/// <summary>
/// 从文件数据流中读取图形控制扩展(Graphic Control Extension)
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
public LogicalScreenDescriptor GetLCD(Stream stream)
{
LogicalScreenDescriptor lcd = new LogicalScreenDescriptor();
lcd.Width = ReadShort();
lcd.Height = ReadShort();
lcd.Packed = (byte)Read();
lcd.GlobalColorTableFlag = ((lcd.Packed & 0x80) >> 7) == 1;
lcd.ColorResoluTion = (byte)((lcd.Packed & 0x60) >> 5);
lcd.SortFlag = (byte)(lcd.Packed & 0x10) >> 4;
lcd.GlobalColorTableSize = 2 << (lcd.Packed & 0x07);
lcd.BgColorIndex = (byte)Read();
lcd.PixcelAspect = (byte)Read();
return(lcd);
}
/// <summary>
/// 合并多个gif动画,在空间坐标上
/// </summary>
/// <param name="sourceGifs">原图像</param>
/// <param name="outPath">合并后图像</param>
public static void Merge(List <string> sourceGifs, string outPath)
{
List <List <GifFrame> > frames = new List <List <GifFrame> >();
foreach (string source in sourceGifs)
{
if (!File.Exists(source))
{
throw new IOException(string.Format("文件{0}不存在!", source));
}
using (Bitmap ora_Img = new Bitmap(source))
{
if (ora_Img.RawFormat.Guid != ImageFormat.Gif.Guid)
{
throw new IOException(string.Format("文件{0}!", source));
}
}
GifImage gifImage = GifDecoder.Decode(source);
ThinkDisposalMethod(gifImage);
int index = 0;
foreach (GifFrame f in gifImage.Frames)
{
if (frames.Count <= index)
{
List <GifFrame> list = new List <GifFrame>();
frames.Add(list);
}
List <GifFrame> frameList = frames[index];
frameList.Add(f);
index++;
}
}
List <GifFrame> frameCol = new List <GifFrame>();
int frameIndex = 0;
foreach (List <GifFrame> fs in frames)
{
GifFrame frame = Merge(fs);
frameCol.Add(frame);
if (frame.Image.Width != frameCol[0].Image.Width ||
frame.Image.Height != frameCol[0].Image.Height)
{
frame.ImageDescriptor.XOffSet = frames[frameIndex][0].ImageDescriptor.XOffSet;
frame.ImageDescriptor.YOffSet = frames[frameIndex][0].ImageDescriptor.YOffSet;
frame.GraphicExtension.DisposalMethod = frames[frameIndex][0].GraphicExtension.DisposalMethod;
}
frame.GraphicExtension.Delay = frame.Delay = frames[frameIndex][0].Delay;
frameIndex++;
}
GifImage gifImg = new GifImage();
gifImg.Header = "GIF89a";
LogicalScreenDescriptor lcd = new LogicalScreenDescriptor();
lcd.Width = (short)frameCol[0].Image.Width;
lcd.Height = (short)frameCol[0].Image.Height;
gifImg.LogicalScreenDescriptor = lcd;
ApplicationEx ape = new ApplicationEx();
List <ApplicationEx> apps = new List <ApplicationEx>();
apps.Add(ape);
gifImg.ApplictionExtensions = apps;
gifImg.Frames = frameCol;
GifEncoder.Encode(gifImg, outPath);
}
/// <summary>
/// 写逻辑屏幕标识符
/// </summary>
/// <param name="lsd"></param>
public void WriteLSD(LogicalScreenDescriptor lsd)
{
WriteBytes(lsd.GetBuffer());
}