一个图形
        /// </summary>
        /// <param name="Image">图形</param>
        /// <param name="p_DelayTime">显示时间</param>
        /// <param name="p_UserColorTable">是否使用全局色彩表 true使用 false 不使用</param>
        private GraphicControlExtension GetGraphicsControl(Image p_Image, ushort p_DelayTime, bool p_UserColorTable, DisposalMethod p_Disposal)
        {

            MemoryStream _MemOry = new MemoryStream();

            Image _Image = ToImageGif((Bitmap)p_Image, Color.White);   //透明的方法可以加到这里
            _Image.Save(_MemOry, ImageFormat.Gif);        //保存成GIF图形

            int _Index = 783;   //开始位置781 0x21 0xF9 已经计算
            bool _Open = false;
            GraphicControlExtension _Graphics = new GraphicControlExtension(_MemOry.GetBuffer(), ref _Index, ref _Open);
            _Graphics.DelayTime = p_DelayTime;
            _Graphics.TransparentColorFlag = true;
            _Graphics.TransparentColorIndex = 16;

            ColorTable _Table = new ColorTable();
            Image _AddImage = Image.FromStream(_MemOry);  //获取压缩后的图形

            for (int i = 0; i != _AddImage.Palette.Entries.Length; i++)      //获取图形颜色表
            {
                _Table.ColorTableList.Add(_AddImage.Palette.Entries[i]);
            }

            if (m_GlobalColorTable == null) m_GlobalColorTable = _Table;     //不管怎么样都要全局色彩表

            if (p_UserColorTable == false)
            {
                _Graphics.ColorTable = _Table;      //根据需要设置全局颜色表
                _Graphics.UserColorTable = !p_UserColorTable;
            }

            _Graphics.Disposal = p_Disposal;

            return _Graphics;
        }
        /// <summary>
        /// 添加一个图形图形可以大于虚拟屏幕就是显示不出来而已........
        /// </summary>
        /// <param name="Image">图形</param>
        /// <param name="p_DelayTime">显示时间</param>
        /// <param name="p_UserColorTable">是否使用全局色彩表 true使用 false 不使用</param>
        public void AddImage(Image p_Image, ushort p_DelayTime, bool p_UserColorTable, DisposalMethod p_Disposal)
        {
            GraphicControlExtension _Info = GetGraphicsControl(p_Image, p_DelayTime, p_UserColorTable, p_Disposal);

            if (_Info != null) m_GraphicControlExtension.Add(_Info);
        }

        /// <summary>
        /// 删除一个图形
        /// </summary>
        /// <param name="p_Index"></param>
        public void RemoveImage(int p_Index)
        {
            if (p_Index > m_GraphicControlExtension.Count - 1) return;
            m_GraphicControlExtension.RemoveAt(p_Index);
        }
        /// <summary>
        /// 插入一个图形
        /// </summary>
        /// <param name="Image">图形</param>
        /// <param name="p_DelayTime">显示时间</param>
        /// <param name="p_UserColorTable">是否使用全局色彩表 true使用 false 不使用</param>
        public void InsertImage(Image p_Image, ushort p_DelayTime, bool p_UserColorTable, int p_Index, DisposalMethod p_Disposal)
        {
            if (p_Index > m_GraphicControlExtension.Count - 1) return;
            GraphicControlExtension _Info = GetGraphicsControl(p_Image, p_DelayTime, p_UserColorTable, p_Disposal);
            if (_Info != null) m_GraphicControlExtension.Insert(p_Index, _Info);
        }
        #endregion

        /// <summary>
        /// 设置一个图形播放的时间
        /// </summary>
        /// <param name="p_Index">索引</param>
        /// <param name="p_DelayTime">播放时间</param>
        public void SetImageTime(int p_Index, ushort p_DelayTime)
        {
            if (p_Index > m_GraphicControlExtension.Count - 1) return;
            m_GraphicControlExtension[p_Index].DelayTime = p_DelayTime;
        }
        /// <summary>
        /// 设置一个图形开始位置
        /// </summary>
        /// <param name="p_Index">索引</param>
        /// <param name="p_X">X坐标</param>
        /// <param name="p_Y">Y坐标</param>
        public void SetImageLocatch(int p_Index, Point p_Point)
        {
            if (p_Index > m_GraphicControlExtension.Count - 1) return;
            m_GraphicControlExtension[p_Index].Point = p_Point;
        }
        /// <summary>
        /// 设置处理模式
        /// </summary>
        /// <param name="p_Index">索引</param>
        /// <param name="p_DisposalMethod">处理模式</param>
        public void SetImageDisposalMethod(int p_Index, DisposalMethod p_DisposalMethod)
        {
            if (p_Index > m_GraphicControlExtension.Count - 1) return;
            m_GraphicControlExtension[p_Index].Disposal = p_DisposalMethod;
        }

