public void Dispose()
{
//IEND: The end of the Png datastream. 0 bytes (Length + Type + CRC, 4 bytes each) = 12 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(0u)); //Length, 4 bytes.
InternalStream.WriteBytes(Encoding.ASCII.GetBytes("IEND")); //Chunk type, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(CrcHelper.Calculate(InternalStream.PeekBytes(InternalStream.Position - 4, 4)))); //CRC, 4 bytes.
InternalStream.Flush();
//Resets the stream position to save afterwards.
InternalStream.Position = 0;
}
internal void AddFrame(string path, Int32Rect rect, int delay = 66)
{
using (var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
{
if (IsFirstFrame)
{
//Png Header: 8 bytes.
InternalStream.WriteBytes(stream.ReadBytes(8));
//IHDR chunk. 13 bytes (Length + Type + CRC, 4 bytes each) = 25 bytes.
InternalStream.WriteBytes(stream.ReadBytes(25));
//acTL: Animation control chunk. 8 bytes (Length + Type + CRC, 4 bytes each) = 20 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(8u)); //Length, 4 bytes.
InternalStream.WriteBytes(Encoding.ASCII.GetBytes("acTL")); //Chunk type, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)FrameCount)); //NumFrames, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)RepeatCount)); //NumPlays, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(CrcHelper.Calculate(InternalStream.PeekBytes(InternalStream.Position - 12, 12)))); //CRC, 4 bytes.
}
//fcTL: Frame control chunk. 26 bytes (Length + Type + CRC, 4 bytes each) = 38 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(26u)); //Length, 4 bytes.
InternalStream.WriteBytes(Encoding.ASCII.GetBytes("fcTL")); //Chunk type, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)SequenceNumber++)); //SequenceNumber, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)rect.Width)); //Width, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)rect.Height)); //Height, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)rect.X)); //OffsetX, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)rect.Y)); //OffsetY, 4 bytes.
InternalStream.WriteUInt16(BitHelper.ConvertEndian((ushort)delay)); //Delay numerator, 2 bytes.
InternalStream.WriteUInt16(BitHelper.ConvertEndian((ushort)1000)); //Delay denominator, 2 bytes.
if (IsFirstFrame)
{
InternalStream.WriteByte((byte)DisposeOps.None); //DisposeOp, 1 byte.
InternalStream.WriteByte((byte)BlendOps.Source); //BlendOp, 1 byte.
}
else
{
InternalStream.WriteByte((byte)DisposeOps.None); //DisposeOp, 1 byte.
InternalStream.WriteByte((byte)BlendOps.Over); //BlendOp, 1 byte.
}
InternalStream.WriteUInt32(BitHelper.ConvertEndian(CrcHelper.Calculate(InternalStream.PeekBytes(InternalStream.Position - 30, 30)))); //CRC, 4 bytes.
//fdAT: Frame data chunk. 4 + n bytes (Length + Type + CRC, 4 bytes each) = 16 + n bytes, where n is the frame data.
var dataList = GetData(stream);
foreach (var data in dataList)
{
if (IsFirstFrame)
{
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)data.Length)); //Length, 4 bytes.
InternalStream.WriteBytes(Encoding.ASCII.GetBytes("IDAT")); //Chunk type, 4 bytes.
InternalStream.WriteBytes(data); //Frame data, n bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(CrcHelper.Calculate(InternalStream.PeekBytes(InternalStream.Position - (data.Length + 4), data.Length + 4)))); //CRC, 4 bytes.
}
else
{
InternalStream.WriteUInt32(BitHelper.ConvertEndian(4 + (uint)data.Length)); //Length, 4 bytes.
InternalStream.WriteBytes(Encoding.ASCII.GetBytes("fdAT")); //Chunk type, 4 bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian((uint)SequenceNumber++)); //SequenceNumber, 4 bytes.
InternalStream.WriteBytes(data); //Frame data, n bytes.
InternalStream.WriteUInt32(BitHelper.ConvertEndian(CrcHelper.Calculate(InternalStream.PeekBytes(InternalStream.Position - (data.Length + 8), data.Length + 8)))); //CRC, 4 bytes.
}
}
IsFirstFrame = false;
}
}
