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using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace Tango.AnimatedGif.Decoding
{
internal class GifFile
{
public GifHeader Header { get; private set; }
public GifColor[] GlobalColorTable { get; set; }
public IList<GifFrame> Frames { get; set; }
public IList<GifExtension> Extensions { get; set; }
public ushort RepeatCount { get; set; }
private GifFile()
{
}
internal static GifFile ReadGifFile(Stream stream, bool metadataOnly)
{
var file = new GifFile();
file.Read(stream, metadataOnly);
return file;
}
private void Read(Stream stream, bool metadataOnly)
{
Header = GifHeader.ReadHeader(stream);
if (Header.LogicalScreenDescriptor.HasGlobalColorTable)
{
GlobalColorTable = GifHelpers.ReadColorTable(stream, Header.LogicalScreenDescriptor.GlobalColorTableSize);
}
ReadFrames(stream, metadataOnly);
var netscapeExtension =
Extensions
.OfType<GifApplicationExtension>()
.FirstOrDefault(GifHelpers.IsNetscapeExtension);
if (netscapeExtension != null)
RepeatCount = GifHelpers.GetRepeatCount(netscapeExtension);
else
RepeatCount = 1;
}
private void ReadFrames(Stream stream, bool metadataOnly)
{
List<GifFrame> frames = new List<GifFrame>();
List<GifExtension> controlExtensions = new List<GifExtension>();
List<GifExtension> specialExtensions = new List<GifExtension>();
while (true)
{
var block = GifBlock.ReadBlock(stream, controlExtensions, metadataOnly);
if (block.Kind == GifBlockKind.GraphicRendering)
controlExtensions = new List<GifExtension>();
if (block is GifFrame)
{
frames.Add((GifFrame)block);
}
else if (block is GifExtension)
{
var extension = (GifExtension)block;
switch (extension.Kind)
{
case GifBlockKind.Control:
controlExtensions.Add(extension);
break;
case GifBlockKind.SpecialPurpose:
specialExtensions.Add(extension);
break;
}
}
else if (block is GifTrailer)
{
break;
}
}
this.Frames = frames.AsReadOnly();
this.Extensions = specialExtensions.AsReadOnly();
}
}
}
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