        /// <summary>
        /// 保存文件
        /// </summary>
        /// <param name="p_FileName"></param>
        public void SaveFile(string p_FileName)
        {
            if (m_GraphicControlExtension.Count == 0) return ;

            FileStream _File = new FileStream(p_FileName, FileMode.Create);
            _File.Position = 0;
            byte[] _Temp = m_Header.GetByte();
            _File.Write(_Temp, 0, _Temp.Length);

            _Temp = m_LogicalScreen.GetByte();
            _File.Write(_Temp, 0, _Temp.Length);

            _Temp = m_GlobalColorTable.GetByte();
            _File.Write(_Temp, 0, _Temp.Length);

            _Temp = m_ApplicationExtension.GetByte();
            _File.Write(_Temp, 0, _Temp.Length);

            for (int i = 0; i != m_GraphicControlExtension.Count; i++)  //保存图形
            {
                _Temp = m_GraphicControlExtension[i].GetByte();
                _File.Write(_Temp, 0, _Temp.Length);
            }
            for (int i = 0; i != m_ExtensionIntroducer.Count; i++)  //保存描述
            {
                _Temp = m_ExtensionIntroducer[i].GetByte();
                _File.Write(_Temp, 0, _Temp.Length);
            }
            _File.WriteByte(0x3B);
            _File.Close();
        }

        #region 获取图形
        /// <summary>
        /// 内部方法保存一个图形
        /// </summary>
        /// <param name="m_Stream">数据流</param>
        /// <param name="p_Index">图形索引</param>
        /// <returns>图形</returns>
        private Stream GetImage(Stream m_Stream, int p_Index)
        {
            if (p_Index < 0 || p_Index > ImageCount) return null;
            m_Stream.Position = 0;
            byte[] _Temp = m_Header.GetByte();
            m_Stream.Write(_Temp, 0, _Temp.Length);

            _Temp = m_LogicalScreen.GetByte();
            m_Stream.Write(_Temp, 0, _Temp.Length);

            _Temp = m_GlobalColorTable.GetByte();
            m_Stream.Write(_Temp, 0, _Temp.Length);

            _Temp = m_ApplicationExtension.GetByte();
            m_Stream.Write(_Temp, 0, _Temp.Length);

            _Temp = m_GraphicControlExtension[p_Index].GetByte();
            m_Stream.Write(_Temp, 0, _Temp.Length);

            for (int i = 0; i != m_ExtensionIntroducer.Count; i++)  //保存描述
            {
                _Temp = m_ExtensionIntroducer[i].GetByte();
                m_Stream.Write(_Temp, 0, _Temp.Length);
            }
            m_Stream.WriteByte(0x3B);

            return m_Stream;
        }
        /// <summary>
        /// 根据索引获取图形
        /// </summary>
        /// <param name="p_Index">索引</param>
        /// <returns>图形</returns>
        public Image GetImage(int p_Index)
        {
            MemoryStream _Memory = new MemoryStream();

            return Image.FromStream(GetImage(_Memory, p_Index));
        }
        /// <summary>
        /// 根据索引获取图形
        /// </summary>
        /// <param name="p_Index">索引</param>
        /// <returns>图形</returns>
        public void GetImage(int p_Index, string p_FileName)
        {
            FileStream _File = new FileStream(p_FileName, FileMode.Create);

            GetImage(_File, p_Index);

            _File.Close();
        }
        #endregion

        /// <summary>
        /// 处理模式
        /// </summary>
        public enum DisposalMethod
        {
            /// <summary>
            /// 不使用处置方法一般的GIF都是这个
            /// </summary>
            NoDisposalMethod = 0,
            /// <summary>
            /// 不处置图形，把图形从当前位置移去
            /// </summary>
            NoDisposalImage = 1,
            /// <summary>
            /// 回复到背景色
            /// </summary>
            RestoreBackgroundColor = 2,
            /// <summary>
            /// 回复到先前状态
            /// </summary>
            RestoreFrontState = 3,
            /// <summary>
            /// 为定义4-7
            /// </summary>
            Null

