public void Load(Stream stream)
{
chunks = new List <APNGChunk>();
pngs = new List <PNG>();
// Create a new header (should be 1 per file) and
// read it from the stream
var header = new APNGHeader();
try
{
header.Read(stream);
}
catch (Exception)
{
stream.Close();
throw;
}
APNGChunk chunk;
PNG png = null;
// Read chunks from the stream until we reach the MEND chunk
do
{
// Read a generic Chunk
chunk = new APNGChunk();
try
{
chunk.Read(stream);
}
catch (Exception)
{
stream.Close();
throw;
}
// Take a look at the chunk type and decide what derived class to
// use to create a specific chunk
switch (chunk.ChunkType)
{
case acTLChunk.NAME:
if (headerChunk != null)
{
throw new ApplicationException(String.Format(
"Only one chunk of type {0} is allowed", chunk.ChunkType));
}
chunk = headerChunk = new acTLChunk(chunk);
break;
case MENDChunk.NAME:
chunk = new MENDChunk(chunk);
break;
case TERMChunk.NAME:
chunk = new TERMChunk(chunk);
break;
case BACKChunk.NAME:
chunk = new BACKChunk(chunk);
break;
case BKGDChunk.NAME:
chunk = new BKGDChunk(chunk);
break;
case fcTLChunk.NAME:
// This is the beginning of a new embedded PNG
chunk = new fcTLChunk(chunk);
png = new PNG {
FCTL = chunk as fcTLChunk, IHDR = ihdrChunk
};
pngs.Add(png);
break;
case IHDRChunk.NAME:
chunk = new IHDRChunk(chunk);
ihdrChunk = chunk as IHDRChunk;
break;
case IDATChunk.NAME:
chunk = new IDATChunk(chunk);
if (png != null)
{
png.IDAT = chunk as IDATChunk;
}
break;
case fdATChunk.NAME:
chunk = new fdATChunk(chunk);
if (png != null)
{
chunk.ChunkType = IDATChunk.NAME;
png.IDAT = new IDATChunk(chunk);
}
break;
case IENDChunk.NAME:
chunk = new IENDChunk(chunk);
for (var i = 0; i < pngs.Count; i++)
{
pngs[i].IEND = chunk as IENDChunk;
}
break;
default:
break;
}
// Add the chunk to our list of chunks
chunks.Add(chunk);
}while (chunk.ChunkType != IENDChunk.NAME);
}
/// <summary>
/// Save the APNG to file.
/// </summary>
/// <param name="filename">The filename to output to.</param>
public void Save(string filename)
{
using BinaryWriter writer = new BinaryWriter(new FileStream(filename, FileMode.OpenOrCreate, FileAccess.Write));
int frameWriteStartIndex = 0;
//Write signature
writer.Write(Frame.Signature);
//Write header
writer.Write(this.IHDRChunk.RawData);
//If acTL exists
if (acTLChunk != null)
{
//write actl.
writer.Write(acTLChunk.RawData);
}
//Write all other chunks. (NOTE: These should be consistently the same for all frames)
foreach (OtherChunk otherChunk in defaultImage.OtherChunks)
{
writer.Write(otherChunk.RawData);
}
uint sequenceNumber = 0;
//If Default Image is not animated
if (!DefaultImageIsAnimated)
{
//write IDAT
defaultImage.IDATChunks.ForEach(i => writer.Write(i.RawData));
}
else
{
frames[0].fcTLChunk.SequenceNumber = sequenceNumber++;
//Write fcTL
writer.Write(frames[0].fcTLChunk.RawData);
//Write IDAT of first frame.
frames[0].IDATChunks.ForEach(i => writer.Write(i.RawData));
//Set start frame indes to 1
frameWriteStartIndex = 1;
}
//Foreach frame
for (int i = frameWriteStartIndex; i < frames.Count; ++i)
{
frames[i].fcTLChunk.SequenceNumber = sequenceNumber++;
//write fcTL
writer.Write(frames[i].fcTLChunk.RawData);
//Write fDAT
for (int j = 0; j < frames[i].IDATChunks.Count; ++j)
{
fdATChunk fdat = fdATChunk.FromIDATChunk(frames[i].IDATChunks[j], sequenceNumber++);
writer.Write(fdat.RawData);
}
}
//Write IEnd
writer.Write(defaultImage.IENDChunk.RawData);
writer.Close();
}