        }
        #region 类定义
        /// <summary>
        /// GIF文件头
        /// </summary>
        private class Header
        {
            /// <summary>
            ///文件头必须是GIF
            /// </summary>
            private byte[] _Signature = new byte[] { 0x47, 0x49, 0x46 };
            /// <summary>
            /// 版本信息
            /// </summary>
            private byte[] _Version = new byte[] { 0x38, 0x39, 0x61 };

            public Header(byte[] p_Byte, ref int p_Index, ref bool p_Open)
            {
                p_Open = false;
                if (p_Byte[0] != _Signature[0] || p_Byte[1] != _Signature[1] || p_Byte[2] != _Signature[2])
                {
                    return;
                }

                _Version[0] = p_Byte[3];
                _Version[1] = p_Byte[4];
                _Version[2] = p_Byte[5];
                p_Index += 6;
                p_Open = true;
            }

            public Header()
            {

            }

            /// <summary>
            /// 返回版本号
            /// </summary>
            public string Version
            {
                get
                { return Encoding.ASCII.GetString(_Version); }

                set
                {
                    if (value == "87a") _Version[1] = 0x37;
                }
            }

            public byte[] GetByte()
            {
                byte[] _Temp = new byte[6];
                _Temp[0] = _Signature[0];
                _Temp[1] = _Signature[1];
                _Temp[2] = _Signature[2];
                _Temp[3] = _Version[0];
                _Temp[4] = _Version[1];
                _Temp[5] = _Version[2];
                return _Temp;
            }
        }
        /// <summary>
        /// 逻辑屏幕标识符
        /// </summary>
        private class LogicalScreen
        {
            /// <summary>
            /// 图形宽
            /// </summary>
            private byte[] _Width = new byte[2];
            /// <summary>
            /// 图形高
            /// </summary>
            private byte[] _Height = new byte[2];
            /// <summary>
            /// 第8位 - 全局颜色列表标志(Global Color Table Flag)，当置位时表示有全局颜色列表，pixel值有意义.
            /// 第5位第6位第7位颜色深度(Color ResoluTion)，cr+1确定图象的颜色深度.
            /// 第4位分类标记如果置位表示全局颜色列表分类排列.
            /// 第1位第2位第3位全局颜色列表大小，pixel+1确定颜色列表的索引数（2的pixel+1次方）.
            /// </summary>
            private byte[] _BitArray = new byte[1];
            /// <summary>
            /// 背景色索引
            /// </summary>
            private byte _Blackground = 0;
            /// <summary>
            /// 像素宽高比
            /// </summary>
            private byte _PixelAspectRadio = 0;

            public LogicalScreen(byte[] p_Byte, ref int p_Index, ref bool p_Open)
            {
                p_Open = false;
                _Width[0] = p_Byte[p_Index];
                _Width[1] = p_Byte[p_Index + 1];
                _Height[0] = p_Byte[p_Index + 2];
                _Height[1] = p_Byte[p_Index + 3];
                _BitArray[0] = p_Byte[p_Index + 4];
                _Blackground = p_Byte[p_Index + 5];
                _PixelAspectRadio = p_Byte[p_Index + 6];

                p_Index += 7;

                p_Open = true;
            }

            public LogicalScreen(ushort p_Width, ushort p_Height)
            {
                Width = p_Width;
                Height = p_Height;
                _Blackground = 0;
                _PixelAspectRadio = 0;
                _BitArray[0] = 135;
            }

            /// <summary>
            /// 高
            /// </summary>
            public ushort Width { get { return BitConverter.ToUInt16(_Width, 0); } set { _Width = BitConverter.GetBytes(value); } }
            /// <summary>
            /// 宽
            /// </summary>
            public ushort Height { get { return BitConverter.ToUInt16(_Height, 0); } set { _Height = BitConverter.GetBytes(value); } }
            /// <summary>
            /// 背景索引
            /// </summary>
            public byte Blackground { get { return _Blackground; } set { _Blackground = value; } }
            /// <summary>
            /// 像素宽高比
            /// </summary>
            public byte PixelAspectRadio { get { return _PixelAspectRadio; } set { _PixelAspectRadio = value; } }

            /// <summary>
            /// 全局颜色列表标志
            /// </summary>
            public bool GlobalPal
            {
                get
                {
                    BitArray _BitList = new BitArray(_BitArray);
                    return _BitList[7];
                }
                set
                {
                    BitArray _BitList = new BitArray(_BitArray);
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原文地址：https://www.cnblogs.com/hyruur/p/gif.html